REOl 
 
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SOME VIEWS OF OUR 
 NEW BUILDING 
 
 SCIENTIFIC INSTRUMENT WORKS 
 
 l-e-knott^pparatus co. 
 
 OUR BUILDING IS OF MOST MODERN CONSTRUCTION OF 
 REINFORCED CONCRETE, FIREPROOF, WELL-LIGHTED AND 
 WELL-VENTILATED. IT IS AN IDEAL BUILDING FOR THE 
 MANUFACTURE OF SCIENTIFIC INSTRUMENTS. 
 
 L. E. KNOTT APPARATUS COMPANY 
 
 CAMBRIDGE STATION A BOSTON, MASS. 
 
L. E. KNOTT APPARATUS COMPANY, BOSTON 
 
 OUR LARGE AND WELL-LIGHTED SALESROOM 
 GIVES US AN UNUSUAL OPPORTUNITY TO DIS¬ 
 PLAY THE VARIOUS INSTRUMENTS OF OUR 
 MANUFACTURE. THE VIEW ABOVE SHOWS 
 THE MASSACHUSETTS INSTITUTE OF TECH¬ 
 NOLOGY BEYOND. 
 
L. E. KNOTT APPARATUS COMPANY, BOSTON 
 
 WE EXTEND TO ALL PERSONS WHO MAY 
 FIND THEMSELVES IN BOSTON OR VICINITY 
 A CORDIAL INVITATION TO VISIT US. WE ARE 
 LOCATED FOUR MINUTES’ WALK WEST OF THE 
 KENDALL SQUARE STATION OF THE CAM¬ 
 BRIDGE SUBWAY. (THREE MINUTES FROM 
 PARK STREET.) 
 
L. E. KNOTT APPARATUS COMPANY, BOSTON 
 
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A Catalogue 
 
 of 
 
 Scientific Instruments 
 
 Catalogue 21 
 
 i 
 
 L. E. Knott Apparatus Company 
 
 AMES AND AMHERST STREETS 
 
 (Cambridge A Station) 
 
 BOSTON 
 
 ELEAZAR CATE 
 
 President 
 
 ROLAND E. STEVENS 
 
 Vice-President 
 
 ARTHUR W. HALL 
 
 Treasurer 
 
 WARREN L. MAXCY 
 
 Secretary 
 
4 # 
 
 W E have copyrighted this entire book for the purpose of 
 protecting ourselves against the unauthorized use of our 
 text or original illustrations by dealers who seek to create 
 the impression that their goods are the same as the special apparatus 
 which we manufacture or control. 
 
 The trade is notified that no use of our illustrations or descrip¬ 
 tions will be permitted, and that we shall take prompt action in the 
 case of piracy. 
 
 Copyright, 1916, by 
 The L. E. Knott Apparatus Co. 
 
 N A. LINDSEY & CO., PRINTERS, BOSTON, MASS. 
 
 THE GETTY CENTER 
 
 LIBRARY 
 
PREFACE 
 
 W E offer in the following pages a series of scientific instruments and a list of 
 physical apparatus which will be found adequate for the study of Physics in the 
 most advanced laboratory. All instructors in science will recall that we are by 
 direct descent the oldest apparatus house in this country, dating back to 1854. We still 
 have with us men who have worked under and were intimately connected with such men 
 as E. S. Ritchie, A. P. Gage, and A. E. Dolbear. Many will recall that it was Mr. E. S. 
 Ritchie whom Professor Tyndall selected to assist him during his American lectures. 
 
 The number of this catalogue indicates the number of years that the L. E. Knott 
 Apparatus Company, under its present name, has been in business. During this time 
 it has doubtless equipped more laboratories and furnished more material to colleges and 
 schools than any other house of its line. We therefore feel that we are peculiarly well 
 fitted to offer a catalogue such as this. We ask your consideration of the following pages. 
 
 Under each subject we have aimed to include only those pieces best suited for the 
 particular experiment and demonstration. In making this selection from our complete 
 line we have found that it requires even greater judgment to determine what to omit than 
 it does to determine what to include, but unnecessary duplication has been carefully 
 avoided. We realize that the instructor whose duty it is to equip or improve a laboratory 
 should buy only the best and at the same time strive to make his appropriation go as far as 
 possible. 
 
 A large proportion of the articles offered have been designed and developed in our 
 own laboratory under the supervision of men whose training and experience have well 
 fitted them for the task. In making the selection we have been guided by numerous sug¬ 
 gestions received from our customers, an obligation which we are pleased at this time 
 to acknowledge, with the hope that all of our customers will feel it an obligation as well 
 as a pleasure to favor us with any further suggestions which their experience develops. 
 
 Such a complete line of educational instruments as we here list could hardly have 
 been offered at this time had it not been for the greatly improved and well-nigh perfect 
 facilities which our new reinforced concrete building has placed at our disposal. At first 
 the European war caused some forebodings as to its effect on the completeness of our line, 
 but the advantage offered by our new factory has dispelled all fears of this nature. 
 
 We wish to emphasize the fact that in the compiling of this catalogue we have endeav¬ 
 ored to make it more than a price-list. The arrangement, we believe, will be found to have 
 been made on a scientific basis, each instrument being classified and appearing in its proper 
 place. We have embodied in our descriptions many valuable suggestions concerning the 
 use of the apparatus on the lecture table and in the laboratory. The illustrations are 
 original, prepared from photographs taken from the completed instrument itself. 
 
DIRECTIONS AND TERMS 
 
 THIS CATALOGUE SUPERSEDES AND DISPLACES ALL PREVIOUS 
 
 EDITIONS 
 
 CORRESPONDENCE: — Persons writing to us should use an official letter-head when¬ 
 ever possible. If such stationery is not available, kindly advise what institution you 
 are connected with and the position you hold. 
 
 ORDERS: — Order blanks will be furnished to prospective buyers upon request. When 
 making out your orders, specify the catalogue number and the edition, with sufficient 
 • description to indicate clearly the article desired. This will prevent errors which might 
 occur where the catalogue number alone is given, or where the description alone is 
 given. 
 
 SHIPPING: — Specify clearly the place to which the goods are to be consigned, giving 
 the County, City and State address. Indicate your preference as to whether you 
 desire to have the goods sent by freight, express or mail. It should be borne in mind 
 that express rates are much higher than freight, and customers at a distance should give 
 instructions to ship by express only when they are prepared to pay the additional 
 charges for quick delivery. Where no instructions are given, we exercise our best 
 judgment as to the manner and route of shipment. Unless the customer has a prefer¬ 
 ence, we suggest that the matter be'left to our experienced judgment. Small articles 
 which we are instructed to send by mail are consigned at the customer’s risk, but will 
 be registered if requested. We charge for boxing and casing at cost. 
 
 REMITTANCES: — Our terms are net thirty days. We allow a cash discount of 1 per 
 cent, from the face of the bill if the check is sent to us within ten days from the date 
 of invoice. Interest at the usual rate is charged for overdue accounts. All remit¬ 
 tances should be made in checks payable through the New York or Boston Clearing 
 House. On checks or drafts payable at other points, the proper amount to cover the 
 exchange should be added. School Warrants should be registered and if it be known 
 that no money is immediately available for payment, please advise us when funds will 
 be provided. If local banks are prepared to purchase these warrants at par, the names 
 of such banks should accompany the warrant. 
 
 RETURNS: — If for any reason it is desirable to return goods, kindly advise us by mail 
 concerning the conditions so that no misunderstanding may arise. We are always 
 glad to accommodate but we cannot accept or give credit for goods which are returned 
 without previous arrangement having been made. 
 
 REPAIRS: — If goods are sent to us for repair, see that the case is properly marked, giving 
 the name of the sender. Send us a letter at the same time stating what you are re¬ 
 turning and what you wish to have done to it. 
 
LABORATORY 
 
 FURNITURE 
 
 S INCE 1896 we have maintained a special department for the critical 
 investigation and study of laboratory and lecture-room needs. It has 
 been the duty of this department to design and manufacture both 
 the laboratory and lecture-room tables and the special and distinctive general 
 fittings which are necessary in order to secure the best possible facilities for 
 high-grade science work. 
 
 That this service has been appreciated is evidenced by the constantly in¬ 
 creasing business which this department has been called upon to handle. 
 
 It is a source of great satisfaction to us that architects, school boards and 
 superintendents of schools are more and more availing themselves of the techni-. 
 cal experience of this department, appreciating as they do that two decades of 
 constant application to this work have put us in position to render valuable 
 assistance. 
 
 On the following pages we list a few of the standard designs which have 
 proven most generally serviceable. These designs will serve to illustrate the 
 high character of our laboratory furniture: 
 
 t 
 
 1st. Each piece is designed with a complete knowledge of the 
 conditions under which it is to be used. 
 
 2nd. Full consideration has been given to the fact that a labo¬ 
 ratory table becomes a permanent part of the building 
 and hence should be as rigid and as substantial as the 
 building itself. 
 
 3rd. Material, finish, and workmanship should be of the best, 
 to insure durability equal to the life of the building. 
 
 The services of this department are freely offered to those who are plan¬ 
 ning new laboratories. 
 
2 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • » 
 
 STANDARD PHYSICS TABLE 
 
 No. 1-100 
 
 1-100 PHYSICS TABLE with FIXED UPRIGHT and ADJUSTABLE CROSS-BAR. This table 
 
 has been so extensively used for the last fifteen years that it is considered the Standard 
 Physics Laboratory Table. The body is made of selected kiln-dried ash, oil and wax 
 finish, presenting a handsome finish, accentuating the grain of the wood. The top is 
 built up of selected, straight-grained, kiln-dried strips, machined, matched and joined 
 in such a manner as to prevent warping. It is finished a durable black acid-proof finish. 
 Uprights and cross-bar are of ash, inches by 3 inches, finished to match body, cross¬ 
 bar being held by the Knott Special Three-Part Clamp which readily allows adjustment 
 without binding and which will hold the bar firmly in any desired position. 
 
 This table is 6 feet long, 4 feet wide and 34 inches high. It is equipped with four drawers, 
 two on each side. 
 
 Each, f. o. b. Factory, $29.75 
 
 We are prepared to furnish tables of any desired finish to match furniture already in the 
 building, and, if the order is sufficiently large, this can be done without extra charge. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 3 
 
 PHYSICS TABLE 
 
 No. 1-120 
 
 1-120 PHYSICS TABLE. This table has found considerable favor in Physics Laboratories 
 from the fact that the rods and clamps with which laboratories are so universally equipped 
 may be utilized for the uprights and cross-bar. The detachable feature, leaving clear 
 the whole top of the table, is a distinct advantage. 
 
 This table is of the same high quality as No. 1-100. It is six feet long, four feet wide, 
 thirty-four inches high. It is not provided with drawers, as in laboratories provided 
 with ample storage facilities they may be considered unessential. 
 
 With each table accessories for uprights and cross-bar attachments are furnished as follows: 
 
 Two 5-1150 “Harcourt” Universal Basic Clamps “B.” 
 
 Two 5-20e Threaded Rods, 19 millimeters diameter, for uprights. 
 
 Two 5-765 Right Angle V Clamps. 
 
 One 5-40c Support Rod for Cross-Bar, 19 millimeters diameter. 
 
 Table complete as above, f. o. b. Factory, $29.75 
 
 1-125 PHYSICS TABLE, —same table as No. 1-120, but furnished without uprights and cross¬ 
 bar, as they are not required where a laboratory already has such an equipment. 
 
 Table only, f. o. b Factory, $21.00 
 
 We are prepared to furnish tables of any desired finish to match furniture already in the 
 building, and, if the order is sufficiently large, this can be done without extra charge. 
 
4 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 STANDARD LECTURE TABLE 
 
 No. 1-150 
 
 1-150 COMBINATION LECTURE TABLE for either PHYSICS or CHEMISTRY LECTURE 
 ROOM. This table has the distinctive qualities of all our laboratory furniture. The body 
 is made of selected kiln-dried ash, oil and wax finish. Top is built up from selected 
 narrow, straight-grained, kiln-dried strips, machined, matched and joined in such a 
 manner as to prevent warping. It has a durable black acid-proof finish. 
 
 It is furnished equipped with plumbing to the floor line for both gas and water and supplied 
 with the Knott special goose-neck water faucet which carries three attachments, - 
 one for small rubber hose, one for large, and one for attaching an aspirator. It has, 
 in addition, one four-way Knott Turret for gas supply and a Special Gas Cock with 
 lever handle and long serrated ends. 
 
 It is equipped, also, with two No. 5-274 nickel-plated Flush Sockets, two No. 5-20e Sup¬ 
 port Rods, two No. 5-765 Right Angle Clamps and No. 5-40b Support Rod for Cross- 
 Bar. 
 
 The design of this desk is such as to afford best facilities for Lecture Table Demonstration. 
 Top is supplied with lead-lined pneumatic sink, 18 inches square by 16 inches deep, with 
 a shelf 8 inches wide placed 6 inches from the top. The front and ends are paneled and 
 back is equipped with three large and two small drawers, four open shelves and com¬ 
 modious cupboard. ' 
 
 This table is 8 feet long, 3 feet wide and 34 inches high. 
 
 Each, f. o. b. Factory, $103.00 
 
 We are prepared to furnish tables of any desired finish to match furniture already in the 
 building, and, if the order is sufficiently large, this can be done without extra charge. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 5 
 
 INSTRUCTORS TABLE 
 
 No. 1-200 
 
 1-200 INSTRUCTOR’S LABORATORY TABLE for small lecture room. The body of this table 
 is of ash, oil and wax finish. The top is built up from straight-grained, kiln-dried strips 
 with special black acid-proof finish. 
 
 It is furnished equipped with plumbing to the floor line for gas and water and supplied with 
 the Knott special goose-neck faucet which carries three attachments, — one for small 
 and one for large rubber tubing connections, and one for attaching an aspirator, a two- 
 way turret for gas connections with a special lever-handle gas cock with long serrated 
 ends. Set into the top of the table is a lead-lined sink, 16X10X9 inches deep. 
 
 The top is further equipped with three No. 5-270 and two No. 5-274 Flush Plates for 
 the three No. 5-10e and two No. 5-20e Support Rods, one No. 5-40a Support Rod for 
 Cross-Bar and two No. 6-765 Right Angle V Clamps. Electrical Connections illustrated 
 are furnished only on application and at an extra charge. 
 
 This table is designed to offer the best possible facilities in the smallest space. The 
 front and ends are paneled; the back has five drawers and commodious cupboard space. 
 
 The table is 5 feet long by 2 x /i feet wide by 34 feet high. 
 
 Each, f. o. b. Factory, $67.50 
 
 We are prepared to furnish tables of any desired finish to match furniture already in the 
 building, and, if the order is sufficiently large, this can be done without extra charge. 
 
 # 
 
6 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 APPARATUS CABINET 
 
 An experience extending over two decades has demonstrated positively to us that education- 
 al institutions in need of adequate and serviceable storage space for any of the branches of science 
 have felt a far greater satisfaction in purchasing cabinets built especially to fit and meet individual 
 conditions. 
 
 We have the best of facilities for building such furniture to order. 
 
 % 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 7 
 
 LOOSE-LEAF FILING CABINET 
 
 No. 1-660 
 
 1-650 LOOSE-LEAF CABINET for storing and filing loose-leaf material of all kinds. 
 
 This cabinet, originally designed to fulfil the demand for storage and filing facilities for 
 Loose-Leaf Note-Book material, has found a place of equal value in the offices of school 
 superintendents and principals. Its adaptability to the filing of school records for instant 
 reference, is unsurpassed by any system of filing. By opening the two doors, the entire 
 fifty-six compartments, all legibly numbered, become at once available. Each compart¬ 
 ment has a capacity of from 150 to 200 separate sheets of paper, with four wide com¬ 
 partments at the bottom, each capable of holding 1,000 or more sheets. 
 
 The convenience of this cabinet in the storing of Direction Sheets of Loose-Leaf Note- 
 Books is at once apparent, and Educational Institutions using a Loose-Leaf System of 
 Instruction will readily realize the necessity of ample storage, indexed for ready reference. 
 
 The cabinet is substantially built of ash with paneled sides and doors, heavy moulding at 
 top and bottom. It is carried in stock attractively finished in antique oak. 
 
 Dimensions over all, — height 40 inches, width inches, depth 13^ inches. 
 
 Each, f. o.b. Factory, $19.75 
 
 We are prepared to furnish cabinets of any desired finish to match furniture already in 
 the building, and, if the order is sufficiently large, this can be done without extra charge. 
 
8 
 
 L. E., KNOTT APPARATUS CO., BOSTJON 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 9 
 
 THE KNOTT 
 
 SCIENCE LABORATORY FITTINGS 
 
 Twenty years ago when we, as pioneers in building laboratory furniture, required gas and water fixtures adapted 
 particularly to science laboratory requirements, it was with considerable surprise that we found that there were no 
 commercial fittings adapted to such special and exacting conditions. After a most critical investigation and study 
 of laboratory and lecture-room needs, we designed the following fittings which have found universal favor. They 
 are used exclusively on all of our laboratory furniture. 
 
 No. 1-760 
 
 No. 1-800 
 
 No. 1-726 No. 1-700 
 
 No. 1-801 
 
 KNOTT’S GAS COCKS 
 
 No. 1-802 
 
 The Knott Gas Cocks are of brass. The nipples are long and with five sharp serrations which make it easy 
 to slip on rubber tubing, but impossible to pull it off accidentally. Adjustment is secured by means of a lever handle. 
 
 1-700 KNOTT’S LEVER HANDLE GAS COCK, M inch I. P.$0.66 
 
 1-710 KNOTT’S SINGLE GAS TURRET, one gas cock. 1.46 
 
 1-716 KNOTT’S TWO-WAY GAS TURRET, two gas cocks . . 1.86 
 
 1-720 KNOTT’S THREE-WAY GAS TURRET, three gas cocks. 2.26 
 
 1-726 KNOTT’S FOUR-WAY GAS TURRET, four gas cocks. 2.66 
 
 1-760 THE KNOTT MOUNTED FOUR-WAY GAS TURRET. The use of this design obviates all 
 necessity of cutting a table top. It is connected by rubber tubing to a supply cock left at the 
 floor line or above the table. 4.60 
 
 WATER FAUCETS 
 
 These faucets are of heavy brass with full nickel finish. Three interchangeable attachments are provided,— 
 two for connecting rubber tubing from to % inch in diameter, the third, a regular hose bib coupling for attaching 
 an aspirator. Adjustment is secured by a large wheel handle which in actual use has been found the best for student 
 use. 
 
 1-800 KNOTT’S WHEEL HANDLE INTERCHANGEABLE NOZZLE STRAIGHT WATER FAUCET, 
 
 inch I. P.$2.90 
 
 1-801 -, BENT WATER FAUCET y 2 inch I. P. 3.60 
 
 1-802 -, GOOSE-NECK WATER FAUCET, inch I. P. 6.00 
 
10 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 LABORATORY SUPPORT RODS 
 
 Our Rods are of cold rolled Bessemer steel, copper-plated and heavily nickeled, thus ob¬ 
 viating the possibility of rust deterioration. They are straight, of uniform diameter, machine 
 threaded, and shoulders faced to attain a perfect junction when used on our bases and flush 
 plates. 
 
 No. 5-40 
 
 M 
 
 R 
 
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 Nos. 6-10 to 6-56 
 
 AT US 
 
 
 
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 ASS 
 
 t 
 
 
 6-10 SUPPORT RODS, 10 millimeter diameter, threaded to fit any hole tapped 34 X 20. 
 
 abode 
 Length. 10 15 20 30 40 centimeters. 
 
 Each.$0.16 .18 .20 .26 .29 
 
 5- 16 SUPPORT RODS, 13 millimeter diameter, threaded to fit any hole tapped Yi X 16. 
 
 d< b c d 6 
 
 Length. 20 40 60 80 100 centimeters. 
 
 Each.$0.26 .35 .48 .60 .80 
 
 6- 20 SUPPORT RODS, 19 millimeter diameter, threaded to fit any hole tapped 34 X 12. 
 
 a b c d e f 
 
 Length. 30 40 60 80 100 120 centimeters. 
 
 Each.$0.42 .62 .70 .88 1.00 1.36 
 
 6-30 SUPPORT RODS, 30 millimeter diameter, threaded to fit any hole tapped % X 10. 
 
 3, t) C d 6 
 
 Length. 60 80 100 120 160 centimeters. 
 
 Each.$1.66 1.90 2.30 2.46 3.36 
 
 6—40 SUPPORT RODS, for use as horizontal rods, 19 millimeter diameter, ends rounded. 
 
 a b c 
 
 Length. 100 125 185 centimeters. 
 
 Each.$1.10 1.36 2.20 
 
 6-60 SQUARE SUPPORT RODS, 19 millimeters square, one end turned to 19 millimeter diameter, and threaded 
 to fit any hole tapped Y X 12. No. 6-60 d-f are most frequently used as bed-rods of optical benches. 
 
 a b c d e f 
 
 Length. 40 60 80 100 120 200 centimeters. 
 
 Each.$1.16 1.66 1.96 2.30 3.40 4.46 
 
 6-66 SQUARE SUPPORT RODS, same as Nos. 6-50d and 6-50f, but graduated to millimeters. A few of these 
 rods are valuable additions to every laboratory, as they may be used in many ways besides as bed-rods for 
 optical benches, — the purpose for which they were originally intended. 
 
 a b 
 
 Length. 100 200 centimeters. 
 
 Each.$6.60 10.76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 ii 
 
 Nos. 5-100 to 5-215 
 
 TRIPOD BASES 
 
 Our line of Tripod Bases is scientifically designed to give the greatest possible degree of stability without oc¬ 
 cupying too much room on the working table. The nine sizes of the series fill all needs from the standpoint of size, 
 stability, and the use of all the rods listed on the previous page. Each tripod is faced top and bottom that shoulders 
 of Support Rods may make close junction and may be in true perpendicular with the plane of the base. All holes 
 are machine drilled and threaded. 
 
 Our castings are uniformly smooth, thus offering a good surface for a strikingly smooth and beautiful finish. 
 All sizes are carried in stock with and without leveling screws. 
 
 5-100 TRIPOD BASE, with leveling screws, length of leg 6 centimeters, tapped 34 X 20 to take any 10 
 
 millimeter rod. $0.84 
 
 5-101 “ “ Same as above, without leveling screws. .26 
 
 5- 104 TRIPOD BASE, with leveling screws, length of leg 8 centimeters, tapped 34 X 20 to take any 10 
 
 millimeter rod.98 
 
 6- 105 “ “ Same as above, without leveling screws.28 
 
 5-110 TRIPOD BASE, with leveling screws, length of leg 10 centimeters, tapped 34 X 20 to take any 10 
 
 millimeter rod. 1.10 
 
 5-111 “ “ Same as above, without leveling screws.48 
 
 5- 114 TRIPOD BASE, with leveling screws, length of leg 12 centimeters, tapped 34 X 20 to take any 10 
 
 millimeter rod. 1.20 
 
 6- 115 “ “ Same as above, without leveling screws.68 
 
 5-120 TRIPOD BASE, with leveling screws, length of leg 14 centimeters, tapped 24 X 16 to take any 13 
 
 millimeter rod. 1.35 
 
 5- 125 “ “ Same as above, without leveling screws.72 
 
 6- 130 TRIPOD BASE, with leveling screws, length of leg 18 centimeters, tapped 24 X 16 to take any 13 
 
 millimeter rod. 1.85 
 
 5- 136 “ “ Same as above, without leveling screws. 94 
 
 6- 140 TRIPOD BASE, with leveling screws, length of leg 18 centimeters, tapped 34 X 12 to take any 19 
 
 millimeter rod.'. 1.86 
 
 6-146 “ “ Same as above, without leveling screws. 94 
 
 6-150 TRIPOD BASE, with leveling screws, length of leg 21 centimeters, tapped 34 X 12 to take any 19 
 
 millimeter rod .... 2.15 
 
 5-165 “ “ Same as above, without leveling screws. 1.10 
 
 5- 160 TRIPOD BASE, with leveling screws, length of leg 26 centimeters, tapped 34 X 12 to take any 19 
 
 millimeter rod. 3.15 
 
 6- 165 “ “ Same as above, without leveling screws. 1.65 
 
 6-170 TRIPOD BASE, with leveling screws, length of leg 26 centimeters, tapped 24 X 10 to take any 30 
 
 millimeter rod. 3.15 
 
 6-176 “ “ Same as above, without leveling screws. 1.65 
 
 6-180 TRIPOD BASE, with leveling screws, length of leg 50 centimeters, tapped 24 X 10 to take any 30 
 
 millimeter rod. 6.90 
 
 6-186 “ “ Same as above, without leveling screws. 4.80 
 
 ROUND BASES 
 
 In the design of our Round Bases we have followed the same rules for stability as in Tripod Bases listed above. 
 Our Castings are uniformly smooth, bases faced top and bottom, machine drilled and tapped, handsomely finished. 
 
 6-200 ROUND BASE, diameter 8 centimeters, tapped J4 X 20 to take any 10 millimeter rod .$0.20 
 
 6-206 -, diameter 10 centimeters, tapped 34 X 20 to take any 10 millimeter rod.22 
 
 6-210 -, diameter 12 centimeters, tapped 24 X 16 to take any 13 millimeter rod.36 
 
 6-216 -, diameter 15 centimeters, tapped 24 X 16 to take any 13 millimeter rod.60 
 
12 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 6-240 “INSTITUTE” H-BASE. The distinctive shape of this base affords a stability equal to that of a 
 round base and in addition enables the experimenter to place a jar or other apparatus within one 
 inch of the support rod. The curvature is somewhat greater than that of a 4 X 5 battery jar. 
 Threaded 34 X 20 to take any of our 10 mm. rods.$0.60 
 
 No. 6-242 
 
 6-242 “HARCOURT” SPECIAL H-BASE. This base is more massive than 
 above and is threaded 34 X 12 to take any of our 19 mm. rods. 
 Curvature somewhat greater than that of a 6 X 8 battery jar. 
 
 We utilize this base in a number of our instruments. See Nos. 
 
 43-270, 62-10, 63-200, 53-206, 53-215, 62-50, 92-76, etc., etc. $1.00 
 
 THE KNOTT ADJUSTABLE ECCENTRIC LEVELING BASES 
 
 The design of our Adjustable Eccentric Leveling Base is the outgrowth of a demand for a base of great stability, 
 yet one which will permit placing the base close to other apparatus on the lecture table. The telescoping extension 
 legs give wide range of usefulness. With the two sizes we are able to meet the stability of any round bases from 
 1134 to 32 inches in diameter. The eccentric discs on the end of each extension leg give a positive and easily operated 
 level adjustment. 
 
 No. 6-250 
 
 Patent Pending 
 
 No. 6-252 
 
 Patent Pending 
 
 6-250 “THE KNOTT” ADJUSTABLE ECCENTRIC LEVELING BASE, adjustable to cover an area 
 
 from 1134 to 1834 inches in diameter.$2.35 
 
 6-252 -, adjustable to cover an area from 1834 to 32 inches in diameter. 3.66 
 
 No. 6-260 
 
 6-260 ANDREW’S PLATE BASE. There has been considerable demand for a base of the right dimen¬ 
 sions to carry a number of support rods so that apparatus might be set up on a lecture table and 
 moved bodily from place to place. The base which we list was designed by Mr. Calvin H. 
 Andrews of the High School of Commerce, Worcester, Mass., and is the most satisfactory design 
 which we have yet seen. 
 
 It is provided with five holes on a line through the center of the base, one threaded %-16 and four 
 34 - 12, properly located for most convenient use. The base is massive in construction, size 
 10 X 18 inches. We recommend two of these bases for each lecture table.Each, $4.90 
 
 Nos. 5-270 to 6-274 
 
 FLUSH PLATES, for inserting in any laboratory table flush with the top. These plates are heavily nickel-plated 
 and polished. When fitted to a table and screwed into place, they offer a support amply rigid for all laboratory oper¬ 
 
 ations. 
 
 6-270 FLUSH PLATE, tapped 34 X 20 to take any 10-millimeter rod.$0.35 
 
 6-272 -, tapped 34 X 16 to take any 13-millimeter rod.46 
 
 6-274 -, tapped 34 X 12 to take any 19-millimeter rod.70 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 13 
 
 6-350 
 
 6-360 
 
 No. 6-350 
 
 No. 6-365 
 
 MISCELLANEOUS 
 
 SUPPORTS 
 
 TABLE CLAMP for attaching to edge of 
 table to hold round or square rods in 
 either horizontal or vertical position. V’s 
 and extra broad flange are carefully 
 milled. To be used on table 7.5 centi¬ 
 meters or less thick. $1.40 
 
 TABLE CLAMP for attaching to edge of 
 table to hold round or square rods in ver¬ 
 tical position. This design obviates dan¬ 
 ger of injury to table, yet at same time, 
 from its structure offers a rigid support. 
 
 May be used with our Interlocking T- 
 Beam Attachments, “Series B.” Tapped 
 
 X 12 to take 19-millimeter rod . . . 1.90 
 
 No. 5-360 
 
 No. 5-375 No. 5-386 No. 6-375 
 
 5-365 TABLE CLAMP, similar to above but less massive and cannot be used with our Interlocking T-Beam 
 
 Attachments, “Series B.” Tapped % X 16 to take any of our 13 mm. rods.$ .85 
 
 5-366 -, tapped X 12 to take any of our 19 mm. rods. 1.00 
 
 5- 375 END SUPPORTS for supporting rods in a horizontal position, originally designed for holding bed-rod 
 
 of optical benches. Extreme care is exercised in machining these supports so that they will meet 
 
 all requirements.Each .55 
 
 6- 386 SECONDARY SUPPORTS for attaching to round or square rods to support objects in horizontal 
 
 position. Convenient for holding telescopes; also for levels in level-testing experiments , Each .42 
 
 Nos. 6-400 to 6-416 
 
 5-400 STAND TUBE, into which a 13-millimeter rod may be telescoped and clamped at desired heights 
 within range of 20 centimeters, — the height of the tube. In conjunction with a base tapped % X 16 
 and with STAND TOPS Nos. 6-475 and 5-480, will make an adjustable table support .... $1.26 
 
 5-405 -, same as above, but 30 centimeters long. 1.46 
 
 5-410 STAND TUBE for use as in No. 6-400, to take 19-millimeter rod, and will fit any base tapped ^ X 12. 
 
 Length 30 centimeters. Will require No. 6-486 or 6-490 . 2.00 
 
 5-415 -, same as above, but 40 centimeters long. 2.25 
 
14 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 Nos. 5-430 to 5-440 
 
 No. 5-450 
 
 5-430 EXTENSION CLAMP, for holding two rods adjustably parallel to each other. For two 19 millimeter 
 
 rods . .$0.65 
 
 5- 435 -, same as above, but for two 13 millimeter rods.;.64 
 
 4 
 
 6- 440 -, same as above, but for two 10 millimeter rods.44 
 
 5-450 V OPENING EXTENSION CLAMP for holding two rods adjustably parallel to each other. This 
 clamp has been designed to obviate the inconveniences of the old form with parallel holes which 
 must be attached to the rod by placing it over the ends. Our new design for use with 10 to 19 milli¬ 
 meter rods may be slipped on the rod and clamped by the nickel-plated T screw.55 
 
 Nos. 6-470 to 5-490 
 
 5-470 STAND TOP, 15 centimeters diameter, tapped for 
 use with any 10 millimeter rod threaded ^ X 20. 
 Frequently used in conjunction with Stand Tube 
 No. 6-400 or 5—405, and a suitable base to form 
 an adjustable table. Made of three-ply wood to 
 prevent warping. 
 
 5-476 STAND TOP, 15 centimeters in diameter, but tapped 
 to receive any 13 millimeter rod threaded % X 16 
 
 5- 480 -, same as above, but 20 centimeters in diameter 
 
 6- 485 STAND TOP, 20 centimeters in diameter, but tapped 
 
 to receive any 19 millimeter rod threaded }/% X 12 
 
 6-490 — —, same as above, but 30 centimeters in diameter. 
 
 $0.98 
 
 .98 
 
 1.22 
 
 1.44 
 
 1.64 
 
 
 
 6-610 ADJUSTABLE LABORATORY STAND for table use. This stand is substantially built of metal, 
 with three-ply wood top. This top is adjustable in height from the minimum height of 40 centi¬ 
 meters to a maximum of 70 centimeters. 
 
 This stand will be found of great convenience on the lecture table. The stand being heavy and the 
 center of gravity low, the top may be clamped as any table top and a system of rods and clamps 
 utilized to gain greater latitude and adjustment.$ 9.60 
 
 ■, same as above, top adjustable from 70 to 130 centimeters 
 
 15.00 
 
 
 8-511 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 15 
 
 No. 6-515 
 
 No. 6-515a 
 
 No. 5-515b 
 
 5-515 GEOMETRIC STANDS, for blocking up apparatus. Set consists of six tripods fitting into each 
 other, the uppermost surmounted by neat wooden top 13 inches in diameter. Top alone with its 
 leveling screws gives an adjustment from 2% inches, the minimum height, to 3 inches, the maxi¬ 
 mum. Each tripod varies height by 13^ inches. Total maximum height 8)4 inches. Per Set of Six $4.65 
 
 6-515a TRIPOD WITH WOOD TOP, and LEVELING SCREWS, as used in above.Each 2.25 
 
 6-515b TRIPOD only, as used in above.Each .60 
 
 5-525 PLATFORM for 10 millimeter rod. Made of cast iron, top carefully milled true. Top 7 X 8.5 
 
 centimeters. .$0.60 
 
 5- 527 - , same as above, for 19 millimeter rod .60 
 
 6- 530 -, same as above, for 10 millimeter rod, top 8.5 X 11.5 centimeters.76 
 
 5- 535 - , same as above, for 13 millimeter rod, top 8.5 X 11.5 centimeters.76 
 
 6- 540 - —, same as above, for 13 millimeter rod, top 11.5 X 15.5 centimeters .94 
 
 6-646 -, same as above, for 19 millimeter rod, top 14.5 X 21.5 centimeters . 1.60 
 
 No. 5-670 
 
 5-570 WALL STAND, of general utility in laboratory practice. Designed to be placed on a rail fixed to the 
 wall or laboratory table. Wood plate, 30 centimeters in diameter, oil and wax finish, mounted 
 adjustably on 19 millimeter rod. $12.50 
 
i6 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6-690 
 
 No. 6-696 
 
 Patent Pending 
 
 6-690 KNIFE EDGE BRACKET for attachment to the side of a room as a knife edge support for a rod 
 in Bending Beam experiments. 
 
 This bracket is made of cast iron from a pattern of our own design. It is handsomely japanned and 
 
 the knife edge carefully milled true..Each 
 
 6-696 KNIFE EDGE CLAMP for attaching to the edge of a table top to form an adjustable support for a 
 beam in Bending Beam experiments. 
 
 This clamp is one of our T-Beam Series (see No. 6—1060) and highly recommended for the universal 
 adaptation which is one of its unique features. 
 
 Clamp complete as illustrated . 
 
 6-1060 KNIFE EDGE CLAMP ATTACHMENT ONLY.. . . 
 
 6-1000 “HARCOURT” UNIVERSAL T-BEAM BASIC CLAMP “A.”. 
 
 6-696 KNIFE EDGE CLAMP for attaching to the edge of a table, but knife edge not adjustable 
 
 $0.60 
 
 1.69 
 
 .66 
 
 .94 
 
 .65 
 
 No. 5-610 
 
 6-610 LEVELING SCREWS for use in sets of three for rapidly leveling a plane surface. Made entirely of 
 metal, base accurately milled. Adjustable from minimum height of 65 millimeters to 90 millimeters. 
 
 Per set of three . . 1.40 
 
 6-636 
 
 6-636 
 
 6-637 
 
 6-638 
 
 6-646 
 
 6-646 
 
 6-647 
 
 Nos. 6-646 to 6-647 
 
 COLLAR for allowing a clamped rod to freely revolve and yet keeping rod at height fixed by position 
 
 of collar. Designed for 30 millimeter rod. 
 
 -, same as above but for 19 millimeter rod . 
 
 -, same as above but for 13 millimeter rod . 
 
 -, same as above but for 10 millimeter rod . 
 
 HOOK COLLAR for 10 millimeter rod. The addition of a hook to a collar has been found exceedingly 
 useful in our laboratory work. Its use as a support may be noted in illustration of Nos. 27-290 and 
 27-300. It may readily be adapted to a multitude of uses when a system of Interchangeable 
 
 Laboratory Supports is a part of the school equipment.Each 
 
 -, same as above but for 13 millimeter rod.Each 
 
 -, same as above but for 19 millimeter rod.Each 
 
 $0.58 
 
 .48 
 
 .39 
 
 .33 
 
 .24 
 
 .28 
 
 .65 
 
 No. 6-670 
 
 RIGHT ANGLE PIECE for clamping two 10 millimeter rods at right angles to each other, 
 nickel-plated with two nickel-plated T-screws. 
 
 Neatly 
 
 $0.50 
 
 5-670 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 17 
 
 CLAMPS 
 
 Our Clamps are designed to give maximum strength at stress points with use of as little 
 metal as practical to preserve symmetry. All our clamps are ribbed at points of stress; our cast¬ 
 ings are uniform and smooth, thus presenting a good surface for a smooth, handsome, and durable 
 finish; all parts designed to be at right angles or parallel are as accurately so as machinists’ skill 
 can produce. As jigs and standard gauges are used as far as practicable, each lot will be found 
 uniform in dimensions. All holes are reamed to a sliding fit; all screws are heavily nickel plated 
 and of size proportional to size of clamp; all V’s are accurately milled. 
 
 No. 6-725 
 
 No. 5-746 
 
 No. 6-760 
 
 No. 5-765 
 
 No. 5-770 
 
 No. 5-785 
 
 No. 5-810 
 
 No. 6-825 
 
 6-725 RIGHT ANGLE CLAMP, for holding two rods in planes accurately at right angles to each other. 
 
 V opening to clamp 13 millimeter rod, hole for 10 millimeter rod. $0.46 
 
 5- 730 -, same as above, but V opening to clamp 19 millimeter rod, hole for 13 millimeter rod. .66 
 
 6- 736 -, for use in holding optical bench accessories. V opening to clamp 19 millimeter rod, hole for 
 
 13 millimeter rod. Central (zero) point indicated. .90 
 
 6-746 RIGHT ANGLE CLAMP, V opening to clamp 30 millimeter rod, hole 19 millimeters. .90 
 
 5- 760 RIGHT ANGLE CLAMP, for holding two rods in planes accurately at right angles to each other. 
 
 Two V openings for clamping 13 millimeter rods. .44 
 
 6- 766 -, same as above, but with two V openings for clamping 19 millimeter rods. .63 
 
 6-770 “HARCOURT” RIGHT ANGLE CLAMP, for holding two rods in same plane at right angles to 
 each other. Two V openings for clamping 13 to 19 millimeter rods, one accurately perpendicular to 
 
 the other. 
 
 This form of clamp will be found a marked improvement over types on the market, as more rapid 
 changes and adjustments are possible. Its universal adaptability to work not possible with old 
 forms is readily apparent. .96 
 
 6-786 RIGHT ANGLE CLAMP, for holding two rods in same plane but accurately at right angles to each 
 
 other. V opening to clamp 19 millimeter rod, tapped x /i X 20 to receive 10 millimeter rod ... .46 
 
 6-790 -, same as above, but tapped % X 16 to receive 13 millimeter rod . .66 
 
 5- 810 RIGHT ANGLE CLAMP, for holding two rods in same plane but at right angles to each other. V 
 
 opening to clamp to 19 millimeter rod, hole 10 millimeters. Convenient for holding accessories 
 having shank 10 millimeters in diameter. .68 
 
 6- 816 OPTICAL BENCH RIGHT ANGLE CLAMP, same as above, but with central (zero) point indi¬ 
 
 cated. V opening to clamp to 19 millimeter rod, hole for 10 millimeter rods. .78 
 
 6-820 -, same as above, but V opening to clamp 19 millimeter rod, hole 13 millimeters ....... .85 
 
 5-826 RIGHT ANGLE CLAMP WITH SLIDING SPRING CONTACT, same as No. 5-816, but with addi¬ 
 tion of device which holds clamp firmly to the bed-rod yet at same time allowing of firm sliding 
 motion along the rod. This clamp is advised for use as support for Photometer Boxes as it allows 
 of motion along rod without unlocking the set screw . . . ... Each 1.70 
 
i8 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 No. 5-840 
 
 Patent Pending. 
 
 6-840 SWIVEL-CLAMP UNIVERSAL HOLDER, for holding in any position flat or round objects, 
 thermometers, burettes, tubes, screens, telescopes, telescope scales, and, in fact, any object flat or 
 cylindrical which is not over 50 millimeters in diameter nor over 155 millimeters wide and 30 milli¬ 
 meters thick. 
 
 This device consists essentially, of two parts,—a holder and a swivel-clamp, the holder attached to 
 the swivel-clamp in an ingenious manner by which it may be firmly set in position by a T screw, 
 and yet without removing from the rod, capable of universal motion in one plane by simply dimin¬ 
 ishing the pressure of the screw against the rod. This swivel-clamp will be found a prominent 
 feature in the use of this holder. 
 
 . The holder is designed to meet the requirements of a general lecture table clamp. The essential part 
 is a broad plate. At the edge of this broad plate are two projections against which the object to be 
 held is laid. A plunger rod carries an arm which is adjustable along the rod and it in turn carries 
 an adjustable contact rod tipped with cork. In use the object is placed against the projections at 
 the edge of the broad plate. Knob at end of plunger rod is pushed in, thus acting against a com¬ 
 pression spring. The arm carrying the contact rod is adjusted on the plunger rod and the posi¬ 
 tion of the contact rod on this arm is adjusted so that when pressure of thumb is removed from 
 compression spring the object is firmly clamped by force of the spring. (See Figure 1.) The pro¬ 
 jection to the rear of the arm is a straight rod to be used with arm reversed on plunger rod when a 
 flat object is to be clamped. (See Figures 2 and 3.) 
 
 This Universal Holder will be found a valuable addition to any laboratory. Its use is unlimited; 
 positions possible are multitudinous; facility, convenience, and rapidity of changes are unexcelled. 
 
 As it will hold a great range of sizes from small to large, adapting itself instantly to these changes, 
 and support objects in any position it might well be called a system of clamps combined in one. 
 
 It is handsomely finished in bright nickel-plate. All parts are carefully fitted and substantial in 
 structure. The most convenient and generally useful lecture table clamp yet designed. Two 
 should be provided for each lecture table.Each $4.60 
 
 I 
 
 Fig. 2 
 
 Fig. 3 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 19 
 
 Nos. 6-850 and 6-866 
 
 No. 6-875 
 
 6-860 UNIVERSAL RIGHT ANGLE CLAMP, for holding two rods in various planes at right angles to 
 
 each other. Provided with swivel for locking. Two V openings to clamp 19 millimeter rods . . . $1.06 
 
 &-856 -, same as above, but with two V openings for clamping 13 millimeter rods. 90 
 
 5-876 UNIVERSAL CLAMP, for large objects up to 8 centimeters in diameter, regular or irregular in shape. 
 
 Position adjustable by swivel through 180 degrees. Finished in japan and nickel plate. 1.76 
 
 No. 5-886 No. 6-889 No. 6-895 
 
 6-885 BOTTLE CLAMP, for clamping a bottle by its neck and supporting same to an upright. V clamp 
 for 13 millimeter rod. Will clamp firmly any diameter from 25 millimeters to 30 millimeters. In 
 use see No. 63-200 .$0.85 
 
 5- 887 ADJUSTABLE TUBE CLAMP, for supporting a tube in an upright or horizontal position. This is 
 
 a two-part casting, one part designed with a V clamp for attaching to a 13 millimeter rod, the 
 second part held adjustably to the first by two thumb screws, thus accommodating a tube from 
 134 inches (32 millimeters) to 1 % inches (45 millimeters) in diameter. In use see No. 63-200 . .96 
 
 6- 889 ADJUSTABLE ARM SUPPORT WITH CLAMP. This is a two-part casting, one provided with a 
 
 V for clamping to a 13 millimeter rod, the other with countersunk hole at the end of a slotted arm. 
 
 This arm is adjustable to the length of the slot and may be clamped in any position by means of a 
 thumb screw. In use see No. 63-200 .85 
 
 6-891 ROD V CLAMP, for use with any V clamp in securing a greater latitude of adjustment. V opening 
 
 to take 10 or 13 millimeter rod. Rod 13 millimeters diameter, 11 centimeters long.65 
 
 6-895 METER STICK CLAMP, V opening for clamping to a 13 or 19 millimeter rod, face plate and 
 adjustable locking device for holding the standard meter stick. Surfaces of V and of face plate 
 carefully milled parallel...64 
 
20 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 5-900 FOUR PENDULUM CLAMP, for adjustably supporting four pendulums. This 
 clamp, similar in design to the one on the market is improved so that it may 
 carry four pendulums, thus making possible a direct comparison of pendulum 
 lengths of periods as 1: 2: 3: 4. The clamp itself is of a smooth, uniform casting, 
 carrying four removable clamps designed to give exact points of suspension 
 for accurate measurement of lengths. This clamp consists of a flat brass piece 
 with guide pin held to the main clamp by a polished and lacquered thumb 
 
 screw. . $ 1.75 
 
 5-902 THREE PENDULUM CLAMP, similar to above but usual form designed to hold 
 
 three pendulums. .76 
 
 For Complete Pendulum Apparatus, see Section 25. 
 
 No. 6-905 
 
 5-905 BI-FILAR PENDULUM CLAMP for holding four pendulums in bi-filar suspensions. 
 
 This clamp obviates the inconveniences of the ordinary type in that it gives a direc¬ 
 tive force to the swinging pendulums. It is especially adapted for four pendulums 
 of different vibration periods. 
 
 It consists of a smooth uniform casting in which are placed tapered plugs, two for each 
 pendulum ball. These tapered plugs are carefully fitted to their respective holes, 
 and the lengths of the suspending cords are readily adjusted and held by the 
 friction of the tapers against the sides of the holes . . .,. $ 2.36 
 
 For Complete Apparatus, see Section 26. 
 
 No. 5-916 
 
 5-915 HAND BALANCE SUPPORT or CLAMP for attaching to a Tripod Stand, and 
 supporting adjustably a hand balance. This clamp is designed for use on a 13 
 millimeter rod. In use, a stiff tape, a shoestring being excellent, is threaded 
 through the ring of the hand balance and then the ends threaded through the 
 holes in the clamp, then wrapped once about the binding screw. 
 
 Height of the balance is readily adjusted,'first (coarse adjustment), by position of 
 clamp on the rod, second (fine adjustment), by drawing tape through the holes in 
 the clamp. $ 0.28 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 21 
 
 No. 5-920 
 
 5-920 TELESCOPE CLAMP, for holding any round or square object from 7.5 to 16 centimeters in length, 
 especially designed for holding Reading Telescopes. This clamp is constructed of metal through¬ 
 out, with clamping device consisting of two V’s adjustable along the clamping rod to accommodate 
 the different lengths of the objects. A strap adjustable to the size of the object is designed to 
 bind it without danger of injury. The clamping rod is tapped by 20 on two faces to take the 
 10 millimeter rod, securing positions as may be noted in the illustration.$2.45 
 
 MECHANICAL ROTATOR 
 
 Mounted horizontally 
 
 The accompanying illustrations show the method employed in setting 
 up a Mechanical Rotator, using the attachments listed below in conjunction 
 with No. 5-350 Table Clamp and No. 6-20e Support Rod. 
 
 6-926 MECHANICAL ROTATOR ATTACHMENTS, consisting of a Drive 
 Wheel and Clamp and a Spindle and Clamp, the latter provided 
 on one end with groove for belt, socket and setscrew; on the other, 
 
 with a special headed lock nut. 
 
 Drive Wheel and Clamp, Spindle and Clamp and Round Belt . . . $6.75 
 
 6-926 DRIVE WHEEL and CLAMP, including Round Belt. 3.50 
 
 6-927 SPINDLE and CLAMP, one end grooved for round belt and pro¬ 
 vided with socket and set screw; other with special headed lock 
 
 nut... 3.25 
 
 6-928 ROUND LEATHER BELT with patent belt fastener. .65 
 
 For other Mechanical Rotator see No. 21-10. 
 
 Mounted vertically 
 
22 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • » 
 
 No. 6-960 
 
 MOUNTED PULLEYS, MIRRORS 
 LENS HOLDERS, ETC. 
 
 No. 6-952 
 
 No. 6-960 
 
 No. 6-970 
 
 No. 6-976 
 
 6-960 BALL-BEARING PULLEY MOUNTED ON ROD, axis at right angles to rod. Nickel plated, BALL¬ 
 BEARING, STEEL PULLEY, 60 millimeters diameter, mounted in stirrup and attached to nickel- 
 plated rod, 10 millimeters diameter, 15 centimeters long. These MOUNTED PULLEYS must not 
 be confused with the brass pulleys mounted on cone bearings, as by means of ball race we secure 
 a frictionless pulley, running true, tested to uphold 50 pounds. 
 
 6-962 BALL-BEARING PULLEY MOUNTED ON ROD, axis in same plane as rod: i. e., pulley will run 
 at right angles to rod. BALL-BEARING PULLEY, 60 millimeters diameter, mounted on nickel- 
 plated rod, 10 millimeters diameter, 15 centimeters long, pulley tested to uphold 50 pounds . . 
 
 6-960 ADJUSTABLE 60 M. M. PLANE MIRROR ON ROD. Mirror 50 millimeters diameter, adjustable 
 in stirrup about a horizontal axis, adjustable on rod about a vertical axis. Mounted on nickel- 
 plated rod, 10 millimeters diameter, 15 centimeters long. 
 
 6-970 UNIVERSAL LENS HOLDER, for lenses up to 4 inches in diameter. This ingenious holder is adjust¬ 
 able by means of the rods and set screws to hold and clamp firmly in or off center, lenses up to 
 4 inches diameter. Handsomely oxidized black with nickel-plated rods. 
 
 5-976 - —, same as above, for holding lenses up to 2 inches in diameter. 
 
 $0.94 
 
 .90 
 
 1.96 
 
 .88 
 
 .78 
 
 t 
 
 BASES, SUPPORT RODS, CLAMPS 
 
 No. 6-990 LECTURE LIST “A” 
 
 A carefully selected list of bases, rods, clamps, and attachments, covering the essentials and 
 designed for schools not in position to procure a more complete outfit: 
 
 Quan. 
 
 Number 
 
 Item 
 
 
 Quan. 
 
 Number 
 
 Icem 
 
 
 
 SUPPORT BASES 
 
 
 
 
 MISCELLANEOUS 
 
 2 
 
 6-260 
 
 Eccentric leveling Bases 
 
 1 
 
 6-540 
 
 Platform 
 
 
 
 
 
 4 
 
 6-646 
 
 Hook Collars for 13 mm. rod 
 
 
 
 SUPPORT RODS 
 
 
 1 
 
 6-950 
 
 Pulley on rod 
 
 1 
 
 6-15b 
 
 Support Rod 13 mm. 
 
 X 40 cm. 
 
 2 
 
 5-952 
 
 Pulleys on rod 
 
 1 
 
 6-15c 
 
 “ “ 13 mm. 
 
 X 60 cm. 
 
 1 
 
 6-976 
 
 Universal Lens Holder 
 
 1 
 
 6-20b 
 
 “ “ 19 mm. 
 
 X 40 cm. 
 
 
 
 
 1 
 
 5—40b 
 
 “ “ 19 mm. 
 
 X 125 cm. 
 
 
 T-BEAM BASIC CLAMPS 
 
 2 
 
 6-20e 
 
 “ “ 19 mm. 
 
 X 100 cm. 
 
 2 
 
 6-1000 
 
 Basic Clamps “A” 
 
 
 
 
 
 2 
 
 6-1160 
 
 Basic Clamps “B” 
 
 
 
 CLAMPS 
 
 • 
 
 1 
 
 6-1006 
 
 Basic Rod Swivel Clamp 
 
 2 
 
 6-460 
 
 Extension Clamps 
 
 
 1 
 
 6-1026 
 
 Single Rod Attachment 
 
 2 
 
 6-766 
 
 Right Angle Clamps 
 
 
 1 
 
 6-1030 
 
 Three Rod Attachment 
 
 2 
 
 6-770 
 
 Right Angle Clamps 
 
 
 1 
 
 6-1036 
 
 Swivel Post Attachment 
 
 1 
 
 6-860 
 
 Swivel Clamp 
 
 
 2 
 
 5-1060 
 
 Knife Edge Attachments 
 
 1 
 
 5-895 
 
 Meter Stick Clamp 
 
 
 1 
 
 6-1070 
 
 Balance Cradle 
 
 1 
 
 6-900 
 
 Pendulum Clamp 
 
 
 1 
 
 5-1080 
 
 Pulley Clamp 
 
 6-990 LECTURE LIST “A” complete, as listed above . . . . 
 
 (See next page ) 
 
 Set $36.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 23 
 
 BASES, SUPPORT RODS, CLAMPS 
 
 No. 5-995 LECTURE LIST “B” 
 
 The following list has been made up by teachers of long experience and is considered and ad¬ 
 vised by them as an equipment ample for lecture table demonstrations. The selection has been 
 made with the intention of covering every need for the lecture table, with suitable bases, support 
 rods, clamps, and attachments which will be needed in assembling and adjusting the apparatus 
 used in the most complete lecture table demonstration courses. Suggestions for enriching this 
 list either by new designs or by additions of old will be greatly appreciated. 
 
 Quan. Number Item 
 
 Quan. 
 
 Number 
 
 Item 
 
 
 
 SUPPORT BASES 
 
 
 
 CLAMPS 
 
 1 
 
 6-101 
 
 Tripod Base, 6 cm. for 10 mm. rod 
 
 1 
 
 5-891 
 
 Rod V Clamp 
 
 2 
 
 6-106 
 
 “ 8 cm. for 10 mm. rod 
 
 1 
 
 5-896 
 
 Meter Stick Clamp 
 
 1 
 
 6-114 
 
 “ 12 cm. for 10 mm. rod 
 
 1 
 
 5-900 
 
 Pendulum Clamp 
 
 2 
 
 6-116 
 
 “ 12 cm. for 10 mm. rod 
 
 1 
 
 6-906 
 
 Bi-filar Pendulum Clamp 
 
 1 
 
 6-140 
 
 “ “ 18 cm. for 19 mm. rod 
 
 
 
 1 
 
 5-170 
 
 “ 26 cm. for 30 mm. rod 
 
 
 
 MISCELLANEOUS 
 
 4 
 
 2 
 
 6-260 
 
 6-262 
 
 Eccentric Leveling Bases, 11J^-18J4 inches 
 “ “ “ 18^-32 inches 
 
 1 
 
 1 
 
 6-610 
 
 6-516 
 
 Adj. Lab. Stand, 40-70 cm. 
 
 “ “ “ 70-130 cm. 
 
 
 
 SUPPORT RODS 
 
 1 
 
 1 
 
 6-626 
 
 6-627 
 
 Platform, rod 10 mm., 7 X 8.5 cm. 
 
 “ rod 19 mm., 7 X 8.5 cm. 
 
 2 
 
 6-10b 
 
 Support Rods, 10 mm. X 15 cm. 
 
 1 
 
 6-630 
 
 rod 10 mm., 8.5 X 11.5 cm. 
 
 2 
 
 5-10c 
 
 “ “ 10 mm. X 20 cm. 
 
 1 
 
 6-636 
 
 rod 13 mm., 8.5 X 11-5 cm. 
 
 2 
 
 5-10e 
 
 “ “ 10 mm. X 40 cm. 
 
 1 
 
 5-640 
 
 rod 13 mm., 11.5 X 15.5 cm. 
 
 2 
 
 6-16b 
 
 “ “ 13 mm. X 40 cm. 
 
 1 
 
 6-646 
 
 rod 19 mm., 14.5 X 21.5 cm. 
 
 2 
 
 6-16c 
 
 “ “ 13 mm. X 60 cm. 
 
 1 
 
 6-260 
 
 Plate Base 
 
 2 
 
 5-16e 
 
 “ 13 mm. X 100 cm. 
 
 1 
 
 5-480 
 
 Stand Top, 20 cm. for 13 mm. rod 
 
 2 
 
 5-20b 
 
 “ “ 19 mm. X 40 cm. 
 
 1 
 
 6-486 
 
 “ 20 cm. for 19 mm. rod 
 
 2 
 
 6-20c 
 
 “ 19 mm. X 60 cm. 
 
 1 
 
 6-490 
 
 “ “ 30 cm. for 19 mm. rod 
 
 2 
 
 5-20e 
 
 “ “ 19 mm. X 100 cm. 
 
 1 pr. 
 
 6-376 
 
 End Supports 
 
 1 
 
 6-20f 
 
 “ “ 19 mm. X 120 cm. 
 
 1 pr. 
 
 6-386 
 
 Secondary Supports 
 
 1 
 
 6-3Qd 
 
 “ “ 30 mm. X 120 cm. 
 
 1 pr. 
 
 6-690 
 
 Knife Edge Brackets 
 
 1 
 
 6—40a 
 
 “ “ 19 mm. X 100 cm. 
 
 1 set 6-610 
 
 Leveling Screws 
 
 1 
 
 6-40c 
 
 “ “ 19 mm. X 185 cm. 
 
 1 
 
 6-636 
 
 Collar for 30 mm. rod 
 
 1 
 
 6-50d 
 
 “ “ 19 mm. X 100 cm. 
 
 2 
 
 6-636 
 
 “ for 19 mm. rod 
 
 1 
 
 6-60e 
 
 “ “ 19 mm. X 120 cm. 
 
 1 
 
 6-637 
 
 “ for 13 mm. rod 
 
 1 
 
 6-400 
 
 Stand Tube, 20 cm. for 13 mm. rod 
 
 1 
 
 6-638 
 
 “ for 10 mm. rod 
 
 1 
 
 6-406 
 
 “ 30 cm. for 13 mm. rod 
 
 6 
 
 6-646 
 
 Hook Collars for 10 mm. rod 
 
 1 
 
 6-410 
 
 “ 30 cm. for 19 mm. rod 
 
 10 
 
 6-646 
 
 “ “ for 13 mm. rod 
 
 1 
 
 6-416 
 
 “ 40 cm. for 19 mm. rod 
 
 4 
 
 6-950 
 
 Pulleys on rod 
 
 
 
 
 4 
 
 6-952 
 
 “ on rod 
 
 
 
 CLAMPS 
 
 1 
 
 6-960 
 
 Mirror on rod 
 
 2 
 
 2 
 
 6-360 
 
 6-460 
 
 Table Clamps 
 
 Extension Clamps 
 
 1 
 
 1 
 
 6-970 
 
 6-975 
 
 Universal Lens Holder, lenses up to 4- 
 “ “ “ “ up to 2- 
 
 2 
 
 2 
 
 6-726 
 
 6-736 
 
 Right Angle Clamps 
 
 “ “ “ V, 19 mm. hole 13 mm. 
 
 
 
 T-BEAM BASIC CLAMPS 
 
 1 
 
 6-746 
 
 “ “ “ V, 30 mm. hole 19 mm. 
 
 “ “ “ 2 V’s, 13 mm. 
 
 4 
 
 6-1000 
 
 Basic Clamps “A” 
 
 2 
 
 6-760 
 
 2 
 
 6-1160 
 
 Basic Clamps “B” 
 
 2 
 
 6-766 
 
 “ “ “ 2 V’s, 19 mm. 
 
 2 
 
 6-1005 
 
 Basic Rod Swivel Clamps 
 
 4 
 
 6-770 
 
 “ “ “ 2 V’s, 19 mm 
 
 1 
 
 6-1026 
 
 Single Rod Attachment 
 
 1 
 
 6-786 
 
 “ “ “ V, 19 mm., tapped 
 
 2 
 
 6-1030 
 
 Three Rod Attachments 
 
 
 
 X X 20 
 
 1 
 
 6-1036 
 
 Swivel Post Attachment 
 
 1 
 
 6-790 
 
 “ “ “ V, 19 mm., tapped 
 
 2 
 
 6-1045 
 
 Secondary Basic Attachments 
 
 
 
 X X 16 
 
 1 
 
 6-1060 
 
 Upright Secondary Attachment 
 
 5 
 
 6-810 
 
 “ “ “ for optical bench 
 
 1 
 
 6-1066 
 
 Meter Stick Attachment 
 
 1 
 
 6-826 
 
 “ “ “ for photometer 
 
 2 
 
 6-1060 
 
 Knife Edge Attachments 
 
 1 
 
 6-840 
 
 Universal Clamp 
 
 *4 
 
 6-1066 
 
 Stone’s Tension Clamp Attachments 
 
 1 
 
 6-860 
 
 Swivel Clamp for 19 mm. rods 
 
 4 
 
 6-1070 
 
 Balance Cradle Attachments 
 
 1 
 
 6-866 
 
 “ “ for 13 mm. rods 
 
 1 
 
 6-1076 
 
 Micrometer Screw Attachment 
 
 1 
 
 6-876 
 
 Universal Clamp 
 
 1 
 
 6-1080 
 
 Universal Pulley Attachment 
 
 1 
 
 6-887 
 
 Adjustable Tube Clamp 
 
 1 
 
 6-1085 
 
 Chladni’s Plate Attachment 
 
 1 
 
 6-889 
 
 Adjustable Arm 
 
 1 
 
 6-1185 
 
 Bench Anvil-Vise Attachment 
 
 6-996 LECTURE LIST “B” complete, as listed above 
 
 Set $173.00 
 
24 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 HARCOURT UNIVERSAL T-BEAM 
 
 CLAMPS 
 
 The Harcourt Universal T-Beam Clamps have been so designed that they accomplish three 
 very important results: 
 
 FIRST: They supply to the instructor a series of clamps 
 
 which, with appropriate rods, will enable him to 
 set up his apparatus in a minimum amount of time. 
 
 SECOND: They hold the apparatus, when so set up, cor¬ 
 rectly and rigidly. 
 
 THIRD: They do this at a reasonable cost. 
 
 The line which is listed in the following pages, with its lathe-rest interlocking attachments 
 and interchangeable features, gives latitude of operation never before obtained with laboratory 
 accessories. 
 
 The Harcourt Universal T-Beam Clamps are divided into two groups, Series “A” and 
 Series “B.” In the first series are two basic clamps: the Harcourt Universal T-Beam Basic Clamp 
 “A” and the Basic Rod Clamp. To these basic clamps may be clamped the various Lathe-rest 
 Interlocking Attachments. In Series “B” only one basic clamp is required, as this series is de¬ 
 signed only for heavier work, the nature of which would prohibit its use on a rod. The Lathe- 
 rest Interlocking Attachments, therefore, in this series are few compared with those listed in 
 Series “A.” 
 
 Illustrations covering the vast utility of these series are practically impossible. We secure 
 a greater range of usefulness and stability with our series than heretofore obtained by any other 
 system of laboratory hardware. In our experiments, we have been able to cover practically 
 the entire field of the “Interchangeable Laboratory Supports” by the few attachments which 
 are herewith listed, widening the field and adding to the interchangeable features. If any po¬ 
 sition or “set-up” is desired that is neither illustrated nor can be procured with our line, we most 
 urgently request the co-operation of the teachers in making known their particular needs. 
 
 On the following pages we have listed these two series of Basic Clamps and Interlocking 
 Lathe-rest Attachments. It has seemed impracticable, however, in this catalogue to show by 
 illustrations and descriptions the many ways by which the few designs can be utilized to ad¬ 
 vantage in the lecture desk demonstrations that previous to the introduction of this line required 
 the many designs heretofore offered. 
 
 In a special circular, now in press, we have endeavored to picture a few of the many exper¬ 
 iments where intelligent use of Basic Clamps and Interlocking Attachments greatly simplifies 
 lecture and laboratory conduct. Send for this circular. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 25 
 
 SERIES “A” 
 
 (Letters used in the following descriptions refer to corresponding letters in illustration above.) 
 
 5-1000 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “A” for clamping to a 
 table or any surface not over 6 centimeters thick, as the fundamental support 
 for attaching any of our Universal Lathe-rest Interlocking Attachments listed 
 in this series, (“a” in illustration.). . $0.94 
 
 5-1005 HARCOURT UNIVERSAL T-BEAM BASIC ROD SWIVEL CLAMP for clamp¬ 
 ing to any 13 or 19 millimeter rod for attaching any of our Universal Lathe- 
 rest Interlocking Attachments listed in this series, (“b” in illustration.) As 
 may be noted from the illustration of this clamp, it is in design similar to the 
 Basic Clamp “A.” It has a further important feature, however, impossible of 
 adequate illustration. This feature allows of clamping the double bevel slide 
 in any position without movement of the clamp along the rod. The universal 
 movement is secured by means of an ingenious swiveled V-clamp device read¬ 
 ily operated by the nickel-plated T-Screw. 1.65 
 
26 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 •t 
 
 UNIVERSAL LATHE-REST INTERLOCKING 
 
 ATTACHMENT 
 
 SERIES “A” 
 
 6-1025 
 
 6-1030 
 
 6-1035 
 
 5-1040 
 
 5-1046 
 
 5-1050 
 
 5- 1055 
 
 6- 1060 
 
 5- 1065 
 
 6- 1070 
 
 5- 1076 
 
 6- 1080 
 6-1085 
 6-1090 
 
 5-1160 
 
 5- 1176 
 
 6- 1180 
 
 5-1185 
 
 5-1186 
 
 SINGLE-ROD ATTACHMENT for holding a 10 millimeter rod either perpendicular or parallel to 
 face of clamp. The rod is clamped rigidly in place by means of a nickel-plated T screw. (“c” 
 
 in illustration.) In use, see No. 23-10... $0.68 
 
 THREE-ROD ATTACHMENT, tapped % X 20, % X 16, and M X 12, to hold either a 10, 13 or 19 
 
 millimeter rod. (“d” in illustration.).•. .66 
 
 SWIVEL-POST ATTACHMENT for clamping a 13 millimeter rod which may be swiveled through 
 an arc of 180 degrees and fixed in any position by a wing nut. (“e” in illustration.) In use, see 
 
 Adjustable Inclined Plane Support, Section 25. .84 
 
 THREADED SWIVEL-POST ATTACHMENT, similar to above, but provided with a boss threaded 
 to receive any rod tapped % X 16. (“f” in illustration.) In use, see Hand Air Pump, Section 42 .74 
 
 SECONDARY BASIC ATTACHMENT for use in conjunction with Basic Clamp “A” to secure a 
 lathe-rest support at right angles to that of the basic clamp, (“g” in illustration.) ....... .66 
 
 UPRIGHT SECONDARY BASIC ATTACHMENT for use in conjunction with Basic Clamp “A,” 
 
 lathe-rest slide perpendicular to clamp, (“h” in illustration.).. .68- 
 
 METER STICK ATTACHMENT for clamping a meter stick in an upright position, (“i” in illustra¬ 
 tion.) . .74 
 
 KNIFE-EDGE ATTACHMENT, (“j” in illustration.) In use see Knife-Edge Clamp, Section 5; 
 
 also Bending Beam Apparatus, Section 23. ' .66- 
 
 STONE’S TENSION CLAMP ATTACHMENT, (“k” in illustration.) In use, see Parallelogram 
 
 of Force Apparatus, Section 24. .48 
 
 BALANCE CRADLE ATTACHMENT, designed for the standard 250, 500 or 2000 gram Spring Bal¬ 
 ances. (“1” in illustration.) In use, see Parallelogram of Force Apparatus, Section 24. .66 
 
 MICROMETER SCREW ATTACHMENT, swiveled split-post tension, (“m” in illustration.) For 
 complete description, see Micrometer Screw, Section 12. In use, see Flexure of Beams Apparatus, 
 
 Section 23.:. 3.26 
 
 UNIVERSAL PULLEY ATTACHMENT, (“n” in illustration.) For complete description see 
 
 Universal Pulley, Section 27.‘. 1.76 
 
 CHLADNI’S PLATE ATTACHMENT, (“o” in illustration.) In use, see Chladni’s Figures Appara¬ 
 tus, Section 54.*.. .60 
 
 ROD V CLAMP ATTACHMENT (“t” in illustration.) This clamp will be required if it is desired to 
 clamp one rod to another, especially in obtaining a cross-bar support. .68 
 
 SERIES “B ” 
 
 (Letters used in following descriptions refer to corresponding 
 
 letters in illustration on preceding page.) 
 
 HARCOURT UNIVERSAL T-BEAM BASIC 
 CLAMP “B” for clamping to a table or any 
 surface not over 8J^ centimeters thick as the 
 fundamental support for attaching any of our 
 Universal Lathe-rest Interlocking Attach¬ 
 ments listed in this series, (“p” in illus¬ 
 tration.) The top plate is drilled and 
 threaded for taking any of our 19 mm. 
 threaded support rods. It will be found 
 particularly useful for holding the up¬ 
 
 rights on our Physics Table No. 1-120 . . $1.65 
 
 BALL-BEARING TORSION OF BEAMS 
 ATTACHMENT, (“s” in illustration.) In 
 use and for description, see Torsion Appa¬ 
 ratus, Section 23. 3.90 
 
 FIXED HEAD TORSION OF BEAMS AT¬ 
 
 TACHMENT. (“r” in illustration.) In 
 use and for description, see Torsion Appa¬ 
 ratus, Section 23. May be used in four 
 
 positions. 1.35 
 
 BENCH ANVIL-VISE ATTACHMENT, in¬ 
 terlocking with Basic Clamp “B” to secure 
 a rigid, substantial bench anvil vise. Spread 
 5J4 inches, jaws 2% inches. Provided with 
 
 hardened steel cutting-off tool. 7.45 
 
 BENCH ANVIL-VISE, consisting of No. 
 
 5-1160 Basic Clamp and above attach¬ 
 ment, complete. 9.10 
 
 No. 5-1186 Patent Pending. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 27 
 
 DIRECTION SHEETS 
 
 FOR LOOSE-LEAF SYSTEM OF INSTRUCTION 
 
 By GEORGE M. TURNER and C. BROOKS HERSEY 
 
 Masten Park High School, Buffalo, N. Y. 
 
 Perhaps the most distressing problem confronting the science teacher is that of the choice 
 of a suitable laboratory guide for his classes. Requirements differ in different localities. These 
 requirements are governed by many factors, principal among which may be cited the following, 
 — some localities are manufacturing centers, some agricultural, in short, an industrial factor; 
 some schools are not equipped to- teach from any one laboratory guide, a condition arising per¬ 
 haps from frequent changes in the instruction force, each of whom had individual methods. 
 Last, but not least, is the all-important factor of non-uniformity of College Entrance Require¬ 
 ments throughout the country. 
 
 Many instructors have solved the problem of meeting the individual school demands by 
 formulating manual directions to meet their own particular conditions, but the problem had 
 never been satisfactorily faced until Messrs. Turner and Hersey edited and authorized for pub¬ 
 lication the LOOSE-LEAF NATIONAL PHYSICS NOTE-BOOK DIRECTION SHEETS. In 
 this publication, in which we have SOLE SELLING RIGHTS, a teacher is given a latitude 
 for choice, and the extensive sale of these sheets has demonstrated their success in meeting the 
 particular individual demand of the many who use them in preference to bound manuals. 
 
 The number of experiments covered up to the issuance of this catalogue is 132. In this list 
 will be found, not only a latitude for choice of experiments but also for choice in method, thus- 
 meeting the demand for Manual Directions to conform to individual equipments. As this num¬ 
 ber is constantly increasing to keep pace with the advances made in science teaching, the NA¬ 
 TIONAL PHYSICS NOTE-BOOK WILL NEVER BECOME OBSOLETE. 
 
 Results of experience developed the following features: 
 
 Saving in the Teacher’s Time. 
 
 Saving in the Pupil’s Time. 
 
 Intense Interest Aroused in Pupils. 
 
 Clearness in the Ideas Developed. 
 
 Perfect Adaptability to Meet each Local Requirement. 
 
 Flexibility,—Meeting Teachers’ Individual Desires. 
 
 Space does not permit of a complete INDEX of the NATIONAL PHYSICS NOTE-BOOK, 
 but upon request we will mail gratis a COMPLETE INDEX with typical direction sheets. We 
 have in our files many courses which are used with, complete satisfaction by thousands of schools, 
 and have prepared for distribution PRINTED INDICES covering requirements of many States, 
 each course having been tested and found highly satisfactory. These INDICES, with typical 
 direction sheets, will be mailed upon request. 
 
 National Physics Experiment Sheets.Each net $0.01 
 
 Note .—Any selection or number of experiments in the series may be ordered at rate given. 
 
 Certification Sheets.. . Each net .01 
 
 Harcourt Binders, cloth backs, with binding cord, for holding National 
 
 Physics Experiment Sheets.Each net .18 
 
28 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 HARCOURT PORTRAITS 
 
 OF 
 
 SCIENTISTS 
 
 The HARCOURT PORTRAITS OF SCIENTISTS are admirably adapted to mural decora¬ 
 tions. They are faithful likenesses, many being reproductions in platinum prints from paint¬ 
 ings by renowned artists. They are made on heavy paper, 8 X 10 inches. When framed, they 
 should measure 16 X 20 inches, thus affording a size that will be highly decorative and ample 
 for class or lecture-room use. < 
 
 Additions to our series are made from time to time, but the present Harcourt Series numbers 
 26, as follows: 
 
 
 CHEMISTS 
 
 
 Priestley 
 
 Faraday 
 
 Wohler 
 
 Lavoisier 
 
 Bunsen 
 
 Moissan 
 
 Dalton 
 
 Ostwald 
 
 Remsen 
 
 Davy 
 
 Liebig 
 
 Pasteur 
 
 Mendelejeff 
 
 Boyle 
 
 
 PHYSICISTS 
 
 
 Newton 
 
 Tyndall 
 
 Rowland 
 
 Faraday 
 
 Helmholtz 
 
 Galileo 
 
 Henry 
 
 Kelvin 
 
 Boyle 
 
 
 BIOLOGISTS 
 
 
 Pasteur 
 
 Linnaeus 
 
 Cuvier 
 
 Huxley 
 
 Darwin 
 
 Spencer 
 
 Single Portraits, postpaid, 
 Choice any 6, 
 
 Choice any 12, 
 
 $ 1.00 
 5.40 
 10.00 
 
 THE MILLER COLLECTION OF 
 
 LANTERN SLIDES IN PHYSICS 
 
 From the negatives of Fred R. Miller, Instructor of Physics 
 in the Boston English High School. 
 
 The slides in this collection cover the various branches of Physics and offer to the prospec¬ 
 tive buyer considerable latitude for choice. The subjects were selected to conform to the peda¬ 
 gogic demands. Thus there will be found not only the modern types of machines, but slides 
 showing historical development as well. The sectional and diagrammatical slides will be found 
 of special value. 
 
 This collection is continually increasing, but at the time of issuance of this catalogue, num¬ 
 bered 324, — Mechanics 75; Heat 99; Light 40; Sound 10; Electricity 100. 
 
 A descriptive circular will be sent upon request. 
 
 Single slides.Each $ 0.40 
 
 Any 50 will be furnished in a regular Lantern Slide Box for. 20.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 29 
 
 10-10 
 
 10-20 
 
 ILLUSTRATIVE DEMONSTRATION 
 
 APPARATUS 
 
 Used by express permission of Copyright owner 
 
 No. 10-10 
 
 LARGE SIZE METRIC CHART, presenting graphically a comparative grouping of the Metric and 
 English units of weights and measures. 
 
 The chart is 50 inches wide and 46 inches high, and the illustrations, beautifully lithographed in colors, 
 are grouped in the best manner for direct comparisons of the two systems. The type is large and 
 distinct and the coloring of the whole chart is such that it will be found not only a valuable, but 
 an ornamental accessory to any laboratory. 
 
 Mounted on cloth back and provided with common rollers with hooks for hanging. 
 
 No. 10-20 
 
 POLISHED DISSECTED LITER BLOCK, graduated, dissected, and weighted for the ocular as well 
 as quantitative comparisons in the Metric System of length, area, volume, capacity, and weight. 
 
 This block is graduated,—one edge to millimeters, each face into square centimeters; dissectible to 
 1-10, 1-100, and 1-1000 of its volume; weighted so that each section has a mass equal to an equivalent 
 volume of water. 
 
 Made of selected hardwood, oil and wax finish, all graduations showing white. 
 
 $2.50 
 
 $3.00 
 
30 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • * 
 
 B 555I!5Hil 
 
 liaRBQIHRN 
 
 5 
 
 
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 8 M{ 
 
 No. 10-25 
 
 10-25 GRADUATED SOLID LITER BLOCK, for illustrative comparisons of units of length and volume in 
 the Metric System. ‘ 
 
 This block is graduated as No. 10-20 but neither loaded nor dissectible. 
 
 Made of selected hardwood, oil and wax finish, all graduations showing white.$1.35 
 
 10-30 UNGRADUATED CUBIC DECIMETER LITER BLOCK for illustration of size of one cubic deci¬ 
 meter (1000 cubic centimeters). 
 
 This block, not being graduated, dissectible, or weighted, does not have the same pedagogic value 
 as the preceding, yet will be found effective in the review of facts deduced by their use. 
 
 Made of hardwood with oil and wax finish . . .*. .65 
 
 Note. —Under No. 10-50 will be found listed a block accurately one foot on an edge. It will be found a valuable addition if ocular 
 comparison of size of cubic liter and cubic foot is desired. 
 
 No. 10-35 
 
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 HpuUHUIIl 
 
 
 No. 10-45 
 
 10-35 BURNISHED COPPER LITER CASE, illustrating quantitatively metric equivalents in measures of 
 capacity, volume, and weight. 
 
 This case is constructed so that each edge measures 10 centimeters (one decimeter), having, 
 therefore, a capacity of one cubic decimeter. It is especially adapted to the study of Archimedes’ 
 Principle and, applying this principle, to determining the specific gravity and volume of any irregular 
 solid. This case is provided with glass face for inspection of contents of case, an accurate metal scale 
 for measuring contents, and a stop-cock for inlet or outlet of water. By using a balance it may be 
 determined that for every millimeter rise or fall of water as indicated by the scale the net weight 
 varies by 10 grams, thus demonstrating that one gram of water occupies one cubic centimeter space. 
 
 Made of burnished copper with water-tight glass face, accurate metal scale and brass inlet cock . . . $3.00 
 
 10-40 CUBIC DECIMETER LITER CASE with capacity for holding exactly one liter of water. Accurately 
 
 made of non-corrosive metal, measuring one decimeter on edge internal measurement. 1.10 
 
 10-45 GRADUATED CUBIC DECIMETER LITER CASE, same as No. 10-40 but with one face graduated 
 
 into square centimeters. 1.60 
 
 10-50 SOLID CUBIC FOOT BLOCK, furnishing for demonstrative work a striking illustration of the size 
 and weight of a cubic foot of wood. Used also to advantage in density demonstrations. 
 
 Built up in sections to prevent warping and cracking, weight neatly printed in large type on one face 7.65 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 3i 
 
 No. 10-60 
 
 10-60 COMPARATIVE DENSITY WOODEN CUBES, admirably adapted for work in density, offering 
 also objects for simple measurements. 
 
 A set of eight cubes, each accurately 4 centimeters on an edge and each of different woods as follows: 
 mahogany, satinwood, poplar, oak, boxwood, walnut, ebony, and lignum-vitae. Per set, in card¬ 
 board case. .. $3.30 
 
 No. 10-70 
 
 10-66 CARDBOARD STRIP after Turner and Hersey (Exp. M011) for study of principle of a vernier 
 
 caliper.. $0.10 
 
 10-70 LECTURE ROOM VERNIER MODEL for demonstration and study of simple vernier. Model has 
 total length of 50 centimeters and is divided into 25 spaces of 2 centimeters each. Divisions and 
 figures are clearly defined and large and may be seen across the ordinary lecture room. 
 
 Made of wood with sandpaper and oil finish. 1.60 
 
 10-76 LECTURE ROOM VERNIER CALIPER MODEL for demonstrative and quantitative work. 
 
 This Caliper Model is 30 centimeters long with graduations to centimeters. It is sufficiently accurate 
 for most simple measurements, for the vernier will give readings to 1 millimeter. 
 
 Made of clear grain boxwood neatly finished, metal slides nickel plated. 2.95 
 
 10-80 LECTURE ROOM VERNIER ARC MODEL, demonstrating principle of vernier arc in angle meas¬ 
 urements. 
 
 This model is substantially made of hardwood with arc of 25 centimeters radius, vernier slides smooth¬ 
 ly and graduations are clearly and accurately made. 9.00 
 
 No. 10-85 
 
 10-86 SQUARE COMPARATIVE METER STICK for teaching the general principles of linear measure in the 
 Metric System. This stick is a full meter in length and has a cross section measurement of 2 cen¬ 
 timeters. First side is graduated into centimeters and millimeters; second, into centimeters 
 only; third, into decimeters only; fourth, ungraduated. The second and third sides have further 
 
 feature of having spaces painted alternate black and white..$1.50 
 
 10-87 METER STICK (School Meter), of maple, 2 cm. square. One surface plain showing simple meter; 
 
 second face graduated to tenths or decimeters; third, to hundredths or centimeters; fourth, to 
 thousandths or millimeters with divisions showing also decimeters and centimeters. Not painted 
 as No. 10-85.68 
 
32 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 10-100 
 
 10-100 BURNISHED COPPER LIQUID MEASURES for quantitative measures of capacity and for illus¬ 
 trative teaching of units of capacity in the metric system. 
 
 Consists of seven measures, — one litdr, and fractional parts of liter as follows: 34 liter, 2 deciliters, 
 
 1 deciliter, 34 deciliter, 2 centiliters, and 1 ceiltiliter. 
 
 Made of burnished copper.$4.90' 
 
 10-105 -, consisting of liter, deciliter, and centiliter measure?. 
 
 Made of burnished copper, same accuracy as No. 10-100. Set of three measures. 2.25 
 
 10-110 LIQUID MEASURES, same as No. 10-100, but made of tin and with the addition of a 2-liter 
 
 measure. Set of eight measures... 2.40 
 
 10-115 BURNISHED COPPER LITER MEASURE, an accurate burnished copper liter measure .... 1.00 
 
 10-120 BURNISHED COPPER QUART MEASURE, an accurate burnished copper quart measure. Useful 
 
 in conjunction with any of the above measures in comparing units in Metric and English systems 1.00 
 10-126 WOOD DRY MEASURES, 34 bushel to 1 quart, 5 pieces. 1.45 
 
 MEASURES OF LENGTH 
 
 No. 11-10 
 
 11-10 METER STICK of maple wood. Divided one side into fractional parts of foot and inch to 34 inch; 
 
 other side into fractional parts of meter and centimeter to millimeters. $0.28' 
 
 11-10A METER STICK with SET SCREW and SLOT after Turner and Hersey (Exp. M151). 38 
 
 11-11 --, same as No. 11-10, but with ends tipped with brass. .36 
 
 11-16 HALF-METER STICK, same quality as No. 11-11. Tipped with brass. .24 
 
 11-20 DOUBLE-METER STICK, same quality as No. 11-11. Tipped with brass. 1.36 
 
 11-40 TEN CENTIMETER METRIC RULE of maple. This is a convenient 10 centimeter length cut from 
 
 a meter stick and will be found of great utility in many experiments. 07 
 
 11-60 DOUBLE BEVEL BOXWOOD RULE, Metric and English Scales, with 34 inch blank ends. On 
 Metric bevel 30.5 centimeters are divided to millimeters; on English, 12 inches to sixteenths. Rule 
 
 is 1234 inches long, J-g inch wide, and % inch thick. Excellent quality.Each $0.12 
 
 Per doz. 1.40 
 
 11-66 DOUBLE BEVEL MAPLE RULE, Metric and English Scales as in No. 11-60 .Each .04 
 
 Per doz. .40 
 
 No. 11-60 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 33 
 
 
 J ^r ~ 
 
 
 
 No. 11-65 
 
 11-65 TRIANGULAR BOXWOOD RULE AND SCALE, indispensable for rapid draw¬ 
 ing to scale or in calculating actual dimensions from scale drawings. 
 
 This Rule and Scale has the merit of having six different surfaces for graduation, 
 and there are offered ten different scales to the foot: % 2 , M, Y%, iHs. Y, 
 
 1, \]/ 2 , and 3 inches to the foot. One edge graduated to sixteenths of an inch. 
 
 Made of boxwood, hand polished, 12J^ inches long with Yi inch blank ends . . $0.56 No. 11-70 
 
 11-70 VERTICALLY MOUNTED RULE. Used frequently with indicating lever in bending experiments . $0.16 
 
 11-80 STRAIGHT-EDGE RULE, especially designed for the drawing of diagrams; useful in light experiments 
 and many other experiments, chiefly in Mechanics. 
 
 Made of light, clear-grain selected stock.Per Pair .16 
 
 No. 11-100 
 
 11-100 STANDARD STEEL RULES, Metric and English Scales subdivided with greatest care and accuracy. 
 
 The 5 and 10 centimeter rules listed are divided as follows: first corner graduated to % millimeter; sec¬ 
 ond, to 1 millimeter; third, to %4 inch; fourth, to %oo inch. The remaining listed rules: first corner, to Y 
 millimeter; second, to 1 millimeter; 2 inches of third, to inch, the remainder to Y& inch; 2 inches of 
 fourth, to %oo inch, the remainder to Ys o inch. 
 
 a b c d e f 
 
 Length. 5 10 20 30 50 100 centimeters 
 
 Each. $0.30 .65 1.00 1.35 2.25 7.60 
 
 No. 11-105 
 
 11-106 POLISHED STEEL DECIMETER RULE, “A Key to the Metric System.” This rule is “one milli¬ 
 meter thick, one centimeter wide and one decimeter long. Its volume is one cubic centimeter. 
 
 Its weight in grams is the specific gravity.” One side is graduated to millimeters and centimeters. 
 
 There is also the statement that “one cubic decimeter of water weighs one kilogram and measures 
 one liter.” 
 
 Each rule sent in metal-bound leather case. . $0.68 
 
 iijjiii|!ii|iii t |iii|iii|iM|!iyiii!iii|iii!iiyiii|iii|iii|iiijiii|iii|i!i|iiL|iii|iii|iiipii 6 ] 
 
 L.E. KNOTT APPARATUS CO. 
 
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 No. 11-130 
 
 11-130 CELLULOID RULE, Metric and English, 6 inches long, with distinct black-filled accurate divisions' 
 showing clearly on the white celluloid. 
 
 The adaptability of these rulers as book markers and to the vest pocket and their flexibility to mani¬ 
 fold usage has fully warranted their popularity .... Each $0.05 Per doz. $0.60 Per 100 $4.25 
 
 L. C. KNOTT APPARATUS CO., tooto*. Him LABORATORY EQUIPMENT 
 
 *CCunU «"d «»pMj miiiu'.mtM of fUt IvdtM CitimtlM to «t|p tonth m *w. >»* y 
 
 |hil »c»U li *up*ito» to tho wood ««•#. with ioi»o»stil* «ctw'«cy. ' 
 
 No. 11-135 
 
 11-136 BRISTOL BOARD METRIC RULE, generally useful but especially adapted to measuring curved 
 surfaces. 
 
 Twenty centimeters long, graduated to millimeters with margin of about 20 millimeters on either end. 
 
 Per doz. $0.16. Per 100 $0.90 
 
34 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 11-140 
 
 11-140 BRISTOL BOARD DIAGONAL SCALE, very carefully divided, will read accurately to H) millimeter. 
 
 Length 16 centimeters..... Each $0.02 
 
 Per 100 1.40 
 
 11-146 BRISTOL BOARD COMPARING SCALE for rapid determinations of Metric and English linear 
 equivalents. 
 
 Fifty centimeters long, engine divided. $0.28 
 
 11-160 PAPER METRIC RULE, 20 centimeters long, same as No. 11-135, but of heavy bond paper . Per 100 .67 
 
 11-165 PAPER METRIC SCALE, 100 centimeters long, graduated to millimeters. Accurately printed on 
 
 heavy bond paper.Each .07 
 
 No. 11-175 
 
 11-175 STANDARD METER, graduated throughout entire length to millimeters, attaining highest possible 
 accuracy at 18 degrees Centigrade. 
 
 Graduated on brass and included in neat case.Duty Free $30.00 
 
 11-177 STANDARD METER. Same as No. 11-175, one decimeter graduated to millimeters, remainder 
 to centimeters. 
 
 Including neat case..Duty Free 21.50 
 
 11-186 FOLDING STEEL POCKET RULE, Metric and English Scales, engine divided, polished surface 
 with black, distinct figures and graduations. Graduated to millimeters on one side, to inches and 
 sixteenths on the other. 
 
 Length one foot, % inch wide, No. 28 gauge steel, folding to 4 inches. 
 
 Enclosed in metal-bound leather case. .60 
 
 STEEL POCKET MEASURING TAPE, METRIC AND 
 ENGLISH, spring wind, with stop, German silver case. 
 Graduated to inches and sixteenths on one side, to millimeters 
 
 on the other. Length 1 meter. .96 
 
 -, same as above, but 5 meters long. 4.25 
 
 LINEN POCKET MEASURING TAPE, METRIC AND 
 ENGLISH, waterproof-coated Yi inch corded tape, in 
 brass-bound case with brass folding handle, brass ring and 
 trimmings. 
 
 Marked feet and inches one side; meters and centimeters 
 
 other side. Length 10 meters. .67 
 
 -, same as above, but 25 meters long. 1.35 
 
 No. 11-220 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 35 
 
 MEASURING INSTRUMENTS 
 
 Calipers, Micrometers, Verniers, Spherometers, Gauges, etc. 
 
 Nos. 12-10 to 12-11 
 
 Nos. 12-25 to 12-26 
 
 Nos. 12-27 to 12-28 
 
 12-10 COMBINATION, OUTSIDE AND INSIDE CALIPERS, polished steel. Length 4 inches .... $0.20 
 
 12-11 -, same as above, but 6 inches long. .25 
 
 For other Calipers see Index. 
 
 12-25 OUTSIDE SPRING CALIPER, extra quality polished steel machinist’s caliper. Length 4 inches . . .80 
 
 12-26 -, same as above, but 6 inches long. .90 
 
 12-27 INSIDE SPRING CALIPER, extra quality polished steel machinist’s tool. Length 4 inches .... .80 
 
 12-28 -, same as above, but 6 inches long. .90 
 
 Nos. 12-35 to 12-36 No. 12-95 No. 12-97 
 
 12-35 SPRING GAUGE CALIPER, indispensable for the measuring of thicknesses of lenses, sufficiently 
 accurate for ordinary laboratory measurements of sheet metal and wire. Rapid and accurate, 
 
 reading directly to % millimeter. Measuring up to 10 millimeters. $1.60 
 
 12-36 -, same as above, but measuring up to 14 millimeters. 1.96 
 
 12-40 CALIPER GAUGE for measuring thickness of plates, boards, etc., within range of t4o to 1% inches, the 
 range of the caliper. Slide rod is graduated on opposite sides, one side reading 32ds, the other 
 40ths of an inch. All readings are made from the top of the knurled friction slide, and when in 
 
 operation the contact ends of the gauge are brought together against the object being measured, 
 the measuring rod may be removed from the hook part and the whole taken to the light and the 
 
 correct measure indicated above the friction slide easily taken. 2.60 
 
 12-42 -, same as above, but graduated in Metric System. Capacity 47 millimeters, rod graduated 
 
 on one side into millimeters, on the other into ^ millimeters. 2.60 
 
 12-95 LARGE DIAL MICROMETER CALIPER for measuring the thicknesses of thin plates, also diameters 
 of wires. This instrument consists of a dial, 45 millimeters diameter, divided into one hundred di¬ 
 visions. The indicator moves with the screw. Will measure thicknesses and diameters up to 5 
 
 millimeters by Yioo millimeter. Handsomely nickel plated. 6.65 
 
 12-97 -, similar to above, but provided with Friction Head. 7.16 
 
36 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 Nos. 12-110 to 12-120 
 
 12-110 FRICTION HEAD METRIC MICROMETER CALIPER. It is graduated to read to 0.01 mm. 
 
 and will measure up to 25 mm. Frame of drop forged steel nickel finished. The friction head in¬ 
 
 sures that all measurements are made with the same degree of pressure.$3.35 
 
 12-116 RATCHET STOP METRIC MICROMETER CALIPER, graduated to read to 0.01 mm. and will 
 measure up to 25 mm. This caliper is similar to above but with compensated speeded screw and 
 
 ratchet stop. 6.00 
 
 12-118 RATCHET STOP ENGLISH MICROMETER CALIPER, same as above but graduated to read 
 
 to 0.001 inch and will measure up to one inch. 6.00 
 
 12-120 RATCHET STOP DOUBLE MEASURE ENGLISH MICROMETER CALIPER, similar to above 
 
 but can be set to read to'0.001 or 0.0001 inch and will measure up to one inch. 7.40 
 
 No. 12-140 
 
 12-140 SLIDING CALIPER, English and Metric measures, of boxwood, with ivory sliding scale. Will 
 
 measure up to 3 inches by 16ths, or up to 72 millimeters by millimeters. Finer estimations possible $1.10 
 
 Models for the illustrative demonstration of principle of verniers will be found listed in Section 10. 
 
 For accurately working model of Vernier Caliper see No. 10-70. 
 
 No. 12-166 
 
 12-165 VERNIER CALIPER, Metric measure, generally useful in outside, inside, and depth measurements. 
 
 In use as outside caliper either square or caliper jaw may be used. In use as inside caliper, read 
 as for outside caliper and add 2 millimeters for width of the points. In reading for depth meas¬ 
 urement use upper row of figures and other end of vernier. Range 0 to 10 centimeters. 
 
 Made of polished steel.$2.15 
 
 12-160 VERNIER CALIPER, Metric and English measures with verniers for each. Outside, inside and 
 depth measurements each possible with great accuracy. Will measure objects up to 10.7 centi¬ 
 
 meters by millimeter, or up to inches by V 128 of an inch. 
 
 Made of polished steel and provided with thumb knob and set screw.$2.20 
 
 12-161 -, same as above, in neat leather case. 2.46 
 
 12 165 -, same as No. 12-160, but with addition of micrometer screw adjustment. In neat leather 
 
 case. 3.70 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 37 
 
 No. 12-170 
 
 12-170 TWO-HUNDRED MILLIMETER VERNIER CALI¬ 
 PER, Metric and English, for outside measurements 
 up to 200 millimeters, reading by vernier to % milli¬ 
 meter; English graduations reading by % inch up to 
 8 inches. 
 
 This caliper, constructed of polished steel, is accurately 
 
 graduated. Jaws are 55 millimeters long, the movable one 
 provided with thumb friction slide which binds automatically 
 as soon as pressure of thumb is removed.$4.60 
 
 No. 12-176 
 
 12-176 TWO-HUNDRED MILLIMETER OUTSIDE 
 AND INSIDE VERNIER CALIPER, Metric, 
 outside and inside measurements reading up 
 to 200 millimeters by Jfo millimeter. Caliper 
 jaws 11.5 cm. long, square jaws 6 cm. long. 
 
 Made of polished steel accurately graduated 
 
 $4.90 
 
 12-180 METER ROD CALIPER ARMS WITH VER¬ 
 NIER, Bonnell design, for use with Meter Stick 
 in assembling a Vernier Caliper of large range. 
 
 These arms are smooth metal castings made 
 to fit the standard Meter Stick. One arm is 
 designed for setting at some point arbitrarily 
 selected as the zero of the Meter Stick, while 
 the other carries two verniers, one to read to 
 %o of an inch on the English side, the other 
 to read to % millimeter on side with Metric 
 divisions. 
 
 Vernier arms only, neatly nickeled, per pair . . 
 
 $2.85 
 
 No. 12-185 
 
 No. 12-190 
 
 12-185 CALIPER RULE, for use as a folding pocket rule and caliper. Rapid caliper measurement possi¬ 
 ble where accuracy not greater than Vs 2 inch is desired. 
 
 Two fold, brass bound, brass slide, boxwood caliper rule, slide graduated to Vs 2 , rule to 8ths, lOths, 
 12ths, and 16ths of an inch. Total length possible, 6 inches. 
 
 12-187 -, same as above, but four fold and 12 inches long. 
 
 12-190 CYLINDROMETER for measuring diameters of spheres and cylinders from 4 centimeters upwards. 
 
 With directions... 
 
 10-76 VERNIER CALIPER MODEL for demonstrative and quantitative work. 
 
 This Caliper Model is 30 centimeters long with graduations to centimeters. It is sufficiently accu¬ 
 rate for most simple measurements, for the Vernier will give readings to one millimeter. 
 
 Made of clear grain boxwood, neatly finished, metal slides, nickel plated. For illustration, see Sec¬ 
 tion 10 . 
 
 $0.45 
 
 .55 
 
 .90 
 
38 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 12-206 No. 12-210 
 
 12-206 SPHEROMETER for measuring curvature of lenses, mirrors, etc. Steel screw accurately 1 milli¬ 
 meter pitch, silvered brass head 2 inches in diameter graduated into 50 parts. Legs cover sur¬ 
 face of 25 millimeters radius. Will measure surfaces of 5 millimeters concavity or convexity. Reads 
 directly to Vso millimeter, but as divisions on head are approximately 3 millimeters apart, esti¬ 
 
 mations to V 200 are readily possible.. $6.90 
 
 12-210 SPHEROMETER, inexpensive, serviceable form, reading directly to Y 100 millimeter. Concave 
 
 measurements to 5 millimeters, convex up to 15 millimeters. 3.30 
 
 Showingifront view of attachment Showing rear view of attachment 
 
 12-226 HARCOURT UNIVERSALLY-ADJUSTABLE T-BEAM MICROMETER SCREW for general 
 
 application in laboratory practice where a micrometer screw is needed. 
 
 The above illustration represents a form of Micrometer Screw originated by us for attachment to 
 our No. 6-1000 Harcourt Universal T-Beam Clamp “A”. This attachment consists of a cast¬ 
 ing carrying a swiveled overhanging bracket holding in split-post tension an accurately threaded 
 millimeter screw. The whole is so designed as to permit facing of the screw in either direction and 
 turning the screw in any position in a vertical plane, and a back-and-forth adjustment on the bed of 
 the Basic Clamp. In any of these positions the attachment, screw, and Basic Clamp may be 
 interlocked by the nickel-plated T screws as one rigid instrument. 
 
 The Head of the screw is 45 millimeters in diameter and is divided into 100 parts. The Screw is 
 accurately threaded 1 millimeter pitch, thus making possible a reading to Vioo millimeter. 
 
 HARCOURT UNIVERSALLY-ADJUSTABLE T-BEAM MICROMETER SCREW, complete as 
 illustrated, including Micrometer Screw Attachment and No. 6-1000 Harcourt Universal 
 
 T-Beam Basic Clamp “A”.$4.16 
 
 6-1076 HARCOURT UNIVERSALLY-ADJUSTABLE MICROMETER SCREW ATTACHMENT, illus¬ 
 trated above in connection with No. 12-226 . 3.26 
 
 6-1000 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “A”, illustrated above in connection with 
 No. 12-226 
 
 .94 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 39 
 
 12-230 MOUNTED MICROMETER SCREW. This is a care¬ 
 fully designed instrument. The Stand is massive, pro¬ 
 vided with three milled legs insuring stability and a 
 position in true plumb with the plane of the table. 
 
 The Screw is accurately threaded 1 millimeter pitch 
 and is provided with a head 45 millimeters in diameter 
 divided into 100 parts, thus reading to Yioo millimeter. It 
 is mounted in a split-post tension in an overhanging 
 bracket. Binding screw is provided for electrical con¬ 
 nection. Handsomely finished throughout. $2.90 
 
 No. 12-230 
 
 Reverse Side No. 12-280 
 
 12-276 AMERICAN STANDARD WIRE GAUGE, made of best steel, tempered, adjusted and warranted 
 accurate. Decimal equivalents expressed in thousandths, stamped on back opposite regular gauge 
 
 numbers. Sizes 0 to 36 . . .*. . $2.90 
 
 12-277 -, same as above, sizes 5 to 36. 2.20 
 
 12-280 POCKET SCREW AND WERE GAUGE for measurements of wire as well as machine and wood 
 screws. On front side of left of slot, this gauge is graduated to show all sizes of the American 
 Standard Screw Gauge from 0 to 30; on other side of slot, equivalent fractions of an inch are marked. 
 
 The edge of the gauge is graduated to 32ds and 16ths. The back side is graduated on right of slot 
 from 17 to 0000 as the old or English wire gauge; on the left from 15 to 0000 as the new or Amer¬ 
 ican wire gauge. The angle cut in the side allows the head of a screw to be placed in a positive stop 
 when measuring the length. # . 2.96 
 
 No. 12-296 
 
 12-295 POLISHED STEEL INSIDE TAPER GAUGE for inside measurements of tubes, holes, etc. Made of 
 
 hardened polished steel and about 18 centimeters long; will measure from % to 15 millimeters . . $0.80 
 
 No. 12—300 
 
 12-300 POLISHED STEEL OUTSIDE TAPER GAUGE for outside measurements of rods, etc. Made of 
 polished hardened steel about 15 centimeters long; will measure all diameters from ho to 10 mil¬ 
 limeters .>. . $1.96 
 
40 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 SQUARES AND PROTRACTORS 
 SLIDE RULES 
 
 No. 13-10 
 
 13-10 WALTER SMITH SCHOOL SQUARE. This instrument, simple in design, neat in appearance, 
 and universal in its varied applications as rule, square, and protractor, has from its popularity 
 of 35 years’ unquestioned utility become a standard laboratory instrument. 
 
 a 
 
 Length, inches 7 
 Each .... $0.06 
 
 b c 
 
 8 10 
 
 $0.08 $0.12 
 
 No. 13-30 
 
 13 20 PROTRACTOR TRIANGLE, Transparent, 30 and 60 degree angles, long leg 5 inches, divided to 1 
 
 degree. $0.60 
 
 13-22 -, same as above, but 45 degree angles.. .76 
 
 13-30 SQUARE PROTRACTOR, Ivory, 6X1% inches, graduations to single degrees, scales of %, %, %, 
 
 and 1 inch to the foot, scale of chords, and diagonal scale. 2.10 
 
 13-36 SQUARE PROTRACTOR, Boxwood, otherwise same as No. 13-30.46 
 
 No. 13-60 
 
 13-60 COMBINATION BEVELED PROTRACTOR, RULE, and SQUARE, protractor engine-divided to 
 90 degrees, care being taken to insure that the zero is accurately at right angles to the face of the 
 head. An accurately graduated, hardened, 12-inch adjustable rule passes through the revolving 
 turret and may be clamped at any point by means of the thumb nut. A small level attached to 
 one side of the head is adjustable to show any degree. 
 
 The utility of this combination instrument is unquestioned and its purchase will never be regretted . $3.46 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 4i 
 
 No. 13-75 
 
 13-76 PENFIELD ARM PROTRACTOR AND GONIOMETER for use as a rule, protractor and diagonal 
 scale. As a rule will measure to millimeters up to 14 centimeters; as a protractor ^hundredths 
 of an inch. It is an accurate goniometer for measuring plane angles. All graduations are engine 
 
 divided and all parts carefully and accurately assembled. Complete with directions.$0.66 
 
 13-76 PENFIELD CONTACT GONIOMETER for measuring angles of crystals. Similiar to above but 
 
 with the protractor arm opaque for a portion of its length. Complete with directions. .66 
 
 13-77 PENFIELD CONTACT GONIOMETER for measuring internal angles. Complete with directions. .66 
 
 No. 13-90 
 
 No. 13-100 
 
 13-90 BRASS PROTRACTOR, a good serviceable protractor, 3% inches in diameter, graduated in single 
 
 degrees.$0.12 
 
 13-92 -, engine-divided, best quality, 4J4 inches in diameter, graduated in single degrees. 27 
 
 13-94 ■——, engine-divided, best quality, 534 inches in diameter, graduated in 34 degrees. .48 
 
 13-96 GERMAN SILVER PROTRACTOR, best quality, 434 inches in diameter, graduated in single 
 
 degrees . .48 
 
 13-98 -, best quality, 534 inches in diameter, graduated in 34 degrees. 72 
 
 13-100 TRANSPARENT AMBER PROTRACTOR, semi-circular, solid, graduations and figures stamped 
 from engine-divided plate, and clearly shown in black. 
 
 abed 
 
 Graduations in. 1 34 34 34 degree. 
 
 Diameter. 4 5 6 8 inches. 
 
 Each $0.18 .40 .85 1.36 
 
 13-106 BRISTOL BOARD PROTRACTOR, printed from engine-divided plate, diameter 4 inches, grad¬ 
 
 uated to single degrees, figures reading from each end ...Per doz. .45 
 
 13-107 --, similar to above, but 5 inches in diameter and graduated to 34 degree.12 
 
BOSTON 
 
 
 42 
 
 L. E. KNOTT APPARATUS CO., 
 
 No. 13-135 
 
 13-135LCOMBINATION PROTRACTOR AND DIAGONAL SCALE, brass, silver-finished, 5}/$ inches long, 
 graduations in single degrees, figures reading both directions. Diagonal scale reading 8 centimeters 
 by % millimeter. $0.64 
 
 13-160 METRIC DIAGONAL AND PLOTTING SCALE of boxwood, 15 centimeters long. One side, double 
 diagonal scale, — one ruled square of 2 centimeters width; the other square, 1 centimeter width, 
 thus allowing measurements up to 15 centimeters by Idoo millimeter with one and by %o milli¬ 
 meter with the other. The reverse side is divided as a plotting scale, having reduction scales of 
 
 1:4, 1:6, 1:7, 1:8, and 1:9. $0.10 
 
 No. 13-175 
 
 13-176 STUDENT’S SLIDE RULE for performing arithmetical computations mechanically, — multiplica¬ 
 tion, division, squares, and square roots, ratio, etc. All are possible with accuracy to three figures. 
 This rule is made of the best quality of hard, gloss-finish bristol board, is 5 inches long, with letters, 
 
 figures and graduations neatly and distinctly shown. $0.75 
 
 13-180 MANNHEIM’S SLIDE RULE, graduations on white paper with protective coating, transparent 
 
 indicator in metal frame. 10 inches long. With simple directions. 1.40 
 
 13-185 SLIDE RULE WITH MAGNIFYING LENS ATTACHMENT, highest quality imported computing 
 rule with prominent qualities which recommend it wherever a rapid, accurate, and simple scale is 
 desired. Besides an extreme accuracy of parts and graduation, this rule is substantially construct¬ 
 ed of mahogany and inlaid with celluloid. Results are obtained directly, without mental effort 
 
 and without computations. 
 
 a 
 
 b 
 
 c 
 
 Length . . . . 
 
 25 
 
 36 
 
 50 centimeters. 
 
 Duty Free . . . 
 
 $4.35 
 
 $9.85 
 
 $14.65 
 
 
 
 
 
 
 
 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 43 
 
 14r-10 
 
 14-16 
 
 14-46 
 
 14-60 
 
 CIRCULAR PROTRACTORS, DIVIDING 
 ENGINES, LEVELS, PLUMBS 
 
 WETMORE’S TANGENT SCALE. This design was suggested by the late Prof. E. W. Wetmore, 
 Normal College, Albany. N. Y. It consists of an engine-divided bristol board dial 3% inches in 
 diameter, divided from 0 to 90 degrees in each quadrant to single degrees. On an outer circle tan¬ 
 gents of corresponding angles are indicated. 
 
 With this dial the tangents of deflection may be noted directly instead of angles themselves, thus 
 current strength may be compared directly without reference to any table.Each 
 
 BRISTOL BOARD CIRCULAR PROTRACTOR, 13 inches in diameter, with radial lines every 10 
 degrees and further subdivided on two outer circles to single and to 34 degrees. 
 
 This protractor may be used to advantage in experiments on composition of forces or on torsion Each 
 
 14-20 BRISTOL BOARD CIRCULAR 
 PROTRACTOR, 4 inches in 
 diameter. Graduated in single 
 degrees.Each 
 
 14-26 -, 3 inches in diameter. Grad¬ 
 
 uated to two degrees . . . Each 
 
 No. 14-60 
 
 No. 14-46 
 
 $0.08 
 
 .60 
 
 .08 
 
 .06 
 
 BRISTOL BOARD QUARTER-CIRCLE PROTRACTOR, a full quadrant of circle 13 inches in diam¬ 
 eter, radial lines every 10 degrees, graduated to single and 34 degrees, figured from 0 to 90 degrees 
 in both directions. 
 
 This protractor is used in experiments in torsion. $0.09 
 
 ANGLE-GRAPH for plotting any angle from 0 to 360 degrees, excellent for plotting protractors. 
 
 This instrument consists of a neatly-finished wooden base on which is mounted a brass ring, the upper 
 surface of which is accurately engraved from 0 to 360 degrees. At the geometric center of this circle 
 is fastened a brass rod with projecting screw at its center. An index and sketching arm are held 
 movably about this screw by means of a friction thumb nut. 
 
 In use, the card or paper which is to be divided is placed with its central hole over the rod in the central 
 part of the apparatus. By moving the index arm any angle from 0 to 360 degrees may be plotted. 
 Illustration shows the method of making a circular protractor. 
 
 As the instrument will take in any size up to 13 inches diameter, it will be found of great convenience in 
 
 any laboratory. 4.90 
 
44 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 14-90 
 
 flg No. 14-90 
 
 CHAPIN-STEPHENS CARPENTERS’ STANDARD LEVEL, first quality of polished cherry with 
 
 brass arch top-plate and side views. 12 inches long... 
 
 $0.76 
 
 No. 14-96 
 
 11-96 WOOD POCKET LEVEL, first quality, brass top, 5 inches long.$0.40 
 
 14-100 SOLID ROSEWOOD LEVEL, extra quality, solid rosewood, brass corners, top-plate, ends and side S’*** 
 views. Length 6% inches.. 1.60 
 
 No. 14-110 
 
 No. 14-116 
 
 14-110 BALANCE LEVEL, as used on balances and cameras. Will’indicate in all directions.$1.00 
 
 14-116 TWO-WAY LEVEL AND PLUMB, valuable in plumbing, squaring, and leveling up work. Leveling 
 is indicated in every way without moving the tool. 
 
 Weighs 3 ounces, measures 2 X 3 X M inch thick. 1*96 
 
 No. 14-130 
 
 14-126 MERCURY PLUMB BOB, made from solid steel bored 
 and filled with mercury. Improved byjjpatented slot 
 device for fastening string without tying, also by simple 
 effective device at top for fastening end of string after 
 winding up. Each bob is nickel plated and provided with 
 braided silk line. Weight 6 ounces, length 5 inches, diam¬ 
 
 eter inch. $1.66 
 
 14-130 PLUMB BOB, iron, black japan finish. .12 
 
 No. 14-136 
 
 No. 14-140 
 
 14-136 TWO-FOLD COMBINATION RULE, comprising in itself a Carpenter’s Rule, Spirit Level, Try 
 Square, Plumb, Slope Level, Brace Scale, Draughting Scale, T-Square, Protractor, Right Angled 
 Triangle, and, with a straight edge, a Parallel Rule. 
 
 Illustration shows use as a Level and as a Try Square, the upper cut showing steel blade folded like 
 a knife blade into part which holds it. 
 
 Made of boxwood, hand-polished finish, well protected with heavy brass binding. Folded, measures 
 6 X 1% X % inches. $2.26 
 
 14-140 POCKET REFLECTING LEVEL, bronze metal case, 5 inches long. In leather case complete . . . 6.26 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 45 
 
 BALANCES AND WEIGHTS 
 
 The selection of proper laboratory balances together with appropriate sets of weights for any 
 given laboratory is perhaps one of the most difficult tasks which an instructor is called upon to 
 perform. In the hope that it will be of assistance, we have arranged in tabular form our very com¬ 
 plete line of Balances and Weights, dividing them into three arbitrary groups. We believe that if 
 the instructor will consider carefully the kind of work which is to be performed and will then con¬ 
 sult the tables, he will be able to determine which balances or combination of balances will secure 
 the best results. 
 
 Every laboratory, to be well equipped, should have at least one sensitive Analytical or Assay 
 Balance. Balances of this sort, with the weights to go with them, will be found in Group One. 
 In Group Two, we have included balances of medium grade, that is, — balances of reasonable pre¬ 
 cision where the utmost accuracy and sensitiveness are not required. Group Three contains miscel¬ 
 laneous balances for heavy and general laboratory work. 
 
 In considering the classification given below, it should be borne in mind that it is impossible 
 to draw a hard and fast dividing line between each of the three groups. In making the classification, 
 however, we have been guided by our years’ experience in work of this kind, and we have taken the 
 risk of making the experiment in the hope that the tables will be of assistance to teachers who are 
 not familiar with the capacities and sensibilities of the best balances for general scientific work. 
 Detailed descriptions and illustrations will be found on the following pages under the numbers 
 specified in the tables below. 
 
 ASSAY AND ANA¬ 
 LYTICAL BALANCES 
 
 Number 
 
 Sensibility 
 
 16-10 .... 
 
 .... Moo mg. 
 
 16-20 .... 
 
 
 16-27 .... 
 
 .... ho mg. 
 
 16-30 .... 
 
 . . . . ho mg. 
 
 SCHOOL 
 
 GENERAL LABORATORY 
 
 BALANCES 
 
 Number 
 
 Sensibility 
 
 16-45 .... 
 
 .... K mg. 
 
 15-60 .... 
 
 .... y 2 mg. 
 
 16-56 .... 
 
 .... y 2 mg. 
 
 16-70 .... 
 
 .... 1 eg. 
 
 16-76 .... 
 
 .... 3 eg. 
 
 16-80 .... 
 
 .... 1 eg. 
 
 BALANCES 
 
 Number 
 
 Sensibility 
 
 Number 
 
 Sensibility 
 
 16-100 . 
 
 • -'A. eg. 
 
 16-130 . 
 
 
 16-106 . 
 
 • • l A eg. 
 
 15-136 . 
 
 
 16-116 . 
 
 . . 1 mg. 
 
 16-140 . 
 
 . . 1 eg. 
 
 16-120 . 
 
 . . 5 mg. 
 
 15-160 . 
 
 . . 1 oz. 
 
 16-126 . 
 
 . . 5 mg. 
 
 15- 160 
 
 16- 166 . 
 
 • • y* eg- 
 
 • • 1 eg. 
 
 
 HAND BALANCES 
 
 
 Nos. 16-200 and 16-206 
 Nos. 16-260, Jolly Balance 
 SPRING BALANCES 
 Nos. 16-300 to 16-376 
 
 WEIGHTS for above Balances 
 Nos. 16-10 to 16-100 
 
 WEIGHTS for above Balances 
 Nos. 16-10 to 16-100 and 
 Nos. 16-160 to 16-180 
 
 WEIGHTS for above Balances 
 Nos. 16-300 to 16-386 
 IRON WEIGHTS 
 Nos. 16-426 to 16-478 
 
46 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 BALANCES, ASSAY AND ANALYTICAL 
 
 No. 15-10 
 
 15-10 HIGH-GRADE ASSAY BALANCE, sensibility x ^ 0 milligram, agate edges and planes, 
 
 enclosed in case. 
 
 Beam 19 centimeters long, open construction, made of aluminum alloy possessing a high 
 tensile strength and a uniform density, divided into milligram divisions showing 
 white on black oxidized beam. Edges and Planes are accurately ground from the highest 
 quality stones. Provided with simple Beam Hoist and Pan Arrest. Rider Carriage is 
 operative over full length of beam. Hangers, of usual skeleton type, are made of nickel 
 silver, Pans of aluminum. 
 
 Balance is mounted on Double-Drawer Base topped by Black Glass Slab and provided 
 with Leveling Screws. It is enclosed in Polished Mahogany Case with glass front slide, 
 glass sides and top. All parts are handsomely finished with a durable acid-resisting 
 transparent lacquer. 
 
 Price from stock, $110.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 47 
 
 16-20 KNOTT’S HIGH-GRADE ANALYTICAL BALANCE, capacity 200 grams, sensibility 
 sV milligram, agate edges and planes, enclosed in case. 
 
 Beam 18 centimeters long, open truss construction, made of aluminum alloy possessing a 
 high tensile strength and a uniform density, is divided into milligram divisions filled 
 white on the black oxidized beam. Edges and Planes are ground from carefully selected 
 agate of highest quality. Provided with independently operative Beam Hoist and Pan 
 Arrests, the pan arrests being of special design easily controlled and if desired self locking. 
 Rider carriage of simple double-hook pattern has full clear sweep over entire length of 
 beam. Pans and Bows are of nickel silver, the pans being about 5.5 centimeters in 
 diameter. 
 
 Balance is mounted on Drawer Base topped by heavy Black Glass Slab provided with sensi¬ 
 tive crossed vial Level and Leveling Screws. It is enclosed in Polished French Mahogany 
 Case with front and back glass slides, glass sides and top. It is handsomely and 
 durably finished with an acid-resisting colorless lacquer. 
 
 Price from Stock, $117.60 
 
 16-27 THE “BERLIN” SHORT ARM ANALYTICAL BALANCE, capacity 200 grams, sensi¬ 
 bility ^ milligram, agate edges and planes, enclosed in case. 
 
 Beam, 15 centimeters long, open construction, is divided into Aj milligram. Simple Rider 
 Carriage operates over half of beam. Agate Edges and Planes carefully ground from 
 selected stones. New, effective Pan and Beam Arrestment operative simultaneously. 
 Bows and Pans made of nickel, pan 5 centimeters in diameter being attached. ~ 
 
 Balance is mounted on Black Glass Slab provided with quick-acting Circular Level and 
 Leveling Screws. It is enclosed in Polished Mahogany Case with glass front and back 
 slides, glass sides and top. It is finished with a protective acid-resisting lacquer. 
 
 This balance meets all requirements for accurate and rapid weighings. 
 
 Price from Stock, $65.00 
 
48 
 
 L. E. KNOTT APPARATUS CO., BOSTJON 
 
 No. 16-30 
 
 15^30 HIGH-GRADE ANALYTICAL BALANCE, capacity 100 grams, sensibility T V milligram, 
 agate edges and planes, enclosed in case. 
 
 Beam, 15 centimeters long, open construction, made of aluminum alloy possessing high 
 tensile strength and uniform density, is divided the full length from 0 at center into ^ 
 milligrams. Edges and Planes carefully ground from the highest quality selected agate. 
 
 Independently operative Beam Hoist and Pan Arrest. Simple, single hook Rider Adjust¬ 
 ment has full, clear sweep of entire length of beam. Pans and Bows are of nickel, pans, 
 7.5 centimeters diameter, being attached to bows. 
 
 Balance is mounted on Drawer Base provided with quick-acting Circular Level and Level¬ 
 ing Screws. It is enclosed in Polished Mahogany Case with front and back glass slides, 
 glass sides and top. It is Heavily Platinum Plated throughout, thus insuring against 
 corrosion. 
 
 We call especial attention to the quality of the case of this balance. It is of selected mahog¬ 
 any, carefully seasoned and polished to a piano finish. 
 
 In that all metal parts are heavily platinum plated, the balance is proof against corro¬ 
 sion. Its durability as an accurate analytical balance is permanently assured. 
 
 Price from Stock, $62.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 49 
 
 SCHOOL BALANCES 
 
 No. 16-45 No. 16-60 
 
 15-45 “HARCOURT SPECIAL” QUICK-ACTING BALANCE, capacity 100 grams, sensibility 
 X milligram, agate edges and planes, enclosed in case. 
 
 Beam, 18 centimeters long, open construction, is divided into K milligrams on one side of 
 central knife edge. Agate Edges and Planes carefully ground from selected stones. 
 Simple Beam Hoist and Rider adjustment. Pans, 8.5 centimeters in diameter, are de¬ 
 tachable. 
 
 Balance is mounted on Drawer Base, provided with Plumb Bob and Leveling Screws. 
 It is enclosed in Polished Mahogany Case with glass front slide, glass sides, top and back. 
 
 This balance was designed especially for us and we have no hesitancy in commending it as 
 combining all the essential qualifications of a high-grade balance at a cost within the 
 range of any educational institution. 
 
 Price from Stock, $42.25. Duty Free,. 
 
 15-50 KNOTT’S NORMAL BALANCE, capacity 100 grams, sensibility milligram, agate edges 
 and planes, enclosed in case. 
 
 Beam, 21 centimeters long, open construction. Edges and Planes of carefully-ground 
 agate. Simple, effectively operating Beam Hoist, detachable 8 centimeter pans. 
 
 Balance is mounted on Drawer Base, provided with Plumb Bob and Leveling Screws. 
 It is enclosed in Polished Mahogany Case with front and back glass slides, glass sides and 
 top. 
 
 The balance is lacquered throughout and being made especially for us by a noted manu¬ 
 facturer we unhesitatingly recommend its qualities. 
 
 Price from Stock, $35.00. Duty Free,. 
 
50 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 15-55 HARCOURT SCHOOL BALANCE, capacity 50 grams, sensibility Y milligram, steel edges 
 and planes, enclosed in case. 
 
 Beam, 20.5 centimeters long, closed construction. Edges and Planes of steel accurately 
 ground and polished. Simple Beam Hoist. Detachable 6.5 centimeter Pans. 
 
 Balance is mounted on Drawer Base, provided with Plumb Bob and Leveling Screws. It 
 is enclosed in Polished Mahogany Case, with glass front slide, glass sides and back, 
 lacquered throughout. 
 
 This balance is well made throughout and is dependable in all of its qualifications. 
 
 Price from Stock, $29.50. Duty Free,. 
 
 No. 15-70 No. 15-80 
 
 15-70 EQUAL ARM BALANCE, capacity 20 grams, sensibility 1 centigram, polished steel 
 edges and planes, mounted on drawer base. 
 
 Beam, 23 centimeters long, closed construction with adjusting screws, is provided 
 with eccentric lift. Pans, 7.5 centimeters diameter. Balance is mounted on 
 Polished Mahogany Drawer Base, is polished throughout, with lacquer and 
 nickel-plate finish.$12.00 
 
 15-75 -, similar in design to No. 15-70, but smaller and less sensitive. Beam 15 centi¬ 
 meters long, pans 6 centimeters in diameter, sensibility 3 centigrams .... 8.60 
 
 15-80 EQUAL ARM BALANCE, reliable for small weighings. Beam 15 centimeters long. 
 
 Pans 7.5 centimeters in diameter, Lever Lift. Balance is nickel-plated throughout 
 and is mounted on Polished Oak Drawer Base. 3.75 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 5i 
 
 PHYSICAL LABORATORY BALANCES 
 
 No. 15-100 
 
 16-100 “THE BOSTON” LABORATORY BALANCE, capacity 2000 grams, sensibility 3^ 
 centigram, polished steel knife-edges and planes, mounted on polished mahogany 
 base provided with leveling screws. 
 
 Beam, 32 centimeters between knife-edges, of open truss construction, is divided entire 
 length, with 0 at the left. Rider of improved design is attached movably to beam. 
 Edges and Planes are of polished steel accurately adjusted. Pans, 14 centimeters in 
 diameter, are detachable from stirrups. Beam Hoist of simple eccentric type, operated 
 by knurled head. 
 
 This balance is mounted on highly Polished Mahogany Base provided with Leveling 
 Screws. It is handsomely finished and coated with protective lacquer. Pans are 
 nickel-plated. 
 
 Each balance is provided with accurate counterpoise to take place of one of the stirrups 
 when balance is used in hydrostatic work. 
 
 Prospective purchasers of a balance of this type will do well to investigate our make be¬ 
 fore deciding upon another. Our confidence in our product is such that we will gladly 
 offer every facility for comparative tests on 
 
 1. Beam stability and uniform density. 
 
 2. Careful mechanical construction and, therefore, accuracy and 
 
 sensibility. 
 
 3. Design. 
 
 4. Finish. 
 
 Price from Stock, $22.00 
 
52 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 No. 16-106 
 
 15-105 THE “BAY STATE” LABORATORY BALANCE, capacity 2000 grams, sensibility y 2 
 centigram; polished steel knife-edges and planes, mounted on substantial metal base. 
 
 Beam, 32 centimeters between knife edges, of open truss construction, is divided the 
 entire length from 0 at the left. Improved rider is attached movably on beam but 
 cannot be detached. Edges and Planes are of polished steel. Pans, 14 centimeters 
 in diameter, are detachable from stirrups. 
 
 The support for this balance consists of a neatly japanned metal base to which is mounted 
 a nickel-plated upright which carries the beam. This upright is provided with a damper, 
 which, operated by a thumb screw, dampens the vibrations that rapid readings may 
 be taken. A plumb bob fastened to the upright, and leveling screws in the base, afford 
 ample adjustments for leveling. 
 
 Each balance is furnished with an adjustable shelf for work in hydrostatics. 
 
 Price from Stock, $14.35. Duty Free,. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 53 
 
 No. 15-115 
 
 No. 16-126 
 
 15-116 SPECIFIC GRAVITY BALANCE, capacity 200 grams, sensibility 1 milligram, polished steel edges 
 and planes. Beam 14 centimeters long, of aluminum alloy. Beam lift, detachable pans 7 cen¬ 
 timeters in diameter with removable papier-machejpan linings. 
 
 Each balance is mounted as illustrated and is supplied with a Thermometer Plummet (Reimann’s 
 patent), two Counterpoises of 10 and 5 gram weight, and with a glass Hydrometer Jar. Duty Free 
 
 16-120 WESTPHAL’S SPECIFIC GRAVITY BALANCE, for 
 
 rapid determinations of specific gravity of liquids 
 up to the fourth place of decimals. 
 
 All parts of this balance are most carefully made. In use 
 they are mounted on a polished mahogany box, as il¬ 
 lustrated, which serves as a storage and carrying case. 
 
 Each balance is furnished with an accurate Thermometer 
 (Reimann’s patent), Counterpoise, Jar and eight Riders. 
 
 Price from Stock . . . 
 
 Duty Free. 
 
 15-125 KNOTT’S HYDROSTATIC BALANCE with ADJUSTA¬ 
 BLY SUSPENDED BEAM. This balance is made 
 according to our specifications by a well-known European 
 balance maker. Capacity 250 grams, sensibility 5 
 milligrams, polished steel edges and planes. Beam 
 25 centimeters long graduated the whole length with 
 zero at the center. Beam hoist consists of pulley and 
 capstan. Three counterpoised stirrups with attached 
 pans are supplied; two stirrups are of the same size 
 and the third, somewhat shorter, permitting with beam 
 raised, a clear space of 23 centimeters below the scale 
 pan. Mounted on polished mahogany base. Duty Free . . . 
 
 No. 16-120 
 
54 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 15-130 
 
 No. 15-140 
 
 16-130 HYDROSTATIC BALANCE, prismatic-steel knife-edges, mounted on japanned, round, iron base. 
 
 Beam 834 inches long is supported on polished steel knife-edges on planes held in a stirrup attached 
 to the top of a brass rod which telescopes into a brass tube. 
 
 The two pans attached by chains to hooks near the ends of the beam are 4 inches in diameter and 
 are heavily nickel-plated. One pan is suspended by short lengths of chain and is provided with hook 
 for experiments in specific gravity. The beam may be elevated, giving an adjustment of from 6 
 to 14 inches from the top of the table. This balance will be found satisfactory for experiments 
 in specific gravity. It is of the best workmanship and handsomely finished throughout.$ 6.90 
 
 15-135 SPECIFIC GRAVITY BALANCE, similar in design to No. 15-130, but smaller. Beam is 734 inches 
 
 long, pans 234 inches diameter, adjustment of hook possible from 434 to 10 inches. 4.40 
 
 15-140 TRIPLE BEAM BALANCE, for rapid and accurate weighings in Physical or Chemical Laboratory. 
 Capacity 111 grams, sensibility (guaranteed) 1 centigram. 
 
 As name “Triple Beam” describes, this balance is constructed with three beams so placed one over 
 the other as to secure uniform weight upon the knife-edge. The lower beam has a capacity of 100 
 grams by 10-gram divisions; the middle beam, 10 grams by single grams; the upper beam, 1 gram 
 by 34 and 34oo gram, each beam carrying an accurately adjusted weight attached movably to it. 
 
 Base is substantially made of cast iron neatly japanned and is provided with sensitive spirit level 
 and leveling screw. Upright, neatly nickel-plated, carries an adjustable support for the receptacle 
 in specific gravity experiments. At top of upright there is a knurled head which operates a sim¬ 
 ple lift for beam when not in use. Pan, 10 centimeters in diameter, is detachable. Price from stock 14.00 
 
 15-150 PLATFORM COUNTER SCALE for 
 
 use on a counter or low platform. This 
 scale is the standard platform scale 
 with low pillar. A multitude of uses will 
 be found for it in any laboratory. Ca¬ 
 pacity 200 pounds by 1 ounce. Plat¬ 
 form measures 1034 by 14 inches. 
 
 Complete with Weights. 
 
 $17.60 
 
 No. 16-150 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 55 
 
 The form of this Trip Scale is such as to make it the most 
 convenient balance for laboratory work. 
 
 DESIGN. The center of gravity of the moving system is 
 properly placed. Made of rigid cast metal, it will stand heavy 
 loads without error. The knife-edges are held rigidly in position 
 and cannot change. The equal length of the arms is absolutely 
 assured. 
 
 No. 16-165 
 
 No. 16-180 
 
 NEW FEATURES which have been added are noteworthy in the field of Balance Construction: 
 
 METHOD OF READING. By reference to the cut, it will be noted that we have adopted the straight 
 line indicator which eliminates all errors due to parallax. 
 
 LONG GRADUATED RIDER ARM. The length of the rider arm has been greatly increased so 
 as to give a wide, open scale with a range of 10 grams in % gram divisions. 
 
 SPECIFIC GRAVITY HOOK. For convenience in Specific Gravity Experiments, a hook is securely 
 
 attached to each platform post. 
 
 ADJUSTMENT. The position of the adjusting screw is properly placed to avoid accidental displacement. 
 
 16-160 
 
 16-166 
 
 16-180 
 
 16-182 
 
 6-1160 
 
 16-186 
 
 16-186 
 
 16-187 
 
 STEEL BEARING HARCOURT TRIP SCALE.$5.76 
 
 AGATE BEARING HARCOURT TRIP SCALE. This scale, in addition to above important im¬ 
 provements, is provided with six agate planes accurately secured and set in rigid castings. The 
 agate holders are cut with such a degree of nicety that we are able to guarantee the planes not 
 to loosen or change position even to Vlooo of an inch. 6.66 
 
 THE HARCOURT INTERLOCKING METAL TRIP SCALE SUPPORT for use on the table with 
 above trip scales in specific gravity experiments. 
 
 The design of the various parts of this support is such 
 that danger of balance falling from support or being 
 knocked from same is wholly obviated. The Har- 
 court Special H-Base is designed so that the 6X8 
 inch battery jar or other containing vessel may be 
 placed directly under the suspending hook. Support 
 only. 
 
 CROSS BAR T-BEAM ATTACHMENT TRIP SCALE 
 SUPPORT, for use with our T-Beam Basic Clamp 
 No. 5-1150 in supporting the trip scales above to the 
 cross bar of Standard Physics Table No. 1-100. This 
 attachment is readily secured to the No. 5-1150 clamp 
 and permits of use of trip scale crosswise or lengthwise 
 of the table, in addition, enabling one to readily ad¬ 
 just the height of balance from top of table. 
 
 Complete without T-Beam Basic Clamp No. 5-1150. . 
 
 HARCOURT T-BEAM BASIC CLAMP “B” as re¬ 
 quired for use with above attachment ..>..... 
 
 WOODEN SPREADER FOR HARNESS, after Tur¬ 
 ner and Hersey (Exp. M041). 
 
 WOODEN COUNTERPOISE, after Turner and Hersey 
 (Exp. M041). 
 
 BRASS S-HOOK, after Turner and Hersey (Exp. 
 
 M041). 
 
 1.66 
 .12 
 .12 
 
 .08 No. 16-182 
 
56 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 15-200 HAND BALANCE, first quality stand¬ 
 ard hand balance, inch beam, 
 
 hardened steel knife-edges; horn 
 pans 3 inches diameter; beam, lac¬ 
 quered brass . 
 
 15-205 -, similar to above, but less expen¬ 
 sive in construction. 
 
 5-915 HAND BALANCE SUPPORT OR 
 
 CLAMP for use on a tripod stand as a 
 support for hand balances, affording 
 a simple but effective method of 
 adjusting the position of the pans 
 » to various conditions in experi¬ 
 
 ments in specific gravity. For il¬ 
 lustration see Section 5. 
 
 15-250 IMPROVED JOLLY BALANCE. This is a design utilizing our No. 
 
 22-130 Universal Stand used so extensively in Topic II. To this stand 
 are clamped special clamp castings, one to hold the stirrup to which the 
 spring is attached, another (No. 5-895) for clamping the mirror scale, 
 another (Platform No. 6-627) for supporting the glass vessel. The 
 adjustments possible with this structure and the ready adaptability of 
 the various parts to other uses will be noted. 
 
 Jolly Balance complete as illustrated, with two aluminum scale pans, 
 plummet, two springs, — one for high and one for low tension, and 
 accessories noted above, except glass vessel. 
 
 15-251 JOLLY BALANCE SPRING for low tension. 
 
 15-252 -, for high tension. 
 
 $2.25 
 
 1.65 
 
 7.85 
 
 .50 
 
 .50 
 
 No. 15-250 
 
 SPRING BALANCES 
 
 Nos. 15-300 to 16-315 
 
 Our spring balances are constructed for us according to our specifications and we have, therefore, been able to 
 embody important features not found in stock designs. One of our specifications in our orders to the manufacturer 
 is that the tension of the spring must be uniformly accurate. Graduations are distinct and all parts are Carefully made 
 throughout. Handsomely finished in nickel and black finish. All our balances have double pointer for accurate 
 readings in both horizontal and vertical positions. In use in vertical position the weight of the hook is automati¬ 
 cally deducted by the width of the pointer. 
 
 • • 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 57 
 
 1&-300 
 
 16-305 
 
 16-310 
 
 16-316 
 
 FLAT BACK SPRING BALANCE, double scale, 250 grams by 10-gram divisions’, and 8 ounces 
 
 by 34-ounce divisions.$0.80 
 
 ——, double scale, 500 grams by 20-gram divisions, and 16 ounces by J^-ounce divisions. . . 1.00 
 
 -, double scale, 2000 grams by 25-gram divisions, and 64 ounces by 34-ounce divisions. . . .46 
 
 -, double scale, 15 kilograms by 200-gram divisions, and 30 pounds by J^-pound divisions. . . 1.66 
 
 No. 16-332 
 
 16-330 TEN-POUND LABORATORY DYNAMOMETER in nickel-plated brass tube. English system 
 
 only, 10 pounds by 34 pound. Length, exclusive of hook and ring, 3% inches.$1.40 
 
 16-332 TWENTY-POUND LABORATORY DYNAMOMETER in nickel-plated brass tube. English 
 
 system only, 20 pounds by 34 pound. Length, exclusive of hook and ring, 8 inches. 2.16 
 
 16-334 SIXTY-POUND LABORATORY DYNAMOMETER in nickel-plated brass tube. English sys¬ 
 tem only, 60 pounds by 34 pound. Length, exclusive of hook and ring, 934 inches. 3.20 
 
 No. 16-366 
 
 16-360 SPRING BALANCE CRADLE, for holding a spring balance in a flat position. Made entirely of 
 
 metal for double-scale balances Nos. 16-300 to 16-310.$0.16 
 
 16-366 -, same as above, but made entirely of wood for spring balance No. 16-316.46 
 
 No. 15-376 
 
 16-375 RINTOUL’S SPRING DYNAMOMETER, open movement, an effectively working spring balance. 
 
 Consists of the usual form spring resting in a groove, with hook for attaching to scale pan, etc. A 
 double indicator allows reading from scale from 1 gram up to 250 grams, or from 34 ounce up to 
 8 ounces, with balance in either horizontal or vertical position. An adjustment at top by which 
 the spring can be reset allows for variations in the zero reading, providing spring should become 
 permanently elongated. Made wholly of metal and handsomely finished in bright nickel and 
 japan.$2.50 
 
58 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • i 
 
 WEIGHTS 
 
 STANDARD NORMAL WEIGHTS 
 
 The weights under this heading are adjusted, with the utmost nicety attainable, to the standard 
 which has been verified by the “Bureau International des Poids et Mesures” at 0° in vacuo, to an 
 accuracy of 0.01 milligram. 
 
 No. 16-10 
 
 16-1Q STANDARD NORMAL KILOGRAM, constructed of the hardest attainable drawn-brass 
 rod turned to shape, and trimmed by long and tedious work to practical accuracy, 
 the final finest adjustment being then secured by an adjusting pin ground into the top, 
 and a gold plating. 
 
 Enclosed in polished mahogany, plush-lined lock case. 
 
 Duty Free, $32.50 
 
 16-15 STANDARD NORMAL GRAM, constructed from a single piece of platinum-iridium, 
 trimmed and adjusted with the same nicety as the above. 
 
 Enclosed in polished mahogany, plush-lined lock case. 
 
 Duty Free, $16.75 
 
 16-20 STANDARD NORMAL WEIGHTS, each weight constructed from the hardest attainable 
 hard-drawn brass rod turned to shape, trimmed and adjusted with the same pains¬ 
 taking accuracy as the above. Fractional weights are of platinum, adjusted to finest 
 possible accuracy. Set from 1 milligram up to 100 grams, enclosed in polished mahogany, 
 plush-lined case. 
 
 Duty Free, $38.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 59 
 
 PRECISION AND ANALYTICAL WEIGHTS 
 
 The following weights, Nos. 16-50 to 16-100, are adjusted^to the highest degree of accuracy. Turned from hard- 
 drawn brass rod, they are more durable than cast weights andjmuch superior from standpoint of permanent accuracy. 
 
 No. 16-60 
 
 16-60 PRECISION WEIGHTS, gpld-plated. Fractional weights 500 to 10 milligrams, are of platinum, 
 the smaller ones of aluminum. One milligram up to 50 grams, with ivory-pointed forceps and 
 camel’s-hair brush in velvet-lined, highly polished mahogany case with removable lid. 
 
 Price from Stock $12.00 
 Duty Free. 
 
 16-62 -, same as above, but 1 milligram up to 100 grams. 20.00 
 
 16-64 - —, same as above, but 1 milligram up to 200 grams.Duty Free . . . 
 
 16-70 ANALYTICAL WEIGHTS, gold-plated, similar to Nos. 16-60 to 16-64, but of different, though as 
 accurate adjustment, and enclosed in case of cheaper construction. One milligram up to 50 grams 
 
 Duty Free . . . 
 
 16-72 -, same as above, but 1 milligram up to 100 grams ..Duty Free . . . 
 
 Nos. 16-80 to 16-100 
 
 16-80 ANALYTICAL WEIGHTS, single weights, gold plated, minutely adjusted, as used in sets Nos. 16-70 to 16-72. 
 
 abcdefghi j 
 
 Size, grams 1 2 5 10 20 50 100 200 500 1000 
 
 Each . . . $0.60 $0.76 $0.96 $1.36 $1.60 $1.90 $2.40 $3.10 $4.26 $6.86 
 
 16-90 ANALYTICAL FRACTIONAL WEIGHTS, single weights, — 500 to 10-milligram weights of platinum; 
 5 to 1-milligram weights of aluminum, as used in sets Nos. 16-70 to 16-72. 
 
 a b c 
 
 Size, milligrams 12 5 
 
 Each. $0.20 $0.20 $0.20 
 
 16-100 ANALYTICAL RIDER WEIGHTS, single 
 
 a 
 
 Size, milligrams . . 1 
 
 Each . $0.40 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 10 
 
 20 
 
 50 
 
 100 
 
 200 
 
 $0.30 $0.35 
 
 $0.45 
 
 $0.75 
 
 $1.10 
 
 weights of solid gold. 
 
 
 
 
 b 
 
 c 
 
 d 
 
 e 
 
 
 2 
 
 5 
 
 10 
 
 12 
 
 
 $0.40 
 
 $0.25 
 
 $0.25 
 
 $0.25 
 
 
 500 
 
 $1.95 
 
 For other SINGLE WEIGHTS, FRACTIONAL WEIGHTS, and RIDERS, see Nos. 16-350 to 16-370. 
 
6o 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 TECHNICAL WEIGHTS 
 
 The weights under this heading are intended for technical purposes. They are carefully ad¬ 
 justed, but not to the same degree of accuracy as our Precision and Analytical Weights. Single 
 weights are made of hard-drawn brass rods turned to weights, neatly lacquered and then adjusted. 
 
 No. 16-154 No. 16-178 
 
 16-150 WEIGHTS, 1 milligram to 20 grams, in highly-polished mahogany case with cover. Fractional 
 weights, 500 to 10 milligrams of German silver, 5 to 1 milligram of aluminum; with forceps, under 
 
 stout glass plate.$3.95 
 
 16-161 -, same as above, but 1 milligram to 50 grams. 4.46 
 
 16-152 -, same as above, but 1 milligram to 100 grams. 5.76 
 
 16-153 -, same as above, but 1 milligram to 200 grams.Duty Free 6.40 
 
 16-154 -, same as above, but 1 milligram to 500 grams.Duty Free 6.90 
 
 16-176 WEIGHTS, same quality as above, but in highly polished pear-wood block, fractions under a glass 
 
 cover. One milligram up to 20 grams; with forceps. 2.15 
 
 16-176 , same as above, but 1 milligram up to 50 grams. 2.95 
 
 16-177 —-—, same as above, but 1 milligram up to 100 grams. 3.40 
 
 16-178 ——, same as above, but 1 milligram up to 200 grams. 4.16 
 
 16-179 —-—, same as above, but 1 milligram up to 500 grams. 6.85 
 
 16-180 , same as above, but 1 milligram up to 1000 grams. 8.76 
 
 No. 16-227 No. 16-230 
 
 16-225 ALL-IVORY FORCEPS, 11 centimeters long, best quality.$1.40 
 
 16-227 IVORY-POINTED BRASS FORCEPS, 11 centimeters long.75 
 
 16-230 LACQUERED BRASS FORCEPS, 10 centimeters long. .16 
 
 16-260 FLAT CAMEL’S-HAIR BRUSH, y 2 inch wide, best quality.16 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 61 
 
 GENERAL LABORATORY WEIGHTS 
 
 Nos. 16-300 to 16-302 Nos. 16-310 to 16-316 
 
 No. 16-327 
 
 16-300 BRASS WEIGHTS, 1 centigram up to 50 grams, in polished hardwood box with cover.$1.86 
 
 16-302 -, same as above, 1 centigram up to 100 grams. 2.30 
 
 Note. We recommend these weights in covered boxes, since there is less risk of loss and the weights are kept free from dust. 
 
 16-310 BRASS WEIGHTS, same quality as above, but in block; 1 centigram up to 20 grams ....... 1.20 
 
 16-312 -, same as above, 1 centigram up to 50 grams. 1.40 
 
 16-316 -, same as above, 1 centigram up to 100 grams. 1.86 
 
 16-326 BRASS WEIGHTS, same quality as above, but without fractional weights, 1 gram up to 500 grams 3.96 
 16-327 , same as above, 1 gram up to 1000 grams. 5.60 
 
 Note. The use of No. 16-325 or 16-327 is recommended with Trip Scale No. 15-160 or 15-165, as no smaller weight than 
 1 gram is needed. 
 
 Nos. 16-360 to 16-366 
 
 16-360 SEPARATE BRASS WEIGHTS, as used in “General Laboratory Weights.” 
 
 a b c d e f?| g h i j 
 
 Size, grams 1 2 5 10 20 50 100 200 500 1000 
 
 Each . . . $0.07 $0.08 $0.10 $0.12 $0.16 $0.24 $0.36 $0.68 $1.16 $2.26 
 
 wiS 
 
 16-366 SEPARATE FRACTIONAL WEIGHTS of German silver, as used in “General Laboratory Weights.” 
 
 abcdefghi 
 Size, milligrams ... 1 2 5 10 20 50 100 200 500 
 
 Each.$0.06 $0.06 $0.06 $0.06 $0.06 $0.06 $0.06 $0.06 $0.06 
 
 No. 16-370 
 
 16-360 FRACTIONAL WEIGHTS, German silver and aluminum, one each listed under No. 16-366, with 
 
 duplicates of the 2, 20 and 200-milligram weights. In cardboard box.Per Set $0.66 
 
 16-370 FRACTIONAL WEIGHTS, German silver, as listed under No. 16-360, but in neat wooden, slide- 
 
 top box with separate compartment for each size weight. L24 
 
 16-380 AVOIRDUPOIS BRASS WEIGHTS, V a ounce up to 1 pound. In block. 4.40 
 
 16-386 TROY BRASS WEIGHTS, V 2 grain up to 1 ounce. This set is highly recommended for its peda¬ 
 gogic value in teaching the relation of the Troy system and the other systems of weights .... 1.90 
 
62 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 IRON WEIGHTS 
 
 Nos. 16-425 to 16-430 
 
 Iron weights are now practically universally used in 
 mechanical powers experiments, with sonometers, etc. 
 
 No. 16-440 
 
 16-425 OCTAGONAL IRON WEIGHTS, 52 grams up toll kilogram.Per Set $1.40 
 
 16-430 -, 5 grams up to 2 kilograms.Per Set 2.16 
 
 16—440 DISC IRON WEIGHTS, 1 ounce up to 16 ounces. 
 
 Set comprises weights of 1, 2, 4 and 8 ounces with 
 duplicate of the 1 ounce. 
 
 16-450 INTERHOOKING LABORATORY WEIGHTS for 
 
 general utility in the Physical Laboratory in 
 the study of mechanical advantages of simple 
 machines. 
 
 These weights are accurately adjusted from cast 
 hexagonal blocks of iron, of a design permitting 
 the attaching of one weight to the other by a hook, 
 the top of one to the bottom of the other, the 
 hooking attachment in the bottoms, however, not 
 hindering standing each weight upright. The 
 set consists of a 10, 20, 50, 100, 200, 500, and 1000 
 gram weight, with duplicates of the 20 and the 
 200-gram pieces. Each weight fits readily into an 
 apartment in a neatly japanned cast-metal holder. 
 
 Set complete with holder. 
 
 .95 
 
 2.76 
 
 No. 16-460 
 
 16—452 INTERHOOKING LABORATORY WEIGHTS. 
 
 Set complete as above but without holder . . . 2.25 
 
 16—453 CAST METAL HOLDER with separate compartment for each weight listed 
 
 above . .$0.66 
 
 16-460 SLOTTED METRIC WEIGHTS, accurately adjusted. Set of 1-500, 5-100, 
 
 1-50, 2-20, and 1-10 gram weights mounted on japanned holder. 1.70 
 
 No. 16-460 
 
 16-477 SLOTTED METRIC WEIGHTS and 
 WEIGHT HANGER for use in me¬ 
 chanical powers experiments where large 
 capacity weights are not needed. Con¬ 
 sists of a nickel-plated brass hanger ac¬ 
 curately adjusted to 50 grams weight, and 
 a set of weights same quality and as 
 listed in No. 16-460—1-500, 5-100, 1-50, 
 
 2-20, and 1-10 gram weights. 
 
 Set complete with hanger. 2.20 
 
 16-478 SLOTTED METRIC WEIGHTS, separate 
 weights same quality as listed above. 
 
 a b c d e 
 
 Size, grams . . 10 20 50 100 500 
 
 Each. $0.18 .22 .28 .35 .48 
 
 No. 16-477 
 
 16-479 WEIGHT HANGER, accurately adjusted to weigh 50 grams. Nickel-plated. Same as used in 
 No. 16-477 . 
 
 $0.50 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 63 
 
 ADJUSTED METRIC CAST IRON WEIGHTS 
 
 These weights are made from carefully-designed patterns, provided with groove and raised ring which enables 
 them to be readily piled on top of one another without danger of slipping and producing confusion in the lecture 
 room or laboratory. 
 
 The slot in each is made slightly narrower than the diameter of the hole in the center, enabling the weight to 
 be easily put on and taken off from the Pratt Institute Weight Hanger listed below, and at the same time, preventing- 
 the weights from accidentally falling from the hanger. See above cut. 
 
 These weights, being made of the finest quality of castings, carefully adjusted, may be depended upon for care¬ 
 ful work. 
 
 16-485 . a b c d 
 
 Size, kilos. H 1 2 5 
 
 Each .$0.48 .57 .75 1.60 
 
 16—487 WEIGHT HANGER, Pratt Institute design. 
 
 All of our hangers in this group are made with the upper portion of the rod cut away to fit the slot 
 in the weight, while the main part of the rod is the same size as the hole in the center of the weight. 
 This insures the weights being held securely in position, making it impossible for them to acci¬ 
 dentally fall off, and at the same time rendering it easy to put them on and take them from the 
 hanger without removing the hook from its support. This feature adds materially to the ease of 
 their use in the laboratory and is indispensable where large laboratory divisions are a necessity. 
 
 Hanger accurately adjusted to weigh 500 grams. 
 
 16-489 SLOTTED METRIC WEIGHTS WITH WEIGHT HANGER. Set consists of one each weights 
 listed under No. 16-486 and No. 16-487 Weight Hanger. 
 
 $0.90' 
 
 4.15- 
 
 UNADJUSTED CAST IRON WEIGHTS 
 
 These weights are designed for Mechanical Powers experiments in Applied Physics. While not adjusted to 
 exact weights, being cast uniformly from carefully adjusted patterns, they are sufficiently accurate for all the uses 
 for which they are designed. 
 
 As may be noted from the illustration, there are three series. The slots in all the weights are of uniform size. 
 The rods on all the hangers are of the same size, the only difference being in the size of the supporting disc and in 
 the length of the supporting rod. 
 
 We recommend Hanger d for Weights a, b and c; Hanger g for Weights e and f, and Hanger j for Weights b. 
 and i. (See tabulation below.) 
 
 SERIES 1 
 
 Weights Hanger 
 16-500 ... a be d 
 
 Size, pounds H HI 
 
 Each .... $0.11 .14 .18 .45 
 
 SERIES 2 
 
 Weights 
 e f 
 
 2 5 
 
 $0.27 .68 
 
 Hanger 
 
 g 
 
 SERIES 3 
 
 Weights 
 h i 
 
 10 20 
 
 $1.07 1.74 
 
 Hanger 
 
 j 
 
 .90 
 
 .62 
 
64 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 TIME — INDICATORS — SPEED 
 
 CLOCKS, PENDULUMS, METRONOMES, ETC.; SPEEDOMETERS 
 
 7-10 LABORATORY CLOCK for general use as an accurate time¬ 
 keeper and for beating seconds. 
 
 This clock has an eight-day, standard movement, weight driven, 
 and we guarantee its reliability as an accurate time-keeper. 
 
 The lens-shaped bob is of polished brass and the pendulum 
 is full seconds length, the center of oscillation being readily 
 adjusted by means of a thumb-screw. The dial, designed 
 especially for laboratory usage, is not confused by the usual large 
 hour numerals, for since in laboratory practise seconds beats 
 are essential, the seconds divisions are the most prominent. 
 
 Thus in our dial, the hour and minute divisions with their hands 
 are small, while the seconds divisions are large and the seconds 
 hand is long. All three, however, are sufficient in size to be 
 readily seen from any part of the laboratory. 
 
 The mercury well is of improved design, exposing a thin strip of 
 mercury adjusted by means of an easily accessible knurled 
 thumb-screw. The graduated arc affords an excellent, simple 
 device for leveling, when setting up the clock in the laboratory. 
 
 The case of our clock is of polished mahogany, designed practically 
 dust-proof. It is, in appearance, equal to the excellent quality 
 of the movements which it contains. It is provided with bind¬ 
 ing posts for electrical connections for attaching battery and 
 sounder . . $64.00 
 
 17-15 MAGNETIC CLOCK CONTACT for attachment to any labora¬ 
 tory clock, making an adjustable positive contact that cannot 
 get out of order. 
 
 The design of a magnetic clock contact was first suggested to avoid 
 the disagreeable features accompanying a mercury contact. 
 
 The contact is positive and the make-and-break instantaneous. 
 
 It is readily attached to any seconds pendulum, or any make 
 laboratory clock with swinging pendulum. Complete, ready 
 for attachment.12.00 
 
 17-26 INTERVAL TIMER. This is a well-made, handsomely nickel- 
 plated and reliable interval timer especially valuable in all 
 experiments in which action for a definite length of time is 
 necessary. The alarm may be set to ring at the expiration of 
 any interval from one-quarter of a minute up to two hours. 
 Complete with directions. 2.46 
 
 No. 17-10 
 
 17-40 DISSECTED CLOCK, for student’s use in the study 
 of weight-driven clocks. All parts are mounted on 
 card numbered or lettered for easy reference. All 
 parts are substantially built and accurately fitted and 
 no tools are necessary in assembling. Being of sim¬ 
 ple construction, no mechanical skill is needed to as¬ 
 semble, — directions furnished with each clock being 
 full and simple. Assembled, the clock will keep good 
 time. 
 
 This clock is highly recommended for its educational 
 value in making clear the complexity of parts of an 
 expensive time-keeper. It has the further value of 
 increasing the interest of the student. Complete, 
 with full directions, in a neat box. $2.46 
 
 
 No. 17-40 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 65 
 
 No. 17-60 
 
 No. 17-60 
 
 No. 17-75 
 
 17-60 FULL-SWEEP SECONDS PENDULUM for beating seconds in laboratories where the more expensive 
 laboratory clock *s not available. 
 
 This pendulum consists of a full-sweep seconds pendulum with metal bob, cast lens-shape to over¬ 
 come air resistance, and suspended on ground and polished steel edges in a special stirrup. It is 
 mounted on polished hardwood board with an adjustable mercury well designed to expose a thin 
 strip of mercury sufficient to cause a positive contact. The mercury is adjusted by means of a 
 screw. Further adjustment is possible by the adjustable contact tip. Binding posts are con¬ 
 
 veniently placed for connection of battery and sounder.$ 6.90 
 
 17-66 FLASH SECONDS PENDULUM, after Turner and Hersey (Exp. S010). 1.30 
 
 17-60 ZINC AND IRON COMPENSATING PENDULUM, illustrating employment of metals having 
 different coefficients of expansion in keeping the distance between the center of suspension and 
 the center of oscillation constant. Consists of alternate rods of zinc and iron, so attached that the 
 expansion of one is compensated by the expansion of the other. Mounted on neatly finished base . 12.36 
 
 17-76 COMPENSATING MERCURY PENDULUM, an accurately constructed, handsomely finished, full- 
 length seconds pendulum, compensated by the expansion of mercury. 
 
 This design, a modification of the Graham’s mercury pendulum, consists of a steel rod as in a simple 
 seconds pendulum, but in place of the disc bob are suspended two glass mercury wells in suitable 
 holders. All adjustments are provided. Simply operated and effectively working. The apparatus 
 is handsomely finished throughout and the quality of workmanship is of the finest. 
 
 Complete as illustrated, with stirrup, but without mercury. 6.76 
 
66 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 17-90 CLOCK DEMONSTRATION BALANCE WHEEL, — two compound bars, electrically welded and 
 mounted in connection with a spring, substantial base, pivot bearing, as indicated in the accom¬ 
 panying illustration, showing clearly the principle of the self-regulating balance wheel in watch 
 
 and clock movements. .$4.25 
 
 17-120 METRONOME for time-marking in laboratory experiments in the study of Falling Body, Pen¬ 
 dulum, etc. This instrument has a graduated scale and a marker operated by spring-driven clock¬ 
 work enclosed in polished mahogany case. 3.60 
 
 17-125 METRONOME WITH BELL. This is the same quality Metronome as above, but has the additional 
 feature of a bell attachment which can be regulated to sound every beat, every second, third or 
 
 fourth beat as desired. 6.36 
 
 17-160 STOP WATCH, an indispensable accessory to the equipment of any well-equipped laboratory. 
 
 This watch is of excellent quality, stem wound, lever movement, beating one-fifth seconds, neatly 
 
 polished nickel case with stop.. . . .. 7.10 
 
 17-166 STOP CLOCK, with 5-inch dial and with seconds hand. In highly-polished mahogany case. De¬ 
 signed to be hung on the wall or placed on a table. This clock is an accurate time keeper, having 
 the distinctive feature of being an inexpensive stop clock with qualities that would warrant its 
 adoption in class-room demonstrations. 9.80 
 
 No. 17-200 
 
 17-200 UNIVERSAL SUN DIAL. In our Sun Dial, which may be adapted to any latitude, we offer an in¬ 
 strument scientific in design and capable of accurate work. It is 12 inches square, substantially 
 constructed of metal and can be continuously exposed in any climate without injury. By an 
 ingenious arrangement, not illustrated, a correct setting for any latitude can easily be obtained. 
 
 We supply with each instrument a printed form on which a correction curve for any locality can 
 readily be plotted from full and explicit directions furnished with each instrument. 
 
 Each instrument is durably finished with a protective coating, the figures and lines showing in colors 
 against the black finish on the casting. 
 
 Universal Sun Dial, complete with directions for correct setting for any latitude. 7.60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 67 
 
 No. 17-300 
 
 No. 17-305 
 
 No. 17-326 
 
 [No. 17-310 
 
 17-300 IMPROVED SPEED COUNTER for measuring speed of rotation of shafts in efficiency experi¬ 
 ments, etc. The indicating dial is graduated into one hundred parts and graduations show every 
 revolution and with two rows of figures which read both right and left.'.$1.10 
 
 17—306 SELF-REGISTERING SPEED COUNTER. Registers up to 9,999 revolutions on low or high 
 
 speeds up to 5000 R. P. M. Registers in either direction. When shaft turns one way the counter 
 adds, the other way it subtracts. Complete with one pointed and one flat insulating tip ... . 3.40 
 
 17-310 SELF-REGISTERING SPEED COUNTER. Registers in either direction up to 99,999 revolutions 1.50 
 
 17-326 SELF-REGISTERING HAND COUNTER. Operated by slight hand pressure upon small lever 
 
 shown in illustration. Complete with socket plate. 2.00 
 
 MATHEMATICAL MODELS 
 
 4 li 9^0 & 
 
 13 14 15 16 17 18 19 20 21 
 
 22 23 24 25 26 27 28 29 30 
 
 38 
 
 L^Z. 
 
 39 40 41 42 43 44 
 
 No. 18-10 
 
 18-10 GEOMETRICAL WOODEN FORMS, consisting of twenty-four solids, seventeen surfaces, and 
 three angles, the latter being represented by bent wires. Solids are accurately turned from well- 
 seasoned hard wood, surfaces cut with accurate steel dies from stiff, hard, light-colored board. 
 Complete in strong wooden box, with table of contents pasted on the under side of the cover . . . $2.95 
 
68 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 18-20 No. 18-50 
 
 18-20^ CONE, SPHERE, and CYLINDER for ocular demonstration of the relation between the contents of 
 cone, sphere, and cylinder. The cone and cylinder are 3 inches deep by 3 inches in diameter. Actual 
 demonstration shows that the cone, three times filled with water, fills the cylinder, and that the 
 cylinder filled with water and sphere submerged, enough water will remain in the cylinder to fill the 
 cone, thus showing that their contents are as the ratio 1:2:3 .Per Set $1.10 
 
 18-30 DISSECTIBLE CONE for illustrating conic sections, circle, ellipse, parabola, and hyperbola. This 
 cone is made of different kinds of hard wood, highly polished on the surface, each section held by 
 large- pins. Being of ample proportions, sections are of convenient demonstrating sizes. 3.35 
 
 18-40 TRIANGLE DEMONSTRATION APPARATUS for demonstrating mechanically that the area of a 
 
 triangle is equal to its base multiplied by one-half its altitude. 
 
 The apparatus consists of two triangles so hinged that by simply swinging certain parts on their 
 
 hinges, the triangles resolve themselves into two rectangles 12 inches long by 3 inches high . . . 1.45 
 
 18-60 CIRCLE AREA DEMONSTRATION APPARATUS for demonstrating mechanically that the area 
 of a circle is equal to the radius multiplied by one-half the circumference. The apparatus consists 
 of a large number of sectors attached at their bases by a pliable band connecting them by hinges. 
 
 This band is in two parts, so that the circle made of sectors may be separated into two semi-circles. 
 
 When these two semi-circles are straightened out, two toothed forms result. By inserting the teeth 
 of one form between the teeth of the other a rectangle is formed. The base of this rectangle, then, 
 is a semi-circumference and its height, the radius of the circle. The diameter of disc is 8 inches . 2.10 
 
 18-52 BRASS DISC, 8 centimeters diameter with radius indicated, after Millikan, Gale and Bishop (Exp. 
 
 1).27 
 
 18-66 HOLLOW BRASS CYLINDER, with glass cover, after Millikan, Gale and Bishop (Exp. 2) . . . . .65 
 
 18-60 CUBE ROOT BLOCKS for illustrating in a simple manner the underlying principles of cube root 
 extraction. The apparatus consists of an accurately dissectible wooden cube, the size of the inner 
 cube being 3 inches on an edge and the assembled cube being 4 inches. 2.00 
 
 MODELS OF CRYSTALS 
 
 No. 18-126 
 
 18-126 CRYSTAL MODELS OF SOLID GLASS, a set consisting of six models, representing the six basic 
 
 geometrical forms. In neat cardboard case.$4.76 
 
 18-130 CRYSTAL MODELS OF SOLID GLASS, a set of twenty different forms, surfaces ground and pol¬ 
 ished, axes 3 to 6 centimeters in length. Enclosed in case.Duty Free 8.00 
 
 18-200 CRYSTAL MODELS OF WOOD, consisting of thirteen different forms, representing the most com¬ 
 mon crystal formations. In cardboard box. . . 2.60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 69 
 
 DRAWING INSTRUMENTS 
 
 In listing our line of drawing instruments, we have in mind the elementary requirements of 
 such a class of goods, yet we believe that fewer instruments, rather than cheaper grade, are ad¬ 
 visable if the school’s appropriations will not warrant the expenditure for such instruments. 
 
 The line of instruments which we list are made of hard-pressed German Silver, and finished 
 steel. They have received all the improvements of fine tools and will be found capable of very 
 exact work. 
 
 No. 19-10 
 
 No. 19-12 
 
 19-10 DRAWING INSTRUMENTS, good quality hard-pressed German silver and polished steel, contain¬ 
 ing the following instruments, in a neat leather case, lined with velvet: 
 
 Ruling pen, 5 inches, with patented spring back lever. 
 
 Compass, 534 inches, with fixed needle point, pen, and pencil point. 
 
 Plain dividers, 534 inches. 
 
 Metal protractor, 334 inches. 
 
 Box of leads. Complete set $1.50 
 
 19-12 DRAWING INSTRUMENTS, extra quality hard-pressed German silver and polished steel. Set con¬ 
 taining the following instruments in a neat morocco pocket case lined with velvet: 
 
 Ruling pen, 534 inches, with patented spring back lever. 
 
 Compass, 6 inches, with fixed needle point, pen, pencil point, and lengthening'Jbar. 
 
 Steel divider point. 
 
 Box of leads. . Complete set 2.65 
 
 No. 19-14 
 
 19-14 DRAWING INSTRUMENTS, extra quality hard-pressed German silver and polished steel. Set con¬ 
 taining the following instruments, in morocco pocket case lined with silk velvet: 
 
 Ruling pen, 5 inches, with patented spring steel back. 
 
 Plain divider, 6 inches. 
 
 Compass, 6 inches, with fixed needle point, pen, pencil point and lengthening bar. 
 
 Steel spring bow pencil, 334 inches. 
 
 Steel spring bow pen, 334 inches. 
 
 Steel spring bow divider, 334 inches. 
 
 Box of leads. 
 
 Complete set 4.80 
 
70 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 19-20 
 
 19-23 
 
 19-25 
 
 19-30 
 
 19-32 
 
 19-34 
 
 19-40 
 
 19-41 
 
 19-42 
 
 19-43 
 
 19-50 
 
 No. 19-23 
 
 No. 19-34 
 
 SCHOOL COMPASS, as illustrated in set No. 19-10, with fixed needle point and pencil point . . . 
 UNIVERSAL PENCIL COMPASS for student’s use in diagram work in laboratory. These pencil 
 compasses are inexpensive, yet strong and serviceable. Capable of drawing circles up to 12 inches 
 in diameter. 
 
 Complete as illustrated, with pencil..Per Dozen 
 
 STEEL SPRING BOW DIVIDER, inches, as included in set No. 19-14. 
 
 PARALLEL RULE, best quality, made of clear ebony with brass mountings. Length 12 inches . . 
 
 T-SQUARE, cherry wood, 24 inches long, with fixed cross head. 
 
 AMBRO UNIVERSAL SET SQUARE. This square, imported by us, has many features which can 
 only be realized by use. Designed to secure the same utility as a number of instruments, it has ad¬ 
 vantages over each, in that it can be instantly adjusted to perform their various duties. It is an 
 accurate protractor, graduated to read from 0 to 90 degrees in two directions; it is an accurate try 
 square; it is a right angle triangle; it is a straight edge, etc., etc. 
 
 It is substantially constructed and its accuracy is unexcelled. Its universal adaptation to uses of many 
 instruments at a cost far below that of these instruments is a feature to which we desire to call 
 
 particular attention . . :... 
 
 PEARWOOD TRIANGLE, framed, extra quality, 30 degrees. Size 10 inches. 
 
 -, same as above, but 45 degrees. Size 8 inches. 
 
 TRANSPARENT AMBRO TRIANGLE, 30 and 60 degrees. Size 10 inches. 
 
 -, same as above, but 45 degrees. Size 8 inches. 
 
 DRAWING BOARDS of clear grained pine wood, having two drawing surfaces, with side ledges. 
 
 a b c 
 
 Size. 16 X 22 20 X 24M 23 X 31 inches. 
 
 Each. $1.05 $1.60 $2.15 
 
 $1.15 
 
 1.50 
 
 .72 
 
 1.00 
 
 .40 
 
 1.75 
 
 .26 
 
 .28 
 
 .77 
 
 .77 
 
 Nos. 19-67 to 19-68 
 
 19-65 CROSS-SECTION PAPER, % inch divisions, printed on heavy bond paper 17 X 22 inches. 
 
 Sheet $0.06. Doz. $0.68 
 
 19-67 CROSS-SECTION PAPER. One millimeter divisions with heavy centimeter rulings 15 X 20 centi¬ 
 meters, on heavy bond paper 8J^ X 10j^ inches. This is our National Physics Note-Book Cross- 
 
 Section Sheet with holes punched for use in our Binders.Per 100 Sheets .60 
 
 19-68 CROSS-SECTION PAPER, same ruling as No. 19-67, but printed on drawing paper 22 X 27 cen¬ 
 timeters .Per 100 Sheets 1.80 
 
 
 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 7i 
 
 No. 19-75 
 
 19-70 BLACKBOARD DIVIDER AND COMPASS. Superior quality, substantially constructed and 
 handsomely finished. 
 
 Length 16 inches.$0.60 
 
 19-76 EXTRA LARGE BLACKBOARD DRAWING INSTRUMENTS. Essential where accurately con¬ 
 structed diagrams are required of either teacher or pupil. 
 
 These instruments, imported by us, must not be confused with the ordinary quality on the market. 
 
 The set offered under this number is accurately and substantially constructed, each being provided 
 with conveniently situated handle. The set is made from the best close-grained, well-seasoned 
 wood, polished and oil finished. The ruler is a full meter, graduated the full length into clear, dis¬ 
 tinct, black filled divisions. The triangle, 50 centimeters long, has angles of 45 and 90 degrees. 
 
 The protractor, 40 centimeters in diameter, has two scales, the linear and angular, the latter reading 
 
 in two directions, divisions and figures filled black.Set of Three 6.25 
 
 19-77 -, similar to above but ordinary grade. 4.50 
 
 19-100 GRAPH CHART, graph 36 X 36 inches, 
 lithographed on blackboard canvas 
 3X4 feet, mounted on plain roller. 
 
 Each square measures exactly one 
 inch. The center lines are extra heavy 
 and are accurately squared. 
 
 This chart simplifies the reading of 
 co-ordinates and other mathematical 
 principles, plotting of geometrical 
 figures, projection of planes, curves, 
 etc., for showing progress of experi¬ 
 ments in Physics, and is practically 
 indispensable for graphic representa¬ 
 tion of temperature, rainfall and 
 humidity in Physical Geography. It 
 may be considered a necessity in high 
 school work.$3.25 
 
 J 
 
 No. 19-100 
 
72 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 MECHANICS 
 
 PROPERTIES OF MATTER 
 
 No. 20-10 
 
 No. 20-20 
 
 No. 20-25 
 
 20-10 POROSITY DEMONSTRATION APPARATUS for illustrating the porosity of wood. Apparatus 
 consists of an oak wood funnel, a conveniently sized bell glass and glass dish as illustrated. 
 
 In use, the apparatus is placed grouped as illustrated on the plate of an air pump. Mercury is placed 
 in the wood funnel. After a few strokes of the lever, the mercury will begin to run through the 
 pores of the wood into the glass. Complete as illustrated.$1.70 
 
 20-11 WOOD FUNNEL, as used in above. *86 
 
 20-12 BELL GLASS, as used in above. .86 
 
 20-13 GLASS DISH, as used in above.10 
 
 20-20 VISCOSITY APPARATUS for determining the viscosity coefficient of a liquid. Apparatus consists of 
 a capillary tube with bulb so that;-£he time of outflow is at least 100 seconds. The liquid flows 
 under its own pressure to the capittlry. An accurately known quantity is introduced into the 
 wider tube and then sucked up the other tube until the liquid has risen above the bulb. The 
 time occupied by the liquid flowing from this height to a point below the bulb is noted and co¬ 
 efficient determined. 1.60 
 
 20-25 JENKINS’ SPECIFIC GRAVITY APPARATUS. This apparatus employs, in principle, the ef¬ 
 fusion test of Bunsen which is based on the fact that the specific gravities of two gases are in¬ 
 versely proportional to the squares of the speeds with which they escape through a minute open¬ 
 ing. It is used by the Gas Inspectors of Massachusetts and New York for specific gravity de¬ 
 terminations and will be found sufficiently accurate for all practical purposes. It will be found 
 fully as accurate as the Schilling’s Specific Gravity Apparatus so frequently found in use, and the 
 cost is considerably less. 
 
 The advantages of the Jenkins’ Specific Gravity Apparatus are, — its portability, its low cost, its 
 rapidity and accuracy. 
 
 Complete directions furnished with each outfit sold. Price, complete with stand.12.50 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 73 
 
 20-90 
 
 20-96 
 
 20-100 
 
 20-110 
 
 20-116 
 
 20-117 
 
 20 120 
 
 No. 20-90 
 
 LEAD COHESION DISCS for illustrating molecular cohesion between metals. Apparatus con¬ 
 sists of two hemispheres of lead with faces carefully ground smooth. 
 
 When the two surfaces are pressed tightly together, the cohesion between the lead molecules offers a 
 
 resistance to separation. $0.38 
 
 GLASS COHESION DISCS for illustrating molecular cohesion between two glass plates. Apparatus 
 consists of two all-glass hemispheres with carefully ground faces. 
 
 When the two faces are pressed tightly together, the cohesion between the glass molecules offers a 
 
 resistance to separation. .66 
 
 FILM DEMONSTRATION APPARATUS for illustrating characteristics of films demonstrating 
 Surface Tension and Cohesion. 
 
 The apparatus consists of three wire frames of different forms with pipe for blowing spherical films. 
 
 Striking results are possible from proper use of these frames. Tendency of all films to attain a cir¬ 
 cular form is quite noticeable.Per Set as Illustrated .90 
 
 No. 20-110 
 
 No. 20-116 
 
 PRINCE RUPERT DROPS for illustrating the stress existing between the inside and outside of a 
 glass when it is allowed to cool suddenly. These drops consist of drops of glass which had their 
 surfaces cooled suddenly so that they became rigid, before the inner surface had had time to cool. 
 
 There is considerable stress, therefore, between the outside and the inside, but the stress being 
 distributed over the surface, a state of equilibrium exists which is only disturbed when a small 
 portion is broken, when the drop will explode into very small pieces. In use, therefore, the drop 
 should be covered with a piece of paper so that when the small tail is broken off no one will be 
 exposed to the flying fragments.Per Dozen $0.26 
 
 BOLOGNA PHIALS. These phials are made in a similar manner to the Prince Rupert Drops and 
 illustrate the stress existing by allowing small pieces of flint to move about inside the flask, thus 
 causing small scratches which result in the bottom flying to pieces. This is a spectacular experi¬ 
 ment, as only a very slight scratch will cause the bottom to fly out.Per Ten 1.50 
 
 ADHESION DISC for illustrating adhesion between glass and a liquid. Apparatus consists of a 
 circular glass plate, 3 inches in diameter, having at its center a polished wood cone at the apex of 
 which is fastened a fine thread for attachment to a balance arm when experimenting . . . Each .30 
 
 FRICTION OF WATER APPARATUS for showing the increase of friction caused by a film of water 
 between metal surfaces. (Hall No. XXVH).• 
 
 2.26 
 
74 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 20-126 
 
 20-126 GLASS PLATES FOR ILLUSTRATING CAPILLARITY. Consists of 2 plates of glass, which may 
 be placed in a shallow dish of water at any desired angle, when a curve will result somewhat as 
 
 illustrated . Per Pair $0.26 
 
 4 
 
 20-126 GLASS PLATE SEPARATOR for holding 2 glass plates, as No. 20-125, at any desired angle in a 
 
 dish of water. Consists of a small wedge with detents for holding to tops of the plates. .60 
 
 20-130 TAPERING CAPILLARY TUBES for demonstrating capillarity in tubes. Consists of a tapering 
 glass tube 4 inches long. 
 
 This is a very excellent, inexpensive piece of apparatus for demonstrating capillarity in tubes of 
 
 different diameters. . $0.36 
 
 20-132 CAPILLARY TUBES, set of 4 tubes of different internal diameters, 4 inches in length . . . Per Set .30 
 
 20-134 CAPILLARY TUBES ON SUPPORT, consisting of a set of four tubes of different diameters, mounted 
 
 on support, for placing over top of a small jar. .40 
 
 20-136 SMALL JAR, for use with No. 20-134 Capillary Tubes. J.0 
 
 20-137 CAPILLARY TUBES, set of eight tubes of different internal diameters for illustrating capillarity 
 
 Per Set .46 
 
 20-140 CAPILLARY TUBES AND STAND, consisting of eight tubes of different internal diameters mounted 
 in a stand. 
 
 The stand illustrated is a valuable adjunct in the study of capillarity, in that it allows of view of a 
 
 number of tubes at the same time, also affording convenient means for lantern projection. Fin¬ 
 ished in japan and gun-metal finish. Stand complete with eight tubes of different internal diam¬ 
 eters . 1.16 
 
 20-145 CAPILLARY TUBES, consisting of four capillary tubes of different internal diameters connected to 
 
 a water reservoir. For illustration see No. 20-150 . .76 
 
 20-150 CAPILLARY TUBES AND SUPPORT, consisting of No. 20-145 Capillary Tubes, mounted on a neat 
 cast-iron base. Base is provided wuth lacquered brass clips for holding glass part in place. Stand 
 is handsomely finished in japan. 1.22 
 
 20-156 CAPILLARY U-TUBE, consisting of glass U-tube, one branch of which is a small capillary tube 
 
 with white backing. .33 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 75 
 
 20-160 
 
 20-200 
 
 20-215 
 
 20-220 
 
 22-130 
 
 6-860 
 
 31-266C 
 
 20-222 
 
 CAPILLARY TUBES 
 ON STAND, con- 
 sisting of ten 
 U-tubes, one 
 branch of each 
 being capillary, 
 and all of different 
 internal diameters, 
 mounted on 
 support with scales 
 for noting relative 
 rise of liquid in the 
 tubes. 
 
 
 $6.15 
 
 No. 20-160 
 
 
 ft* 
 
 w 
 
 No. 20-200 
 
 No. 20-215 
 
 $3.70 
 
 1.25 
 
 No. 20-220 
 
 ENDOSMOMETER for illustrating the phenomena of Endosmose 
 and Osmose. 
 
 The apparatus consists of a glass vessel the lower end of which is 
 covered by a membrane, the upper end of which is connected to a 
 glass tube which carries a scale. This vessel is supported so that 
 the membrane is held under solution during examination. 
 
 All parts complete as illustrated. 
 
 STUDENTS’ OSMOSIS APPARATUS for qualitative as well as 
 quantitative work in Osmosis. 
 
 The apparatus consists of an osmosis tube of design as illustrated, 
 held adjustably in a nickel-plated clamp which may be clamped 
 to the side of a jar. One end of the osmosis tube is closed by a thin 
 porous membrane which may be removed and replaced from time 
 to time as needed. 
 
 Apparatus complete as illustrated. 
 
 OSMOSIS APPARATUS after specifications by Thos. B. Freas of the Department of Chemistry, 
 Columbia University, for illustrating the phenomenon of Osmotic Pressure. 
 
 This ingenious device consists of an S. & S. diffusion shell attached to a glass chamber which ends 
 above in a heavy wall barometer tube 5 feet long. Entering this chamber is another tube with 
 a funnel end and stop-cock through which the solution is allowed to flow. 
 
 For ease and rapidity of illustration this apparatus is unexcelled and the results are readily notice¬ 
 able within fifteen minutes from the start. 
 
 Osmosis Tube with diffusion shell only, without support of any kind. $3.90 
 
 Articles illustrated in addition are: 
 
 UNIVERSAL STAND. 2.10 
 
 UNIVERSAL RIGHT-ANGLE CLAMP. 1.05 
 
 BATTERY JAR, 6X8 inches. 40 
 
 DIFFUSION SHELL, as used in above apparatus.Each $0.40, Per Ten 4.00 
 
76 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 20-230 
 
 20-235 
 
 SCHIFF’S SURFACE TENSION APPARATUS for the study of 
 surface tension in liquids. 
 
 Consists of a special U-tube, one limb of which has large bore, the other 
 capillary bore, bent at the top at right angles and with an enlarge¬ 
 ment just at the bend to prevent stoppage of the mouth of the tube 
 by deposited drops. 
 
 HALL’S SURFACE TENSION APPARATUS, designed by Dr. E. H. 
 Hall of Harvard University for quantitative measurement of surface 
 tension. This apparatus will be found most effective for determi¬ 
 ning the surface tension of any liquid not acting on metal. Com¬ 
 plete with stand as illustrated. 
 
 $ 1.10 
 
 3.60 
 
 No. 20-235 
 
 20-235A -, as illustrated, but without Stand.".$2.96 
 
 20-236 SHALLOW FLINT GLASS DISH for above.16 
 
 No. 20-250 
 
 No. 20-260 
 
 No. 20-270 
 
 20-250 INCOMPRESSIBILITY OF LIQUIDS APPARATUS, IMPROVED DE- 
 * SIGN, for the quantitative observation of the incompressibility of liquids. 
 
 This apparatus consists of a tube with indicating capillary. The liquid to 
 be observed should fill the short arm of the tube and should rise in the long 
 arm to near the top of the capillary. If mercury is poured into the long 
 arm, the liquid, if compressible, will indicate the amount, if any, in the 
 capillary. 
 
 Complete as illustrated, mounted on our No. 41-116 Boyle’s Law Stand . $4.26 
 
 20-251 INCOMPRESSIBILITY OF LIQUIDS TUBE, only. 2.60 
 
 20-260 IMPENETRABILITY APPARATUS, illustrating the fact that two bodies 
 
 cannot occupy the same space at the same time. 
 
 This apparatus consists of a frame which answers the double purpose of sup¬ 
 porting the bottle and plunger and of a clamp. In use, the bottle is filled 
 with the liquid, a one-hole rubber stopper placed in the neck, the end of the 
 plunger placed in the hole and the bottle clamped firmly in place by means 
 of the thumb nuts. If the plunger is now thrust into the bottle, the bottle 
 will burst, demonstrating that two objects cannot occupy the same space 
 at the same time, also, that a liquid is incompressible. 
 
 Complete, with three bottles. 1.45 
 
 20-270 INERTIA APPARATUS for illustrative demonstration of Inertia. 
 
 The apparatus consistsjof a neatly finished base on which is mounted a nickel-plated rod with con¬ 
 cave top. A metal spring fastened to the side of the base affords a device for giving the card 
 illustrated a sudden blow on the edge, thus knocking the card from under the small ball, show¬ 
 ing that the ball does not change its position except as gravity causes it to drop into concave 
 top when its prop is knockedjfrom under. 
 
 Complete as illustrated. .85 
 
 I 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 77 
 
 CENTRIFUGAL FORCE 
 
 ROTATORS 
 
 No. 21-10 
 
 21-10 ZIEGLER TWENTY-ONE POUND MECHANICAL ROTATOR OR WHIRLING 
 TABLE with universal chuck for rotating objects to which it is desired to apply 
 a centrifugal force. 
 
 In the design of our Rotator we have observed closely all the scientific requirements 
 of such an instrument. It is made of cast iron, all parts neatly japanned, and 
 may be used in either a vertical or horizontal position. In design of our patterns 
 we have placed the metal at points where the greatest stability may be secured. 
 Furnished with each rotator are the various attachments for fastening the acces¬ 
 sories. Thus there will be found with each instrument a universal chuck for 
 fastening objects with a spindle; also a special lock-nut head designed for fasten¬ 
 ing plates, color discs, etc., and for attaching the string of such accessories as the 
 Disc, Egg, and Chain. 
 
 Important features of this instrument are,— 
 
 1. Extreme rigidity, used in either vertical or horizontal position. 
 
 2. Large Drive Wheel, facilitating either high or low speed. 
 
 3. Handsome and durable finish. 
 
 Rotator only, without accessories, also illustrated, but including the universal 
 
 chuck attachment. .$6.95 
 
78 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 * ) 
 
 THE UNIVERSAL SPEED AND POWER 
 
 ROTATOR 
 
 Nos. 21-30 to 21-35 
 
 Patent Pending 
 
 The motor rotator is desirable, if not essential, in Physical Laboratory demonstration, but the important prob¬ 
 lem of adequate power at low speed has not before been solved, two hundred revolutions being considered the low 
 limit at which reasonable working power may be obtained. 
 
 We have, by the friction drive method, produced a Universal Speed and Power Rotator which runs without 
 unnecessary friction and in which the power is increased as the speed is diminished, a feature which gives to it a 
 breadth of usefulness not ordinarily looked for in these instruments. 
 
 While primarily designed for all of the usual whirling table experiments, it serves admirably as the power plant 
 in prony break tests and in the Mechanical Equivalent of Heat experiments where the greatest smoothness as well 
 as low speed and great power are required. When operated at high speed the outfit is particularly well adapted to 
 the energizing of gyroscopes of high power. 
 
 FEATURES 
 
 UNIVERSAL POSITION. The countershaft housing, being designed so as to rotate through a complete circle, 
 gives any desired position to the chuck holder. 
 
 A SPEED CONTROL which has never before been obtained in a rotator, from 0 to 5000 revolutions. 
 
 A METHOD OF REVERSING which is as simple as it is unique, carrying the shaft from the highest speed on 
 one side gradually down to 0 and gradually up to the desired points on the other side, all without jar or shock, it 
 being accomplished without touching a switch or reversing key. 
 
 POWER. Full power of the motor when the countershaft is running at the same speed as the motor and which 
 increases in the same ratio as the speed diminishes, giving almost unlimited torque at very low speed. The crown¬ 
 ing of the drive disc so as to insure greater contact pressure as the power is increased. 
 
 SAFETY. All parts enclosed so as to eliminate all danger from any moving portions of the instrument. 
 
 SPEED COUNTER. A direct connected speed counter attached to the countershaft, giving actual number of 
 revolutions of the effective shaft. The counter may be thrown in or out of mesh at will. 
 
 UNIVERSAL CHUCK SOCKET. A chuck socket which readily takes all of the whirling table attachments, 
 requiring no wrench for adjustment. 
 
 WEIGHT. The base of the instrument, a solid casting, supported by shock-absorbing points, stands firm and 
 rigid on the lecture table, requiring no clamping. 
 
 VOLTAGE OF CURRENT 
 
 In ordering, specify the current for which the motor is desired:— 110 volts D. C. or 110 volts, 60 cycles A. C. 
 See listing below. 
 
 21-30 Rotator complete with Universal Chuck, for 110 volts D. C.$42.00 
 
 21-36 Rotator complete with Universal Chuck, for 110 volts A. C. 42.00 
 
 .21-46 SPECIAL DRIVE PULLEY for round belt. This drive pulley will be found essential when using 
 above rotators as the driving mechanism for Mechanical Equivalent of Heat Apparatus (see page 
 230) or other apparatus. It is designed with set screw to attach to shaft of either of above ro¬ 
 tators . $1.76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 79 
 
 ROTATOR ACCESSORIES 
 
 21-60 SPEED INDICATOR for attachment to the Whirling Table when quantitative results are desired. 
 
 This indicator is a high-grade instrument especially adapted to use on our Rotator. Illustration 
 
 shows method of attachment to the Rotator.;.$4.16 
 
 21-60 SPRING STEEL DOUBLE CENTRIFUGAL HOOP for illustrating the tendency of a semi-fluid body, 
 such as the Earth, to assume a flattening at the poles when rotating rapidly. 
 
 The apparatus consists of two flexible hoops of spring steel mounted on a central axis for attaching 
 
 to the spindle of the Rotator. 1.05 
 
 21-80 FOUCAULT’S PENDULUM for illustrating conserva¬ 
 tion of the plane of oscillation. 
 
 This design consists of a carefully finished wooden 
 disc with quadrants clearly marked, the under side 
 of which is provided with an accurately centered 
 spindle for attachment to rotator. The uprights 
 support a pendulum, the point of suspension being 
 directly over center of the disc. 
 
 In use, the pendulum is allowed to swing in the plane 
 of the apparatus and then set slowly in rotation. 
 
 The pendulum will maintain the course of its plane 
 of vibration.$6.60 
 
 21-100 CENTRIFUGAL FORCE APPARATUS, consisting of 
 two connected balls of unequal mass mounted on a 
 horizontal rod attached to a frame for connection 
 to the Rotator. 1.90 
 
 No. 21-110 
 
 21-110 CHAIN, EGG and DISC for illustrating the tendency of a body to rotate about its shortest diameter. 
 Consists of a Disc, a Chain and an Egg-shaped solid, each with an attached cord for suspending to 
 the head of the Rotator. 
 
 $0.88 
 
8o 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 No. 21-120 
 
 No. 21-160 
 
 No. 21-176 
 
 21-120 
 
 21-160 
 
 21-162 
 
 21-160 
 
 21-176 
 
 21-186 
 
 21-190 
 
 TYNDALL’S INSULATED HEAT BY FRICTION ATTACHMENT for illustrating heat caused 
 by friction on a brass tube while rotating rapidly. 
 
 Apparatus consists of a cylinder of brass carefully insulated from the brass rod with which it is 
 connected to the rotator. If this cylinder is filled with alcohol and friction caused during rotation 
 by means of the Friction Vise, it will be noted that the liquid is soon boiling. 
 
 Complete as described. $2.00 
 
 CENTRIFUGAL SEPARATOR for separating by centrifugal force solids held in suspension in a 
 liquid. 
 
 The apparatus consists of a spindle with cross head. To the forked end of this cross head, brass 
 collars are held in cone bearings. In these collars are placed the centrifuge tubes with their alumi¬ 
 num shields. 
 
 When rotated rapidly, solids held in suspension in a liquid contained in the tubes will gather at the 
 
 bottom. 2.46 
 
 CENTRIFUGAL TUBE, after Hall (No. XLI) Figure 102 to illustrate centrifugal action. .68 
 
 CENTRIFUGAL DRYER for illustrating the principle of centrifugal devices as used in laundries. 
 
 For illustration see page 77. 3.90 
 
 TWO-IN-ONE GLASS ROTATOR GLOBE for 
 
 showing effect of rotation upon solids or liquids 
 of unequal weight. This apparatus takes the 
 place of both the glass globe for liquids and the 
 open shallow dish for solids, both of which are 
 required for complete demonstrations. 
 
 If three balls of same size but unequal weight, or if 
 two or more liquids of different specific gravities 
 but which do not mix (mercury and water) are 
 placed within the globe and the globe rotated, 
 interesting and instructive phenomena will be 
 noted. This globe is of heavy glass and carefully 
 balanced to rotate evenly. $2.85 
 
 WATT’S GOVERNOR for demonstrating the use¬ 
 fulness of a governor on an engine. 
 
 The apparatus consists of two metal balls suspend¬ 
 ed to two arms which in normal position hang 
 downward, but pivoted so that in rotation they 
 are free to rise and act against a spring. Made of 
 brass throughout and finished in lacquer and 
 nickel. 3.96 
 
 VALVE REGULATOR, to be used in conjunction 
 with above Watt’s Governor in demonstrating 
 the action of a governor in regulating the flow of 
 steam into the steam chest of an engine. Fin¬ 
 ished in bright japan with different parts colored 
 for distinction at a distance from the lecture 
 table. 3.40 
 
 Nos. 21-186 and 21-190 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 81 
 
 No. 21-210 No. 21-226 
 
 21-210 LARGE LECTURE TABLE COLOR DISCS for quantitative work in color mixing and color analysis. 
 
 These discs are of heavy cardboard with hole for attaching to spindle of Rotator. Each disc is slit 
 that two or more colors may be combined, giving a disc of several colors. 
 
 Set of discs of seven primary colors, one each of black and white, and a percentage circular pro¬ 
 tractor for quantitative work.$2.00 
 
 21-226 COMBINATION NEWTON’S COLOR DISC, SIREN DISC and SAVART’S WHEEL for showing 
 white light when fixed portions of primary colors are rotated rapidly, and for demonstrating prop¬ 
 agation of sound by mechanical disturbances which cause vibration in the surrounding media. 
 
 Consists of a flat disc of metal with part of the face covered with colored segments of the seven 
 primary colors in best proportions to show white when disc is rotated rapidly. Outside this col¬ 
 ored portion there are drilled five rows of holes on concentric circles, four of which are evenly 
 spaced and sound the tones C, E, G, and C', while the fifth is unevenly spaced and sounds a harsh 
 tone, — a noise. On the periphery of the disc are cut evenly spaced teeth.Each . 1.60 
 
 No. 21-240 No. 21-246 
 
 t 
 
 21-240 SAVART’S TOOTHED WHEEL for demonstrating that tones are produced by regular impulses 
 given to the surrounding media. 
 
 Consists of four brass discs on the periphery of which are cut teeth, which, when touched by a card 
 during rotation, will sound the tones of C, E, G, and C'. These discs are held fixed to a spindle 
 - for attaching to the socket of the Rotator. Finished in nickel throughout.$2.36 
 
 21-242 -, similar to above, but with only one wheel. For attachment to socket of the Rotator . . . .48 
 
 21-246 SAVART’S TOOTHED WHEEL, mounted on stand for string rotation. Consists of a heavy metal 
 casting with teeth equally spaced on the periphery. This disc is mounted on axle and supported 
 on a heavy casting. Durable japan and black oxidized finish. 7.66 
 
82 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 21-266 
 
 No. 21-267 
 
 SIREN DISC, illustrating sound propagation by regular im¬ 
 pulses given to the surrounding medium. 
 
 Consists of a flat metal plate with five rows of holes in con¬ 
 centric circles, four of which rows have holes equally spaced 
 to sound the tones C, E, G, and C', while the fifth is un¬ 
 equally spaced to sound a “noise.” 
 
 Disc is emery finished and nickel-plated. $1.06 
 
 -, same as above, but with nine rows of holes in concentric 
 
 circles, eight of which are equally spaced to sound the 
 scale of C, D, E, F, G, A, B, and C', while the ninth is 
 unequally spaced to sound a “noise.”. 2.76 
 
 No. 21-267 
 
 21-267 AIR IMPULSE ATTACHMENT for use with Siren Discs Nos. 21-226, 21-265, and 21-257 for 
 
 sounding by air impulses against the holes, one or more notes up to nine. 
 
 This instrument is an ingenious device provided with nine air valves, any or all of which may be 
 opened by small thumb screws. It may be instantly adjusted to our Rotator. It is handsomely 
 finished, positive in action and cannot get out of order. Operated by blowing or by air bel¬ 
 lows, requiringTonly a moderate blast. Attachment only.$2.65 
 
 No. 21-280 
 
 No. 21-290 
 
 No. 21-295 
 
 21-280 CROVA’S DISC AND METAL SHIELD for attaching to Rotator to illustrate compressional waves. 
 
 The apparatus consists of two parts, — a heavy cardboard disc 11 inches in diameter, on the 
 face of which are drawn progressively eccentric circles, and a flat metal shield 12 inches in diameter 
 with special clamp for attaching to a rotator. A slot cut along a radius of the shield exposes a 
 narrow strip of the card showing short sections of the eccentric circles. When the card is rotated 
 
 these short sections show alternate expansion and compression. Complete. $2.45 
 
 21-280a FLAT METAL SHIELD with ATTACHED CLAMP. 2.26 
 
 21-280b CROVA’S DISC, heavy cardboard, 11 inches diameter. 20 
 
 21-290 CUBICAL OR ROTATING MIRROR, for attachment to Rotator for study of reflection from a 
 Rotating Mirror or for Manometric Flame images. 
 
 This design consists of four mirrors, one fastened firmly to each of the four vertical sides of a cubical 
 box, to the under side of which is attached an accurately centered spindle for fastening to socket 
 
 of rotator. All parts finished dead black. 3.15 
 
 21-295 KOENIG’S MANOMETRIC FLAME CAPSULE for transmitting the motion of sound waves to gas 
 flame, which by their pulsations indicate the nature of sound. 
 
 This design consists of two metal castings, between which is sealed a membrane. One casting is 
 provided with jet, other with mouth-piece and connecting tubing. The whole is mounted on a 
 gas tube attached to a substantial metal base. 
 
 Complete as illustrated. 2.76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 83 
 
 No. 21-300 
 
 Patent Pending 
 
 No. 21-300 (Sectional View) 
 
 21-300 REVOLVING MIRROR, WITH POSITIVE SPEED GOVERNOR. To meet the repeated demands 
 for a mirror which may be revolved at varying speed and of a size sufficiently large for ordinary 
 laboratory work we have, after considerable experimentation, devised the above illustrated method. 
 
 This mirror is self-contained in that the power is contained in the base in the form of a battery motor, 
 with “start” and “stop” key. We secure a positive speed, governed by means of a simple, ef¬ 
 fectively operating device noted above the mirror shaft. We are able to secure with this device 
 speeds varying from a few revolutions per minute up to 4000, the maximum speed of the motor. 
 This variation in speed may be made during the revolution of the mirror simply by a movement of 
 the milled screw over the axle. 
 
 As may be noted this design consists of a metal housing which serves also as a substantial base. Cast 
 to this housing is an upright with projecting arm. The mirror is mounted in metal castings 
 carefully centered. The metal housing is provided with binding posts for connections to the 
 motor and also with “start” and “stop” key. The whole is finished in nickel and black oxidized, 
 presenting a handsome appearance. It will be found efficient for all general work for which a 
 rotating mirror is used. 
 
 $9.76 
 
 21-306 
 
 21-310 
 
 No. 21-306 
 
 ARAGO’S MAGNETIC ROTATION APPARATUS, for demonstrating 
 the reaction between the electric currents induced in a rotating copper 
 disc and a magnet, illustrating, also, the damping effect of copper upon 
 a magnetic needle. 
 
 The apparatus consists of a metal casting which may be attached to our 
 rotator as illustrated, and which carries adjustable arms for support¬ 
 ing a clear glass plate with beveled edges. Fastened at the center of 
 this glass plate is a small support for the Magnetic Needle. The appa¬ 
 ratus is finished in lacquered brass and bright japan. 
 
 As the copper disc is rotated, the Magnetic Needle is deflected in the di¬ 
 rection of the rotation, and if the speed is fairly great, the needle will 
 be dragged completely around so that it is set in rotation. When the 
 rotation is stopped the damping effect of the copper is strikingly no¬ 
 ticed. 
 
 Apparatus complete as illustrated, ready for attachment to our rotator. $5.86 
 
 EARTH INDUCTION APPARATUS, for mounting to the socket of a rotator to illustrate induced 
 currents set up in a coil of wire by the inductive action of the earth. 
 
 This apparatus consists of a closed coil of wire wound on metallic frame, provided with com¬ 
 mutator and brushes, ready for attachment to a rotator. 6.86 
 
S 4 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 THE HARCOURT 
 
 UNIVERSAL GYROSCOPE 
 
 No. 21-340 
 
 Patent Pending 
 
 It is with much satisfaction that we list here this valuable series of instruments for demonstrating gyroscopic 
 phenomena. 
 
 The plan on which these instruments are designed is that of using the simple unit to demonstrate the simpler 
 forms of gyroscopic action and to build up from this unit a complete line of accurate and well-worked-out gyroscopes- 
 
 If it is not possible to purchase the complete outfit at once, the simple element with stand may be purchased 
 at first, and other features added at will until the complete system is obtained. By this plan, a full set of gyroscopes 
 may be obtained at much less cost than the separate instruments. 
 
 THE BASIC UNIT. This consists of a perfectly balanced wheel inches in diameter, so designed that the 
 mass is kept as near the periphery as possible. 
 
 DETAILED FEATURES 
 
 LOCK-NUT on Basic Unit. The method of holding the wheel in its gimbal ring is unique, in that the lock-nut 
 is so placed that it serves to prevent the power string from catching in the bearing when in use. 
 
 UNIVERSAL BEARING POST. A convenient and well-designed reversible bearing post is fitted to the base 
 standard. It serves the multiple purpose of providing a suitable pivotal bearing, a thread post for attaching any 
 of the rings, and a cup support for the ball-bearing on the end of the main axle. 
 
 UNIVERSAL GIMBAL BEARING. A valuable adaptation of the gimbal bearing worked out by E. S. Ritchie 
 to give the greatest freedom of motion with the least friction. The use of this bearing is well illustrated in the build¬ 
 ing up of both the COUNTERPOISED and the BOHNENBERGER types of instruments. 
 
 The various parts going to make up the complete outfit may be briefly stated as follows - 
 
 1 STAND, UNIVERSAL ROD with Cone and Cup Bearings. 
 
 2 ROTATING WHEEL SYSTEMS (BASIC UNITS). 
 
 1 EXTENSION ROD WITH COUNTERPOISE. 
 
 1 EXTENSION ROD STILT ATTACHMENT. 
 
 1 GIMBAL RING AND BEARING. 
 
 1 BOHNENBERGER RING AND BEARING. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 85 
 
 It will thus be seen that from the basic unit, by the addition of accessory parts, we are able to assemble all forms 
 illustrated below. For example:— 
 
 In order to assemble the SIMPLE GYROSCOPE No. 21-360, use the Supporting Stand with Universal Cone and 
 Cup Bearing and the Basic Unit. 
 
 To assemble the COUNTERPOISE GYROSCOPE, No. 21—366, the only additional parts would be the Exten¬ 
 sion Rod and Counterpoise, together with the Gimbal Bearing, if desired. 
 
 To assemble the BOHNENBERGER GYROSCOPE, No. 21-360, only the Bohnenberger Ring need be pro¬ 
 vided in addition to the above. 
 
 The COMPOUND GYROSCOPE, No. 21-346, requires one extra Basic Unit. 
 
 The Extension Rod Stilt Attachment supplied with each outfit enables one to set up the STILT GYROSCOPE 
 (not listed or illustrated below) for illustrating the resistance exerted by a spinning gyroscope in the monorail to wind 
 pressure, causing the whole carriage to lean over toward the wind and to lean more and to increase its resistance in 
 exactly the same ratio as the force of wind increases. 
 
 It will thus be seen that the cost of the Gyroscopic Outfit in this form will be much less than the cost of the 
 individual instruments furnished complete. This is our reason for strongly advising the purchase of one complete 
 outfit, if possible. 
 
 21-340 GYROSCOPIC OUTFIT complete as listed..$17.45 
 
 Note. — Great care is exercised in testing out all of the parts with their inteichangeable features before the instruments are shipped. 
 
 21-345 FESSEL’S COMPOUND GYROSCOPE. This Gyroscope consists of two of the Basic Units de¬ 
 scribed on the preceding page, mounted on stand as illustrated. We desire to call attention to the 
 fact that with the purchase of this Compound Gyroscope, simple gyroscopic action as illustrated 
 under No. 21-360 may be demonstrated by dissembling the Compound Gyroscope and using the 
 
 parts as illustrated.$11.00 
 
 21-350 BOHNENBERGER’S GYROSCOPE. This Gyroscope, as may be readily noted, consists of our 
 Basic Unit with the addition of the Bohnenberger Ring and Bearing. It will be noted, also, that 
 this Gyroscope may be dissembled and used in demonstrating simple gyroscopic phenomena as il¬ 
 lustrated under No. 21-360 . 8.75 
 
 21-355 COUNTERPOISE GYROSCOPE, assembled as illustrated from the Simple Gyroscope Basic Unit, 
 Extension Rod and Counterpoise, Gimbal Ring and Bearing, and mounted on a Stand with Uni¬ 
 versal Bearing Post. 7.60 
 
 No. 21-345 
 
 No. 21-360 
 
 No. 21-355 
 
 Fig. 1 No. 21-360 Fig. 2 
 
 21-360 SIMPLE GYROSCOPE, 3}4 inch wheel. This instrument is not a toy, although the illustrations 
 depict its use in positions as so frequently advertised by toy manufacturers. Under this number, we 
 supply the Simple Gyroscope Basic Unit with Supporting Stand and Universal Bearing Post. 
 Perhaps no single instrument is capable of such spectacular results as that of the Simple Gyroscope, 
 and every school equipment should have at least one, constructed scientifically and sufficiently 
 
 massive to place it in the realm of scientific instruments.$5.50 
 
 21-367 SIMPLE GYROSCOPE, light wheel, usual form. 1-90 
 
 21-371 “SPINNING TOPS” by Professor Perry, who, in a very simple and interesting manner, describes 
 
 and explains many interesting experiments.Per copy 1.26 
 
86 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ACTION AND REACTION 
 
 BALLS 
 
 (Used by special permission of copyright owners) 
 
 Nos. 22-10 to 22-110 
 
 PENDULUM BALLS, for use also in Action and Reaction Experiments. 
 
 22-10 WOODEN BALLS: 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 
 Diameter, inches 
 
 3 / 
 
 1 
 
 l X 
 
 2 
 
 
 Price . 
 
 . $0.06 
 
 $0.10 
 
 $0.12 
 
 $0.16 
 
 22-20 
 
 GLASS BALLS: 
 
 
 
 
 
 
 
 a 
 
 b 
 
 c 
 
 
 
 Diameter, inches . 
 
 . x 
 
 1 
 
 l X 
 
 
 
 Price . 
 
 . $0.06 
 
 $0.16 
 
 $0.36 
 
 
 22-30 
 
 IVORY BALLS, accurately turned, polished, and with a 
 
 . hole drilled for suspension 
 
 
 
 a 
 
 b 
 
 c 
 
 
 
 Diameter, inches 
 
 1 
 
 IX 
 
 2 
 
 
 
 Price . 
 
 . $1.60 
 
 $1.90 
 
 $2.60 
 
 
 22-40 
 
 LEAD BALLS, made of cast metal, drilled for suspension: 
 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 
 Diameter, inches 
 
 • X 
 
 % 
 
 1 
 
 IX 
 
 
 Price . 
 
 . $0.06 
 
 $0.09 
 
 $0.16 
 
 $0.64 
 
 22-60 BRASS BALLS, accurately turned, polished, drilled for suspension: 
 
 abed 
 
 Diameter, inches ■ . X X I ^X 
 
 Price .$0.12 $0.17 $0.30 $0.78 
 
 22-60 IRON BALLS, cast, a, b, and c drilled for suspension; d and e with hooks. 
 
 a b c d e 
 
 Diameter, inches . . % 1 1 X 2 3 
 
 Price .$0.06 $0.07 $0.13 $0.20 $0.60 
 
 22-61 MASSIVE IRON BALL WITH THREE HOOKS. 
 
 22-70 HIGHEST GRADE STEEL BALLS, hardened, accurately ground and polished. There are no holes, 
 but the small balls may be suspended by shellacing a thread to them. 
 
 a b c d e f 
 
 Diameter, inches . . % X X 1 ^X 2 
 
 Price .$0.04 $0.06 $0.09 $0.20 $0.40 $1.10 
 
 22-72 STEEL BALLS, with loop attachment for suspension, 1 inch diameter. 
 
 22-80 FINISHED LIGNUM-VITAE BALLS, IX inches in diameter. 
 
 22-90 COPPER BALLS, not turned but drilled for suspension: 
 
 a b c 
 
 Diameter, inches . . X 1 IX 
 
 Price .$0.22 $0.33 $0.67 
 
 22-100 CORK BALLS, lathe turned, and drilled for suspension: 
 
 a b c 
 
 Diameter, inches . . X 1 ^X 
 
 Price .$0.06 $0.10 $0.20 
 
 22-110 COMBINATION SET OF BALLS, for use in collision experiments, giving a variety of weights with 
 approximately the same size. The set consists of \X inch balls of cork, ivory, lignum-vitae, 
 glass, iron, brass, copper and lead.Set 
 
 $ 0.70 
 
 $ 0.60 
 
 .30 
 
 $ 4.20 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 87 
 
 
 ACTION AND REACTION 
 
 IMPACT SECOND LAW OF MOTION 
 
 In this place, we desire to call attention to the fact that we have, wherever practical, discarded wood sup¬ 
 ports, using in all our designs special castings made from expensive patterns. This line, therefore, will be found 
 practically indestructible. It is scientific in appearance and any laboratory may well be proud of a thorough equip¬ 
 ment. Each casting is uniformly smooth and appropriately finished. Wherever a clamp is a part of the casting, 
 the screw is heavily nickel-plated.. 
 
 22-130 UNIVERSAL STAND. It will be noted from this point on, that frequent use is made of a Support 
 Rod mounted in a Tripod Base. We desire to call attention to the extreme utility of this stand. 
 
 Besides forming a rigid support for various accessories illustrative of the Laws of Mechanics under 
 discussion, it presents a handsome appearance and will support practically all of our accessories 
 illustrated in the following pages. It consists of our No. 5-20e Support Rod, 100 centimeters long, 
 
 19 millimeters diameter, and our No. 5-155 Tripod Base. 
 
 We list it herewith as a unit, that we may emphasize its extreme utility. Complete as illustrated . $2.10 
 
 22-131 UNIVERSAL STAND, same as above, but tripod 
 
 provided with three leveling screws .... $3.15 
 
 22-136 
 
 s n>. 
 
 -d 
 
 IMPACT APPARATUS, illustrating by impact 
 of equal masses the resolution of one force into 
 two equal forces. 
 
 The apparatus consists of a casting with clamp 
 for attaching to our Universal Support No. 
 22-130. This casting is provided with friction 
 taper plugs for holding the balls of equal masses 
 in bi-filar suspensions. At rest, the lengths 
 of these suspensions should be adjusted so 
 that the balls just touch each other. 
 
 By impact of one ball simultaneously against the 
 other two, it will be noted that each of the im¬ 
 pinged balls is forced a distance equal to half 
 that which the impinging ball traversed. 
 
 Complete as illustrated, ready for attachment to 
 rod of Universal Stand. 
 
 No. 22-130 
 
 No. 22-135 
 
88 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 22-145 
 
 22-145 IMPACT AND REFLECTION ATTACHMENT for determining the laws of impact, also for de¬ 
 termining law of incidence and reflection of light. 
 
 This attachment consists of a special clamp casting to which is firmly fastened the graduated half¬ 
 circle disc of wood. As a part of this casting, is an impact plate and “boss.” To the latter are 
 swiveled two arms, one of which is equipped with a spring gun, designed to project a ball against 
 the impact plate, the other with stop for receiving ball after rebound from impact plate. 
 
 By setting the arm carrying the spring gun at some position and projecting the ball against the 
 plate, it will be found that the stop will have to be moved to a similar position on the other side of 
 the normal line. 
 
 A simple attachment making this apparatus of greater utility is provided on the spring gun arm. 
 
 This consists of an upright with sight hole. If a lighted candle is placed in the stop, which is de¬ 
 signed for this double purpose, and a mirror attached to the impact plate, it will be found that the 
 sight hole will have to be moved to a similar position on the other side of the normal to receive 
 the reflection of the candle. 
 
 Attachment complete as illustrated, with the addition of a Mirror for determining the law of inci¬ 
 dence and reflection of light.$6.65 
 
 NOTE. ACCESSORY APPARATUS NEEDED 
 
 22-130 UNIVERSAL SUPPORT.. $2.10 
 
 CANDLES. See Index. 
 
 No. 22-160 
 
 22-160 ACTION AND REACTION APPARATUS for quantitative demonstration that Action is equal 
 but opposite to Reaction when two elastic bodies impinge. 
 
 The apparatus consists of a mounted Meter Stick on which are placed and clamped, where desired, 
 two ingenious detents. Two ivory balls suspended from any convenient hanger rest against these 
 detents and are released by a sudden pull on a string which drops the detents, thus allowing the 
 balls to fall towards each other, starting at the same instant. 
 
 Complete apparatus as listed separately below.$5.50 
 
 22-160a METER STICK, with loop for string. .33 
 
 22-160b METAL SUPPORTS for Meter Stick. Per Pair .25 
 
 22-160c DETENTS ready for attachment to Meter Stick.Per Pair .60 
 
 22-160d IVORY BALLS, two of different masses . .’.Per Pair 4.40 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 89 
 
 No. 22-180 No. 22-190 
 
 COLLISION BALL APPARATUS, IMPROVED FORM, for the quantitative and qualitative study of im¬ 
 pinging elastic bodies. 
 
 The apparatus consists of a rectangular metal frame of special design for attachment to our Universal Stand 
 No. 22-131. Ten steel balls, 1 inch in diameter and one steel ball four times the mass of each of the others are at¬ 
 tached to this frame by stout silk cords and held adjustably to it by tapering plugs. As each ball is held in a bi-filar 
 suspension, the directive force of impact is at the will of the operator simply by turning the tapering plugs. A special 
 design graduated arc is necessary for quantitative work. This arc is made to attach directly to the Universal Stand 
 No. 22-131. The lines and figures being especially clear, they may be seen from the rear of any lecture room. 
 
 22-180 COLLISION BALL APPARATUS, complete with No. 22-131 Universal Stand, Rectangular Attach¬ 
 ment with ten steel balls, 1 inch in diameter, and one steel ball of four times the mass of each 
 
 of the others, and with Graduated Arc with Clamp for attachment to the Universal Stand . . $14.76 
 
 22-181 RECTANGULAR FRAME with CLAMP, including all balls, listed above. 9.86 
 
 22-182 GRADUATED ARC with CLAMP as used in No. 22-180 . 2.60 
 
 22-131 UNIVERSAL STAND. 3.16 
 
 22-190 COLLISION BALL APPARATUS for study of impinging elastic bodies. 
 
 This apparatus consists of a rectangular frame similar in general construction to that used above 
 but designed for suspending five lignum-vitse balls, each in bi-filar suspension. The apparatus 
 illustrated is designed to clamp over any 19 millimeter rod. 
 
 Rectangular Frame with the five balls attached. 3.86 
 
90 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 22-200 
 
 No. 22-220 
 
 No. 22-226 
 
 22-200 MOMENTUM APPARATUS for deriving laws of momentum. 
 
 This apparatus is designed for attachment to our Universal Support No. 22-131. It consists of a 
 rectangular metal frame supporting in bi-filar suspension two bodies with masses of the ratio 1: 4. 
 
 The larger body has a special ingenious spring striking attachment operative on both bodies at 
 the same time. In operation, this striking attachment is pulled back against the spring and 
 held by a piece of string. When this string is burned a blow is given to the smaller body which 
 is communicated to the larger at the same time. 
 
 The complete apparatus consists of the Rectangular Frame Momentum Attachment, the Universal 
 
 Support No. 22-131 and a Graduated Arc. Complete apparatus.$11.00 
 
 22-201 MOMENTUM ATTACHMENT only. 6.66 
 
 22-182 GRADUATED ARC WITH CLAMP for attachment to a' 19 millimeter rod. 2.60 
 
 22-220 SECOND LAW OF MOTION APPARATUS consisting of a flexible hardwood strip about 15 inches 
 long and a vise for attaching one end firmly. The hardwood strip has a right angle head with a 
 notch at each upper end in which are placed small marbles. 
 
 In use, the marbles are placed in position in their respective notches; the flexible strip is then bent 
 to one side and released. One marble will shoot out horizontally, while the other, owing to its 
 inertia, will drop automatically, at the same instant taking the course of a straight line, thus dem¬ 
 onstrating the Second Law of Motion. 
 
 Complete with Vise. 1.46 
 
 22-221 BENCH VISE CLAMP as used in No. 22-220 . 1.00 
 
 22-222 FLEXIBLE HARDWOOD STRIP as used in No. 22-220 .46 
 
 22-226 SECOND LAW OF MOTION APPARATUS. This design, above illustrated, is one simplified for use 
 in the hand. The length of the rod is such that when rod and attached ball are pulled against the 
 spring and then allowed to be propelled from the tube, the second ball will drop from the rod at 
 the same instant as the ball and rod leave the tube, both reaching the floor at the same in¬ 
 stant, although one drops in a plumb line and the other describes a parabolic path. 2.90 
 
 22-230 GAGE’S SECOND LAW OF MOTION APPARATUS. 
 
 This apparatus consists of a metal casting holding a rod actuated by a spring. Two spheres are 
 provided, one solid while the other is drilled for slipping over one end of the rod when the spring 
 is held back for releasement. The solid sphere is placed in position as illustrated, so that when 
 the spring is released the end of the rod will inflict a blow upon it, shooting it out in a horizontal 
 position. The rod is of such length that when the spring is released the drilled ball will drop at the 
 same time as the solid ball receives its blow. It will be observed that the solid ball describes a 
 parabola while the drilled ball drops in a plumb line, both reaching the floor at the same instant. 
 
 In use this apparatus should be firmly attached to a heavy wooden block or to a table top .... 2.76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 9i 
 
 STRESS AND STRAIN 
 
 TORSION OF BEAMS TORSION OF WIRES ROTATIONAL VIBRATION 
 FLEXURE OF BEAMS YOUNG’S MODULUS 
 TENSILE STRENGTH OF WIRES 
 
 23-10 HARCOURT T-BEAM TORSION APPARATUS for determining the moment of torsion and the 
 coefficient of torsional rigidity of rods of different lengths and different diameters. The above il¬ 
 lustration shows the adaptability and interchangeability of our Universal T-Beam Series. (Sec¬ 
 tion 6.) 
 
 The distinctive torsion parts consist of a ball-bearing Torsion Wheel (No. 5-1175), in the hub of which 
 the movable end of the rod may be centered and rigidly fixed by set screws. The other end of 
 this rod is firmly fastened in a similar manner in the Fixed Head Torsion of Beams Attachment 
 (No. 5-1180). The twist on the rod so fastened is secured by weights attached to a steel ribbon 
 wound about the flat face of the torsion wheel. The length of the rod under experimentation may be 
 arbitrarily determined by the positions of the Index Arcs and Pointers; the former secured by move¬ 
 ment of the clamp on the table; the latter by movement of the Pointers along the rod. The Index 
 Arcs have interlocking attachments for use on our T-Beam Basic Clamp “A”. The Pointers are 
 fastened to the rod by set screws. 
 
 It will be noted that this design obviates errors due to slipping of the rods at the points where 
 they are clamped. 
 
 Complete apparatus, without clamps and without hanger and weights but including four rods; steel, 
 
 3 mm. and 6 mm. in diameter, brass, 3 mm. and 6 mm. in diameter .... .$9.16 
 
 The Basic Clamps used in above illustration are: 
 
 5- 1000 T-BEAM BASIC CLAMP “A” (two required) . . Each $0.94 
 
 6- 1150 T-BEAM BASIC CLAMP “B” (two required) . . Each 1.65 
 
 23-16 HARCOURT TORSION APPARATUS. This apparatus is the same as above in design except that the 
 Torsion Wheel, the Fixed Head and the Arcs are cast as parts of the table clamps. It is offered 
 to those teachers who, unfortunately, do not have in their laboratories a system of T-BEAM BASIC 
 CLAMPS and INTERLOCKING ATTACHMENTS. Complete with four rods, — steel, 3 mm. 
 and 6 mm. in diameter, and brass, 3 mm. and 6 mm. in diameter.13.35 
 
 WEIGHTS. Section 16. 
 
92 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 23-30 
 
 23-30 SIMPLE TORSION APPARATUS for deriving laws of torsion. 
 
 Complete apparatus, as listed below, including two spring balances.$2.46 
 
 23-30a ASH ROD, V 2 X Vi inch.12 
 
 23-30b -, % X % inch.14 
 
 23-30c COMBINATION BASE LEVER.60 
 
 23-30d GUIDE PIVOT...„.26 
 
 23-30e IRON CLAMP FOR ROD.35 
 
 14-46 QUARTER CIRCLE PROTRACTOR.09 
 
 16-310 SPRING BALANCE.45 
 
 Nos. 23-60 and 23-62 
 
 23-60 IMPROVED SABINE’S TORSION PENDULUM for 
 
 determining the moment of torsion of a wire and the 
 moment of inertia of a ring. 
 
 The design illustrated obviates the annoyances of existing 
 types. It is simple in design, self-contained, and sci¬ 
 entific in structure and appearance. Accurate results 
 are possible with a minimum of trouble. 
 
 Two methods of reading torsional vibrations are possible, 
 — by direct observation of consecutive transits of the 
 index past the zero point of the graduated arc; by ob¬ 
 serving through a telescope the consecutive flashes 
 from the illuminated mirror. 
 
 The disc is 10)4 inches in diameter and is clamped to the 
 wire by means of a small chuck fixed at its middle point. 
 
 This disc is then supported from the frame by a similar 
 chuck having the additional features of an adjusting 
 thumb nut and a set-screw. The index dial is cast from 
 metal and has large raised figures. A ring moment 
 of inertia of which is to be determined has the same 
 diameter and mass as the disc. 
 
 Torsion pendulum, as illustrated but without mirror 
 
 attachment. .$16.60 
 
 23-62 MIRROR ATTACHMENT complete, ready for attach¬ 
 ment as illustrated. 1-26 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 93 
 
 No. 23-90 
 
 23-60 TORSION PENDULUM for determining the moment of torsion for a steel wire and the moment 
 of inertia of two iron weights. 
 
 The apparatus consists of a metal frame mounted to one of our substantial H bases. Suspended from 
 the central part of this frame by means of a simple chuck is the suspension system consisting of a 
 steel wire at the end of which is mounted a cross head carrying two disc-shaped metal weights fixed 
 adjustably along the cross head. 
 
 Complete as illustrated.$ 4.50 
 
 23-62 TORSION SYSTEM as used in above frame, all that is required if No. 23-60 or 23-100 is a part of 
 
 the school equipment. 2.26 
 
 23-90 HARMONIC MOTION APPARATUS for verifying the Laws of Harmonic Motion (Ames and 
 Bliss, page 111) by noting the rotational vibrations of a flat coiled spring. 
 
 This apparatus consists of a flat coiled spring mounted on a vertical axis supported in frictionless 
 bearings, which, in turn, carries an arm with sliding weights to vary the inertia. The oscillations 
 are indicated by a pointer over a graduated aluminum dial. The whole is mounted on a tripod 
 base upright supporting the vertical axis and providing a support for a rod to which one end of the 
 spiral is fixed. Handsomely finished throughout in bright japan, lacquered brass and nickel-plate. 
 
 Complete as illustrated.22.00 
 
 23-100 INERTIA BALANCE for determining the mass of a body without weighing. 
 
 The apparatus consists of a metal frame same as No. 23-60 mounted on our improved H base. To 
 the center of the upper and lower sides are small chucks carrying a wire the upper end of which 
 may be adjusted in length by means of a thumb screw and firmly fixed by a T screw. This 
 wire holds a small metal cone-shaped pan fixed to it by means of two screws. The apparatus is 
 finished throughout in a manner to present a pleasing appearance and is carefully constructed 
 to give the best possible results. 
 
 Complete apparatus as illustrated. 6.00 
 
 23-102 INERTIA SYSTEM as used in above frame, all that is required if No. 23-60 or 23-60 is a part of the 
 
 school equipment. 2.76 
 
 23-106 UNIVERSAL RECTANGULAR CAST METAL SUPPORTING FRAME. Frame support only of 
 
 Nos. 23-60 and 23-100 . 2.26 
 
 No. 23-60 
 
94 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 FLEXURE OF BEAM 
 
 APPARATUS 
 
 > 
 
 23—125 FLEXURE OF BEAM APPARATUS. This “set up’’ for determining by experiment the laws of 
 elasticity of flexure is an arrangement of our Harcourt Universal T-Beam Clamps. (See Section 
 5.) 
 
 Complete-apparatus without basic clamps and weights. 
 
 23-128 KNIFE EDGE CONTACT PIECE. This is a metal stirrup with knife edge, binding post and hook. 
 
 W ith the knife edge resting on the beam, the weights, hanging to the hook, cause a stress at one 
 point only. 
 
 23-130 SCALE PAN.’ ’ * ^ 
 
 WEIGHTS. Section 16. 
 
 Other apparatus illustrated above and listed elsewhere is as follows: 
 
 5—1000 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “A” (three required) 
 
 Each. 
 
 23-136 FLEXURE OF BEAM APPARATUS same as No. 23—125 in design except that the Knife Edges 
 are cast as parts of the table clamps and in place of the T-Beam Clamp and Micrometer Screw, 
 the Mounted Micrometer Screw No. 12-230 is furnished. Complete without weights 
 
 23-140 FLEXURE OF BEAMS AP¬ 
 PARATUS for determining 
 by experiment the laws for 
 elasticity of flexure. 
 
 The apparatus consists of 
 three triangular prisms, 
 two of which are used to 
 support the rod under test, 
 the third to act as the ful¬ 
 crum of the lever indicator. 
 A vertically mounted rule 
 gives the measure of the 
 movement of the long arm 
 of this lever. The scale 
 pan attached directly over 
 the short arm of the lever 
 and over the rod serves as a 
 support for the weights 
 which cause the stress. 
 
 Complete apparatus as illustrated, without weights, including the three prisms, two pine rods of 
 different cross sectional area, one lever indicator with supported scale and scale pan. 
 
 23-141 SUPPORTING TRIANGULAR PRISMS.Per Set of Three 
 
 23-142 PINE ROD, 100 centimeters X H X 1 inch. 
 
 23-143 -, 100 centimeters X 3^ X l A. inch. 
 
 23-144 LEVER INDICATOR. 
 
 23-145 MOUNTED INDEX STRIP after Hall Ex. 14 (No. 34). 
 
 11-70 MOUNTED 10-CENTIMETER SCALE. 
 
 23-130 SCALE PAN. 
 
 WEIGHTS. Section 16. 
 
 23-166 PAIR OF WOODEN SUPPORT BLOCKS, after Millikan, Gale and Bishop’s “Laboratory Physics,” 
 Experiment 13. 
 
 23-157 STEEL ROD, after Millikan, Gale and Bishop’s “Laboratory Physics,” Experiment 13. 
 
 $6.32 
 
 .65 
 
 .12 
 
 .94 
 
 5.15 
 
 $0.70 
 
 .24 
 
 .12 
 
 .10 
 
 .08 
 
 .10 
 
 .16 
 
 .12 
 
 .55 
 
 .10 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 95 
 
 23-180 HOOKE’S LAW and YOUNG’S MODULUS APPARATUS, for testing 
 Hooke’s Law and determining Young’s Modulus for a wire. 
 
 This apparatus consists of two parallel rods supported on a tripod with 
 leveling screws. In the upper casting clamping the rods is a small metal 
 chuck for clamping the upper end of the wire to be tested. In a hole 
 in the center of the movable casting is a second chuck which is set into a 
 cylindrical brass piece which moves with very little play in this hole. 
 This movable casting bears an accurately adjusted optical lever the front 
 feet of which rest on a small table incorporated in the casting. The rear 
 foot rests upon the carefuly ground top surface of the brass piece bearing 
 the chuck. Three two-kilogram and two one-kilogram weights which are 
 supplied with the apparatus may be placed on the weight hanger to 
 give the stretching force. 
 
 This apparatus is solidly built and its structure 
 is of most painstaking type. Accurate results 
 are easily obtained. 
 
 Complete as described.$25.00 
 
 23-191 MIRROR SCALE and UPRIGHT WOODEN 
 SUPPORT after Millikan, Gale and Bishop 
 (Experiment 13). 
 
 23-192 SPRING and WEIGHT HOLDER after Milli¬ 
 kan, Gale and Bishop (Experiment 13) . . . 
 
 .80 
 
 .20 
 
 No. 23-180 
 
 Nos. 23-191 and 23-192 
 
 No. 23-225 
 
 23-225 ELASTICITY OF WIRE APPARATUS, for determining the Coefficient of Elasticity of Wire. 
 
 Complete apparatus as above illustrated, but without Spring Balance and Basic Clamp.$2.16 
 
 SEPARATE PARTS. 
 
 23-226 SPOOL SPRING BRASS WIRE, No. 27.$0.40 
 
 23-227 T. & H. STRETCHING BLOCK WITH WOOD PILLAR AND BRASS BINDING POST ... .90 
 
 23-228 MARKER CLAMP AND STYLUS.20 
 
 5-1150 T-BEAM BASIC CLAMP “B”. 1.66 
 
 16-316 SPRING BALANCE, 15 kilos and 30 pounds. 1.65 
 
 23-231 MOUNTED MILLIMETER SCALE.20 
 
 16-366 SPRING BALANCE SUPPORTING CRADLE.45 
 
g6 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • * 
 
 23-211 BREAKING STRENGTH OF WIRES APPARATUS, for measuring the tensile strength of wires. 
 
 This apparatus must not be confused with the various forms on the market. It is designed to do 
 all and more than the others will do, and to facilitate rapid and accurate determinations. It 
 is constructed entirely of metal. The essential features consist of cast metal legs, to which are 
 rigidly fastened two nickel-plated steel rods to form the bed of the instrument. To the bed are 
 clamped the cradle for the dynamometer and a recoil frame. The ring of the dynamometer slips 
 over a peg on one of the end castings. The hook is attached to the recoil frame. The design of 
 this recoil frame is simple and most effective. It is a metal casting provided with binding device for 
 one end of the wire whose tensile strength is to be tested and the retaining frame with buffer for 
 recoil wedges. Our tension device consists of a crank operating an axle about which the wire 
 winds as the tension increases. Danger of recoil of crank is entirely obviated by means of a rachet 
 and pawl attached to one end of the axle. 
 
 Results of experience have demonstrated that in this design we offer an instrument obviating ob¬ 
 jectionable features of less carefully and scientifically designed instruments. Our instrument will 
 
 form a valuable acquisition for any well appointed laboratory. 
 
 Without dynamometer.$5.00 
 
 23-212 -, same as above, but with double scale dynamometer, 30 pounds and 15 kilos. 6.60 
 
 COMPOSITION OF FORCES 
 
 For the “set up” of the experiment above illustrated no new apparatus is required. Articles shown above 
 are as follows: 
 
 6-1000 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “A.” (Three 
 
 needed). Each $0.94 
 
 5-1065 STONE’S TENSION CLAMP ATTACHMENT. (Three needed) . . Each .48 
 15-310 SPRING BALANCE, 2000 grams and 64 ounces. (Three needed) . . Each .45 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 97 
 
 The only distinctive item shown in accompany¬ 
 ing illustration is the following: 
 
 24-15 STRAIGHT-GRAINED SUPPORT BOARD 
 
 with side ledges and provided with clamp at 
 back for attaching to any 19-millimeter rod . 
 
 Other apparatus illustrated has all been pre¬ 
 viously listed as follows: 
 
 5- 1000 HARCOURT T-BEAM BASIC CLAMP “A.” 
 
 (Three required).Each 
 
 6- 1070 BALANCE CRADLE ATTACHMENT. (Three 
 
 required).Each 
 
 5-250 KNOTT ADJUSTABLE ECCENTRIC LEVEL¬ 
 ING BASE . 
 
 5-20e SUPPORT ROD, 19 millimeters diameter, 100 
 centimeters long. 
 
 $ 2.20 
 
 .94 
 
 .66 
 
 2.35 
 
 1.00 
 
 24-26 
 
 Note. — Universal Stand No. 22-130 may be used in place 
 of the last two items'if so desired. 
 
 COMPOSITION OF FORCE ATTACHMENT for use on any 19 mil¬ 
 limeter rod in the study of equilibrium and composition of forces. 
 This attachment consists of a metal casting with clamp and cross¬ 
 head in one piece. The cross-head is provided with hooks for hanging 
 
 pulleys. 
 
 Attachment only, without pulley or weights illustrated.$1.16 
 
 ACCESSORY APPARATUS ELSEWHERE LISTED: 
 
 22-130 UNIVERSAL STAND.$ 210 
 
 27-150 BALL-BEARING SINGLE PULLEY. (Two required) 
 
 Each .60 
 
 16-460 UNIVERSAL WEIGHTS.Set with holder 2.75 
 
 24-35 STONE’S TENSION CLAMPS for holding either a string or wire firmly yet adjustably; convenient 
 for use with Spring Balances as illustrated in determining the Parallelogram of Forces. 
 
 This clamp consists of a casting with jaws wide enough to fit over the ordinary Physics Laboratory 
 Table. A nickel-plated T-screw is provided for firmly fixing to the table. The wire is threaded 
 under a small cam lever which binds or releases by only a slight motion of the lever. Per set of three $1.14 
 
 Each .38 
 
 24-36 STONE’S TENSION CLAMP 
 
g8 
 
 L. E. KNOTT APPARATUS CO 
 
 
 BOSTON 
 
 No. 24-60 
 
 COMPOSITION OF FORCES 
 
 Items above illustrated assembled will all be found previously listed, and if already a part of the school equip¬ 
 ment will not be needed. They are as follows: 
 
 6-260 KNOTT ADJUSTABLE ECCENTRIC LEVELING BASE . . 
 6-20e SUPPORT ROD, 19 millimeters diameter, 100 centimeters long 
 
 22-130 UNIVERSAL STANDS. (Two required).Each 
 
 6-770 RIGHT-ANGLE CLAMPS. (Two required).Each 
 
 6-962 PULLEY ON ROD. (Two required).Each 
 
 16—460 UNIVERSAL WEIGHTS.Per Set with Holder 
 
 24-16 SUPPORT BOARD. 
 
 $2.35 
 
 1.00 
 
 2.10 
 
 .95 
 
 .90 
 
 2.76 
 
 2.20 
 
 24-60 PARALLELOGRAM OF FORCE TABLE for use in either HORIZONTAL or VERTICAL POSITION 
 
 in deriving Laws of Parallelogram of Forces. 
 
 This instrument is intended for high-grade work in the quantitative determinations of the Laws of 
 Parallelogram of Forces. Built throughout of metal, it is extremely substantial, and being beauti¬ 
 fully nickeled and japanned, presents a handsome appearance. The apparatus consists of a smooth 
 nickeled iron disc 35 centimeters in diameter, divided into degrees. It is mounted in such a manner 
 that it can be used in either a vertical or horizontal position. Frictionless bearing brass pulleys 
 are provided for attachment to the edge of the disc. By the use of a special centering arrangement, 
 weights and weight holders, very accurate results are possible with this table. 
 
 Complete as illustrated, with three frictionless bearing brass pulleys, centering arrangement, weights 
 
 and weight hangers, mounted on a 60-centimeter rod on tripod base. 25.00 
 
 24-61 PARALLELOGRAM OF FORCE TABLE, same as No. 24-60, but mounted on a 100-centimeter rod 
 
 and with tripod with three leveling screws.. 26.00 
 
 WEIGHTS AND WEIGHT HOLDERS. Section 16 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 99 
 
 No. 24-80 
 
 
 24-80 COMPOSITION OF FORCE BOARD, as used in Millikan, Gale and Bishop’s “Laboratory 
 Physics” (Experiment 11). 
 
 This is a well-seasoned board, 30 X 19 Yi inches, to the back of which are fastened two strips of wood, 
 which serve the double purpose of preventing warping and as a support. They are of sufficient 
 length so that the board may rest vertically. Holes into which pegs may be placed are conveniently 
 located on each quarter surface of the board, thus providing a convenient setting for a pin to which 
 strings from a Spring Balance may be attached. 
 
 The Board, with three pegs, but without Balances..$1.60 
 
 24-87 COMPOSITION OF FORCE BOARD for use with Spring Balances in formulating the laws of Com¬ 
 position of Forces. 
 
 This apparatus consists of a square board constructed so as to prevent warping, with holes equally 
 spaced in squares. Pins are provided which may be placed in any hole desired, to which may be 
 attached the strings from the hooks of Spring Balances. That the board may move freely, four 
 spheres are provided, which, when placed next to the retaining rims on the under side, will act as 
 ball bearings. This board has a sandpaper and oil finish and is substantially built throughout. 
 
 Board with four pegs and four balls. 1.66 
 
 24-96 WIRE PENTAGON, after Turner and Hersey (Experiment M274) . .16 
 
 No. 24-100 
 
 24-100 GAGE’S COMPOSITION OF FORCE AND MOTION APPARATUS for the graphic representation 
 of the components and resultant of two forces. 
 
 The apparatus consists of a flat board to which is clamped an attachment consisting of a clamp 
 holding in a sliding fit a square rod, with cross head which in turn carries a slide with pencil clamp. 
 
 This pencil clamp is free to move along a rod parallel to the cross head and is connected by a string 
 around a pulley to the end of the arm attached to the clamp holding the apparatus to the board. 
 
 Results possible with this apparatus arouse the interest of pupils in the Resolution of Forces. It is 
 pedagogically superior to much that is on the market for the graphic representation of forces. 
 
 Complete as illustrated.$9.76 
 
100 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 FORCE OF GRAVITATION 
 
 EQUILIBRIUM — Stable, Unstable and Neutral 
 
 No. 25-65 
 
 No. 26-10 
 
 No. 26-15 
 
 No. 26-50 
 
 1.35 
 
 .76 
 
 25- 10 CENTER OF GRAVITY BOARD for determining the center of gravity of an irregularly-shaped board. 
 
 This apparatus consists of a board of irregular shape drilled at various points. If the board is held 
 suspended from these several points, and a plumb line dropped from each, it will be found that 
 these lines all intersect at one point, — the center of gravity. 
 
 Board complete with handle support and plumb bob.$0.95 
 
 26- 16 MOUNTED CENTER OF GRAVITY ARC for illustrating stable and unstable equilibrium. 
 
 This apparatus consists of a balanced system so designed that the center of gravity may be readily 
 adjusted to demonstrate stable, unstable and neutral equilibrium. 
 
 Complete as illustrated, with supporting stand .,. 
 
 25- 20 CENTER OF GRAVITY SYSTEM for illustrating the center of gravity. 
 
 The apparatus consists of two brass spheres of different sizes connected by a rod in which are drilled 
 two holes, one at the geometric center, the other at the center of gravity. A support handle is 
 supplied with each instrument. 
 
 Complete as illustrated ... 
 
 26- 60 LOADED CYLINDER WHEEL for illustrating the center of gravity of a loaded wheel. 
 
 This apparatus consists of a wooden disc loaded near the edge and drilled at the geometric center 
 
 and at the center of gravity. A suitable upright for support is also furnished. 1.20 
 
 25- 55 LOADED CYLINDER, illustrating the tendency of a body to place its center of gravity as low as 
 
 possible. 
 
 This is a wooden cylinder loaded eccentrically, which, if rolled along a horizontal surface, will strive to 
 rest on its loaded side. 
 
 26- 60 WITCH, illustrating the tendency of a body to keep its center of gravity as low as possible. 
 
 This apparatus consists of a hemispherical piece of metal to which is attached a short length of pith. 
 
 26-76 LEANING TOWER, illustrating stability when a line drawn through 
 the center of gravity comes within base of support. 
 
 This inexpensive device, illustrative of the celebrated Leaning Tower 
 of Pisa, is built of wood with a removable top and foot. With the foot 
 in place, the tower will stand 
 so that its center of gravity is 
 in center of circle of the base. 
 
 With foot removed and top in 
 place, the center of gravity 
 being without the base, the 
 tower will topple over. With 
 top taken off, the tower will 
 stand stable, the center of 
 gravity coming within the 
 base.1 . . 
 
 .30 
 
 .11 
 
 $ 1.20 
 
 No. 26-80 
 
 No. 26-76 
 
 26-80 HORSE AND RIDER, illustrating equilibrium when line drawn 
 through the center of gravity comes within base of support. 
 
 The apparatus consists of wooden figures representing a horse 
 and rider. A wooden ball is attached to the figures so that 
 its weight changes the center of gravity to come within 
 the base of support. A striking illustration of the principle 
 is possible as pictured. 
 
 .95 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 IOI 
 
 FALLING BODIES 
 
 ACCELERATED MOTION 
 
 No. 26-100 
 
 Patented December 17, 1907 
 
 26-100 PACKARD’S FALLING BODY APPARATUS for the determination of the Laws of Accelerated 
 Motion with their application to falling bodies, the data being obtained from the path that the 
 falling body traces during descent. 
 
 This ingenious invention of Mr. John C. Packard of the Brookline High School, Brookline, Mass., 
 is, in its fundamental principle, a greatly improved inclined plane. It consists of a board of a 
 design to meet the special requirements. A quick-acting spirit level is attached for obtaining the 
 * necessary plumb in one plane. Adjustable legs at one end afford facilities for varying the angle 
 of tilt for changing the conditions. In use, a steel ball is allowed to roll down over the smooth 
 surface of a sheet of paper covered with a soft carbon tracing paper. There will be found on the 
 board, effective devices for clamping the paper and for holding and releasing the ball as required. 
 Results obtained by even the most careless students are ample recommendations for the purchase 
 of this instrument. 
 
 Complete with 12 sheets Cross-section Paper and 2 sheets Carbon Paper. Special circular on re¬ 
 
 quest . $6.26 
 
 26-101 CROSS-SECTION PAPER, special ruled.Per Ten Sheets .30 
 
 26-102 CARBON PAPER, especially adapted for use with No. 26-100 .Per Sheet .07 
 
 26-106 DUFF’S ACCELERATION APPARATUS, designed by Dr. A. Wilmer Duff of Worcester Polytechnic 
 Institute, for determining the acceleration of a falling body. 
 
 The apparatus consists of an accurately grooved plank. With the plank placed horizontally on the 
 table, a steel ball placed on one end of the groove will, when released, oscillate back and forth 
 like a pendulum and the time of each swing will remain constant. If, however, one end of the 
 plank be raised a little higher than the other, a ball placed in the middle of the groove will roll 
 down with accelerated motion. 
 
 By combining the oscillatory motion across the groove with the accelerated motion down the in¬ 
 cline, the oscillatory motion may be made to trace in a film of lycopodium powder equal inter¬ 
 vals of time for the study of accelerated motion. 
 
 Grooved Plank complete with Sphere, Releasing Block and package of Lycopodium Powder . . . 6.26 
 
I 
 
 102 L. E. KNOTT APPARATUS CO., BOSTON 
 
 Nos. 26-110 to 26-112 Nos. 26-161 and 26-166 
 
 26-110 FALLING BODY APPARATUS, retardation to free fall secured by INCLINED PLANE according 
 to Millikan and Gale’s “A First Course in Physics,” page 26, for determining the distance 
 traversed by a body under force of gravity in one, two, three, or four seconds under uniformly 
 accelerated motion. 
 
 The apparatus consists of a clear, straight-grained wooden plank, 16 feet long, with accurately cut 
 V groove running the total length, which, when inclined at an angle, affords an inclined plane down 
 which a steel ball may roll in a frictionless path. A block stop for this ball is furnished which 
 may be clamped to the plane at any position desired. Time interval may be noted by any conven¬ 
 ient means. We recommend either a Seconds Pendulum No. 17-60, or a Metronome No. 17-120 $8.60 
 
 26-112 --, same as above, but 8 feet long. This is to be used in connection with above for measuring 
 
 velocity acquired per second by a body under force of gravity in uniformly accelerated motion . . 4.80 
 
 26-120 FOUR-FOOT FREE FALL DEMONSTRATION APPARATUS or GUINEA AND FEATHER 
 TUBE for demonstrating that all bodies, even if of different masses, fall in equal intervals of time 
 if released from friction of air pressure. 
 
 This apparatus consists of a large glass tube, one end sealed air-tight, the other end with a brass cup 
 
 with stop-cock, bodies of different masses being enclosed previous to sealing. 6.76 
 
 25- 140 THE IMPROVED ALL METAL FALLING BODY APPARATUS (Ames and Bliss’ “A Manual of 
 
 Experiments in Physics,” Experiment 21), for determining the velocity and acceleration of a 
 freely falling body. 
 
 The apparatus consists of a weighted glass plate free to slide in a vertical metal frame. The nickel- 
 plated support rod may be adjusted to accommodate different sizes of forks and the clamp adjusted 
 to vary the height of the fork on the rod. 
 
 In use, the plate is covered with an even layer of smoke soot, “Bon Ami,” or whatever is desired 
 to give it a tracing surface. A fork with attached stylus is fastened in the clamp and adjusted so 
 that the stylus will mark the plate as it is allowed to drop from the top of the upright frame. 
 
 Price, without fork. 6.90 
 
 TUNING FORKS. See Section 61. 
 
 26- 161 ACCELERATION APPARATUS for determining the acceleration of a freely-falling body moving 
 
 with uniformly accelerated motion. 
 
 The falling body is a metal frame to which a heavy glass plate is held by spring clamps. This metal 
 frame with its glass plate falls before an electrically driven tuning fork, of known vibration num¬ 
 ber and which may be moved sideways to enable one plate to take several readings. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 103 
 
 In making an observation the plate is drawn to the top of the frame and fastened by a thread. The 
 stylus is now adjusted to touch the plate. The tuning fork is set in vibration, the string is burned in 
 two and the descending plate receives a fine tracing on its blackened or whitened surface. Meas¬ 
 urements are taken directly from the plate by means of a divider or scale. Frequently the trac¬ 
 ing is projected on a screen by means of a lantern. 
 
 The apparatus may be used as an Atwood’s Machine by attaching a light aluminum wheel on ball¬ 
 bearings to the frame. This wheel carries a cord holding the falling plate on one end and the coun¬ 
 terbalancing weights on the other. The platform and ring may be easily attached to the frame. 
 
 Complete without Atwood’s Attachment.$25.00 
 
 25-166 ATWOOD’S ATTACHMENT for use with No. 25-161 and as illustrated.16.00 
 
 Note. — The glass plate of Acceleration Apparatus No. 25-161 is generally coated with lamp-black over a gas-jet or burning 
 camphor. A much more cleanly method will be found in making a thin paste of alcohol and whiting, which may be rapidly ap¬ 
 plied to the plate with long strokes of a camel’s-hair brush or a soft sponge. 
 
 & 
 
 No. 26-180 
 
 25-180 
 
 26-200 
 
 25-201 
 2 5-202 
 
 FREE FALL APPARATUS (Stewart and Gee’s “Elements of Practical 
 Physics,” page 239), for finding the time taken by a body falling freely 
 from a height, and in determining the value of “g.” 
 
 The factors in determining the value of “g” are determined by the free fall 
 of a steel sphere from the bronze-tipped electro-magnet at the end of a 
 vertically adjustable brass rod to a slit at the lower end of a pendulum whose 
 period may be varied. The position and width of the slit is adjusted so 
 that the sphere dropping vertically passes through it when the pendulum 
 is at its lowest point. The electro-magnet holding the sphere and the one 
 drawing the pendulum aside are in the same circuit, which, when opened, re¬ 
 leases both simultaneously. If the time of fall equals the quarter period 
 of the pendulum, the sphere passes through the slit. By raising or lowering 
 the brass rod, this equality may be easily produced. One jaw is covered with 
 lead, in order that the experimenter may determine by ear whether the 
 sphere arrives at the plane of the slit too soon or too late. The period of 
 the pendulum gives the time of the fall. The distance is measured from 
 the bottom of the suspended sphere to the plane of the slit. 
 
 We unhesitatingly recommend this apparatus for very accurate determi¬ 
 nations of “g”.$26.00 
 
 UNIFORMLY ACCELERATED MOTION APPARATUS for study of princi¬ 
 ples of accelerated motion and for determination of factors governing a body 
 under uniformly accelerated motion. 
 
 The apparatus consists of a car which, mounted on a wire inclined at a slight 
 angle, is free to move down the incline. The wire is provided with a hook at 
 one end and a turn-buckle at the other for securing taut wire. 
 
 Apparatus complete as illustrated. 3.40 
 
 LYON’S CAR, with buffer. 1-96 
 
 INCLINED-WIRE OUTFIT, including screw, hooks, and turn-buckle with 
 buffer . L45 
 
 25-210 HALL’S ACCELERATION APPARATUS according to Hall’s “Elements 
 of Physics,” Exercise 17, page 508, 1912 edition. Pendulum Bar with 
 Counterpoise and Support as described. 
 
104 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 PENDULUMS 
 
 No. 26-230 
 
 26-225 FOUR BALL PENDULUM ILLUSTRATION for determining factors governing the laws of pendu¬ 
 lums. 
 
 The apparatus illustrated must not be confused with similar designs on the market, as it will be 
 
 noted that our instrument will support in adjustable suspensions four pendulums. 
 
 Pendulum Clamp with four balls but without support.$1.95 
 
 6-900 FOUR PENDULUM CLAMP only . 1.75 
 
 Support illustrated is No. 22-131 UNIVERSAL STAND. 3.16 
 
 26-227 THREE BALL PENDULUM ILLUSTRATION, same as above, but with our No. 6-902 Pendulum 
 Clamp for holding three pendulums m adjustable suspensions. 
 
 Pendulum Clamp with three balls but without support. .90 
 
 6-902 THREE PENDULUM CLAMP only.76 
 
 25-230 PENDULUM APPARATUS, after Turner and Hersey, for the determination of the Laws of the 
 Pendulum. 
 
 The apparatus consists of a special pendulum clamp, details of which are shown in illustration, each 
 designed to hold two pendulums. For different masses, we list three bobs of different metal; for 
 suspensions, fine wire. 
 
 In use, the pendulum clamp is attached by means of an iron clamp (our No. 6-1160 Harcourt Basic 
 Clamp “B” being shown in the illustration) to a convenient support, the Cross Beam of our 
 Standard Physics Table No. 1-100, being illustrated. 
 
 Apparatus complete without Basic Clamp. 1.74 
 
 SEPARATE PARTS 
 
 26-230a PENDULUM CLAMP as used in above.$0.64 
 
 25-230b SPECIAL CYLINDRICAL IRON BOB.25 
 
 25- 230C SPECIAL CYLINDRICAL LEAD BOB.30 
 
 26- 230d SPECIAL CYLINDRICAL BRASS BOB.30 
 
 25- 230e SPOOL COPPER WIRE, No. 30.36 
 
 6-1150 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “B”. 1.66 
 
 26- 232 SIMPLE AND REVERSIBLE PENDULUM APPARATUS, after Hall (No. XLIV), complete with 
 
 bobs but without meter stick. 1.96 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 105 
 
 25-235 BI-FILAR FOUR PENDULUM ILLUSTRATION for determining factors governing the Laws of 
 Pendulums. 
 
 This apparatus consists of our No. 5-906 Pendulum Clamp with four balls of equal diameter. These 
 balls are attached to the clamp by threads of lengths to obtain vibration periods, as 1: 2: 3: 4. 
 Pendulum Clamp with four balls, but without illustrated support.$2.95 
 
 5-906 BI-FILAR PENDULUM CLAMP only. 2.36 
 
 Support illustrated is 
 
 22-131 UNIVERSAL STAND.'..$3.15 
 
 26-251 CULLER’S ADJUSTABLE LEVER, PULLEY AND PENDULUM CLASP AND HOOK ROD 
 
 after Dr. J. A. Culler, Miami University, Oxford, Ohio. The name of this ingenious device is de¬ 
 scriptive of its manifold uses. (See Experiments VII, X and XI of Culler’s “Laboratory Manual 
 of Physics”.) Clasp and Hook Rod only. 1.60 
 
 25- 251A -, with Clamp... 2.40 
 
 26- 260 REVERSIBLE PENDULUM for determination of centers of suspension and oscillation, and, by 
 
 measurement of the distance between these centers, to determine the length of the equivalent 
 simple pendulum and, from this, the value of the acceleration of gravity. 
 
 This design consists of a nickel-plated metal rod on which are two lens-shaped bobs, each provided 
 with steel knife-edges with the edges of one turned towards the edges of the other. These bobs 
 may be adjusted along the rod as desired, thus changing the centers of suspension or oscillation at 
 will. The pendulum is suspended on the knife-edges of one of the discs on the bracket and stirrup, 
 as above illustrated. The bobs are now fixed at such a distance apart that the pendulum vibrates 
 with the same period, whether it is suspended from knife-edges of one bob or the other, — the 
 center of suspension becoming the center of oscillation when the pendulum is reversed. The 
 distance then between the knife-edges is the length of an equivalent simple pendulum. 
 
 Reversible Pendulum complete with stirrup and bracket. 4.45 
 
io6 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 J. 
 
 GRAVITY AND MOTION 
 
 No. 25-310 
 
 25-320 
 
 25-310 SWIFTEST DESCENT APPARATUS, comparing descents of spheres of the same diameter along 
 inclines of different curvatures. 
 
 The apparatus consists of three tracks placed on an incline to the base line, — one track describing 
 a cycloid curve, the second a concave circular curve, the third an inclined plane. The apparatus 
 is further provided with a device for the simultaneous start of all three spheres. The singular 
 results follow a simultaneous start of all three spheres, — the sphere on cycloidal curve reaches 
 end of track first, on concave circular track second, while the one on the inclined track is the 
 slowest. One other striking experiment will be noted, — no matter from which point on the 
 cycloidal track the sphere is started, the time of descent to the end of the track will always be the 
 
 same. 
 
 Complete with three steel spheres.$21.25 
 
 26-320 DOUBLE CONE AND PLANE for illustrating the seemingly paradoxical phenomenon of a cone 
 moving up an incline, which is of such shape that its axis actually descends. 
 
 Complete as illustrated, of finely grained and neatly polished wood. 1.16 
 
 No. 26-330 
 
 25-330 CENTRIFUGAL RAILWAY, illustrating the opposition offered by a moving body to any influence 
 exerted to counteract its tendency to move in a straight line. 
 
 This apparatus consists of a looped circular railway down which a body may roll unobstructed. At 
 one point in the loop illustrated, the body is held by centrifugal force against the under side of the 
 track in opposition to the force of gravity. 
 
 Complete as illustrated with car. 
 
 $17.50 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 107 
 
 26-10 UNIVERSAL WAVE MOTION APPARATUS, modification of Powell’s and Snell’s designs, combin¬ 
 ing features of both into one instrument capable of demonstrating all principles of each. Thus 
 the combination transverse and longitudinal component illustrating waves on surface of a liquid, 
 wave motion as set up by transverse displacements, and wave motion as set up by longitudinal 
 displacements are all strikingly shown. 
 
 WATER WAVES. In our model we show that the particle or element on the crest moves forward, in 
 the trough backward, and in the intermediate positions both vertically and horizontally. The 
 elliptical or circular orbits of the disturbed particles are ample in size that they may be readily 
 observed by all even in the largest lecture hall. It may also be shown that the wave form is not a 
 sine curve. 
 
 TRANSVERSE WAVE FORM. The demonstration of movement of a particle transversely and the 
 transverse wave form as well as the analysis of the resultant sine curve is especially adapted to this 
 model. 
 
 LONGITUDINAL WAVE FORM. Our model is so designed that in demonstrating any of the above 
 forms the condensations and rarefactions set up by longitudinal vibrations will also be formed, thus 
 affording a striking comparison of wave forms. 
 
 This model stands about three feet high and all parts are so proportioned that it is especially adapted 
 for lecture purposes. The elements are represented by balls; vibrations, transverse or longitudinal, 
 are communicated by brass rods; and the vibrations are set up in the rods by means of peculiarly 
 cam-shaped castings eccentrically mounted, each rod to its own casting, and all on a shaft operated 
 by a single crank. When the rectangular guide frame “A” is in the position illustrated both trans¬ 
 verse and longitudinal wave motions are demonstrated. With “A” in position as indicated by 
 dotted lines water waves and longitudinal waves are demonstrated. 
 
 This apparatus is carefully assembled and all parts accurately made. All woodwork is neatly finished 
 and the whole presents a scientific and handsome appearance. 
 
 $ 66.00 
 
io8 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 26-20 WAVE APPARATUS for illustrating the formation of transverse and 
 longitudinal waves. 
 
 This model consists of a steel ribbon along which, at regular intervals, 
 are securely fixed cross heads bearing at either end a metal ball, rod 
 and balls on either side of the ribbon being painted a distinguishable 
 color that various wave forms may be easily differentiated. This steel 
 ribbon in use is firmly fixed to the ceiling by means of the heavy 
 screw-eye furnished with the apparatus. By giving lowest the cross¬ 
 bar a motion at right angles to the steel ribbon a motion is communi¬ 
 cated to each cross-bar in' turn, illustrating transmission or propa¬ 
 gation of transverse waves. Longitudinal waves are propagated in 
 similar manner by depressing one end of the lowest cross-bar in a 
 vertical direction, the motion thus being communicated throughout 
 the entire length. 
 
 The use of this wave model fully warrants the expense, as results 
 obtained are entirely satisfactory and may be seen from the rear of 
 the largest lecture hall. The model is about 13 feet long, with cross¬ 
 bar attached every five inches.$11.60 
 
 / 
 
 No. 26-29 
 
 26-29 SPIRAL SPRING for illustrating wave motion, either transverse or 
 longitudinal. 
 
 This spring is constructed of spring brass wire coiled in the form of a 
 
 spiral . $1.26 
 
 26-32 RUBBER CORD for illustrating wave motion. .66 
 
 No. 26—40 
 
 26-40 METAL-FRAMED WAVE TROUGH for illustration of water waves. The plate glass sides of this 
 trough are supported by and sealed to the end metal castings and metal base to form a trough 10 
 inches deep by 5 feet long. The water level line is accurately parallel to the base. Waves are set 
 in motion by means of the paddle illustrated. 
 
 This trough, framed of metal, is vastly superior to designs framed of wood, in that possibility of 
 warping and, therefore, leakage, is entirely obviated. It is much more substantial and the metal 
 offers a surface for a durable and handsome japanned finish. 
 
 Complete, with paddle 
 
 $14.26 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 109 
 
 SIMPLE MACHINES 
 
 LEVERS, PULLEYS, WHEEL AND AXLE, INCLINED PLANE, 
 
 WEDGE, SCREW 
 
 No. 27-30 
 
 27-10 
 
 No. 27-46 
 
 27-11 
 
 27-12 
 
 16-300 
 
 27-30 
 
 27-46 
 
 27-60 
 
 27-61 
 27-61a 
 27-61b 
 27-62 
 27-67 
 27-76 
 
 27-60 
 
 27-96 
 
 No. 27-46 (Showing Lever of the First Class) 
 
 COEFFICIENT OF FRICTION APPARATUS for the 
 
 study and determination of the Coefficient of Friction. 
 
 The apparatus consists of a carefully planed white wood 
 strip, 50 X 20 centimeters. The friction between this 
 surface and the face of a wood block, 7.5 centimeters 
 square, is determined by means of a Spring Balance. 
 
 With Spring Balance.$1.37 
 
 WHITE WOOD STRIP, 50 X 20 centimeters. 
 
 WOODEN BLOCK, 7.5 centimeters square. 
 
 SPRING BALANCE, 250 grams and 8 ounces. 
 
 DEMONSTRATION LEVER, illustrating simple balances and also for experimental use as a lever 
 of the first, second, or third class. 
 
 Complete apparatus as illustrated, including pointer, two of No. 27-46 and central knife-edge but 
 
 without Meter Stick.. . 
 
 KITTREDGE LEVER CLAMPS for use with an ordinary Meter Stick in determining the Mechani¬ 
 cal Advantage of a Lever. 
 
 This clamp is made up of two metal stampings riveted together to form of meter stick and which may 
 be clamped to it by means of a thumb screw. A knife-edge protruding on each side offers a friction¬ 
 less support for the loops of a stirrup for attaching weights or hook of the scale pan. Per set of Three 
 LEVER APPARATUS for the study of Mechanical Advantages of a Lever. 
 
 The apparatus consists of a wooden bar to which is attached a graduated movable cross head with 
 metal retaining ends. Complete as illustrated, with a pair of scale pans with improved knife-edge 
 
 bearings after Mr. W. E. Rice. 
 
 LEVER AND SUPPORTING BAR only. 
 
 STRAIGHT LEVER . 
 
 SUPPORTING BAR and PIVOT. 
 
 RICE SCALE PANS...Per Pair 
 
 SCALE PANS, ordinary grade with attached strings.Per Pair 
 
 RIDER BLOCK, after Hall and Bergen (Experiment 12), for use on meter stick in determining Weight 
 
 of Lever Arms .. 
 
 U-SHAPED WIRE SUPPORTING HOOK, after Turner and Hersey (Experiment M130) .... 
 
 COMPOUND LEVER, illustrating a combination of simple levers to secure power equivalent to a 
 simple lever with long arm. 
 
 The apparatus consists of two lacquered brass strips connected and mounted on a convenient wooden 
 
 base 
 
 27-100 STEELYARD, capacity 50 pounds. 
 
 For other COMPOUND LEVERS, see Section 29. 
 
 $0.46 
 
 .12 
 
 .80 
 
 1.74 
 
 .60 
 
 1.30 
 
 .66 
 
 .36 
 
 .20 
 
 .76 
 
 .40 
 
 .18 
 
 .08 
 
 4.60 
 
 1.26 
 
no 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 PULLEYS 
 
 NEW FORM PULLEYS 
 
 The wheels are made of thin pressed steel, 5 centimeters in diameter. Each pulley is carefully mounted and 
 having less bearing surface than the old style, turns more freely. Designed for use as either fixed or movable pulley. 
 
 27-126 SINGLE PULLEY.$0.18 
 
 27-126 DOUBLE PULLEY.30 
 
 27-127 TRIPLE PULLEY.40 
 
 27-128 QUADRUPLE PULLEY.55 
 
 For FRICTIONLESS PULLEYS we recommend the following: 
 
 HARCOURT BALL-BEARING FRICTIONLESS PULLEYS 
 
 A PULLEY is one of the most essential requisites in the study of Mechanical Powers. The attainment of results 
 where guesswork is not required for the formulation of the laws has been confined largely to a class of instruments 
 not within the reach of the appropriation of many educational institutions. In many of the pulley experiments as 
 conducted in these institutions to-day, the student cannot be blamed for the inaccuracies of his conclusions. Our 
 experience has advised and our experimentation has designed our present BALL-BEARING FRICTIONLESS PUL¬ 
 LEY, which we can heartily recommend. It has the further quality of Expansion Possibilities, in that, with a basis 
 of the single unsheaved pulley and with the addition of an outfit of axles and stirrups, any combination up to two 
 pulleys of five sheaves is possible. 
 
 Illustrating Unit Parts to Assemble as Pictured Opposite 
 
 27-166 BALL-BEARING PULLEY UNIT . . . 
 
 27-167 AXLE ROD, Single Pulley. 
 
 27-169 AXLE ROD, Double Pulley. 
 
 27-171 AXLE ROD, Triple Pulley. 
 
 27-173 AXLE ROD, Quadruple Pulley .... 
 27-176 AXLE ROD, Quintuple Pulley . . . . 
 27-177 STIRRUP, Single, Triple, or Quintuple 
 27-179 STIRRUP, Double or Quadruple . . . 
 
 $0.35 
 
 .08 
 
 .08 
 
 .08 
 
 .08 
 
 .08 
 
 .20 
 
 .20 
 
 Our BALL-BEARING FRICTIONLESS PULLEY is shown in detail in the above illustration, and various 
 sheaves are pictured on the opposite page. 
 
 By inspection of the single pulley without stirrup, the face and edge of which are both shown, it will be noted 
 that this pulley is made up of two parts, each stamped out of one piece of metal by means of expensive tools and dies. 
 Both are then riveted firmly together with ball race in place. In assembling it is only necessary to use the metal 
 stirrup, stamped and formed also by tools and dies, and to attach to pulley by means of the shortest axle illustrated. 
 No tools are required, as all attachment is secured by two thumb nuts. In assembling a sheave of two or four pul¬ 
 leys, the wider stirrup is needed, using the correct length axle rod. In assembling a sheave of five pulleys, the nar¬ 
 row stirrup is used with the longest axle rod. 
 
 Each pulley with all parts is neatly nickeled and stirrup is provided with double hooks. For convenience in 
 purchasing, we list assembled sheaves. When experimenting with these pulleys, we desire to urge upon our patrons 
 the necessity of using a cord of about 34 inch diameter. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 hi 
 
 No. 27-154 
 
 No. 27-160 
 
 No. 27-152 
 
 27-160 SINGLE BALL-BEARING PULLEY, comprises one No. 27-165, one No. 27-167, one No. 27-177 . . $0.60 
 27-162 DOUBLE BALL-BEARING PULLEY, comprises two No. 27-165, one No. 27-169, one No. 27-179 . .95 
 27-164 TRIPLE BALL-BEARING PULLEY, comprises three No. 27-166, one No. 27-171, one No. 27-177 . 1.30 
 
 No. 27-156 No. 27-158 
 
 27-156 QUADRUPLE BALL-BEARING PULLEY, comprises four No. 27-165, one No. 27-173, one No. 
 
 27-179 .$1.66 
 
 27-168 QUINTUPLE BALL-BEARING PULLEY, comprises five No. 27-166, one No. 27-176, one No. 
 
 27-177 . 2.00 
 
 HARCOURT STEEL BALL-BEARING PULLEY ASSORTMENTS 
 
 All of the following sets are made up of the well-known Harcourt Ball-Bearing Pulleys fully illustrated and de¬ 
 scribed above. Each set includes pulleys, stirrups, and axle rods sufficient for assembling any of the combina¬ 
 tions as listed. 
 
 27-140 SIMPLE PULLEY ASSORTMENT, parts sufficient to assemble, — 4 Single Pulleys or 2 Double 
 
 Pulleys.Per Set $3.00 
 
 27-141 PULLEY ASSORTMENT, parts sufficient to assemble, — 6 Single Pulleys or 3 Double Pulleys or 
 
 2 Triple Pulleys.Per Set 4.70 
 
 27-142 PULLEY ASSORTMENT, parts sufficient to assemble, — 8 Single Pulleys or 4 Double Pulleys 
 
 or 2 Triple Pulleys or 2 Quadruple Pulleys.Per Set 6.40 
 
 27-143 PULLEY ASSORTMENT, parts sufficient to assemble, — 12 Single Pulleys or 6 Double Pulleys or 
 
 4 Triple Pulleys or 3 Quadruple Pulleys or 2 Quintuple Pulleys.Per Set 9.60 
 
 The above assortment, No. 27-143, will be found adequate for study of the principal combinations of pulleys 
 in deriving mechanical advantages of the same. It is, therefore, highly recommended as a lecture-table demonstra¬ 
 tion assortment. 
 
 27-185 PULLEY CORD, especially adapted for all pulley experiments. This cord is of extra quality 
 
 hemp, % inch diameter.Per hank of 5 yards $0 20 
 
112 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 27-200 
 
 No. 27-216 
 
 No. 27-230a 
 
 No. 27-230b 
 
 No. 27-230C 
 
 27-200 
 
 27-201 
 
 27-216 
 
 LATHE TURNED PULLEY, a frictionless running, brass pulley, inches in diameter, mounted 
 in heavy brass frame on hardened steel cone bearings. Each pulley is carefully turned, centered 
 in a lathe, and, therefore, when mounted runs absolutely true and is in true balance. The rim 
 is turned with square groove that accurate measurement of diameter may readily be secured. Both 
 ends of the frame are provided with hooks one of which may be removed from the frame and re¬ 
 placed by any rod tapped Y X 20 (See No. 6-10). Different combinations as illustrated are 
 possible by use of a pair of steel rods. 
 
 All parts handsomely nickel-plated.Each Pulley 
 
 STEEL RODS for use in making combinations'of above Lathe Turned Pulley.Per Pair 
 
 TRIPLE TANDEM PULLEY for comparison of the mechanical advantages of pulley arrangement. 
 Each tandem pulley consists of three pulley wheels of different diameters fnounted in cone bear¬ 
 ings in a metal frame. Each pulley is lathe turned, carefully mounted and adjusted . . .Each 
 
 $2.45 
 
 .20 
 
 1.05 
 
 6-950 PULLEY ON ROD, axis at right angles to rod..$0.94 
 
 5-952 PULLEY ON ROD, axis in same plane as rod. .90 
 
 TACKLE BLOCKS (HARCOURT PATENT). These commercial pulleys must not be confused with inexpen¬ 
 sive types. They are carefully made from lignum-vitae with self-lubricating iron bushings. Each shell is provided 
 with a swivel hook and becket. 
 
 27-230 
 
 TACKLE BLOCKS, size of sheave 2 x /i X % X % inches; length of shell, 4 inches; requires rope Y inch 
 diameter. 
 
 Each 
 
 a b c 
 
 Single Double Triple 
 
 $1.70 $2.10 $2.85 
 
 We are prepared to furnish the commercial blocks of cheaper construction. For science laboratory use, how¬ 
 ever, we recommend the superior quality as listed above. 
 
 27-235 MANILA CORDAGE, Yi inch diameter, as required with above Tackle Blocks. This rope is con¬ 
 structed of only the best quality of manila hemp. Sold only in multiples of 10 feet. Per 10 Feet $0.26 
 

 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 113 
 
 No. 27-260 (Front View) 
 
 No. 27-260 (Top View) 
 
 No. 27-240 No. 27-242 
 
 27-240 DIFFERENTIAL PULLEY HOIST, for illustration of and determination of mechanical advantage 
 of a commercial differential pulley hoist. 
 
 This hoist is carefully made and thoroughly tested to the capacity of ton before shipping. Only 
 the best of hand-made chain is used, and careful attention to all details makes this a safe instru¬ 
 ment under full capacity and of an accuracy which would be classed under Scientific Apparatus. 
 Regular hoist, 6 feet; minimum distance between hooks, 17 inches; weight, 22 pounds; capac¬ 
 
 ity, ton; chain pull, 72 pounds through 18 feet. $11.75 
 
 27-242 DIFFERENTIAL PULLEY HOIST, smaller model with brass pulleys, mounted on stand. 7.60 
 
 27-260 T-BEAM UNIVERSAL PULLEY. This pulley is one of our Harcourt Universal T-Beam Series, 
 and we justly claim for it advantages that can only be realized when once used. The table clamp 
 is our No. 6-1000 Basic Clamp “A.” Attached adjustably to the beveled slide of this clamp is our 
 Universal Pulley Interlocking Attachment No. 6-1080. This attachment consists of two cast¬ 
 ings, the interlocking base provided with a nickel-plated T-screw for fixing to the beveled slide 
 top of the basic clamp, and a pulley arm which swivels about the post of the interlocking base. 
 
 As may be noted, this arm may be firmly locked by the T-screw in the post. At the end of the pul¬ 
 ley arm, cast as a part of the arm, is a circular block in which are drilled a number of holes, in any 
 of which the pulley rod may be locked by a T-screw. 
 
 The pulley itself is of careful construction and is mounted on cone bearings in a stirrup which is 
 attached to the rod. 
 
 We claim for our design a possibility of adjustments never heretofore attained by any design; in 
 addition, a greater ease and rapidity in securing multitudinous positions. We also secure a back¬ 
 ward and forward movement along the beveled slide. All positions may be firmly locked by 
 the nickel-plated T-screws. 
 
 T-beam Universal Pulley, complete as illustrated. 2.65 
 
 Persons equipped with Universal T-beam Basic Clamp “A” need purchase only Interlocking Attachment. 
 
 6-1000 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “A” . . $0.94 
 6-1080 UNIVERSAL PULLEY INTERLOCKING ATTACHMENT . . . 1.76 
 
114 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 27-275 
 
 27-275 PULLEY DEMONSTRATION APPARATUS. The frequent call for a complete outfit for demon¬ 
 stration of pulleys and the application of the principles thereof to wheels and axles and capstans 
 has led us to design and assemble the above illustrated combination. 
 
 As may be noted, the instrument consists of two upright rods mounted on our new form H-base 
 connecting these upright rods on two cross-bars provided with special clamps for attachment to 
 the rods. To these cross-bars are attached the various combinations which can be assembled 
 from the outfit listed below. 
 
 The apparatus as above illustrated is furnished complete with all accessories as follows, — 
 
 A Complete Equipment of Pulleys for Illustrating: 
 
 Fixed pulley, weight and power equal. 
 
 Fixed and movable pulleys for securing the following combinations: weight and power 
 as 1:2; 1:3; 1:4; 1:5; 1:6; 1:8; and 1:10. 
 
 These pulleys are the Harcourt Steel Ball-Bearing Pulleys (see page 111), an outfit being 
 supplied capable of giving any of the combinations above desired; thus one may secure 
 quintuple, quadruple, triple, double, and single pulleys in various combinations. 
 
 Improved Wheel and Axle, 5 diameters which are based upon simple weight ratios. 
 
 Capstan and Lever. 1 pair triple tandem pulleys. 
 
 The equipment which we furnish consists of the frame itself, the Wheel and Axle, the Cap¬ 
 stan and Lever, a pair of Triple Tandem Pulleys and in addition, a sufficient number of 
 the Harcourt Ball-bearing Pulley Units, Axles and Stirrups to set up the various pulley com¬ 
 binations shown above. 
 
 Apparatus complete as described without weights 
 
 $20.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 115 
 
 PULLEY STUDY APPARATUS 
 
 
 
 
 PULLEY STUDY APPARATUS 
 
 25-251 CULLER’S ADJUSTABLE LEVER, PULLEY AND 
 PENDULUM CLASP AND HOOK ROD after 
 Dr. J. A. Culler, Miami University, Oxford, Ohio. 
 
 The title of this ingenious device is descriptive 
 of its manifold uses. (See Experiments VII, X and 
 XI of Culler’s “Laboratory Manual of Phys¬ 
 ics.”) Clasp and Hook Rod only. $1.60 
 
 No. 27-335 
 
 The only distinctive item required for “set up” illus¬ 
 trated is as follows: 
 
 27-290 CAPSTAN ARM with CAPSTAN. This 
 
 is a special casting with clamp and arm 
 in one piece. At the end is mounted a 
 capstan. $1.90 
 
 Other apparatus illustrated, elsewhere listed. 
 
 6-770 RIGHT ANGLE CLAMP. 95 
 
 22-131 BASE AND ROD. 3.15 
 
 6-645 HOOK COLLARS (4 needed) . . Each .24 
 
 27-160 BALL-BEARING SINGLE PULLEYS (4 
 
 needed) .60 
 
 27-162 BALL-BEARING DOUBLE PULLEY . . .96 
 
 27-326 WHEEL AND AXLE. 1.75 
 
 5-10d SUPPORT ROD. .25 
 
 Note. Our No. 22—130 Tripod Support without levelling screws may 
 be used if desired in.the place of the one illustrated. 
 
 25-251a 
 
 with Clamp.$2.40 
 
 27-306 WOODEN STRIP with TWO HOOKS after Turner and Hersey, Exp. M320 .20 
 
 No. 27-326 
 
 27-325 ALUMINUM FIVE DIAMETER WHEEL AND|AXLE, for attachment to sup¬ 
 port rod by means of a clamp, in determining the Mechanical Advantage 
 of a Wheel and Axle. 
 
 This Wheel and Axle is made from new specifications which have been figured 
 on the basis of simple ratios. It is made of aluminum, nicely finished, with 
 5 diameters. It is mounted in cone pivots in a metal frame attached to a 
 
 Yl inch rod for use in clamp. 
 
 Without Clamp. 1.75 
 
 The Clamp illustrated is No. 6-770 RIGHT ANGLE CLAMP.95 
 
 27-336 WHEEL AND AXLE, after Hall and Bergen’s “A Text-Book of Physics,” para¬ 
 graph 64, for determining the Mechanical Advantage of Wheel and Axle; 
 also provided with attachments showing that the Wheel and Axle is simply 
 a modified lever of the First Class. 
 
 This apparatus consists of two wooden discs combined in one piece attached at its 
 center to a wooden rod by means of a screw, about which it is free to move 
 as an axle. This wooden rod is devised for clamping to the cross beam of the 
 Standard Physics Table or other convenient means of support. At various 
 points on the disc are drilled holes to which cords may be attached by use 
 of brass pins thrust into them. .96 
 
Ii6 L. E. KNOTT APPARATUS CO,, BOSTON 
 
 No. 27-345 No. 27-360 
 
 27-345 HORTVET’S APPARATUS, illustrating that the Mechanical Advantage of the Wheel and Axle is 
 the same as that of the Lever of the first class; also for demonstrating principles of both ma¬ 
 chines which are not possible with the simplified apparatus. 
 
 01 
 
 This apparatus consists of an upright wooden stand, vertically supported on which is a disc of wood 
 having 2 diameters. At various convenient points on this disc are drilled holes into which brass 
 pins may be thrust for support of cords which, suspended from these pins, answer the double purpose 
 of attaching weights and of supplying a plumb line for measuring the diameters of the two discs or of 
 lengths of the “Power” and “Weight” Arms, the readings being taken from the plumb line dropped 
 from the center axle. Just below the disc, attached at right angles to the upright, is a cross head 
 which bears a scale and a narrow mirror which obviates, in reading, errors due to parallax. 
 
 Experimental work on Levers, with fulcrum below or above line of support of “Power” and “Weight,” 
 is one of the features of this instrument not possible on instruments of simple form. Many other 
 interesting problems are possible with this apparatus. 
 
 Apparatus complete as illustrated with the addition of a simple Lever which may be attached in 
 place of the disc on the upright. 
 
 27-360 GAGE’S MECHANICAL POWERS APPARATUS for determining Mechanical Advantage of simple 
 machines such as the Lever of the first, second, or third class, the Wheel and Axle, and the Pulley. 
 
 The apparatus consists of a well-balanced lever arm provided with a brass central piece with holes 
 through which may be thrust the fulcrum pin on which lever may be supported on the forked 
 support in demonstrating an equal arm lever of the first class. A second hole provided in this 
 brass piece serves to illustrate the effect of raising or lowering the center of oscillation. The illus¬ 
 tration shows method of securing levers of the second and third classes, the second class being the 
 one illustrated. 
 
 The forked stand is also for use as a support for the wheel and axle (two being illustrated above, 
 but one only being furnished). The weight is supplied by means of special forms of double-hooked 
 brass weights, ten of which are furnished with each outfit. 
 
 Apparatus complete as illustrated, including one forked stand, one lever bar, one wheel and axle, sup¬ 
 port rod and round base, one clamp and arm, one ball-bearing single pulley, one stirrup, a scale 
 pan, and ten double-hooked weights. 
 
 $7.26 
 
 7.65 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 117 
 
 27-390 
 
 27-392 
 
 27-393 
 
 27-394 
 
 27-400 
 
 27-402 
 
 27-405 
 
 27-410 
 
 HALL’S IMPROVED INCLINED PLANE WITH SIDE RAILS AND SCREW ADJUSTMENT. 
 
 This plane is a neatly finished close-grained wooden plank provided_ivith side ledges. It is 120 
 centimeters long and 15 centimeters wide. It is furnished with screw adjustment for comparison 
 of masses by the acceleration test. (See Hall & Bergen’s “A Text-Book of Physics,” Exer¬ 
 cise 36).$1.60 
 
 MAHOGANY FINISHED POLISHED INCLINED PLANE, after Millikan, Gale and Bishop, “Lab¬ 
 oratory Physics” (Experiment 17). This plane is a smooth hardwood surface, 5 inches wide, 
 
 4 feet long. .76 
 
 PULLEY IN FRAME, as used in above, for attachment to any board .. . .76 
 
 SONOMETER ATTACHMENT for Inclined Plane No. 27-392 .20 
 
 HALL’S INCLINED PLANE APPARATUS for determining the mechanical advantage of the 
 inclined plane. 
 
 This apparatus consists of a wooden base to which is hinged a board, the surface of which is carefully 
 
 smoothed and finished. This board may be inclined at any desired angle as indicated by the grad¬ 
 uated metal arc, and set to same by means of a knurled head. “Power” and “weight” are balanced 
 over a freely running pulley set in pivotal bearings. Graduated scales for both incline and height. 
 
 Plane only, without illustrated scale pan, roller, and weights. 4.45 
 
 -, same as above but is provided with a roller as above illustrated, adjusted to weigh exactly 
 
 one pound. It is also furnished with the scale pan but without weights. 6.60 
 
 ROLLER FOR INCLINED PLANE for use as the “Weight” in determining the Mechanical Ad- 
 
 No. 27-410 
 
 vantage of the Inclined Plane. 
 
 Consists of a carefully turned roller, ends centered and pivoted in metal frame . 
 
 PRATT INSTITUTE INCLINED PLANE for determining mechanical advan¬ 
 tage of an inclined plane. 
 
 This apparatus, manufactured by us, consists of two hinged boards of close- 
 grained hardwood, the upper surface of which is carefully planed and finished 
 smooth. The variable inclines are secured by means of the swiveled brass 
 rods which may be locked in any position desired. “Power” and “weight” 
 are balanced over a ball-bearing single pulley on rod, adjustably mounted 
 in a special bracket casting. For the “power” it is 
 designed that the roller illustrated above and weigh¬ 
 ing 11 pounds be used; for “weight,” 
 hanger and weights illustrated and 
 described in Section 16. 
 
 Inclined Plane only, without illustrated 
 weights, hanger, or roller . . $7.35 
 
 1.95 
 
 27-412 PRATT INSTITUTE INCLINED PLANE ROLLER. This roller as above described weighs 11 
 pounds. The surface is carefully turned and is mounted in a frame in pivotal bearings. Although 
 designed especially for use with the above inclined plane it may be used to advantage on any incline 
 whatsoever. 
 
 Roller only, as above illustrated. 
 
 WEIGHTS. Section 16. 
 
 $3.15 
 
n8 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 •» 
 
 27-420 WEINHOLD’S DEMONSTRATION INCLINED PLANE for the quantitative study of factors 
 
 governing mechanical advantage of an inclined plane. 
 
 In this apparatus, with graduated arc, length, height, and incline dimensions, not only may the 
 Mechanical Advantage of an Incline be quantitatively determined, but also the normal pressure 
 on the plane can be measured. 
 
 The apparatus consists of a frame, as illustrated, similar in appearance to any carefully constructed 
 Inclined Plane. The roll, however, of this plane is provided with three stirrups for use as illus¬ 
 trated in measuring normal pressure on the plane, one component being determined by a mass 
 hung over a pulley attached to the upright rod at the right, the other component, by the mass 
 hung similarly at the left. 
 
 This plane is carefully constructed throughout, all parts being neatly finished. 
 
 Furnished complete as illustrated, but without weights of any kind.Duty Free $28.45 
 
 No. 27-436 
 
 27-435 INCLINED PLANE CAR for use with weights as the “Weight” in determining the Mechanical 
 Advantage of the Inclined Plane. 
 
 In this car we have attempted to obviate the errors of the ordinary four-wheel type, and use a car 
 with three wheels only, thus securing positive wheel action on all three wheels. 
 
 The body of this car is a metal casting, neatly finished in japan; the wheels, mounted in frictionless 
 
 cone bearings, are lacquered brass. A hook for attaching the power is also provided.$1.55 
 
 27-440 INCLINED PLANE CAR, type with four wheels in pivotal bearings. 1.10 
 
 27-450 WOODEN SPREADER for experiments with an Inclined Plane when it is desired to use “Power” 
 parallel to base. 
 
 When there is no slot lengthwise of the incline, this spreader will be found a great convenience . . .10 
 
 27—465 RUBBER CORD for use in experiments with an Inclined Plane Car on Inclined Plane in Inertia 
 
 Experiments, as described in Hall & Bergen’s “A Text-Book of Physics,” Exercise 36 . . Each .20 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 119 
 
 27-475 
 
 MODEL OF WEDGE for determining the Mechanical 
 Advantage of a Wedge. 
 
 This apparatus consists of a wedge-shaped metal skel¬ 
 eton which in operation is held between three easily 
 running pulley wheels supported above and below 
 the wedge. “Power” is attached by means of a 
 cord over the fourth pulley illustrated. “Weight” is 
 supported from above on hinged platform. 
 
 Complete without weights. 
 
 WEIGHTS. See Section 16. 
 
 27-485 WEDGE, consisting of a two-part piece of hard wood, 18 centimeters long, each part 2 Y 2 centimeters 
 
 at point of greatest thickness.Each $0.80 
 
 No. 27-610 No. 27-520 
 
 27-500 MODEL OF A SCREW for the qualitative illustration of the great force of a screw. The design 
 above pictured illustrates the tremendous power that may be secured by means of a screw. 
 
 This design consists of a modification of one of our T-Beam designs, the modification consisting of 
 a special casting attachment with breaking wedges securely fastened to the face of our Basic 
 
 Clamp “B” .$1.65 
 
 27-510 JACK SCREW, demonstrating the Mechanical Advantage of the Screw; also used for leveling up 
 
 purposes. 
 
 This Jack Screw is 1 inches in diameter at the base and has a range from 2 % to 3Y% inches. By 
 use of extension bases B and C, a range of from 2J£ to 6 l /i inches is possible. An auxiliary pointed 
 screw D is supplied which may be used in place of the screw with swivel cap when desired. The 
 base E is also provided for use in special cases. 
 
 Jack Screw complete as illustrated, including A, B, C, D, and E. 1.85 
 
 27-510A JACK, only. 1.00 
 
 27-610B EXTENSION BASE, 2 inches high.30 
 
 27-510C EXTENSION BASE, 1 inch high.20 
 
 27-610D EXTENSION SCREW.20 
 
 27-610E EXTENSION BASE.20 
 
 27-520 FIVE-TON ROLLER-BEARING JACK SCREW. These Jack Screws are of cast iron with a 1 % 
 inch steel screw with square threads and provided with roller bearings. Total height when screw 
 is closed is approximately 8 inches; lifting capacity five tons. 4.30 
 
120 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 MODELS OF COMPLEX MACHINES 
 
 28-10 SIMPLE GEARED WHEELS, illustrating the great mechanical advantage of a system of geared 
 
 wheels. 
 
 This system consists of two wheels with pinions one-fourth the diameter of the wheels, while a third 
 wheel has a drum of the same ratio, thus giving a mechanical advantage of 1 to 64. Gears mounted 
 on rod for clamping to a support. Apparatus as illustrated shows use of our No. 6-770 Right 
 Angle Clamp mounted on the rod of our No. 22-130 Universal Support. 
 
 Geared wheels only, without illustrated clamp.. $3.86 
 
 The clamp illustrated is 6-770 Right Angle Clamp. .96 
 
 28-26 ENDLESS SCREW for determining the mechanical advantage of a gear operated by a screw. 
 
 This apparatus consists of a disc gear with drum for holding weight. This gear is actuated by an 
 endless screw, one end of which terminates in a drum around which is attached the “power.” The 
 whole is mounted to a casting which is attached to a rod by a swivel joint which may be held fixed 
 by a thumb nut. This rod may be clamped to any support by use of any right angle clamp, our 
 
 No. 6-770 Clamp being illustrated. 
 
 Endless screw only, without illustrated clamp. 6.46 
 
 The clamp illustrated is 6-770 Right Angle Clamp.96 
 
 28-76 CRANE DEMONSTRATION APPARATUS for quantitative demonstrations of boom stress and 
 
 guy strains in cranes. 
 
 This apparatus consists of a boom devised to register all stresses in pounds or grams up to 30 pounds 
 or 16 kilograms. It is shown illustrated with apparatus previously listed which, if already a part of 
 the school equipment, need not be added. 
 
 Crane Boom only, with attached chains ..$6.60 
 
 28-78 THREADED HOOK, threaded X 20, for use with No. 6-786 Right Angle Clamp as illustrated .16 
 
 16-332 SPRING DYNAMOMETER, registering 20 pounds.. 2.16 
 
 Other apparatus above illustrated but previously listed is as follows: 
 
 6-1160 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “B”. 1.66 
 
 6-730 RIGHT ANGLE CLAMP.66 
 
 6-785 RIGHT ANGLE CLAMP.46 
 
 6-20e SUPPORT ROD, 19 millimeters diameter, 100 centimeters long. 1.00 
 
 28-79 CRANE BOOM after Fuller and Brownlee (Experiment 24). .26 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 121 
 
 PRATT INSTITUTE APPLIED PHYSICS 
 
 APPARATUS 
 
 On the following pages is illustrated a line of apparatus as new’ to the scientific instrument 
 houses as it is to educational laboratories in America. This line follows the designs as used in Pratt 
 Institute, which have been worked out to meet the definite need of such work as is done at this 
 institution. 
 
 The illustrations showing the line we are now offering were made from the pieces built for 
 Wentworth Institute, Boston, under the immediate supervision of Professor W. H. Timbie, Director 
 of the Applied Physics Department. 
 
 Technical Schools, Trade Schools, Manual Training Schools, and High Schools giving voca¬ 
 tional or manual training courses, will be interested in these pages. 
 
 » 
 
 • DISTINCTIVE FEATURES. While some of the pieces in form, at least, will suggest the older 
 types common in laboratory work, it must be noted that there is an essential difference, viz., size. 
 All the parts are made large for a definite, pedagogical reason, the educational value of muscular 
 reaction serving as the keynote of this work in Applied Mechanics. 
 
 The large crane, for example, will illustrate our point. This stands over seven feet high and 
 is capable of handling a load of over 200 lbs. It at once impresses the student with its commercial 
 importance and hence worthy of his serious attention. The design is such that notwithstanding 
 that the commercial form has been maintained every strain and reaction may be definitely de¬ 
 termined and correct functions deduced. 
 
 No. 27-410 
 
 27-410 INCLINED PLANE. This instrument, when used in connection with the 11-lb. roller as illustrated, 
 is well worked out for the study of,— 
 
 1st, Forces supporting a body on a frictionless surface. 
 
 2d, When used in connection with the Pratt Institute car, catalogue No. 27-435, a study 
 of the forces parallel to the incline may be made. 
 
 3d, When used with a friction block, catalogue No. 27-12, the determination of the coef- 
 cient of friction by the two more common methods is readily made. 
 
 By the use of this plane all of the above problems may be solved in a more effective way, than with 
 the plane usually furnished. 
 
 Inclined Plane as listed, without weights, hanger, and roller.$7.35 
 
 27-412 ROLLER, accurately centered and finished, weight 11 lbs. 3.16 
 
 27-435 PRATT INSTITUTE CAR of accurate construction and correct design. 1.65 
 
 HANGERS AND WEIGHTS. Section 16. 
 
122 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 29 30 SHEAR LEGS. A most impressive illustration of the composition of forces as applied to the shear 
 legs, solving definitely the following: 
 
 1st. The tension in the tie. 
 
 2d. The compression in the legs of shears. 
 
 3d. The forces necessary to keep the legs from spreading. 
 
 Made of seamless tubing, correct design of hinge so that every force is exerted at its proper point. 
 Price complete, without balances, weights, or hanger. 
 
 15-334 SPRING DYNAMOMETER, registering 60 pounds ......... 
 
 HANGERS AND WEIGHTS. Section 16. 
 
 $5.40 
 
 3.20 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 123 
 
 No. 29-60 
 
 29-60 SIMPLE TRUSS. This simple 
 apparatus serves to teach in the 
 most direct manner possible, 
 forces in the Simple Stick and 
 Tie. The angle of inclination 
 and load may be varied at will 
 and the component forces at 
 each angle accurately deter¬ 
 mined. When the angle of the 
 Truss is increased to 90 degrees, 
 the problem is even more inter¬ 
 esting to the student. 
 
 Price, without Balances and 
 
 Weights.$2.86 
 
 29-80 SMALL HOISTING CRANE. A 
 
 substantial, but simply designed 
 apparatus for determining both 
 the tension and compression in 
 the Hoisting Crane. In this ex¬ 
 ercise the weight of the boom, 
 which is material, should be 
 taken into consideration. 
 
 Price, without Balances and 
 
 Weights. 3.85 
 
 16-332 SPRING DYNAMOMETER, 
 
 registering 20 pounds. 2.15 
 
 No. 29-100 
 
 29-100 ROOF TRUSS. The laws of Equilibrium, as manifest in the simple Roof Truss, are strikingly solved 
 with the above apparatus. Note that the pressure at every point is definitely measured. The 
 support for holding the Truss against the side of the wall is so designed that the Truss may be 
 loaded with a block of iron of uniform size, resembling pressure or strains made by the snow load 
 or the wind pressure load on the roof. 
 
 Price of parts complete as illustrated, without Balance, Weights and Hangers.$4.25 
 
 16-334 SPRING DYNAMOMETER, registering 60 pounds. 3.20 
 
 HANGERS AND WEIGHTS. Section 16. 
 
124 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 •» 
 
 DAVIS’ MODEL BRIDGE 
 
 DESIGNED BY 
 
 Prof. HARVEY N. DAVIS, Harvard University, Cambridge, Mass. 
 
 No. 29-110 
 
 29-110 DAVIS’ MODEL BRIDGE for the study of reactions in a bridge truss. As all members are inter¬ 
 changeable, this model will serve to set up and demonstrate the reactions in a Simple Truss, a 
 Four-Panel Pratt Truss, a Five-Panel Pratt Truss, a King Post Truss, Underslung King Post 
 Truss, a Cantilever Truss, etc. 
 
 This apparatus is composed of members of aluminum and mahogany strips and tubes of aluminum. 
 
 The model as illustrated is 7 feet long, 25 inches high, supported on piers designed for convenient 
 use. The test member is of solid mahogany, provided with special cast bronze attachments for 
 clamping to the pins and holding the dynamometers when measuring tensions or compressions of 
 any of the members. 
 
 Complete as illustrated, with piers, tension and compression members, test member, and with special 
 
 attachment for holding the weight hanger, but without weight hanger, weights or dynamometer $38.00 
 
 Upon request we will send free a pamphlet containing a series of laboratory experi¬ 
 ments and exercises carefully prepared by Professors Davis and Black. Addi¬ 
 tional copies for students’ use furnished at a nominal price. 
 
 WEIGHTS and WEIGHT HANGERS. See Section 16. 
 
 DYNAMOMETERS. See Section 16. 
 
 LARGE HOISTING CRANE OR DERRICK 
 
 (For illustration, see following page) 
 
 29-125 LARGE HOISTING CRANE OR DERRICK. The cut will show at a glance the method of determin¬ 
 ing the various forces, such as: 
 
 1st. The tension in the tie. 
 
 2d. The vertical and horizontal forces exerted by a boom against the mast. 
 
 3d. The amount and direction of the total force of the boom against the mast. 
 
 4th The tension in each guy rope. 
 
 5th The vertical and horizontal floor reactions at the foot of the mast. 
 
 6th. The horizontal component of the forces in the guy ropes. Compare this with the 
 
 horizontal reaction at the foot of the mast. 
 
 Complete without Platform Scale, Balances, and Weights.$18.75 
 
 29-130 PLATFORM SCALE, as illustrated opposite. 18.76 
 
 16-334 SPRING DYNAMOMETER, registering 60 pounds. 3.20 
 
 HANGERS AND WEIGHTS. Section 16. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 125 
 
 LARGE HOISTING CRANE OR DERRICK 
 
 See description on preceding page 
 
126 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 29-135 
 
 29-135 FORCES IN A UNIFORM METAL BAR 3 FEET 
 LONG WITH SLIDING LOAD. With this ap¬ 
 paratus the forces acting on a body supported by 
 two cords not parallel, also by two cords parallel, 
 may be definitely worked out. Without knife- 
 edge clamp.$7.50 
 
 No. 29-145 
 
 5-696 KNIFE-EDGE CLAMP, as illustrated in above.$0.55 
 
 29-145 STEELYARD OF LARGE LABORATORY FORM. The apparatus is made from a uniform bar with 
 measurable counterpoises and sliding weights. The apparatus is designed to be calibrated by the 
 student according to the principles evolved in determining the center of mass in Uniform Bar 
 
 Experiments. Without weights and hanger and without support. 9.60 
 
 22-130 UNIVERSAL STAND, suggested as a support for above outfit. 2.10 
 
 5- 16a CROSS BAR SUPPORTING ROD, as illustrated above. .25 
 
 6- 730 RIGHT ANGLE CLAMP, as illustrated above.66 
 
 No. 29-150 
 
 29-150 COMPOUND LEVER AND JACK SCREW. Large in size and substantially built. An apparatus 
 for use on the lecture desk or in the laboratory, in determining the mechanical advantage of the 
 Compound Lever and Jack Screw. 
 
 Consists of a substantial base with metal uprights on which are attached the nickel-plated steel 
 members of the Compound Lever. The Jack Screw is of the commercial type, accurately cut 
 screws and substantially built. 
 
 Without Weights, Weight Hanger and Dynamometer.$14.75 
 
 15-332 TWENTY-POUND DYNAMOMETER, 20 pounds by pound, as illustrated above in outline . 2.15 
 
 WEIGHTS AND WEIGHT HANGERS. See Section 16. 
 
 29-166 WORKING MODEL OF THE ARCH. A four-foot model so designed that all the reactions and 
 thrusts may be definitely determined. 
 
 1. The vertical reaction at the abutments. 
 
 2. The horizontal reaction at the abutments. 
 
 3. The horizontal force at the center of the arch ring. 
 
 Complete without Balances and Weights 
 
 29.75 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 127 
 
 
 
 
 No. 29-166 
 
 29-166 SCREW JACK WITH WHEEL, BASE, AND BAR. The efficiency test-uf the commercial screw 
 jack has heretofore been considered out of the realm of laboratory work, even in technical schools. 
 The use of adequate load to represent real conditions has not been feasible except by this method 
 found so successful in Pratt Institute. 
 
 With the apparatus the working load may be reckoned in terms of tons, while the power is in terms 
 
 of hundreds of pounds. 
 
 The apparatus is made up of a supporting base, a self-oiling commercial jack of best quality, a power 
 wheel 18 inches in diameter grooved for cord, a lever arm 8 feet long capable of sustaining the 2-ton 
 
 load and anchorage bar. 
 
 Without weights and dynamometers.$29.60 
 
 29-167 WEIGHTS for use with the above, unadjusted, in 50-pound units.Each 3.76 
 
 29-169 HANGERS for weights, unadjusted, approximately 50 pounds.Each 6.26 
 
 16-334 SIXTY POUND DYNAMOMETER, 60 pounds by pound, as illustrated above in outline . . . 3.20 
 
 No. 29-180 
 
 29-180 BENT-ARM LEVER AND SUPPORTING TABLE. This apparatus has been developed for the pur¬ 
 pose of determining the relation between the forces acting on a lever. In its design special attention 
 has been given to the eliminating of all directive forces due to gravity and friction, and enabling 
 the use of forces of large dimensions. 
 
 Without Balances.$29.60 
 
 16-332 TWENTY POUND DYNAMOMETER, 20 pounds by pound, as illustrated above in outline . . 2.16 
 
 WEIGHTS AND WEIGHT HANGERS. See Section 16. 
 
128 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 MECHANICS OF LIQUIDS 
 
 DENSITY AND SPECIFIC GRAVITY 
 
 
 No. 31-10 
 
 Nos. 31-20 to 31-27 
 
 No. 31-35 
 
 31-10 ARCHIMEDES’ PRINCIPLE for demonstrating that a body submerged in water displaces an amount 
 equal to its own volume. 
 
 This apparatus consists of a solid cylinder and bucket accurately machined so that the cylinder will 
 exactly fit and fill the bucket. Each is provided with hooks and the bucket is further provided 
 with a handle. 
 
 Polished and lacquered.$1.20 
 
 31-18 OVERFLOW CAN AND CATCH BUCKET for formulating Archimedes’ Principle. This apparatus 
 consists of a nickel-plated spring brass Can with overflow spout near the top. The Catch Bucket, 
 also of nickel-plated spring brass, is provided with a handle and is of convenient height for placing 
 under overflow spout. In use, the Catch Bucket is placed under the mouth of the spout and the 
 Overflow Can filled until water begins to flow. When flow has ceased, the water in the Catch 
 Bucket is discarded and the Bucket is replaced. If, now, an object is placed in the Overflow Can, 
 there is an outflow from the Can into the Catch Bucket which exactly equals the volume of the 
 
 body. 
 
 Overflow Can and Catch Bucket. .90 
 
 31-20 OVERFLOW CAN.65 
 
 31-21 CATCH BUCKET.36 
 
 31-23 LOADED WATERPROOF WOODEN CYLINDER, adapted for use in Displacement and Density 
 
 experiments. 
 
 This is a cylinder loaded to just sink in water, with a water-proof paraffine finish. It is especially 
 
 adapted, from its size (3J^ inches by 1 % inches diameter), for use with Overflow Can No. 31-20 . .16 
 
 31-25 WATERPROOF CHERRY BLOCK, useful as specimen for measurement as well as for experimentation 
 and density work. 
 
 This block is made of cherry with sandpaper finish and paraffined to make water-proof. Its size is 
 
 3 X 3 X lJi inches thick, which makes it especially adapted for individual student work .... .11 
 
 31-27 LOADED WATERPROOF RECTANGULAR BLOCK for Displacement and Density experiments. 
 
 This is a block, 1% inches square by 2% inches high, loaded to just sink in water and made water¬ 
 proof by boiling in paraffine . _. f . .18 
 
 31-35 LEAD SINKER for determining the Specific Gravity of Lead, and for use as Sinker in determining the 
 Specific Gravity of an object lighter than water. 
 
 This Sinker is of uniform density and of convenient mass and size for use in Density experiments. It 
 
 is provided with small brass hook for suspension. .13 
 
 31—40 SULPHUR SPECIMEN for the determination of the Specific Gravity of Sulphur. 
 
 This is a specimen about 3 inches long by 1)^ inches in diameter. .06 
 
 -31-45 SPECIFIC GRAVITY DETERMINATION GROUP, consisting of Nos. 31-20 to 31-40. 1.64 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 129 
 
 No. 31-60 
 
 No. 31-67 
 
 No. 31-85 
 
 No. 31-80 
 
 No. 31-105 
 
 31-56 PURE ALUMINUM BLOCK, of commensurable volume for use in determination of the specific gravity 
 of aluminum, of a liquid by buoyancy method, of a solid lighter than water by the sinker method. 
 
 This is a cubical block of cast metal, 1 y 2 inches on an edge .$0.60 
 
 31-60 ALUMINUM CYLINDER, after Millikan, Gale and Bishop’s “Laboratory Physics” (Experi¬ 
 ment 6 ). .54 
 
 31-66 PARAFFINE CUBE for density experiments. This is a cast cube of paraffine, measuring 5 centi¬ 
 meters on an edge and weighing approximately 100 grams. .27 
 
 31-67 SPECIFIC GRAVITY SPECIMENS for mensuration and specific gravity work. 
 
 These specimens are rods of y 2 inch diameter, 2 inches long, accurately machined. The set consists 
 
 of aluminum, brass, steel, and hard rubber, enclosed in small cardboard box. .85 
 
 31-67a ALUMINUM ROD, H X 2 inches.24 
 
 31-67b BRASS ROD, y 2 X 2 inches.•..18 
 
 31-67c STEEL ROD, X 2 inches..^ .16 
 
 31-67d HARD RUBBER ROD, y 2 X 2 inches.29 
 
 31-70 SPECIFIC GRAVITY SPECIMENS, twenty different substances of irregular shape, of convenient 
 
 size for individual student work in density. In cardboard box. .66 
 
 31-80 SPECIFIC GRAVITY SPECIMENS for exact determinations of volume by direct measurement; 
 
 also for determination of density by measurement of mass, illustrating by direct comparison the 
 relations between volume, mass and density. 
 
 These specimens consist of twelve cubes, accurately machined to exactly one centimeter on an edge, 
 thus giving a volume of one cubic centimeter. The mass, therefore, of each cube will be the density 
 The set consists of the following specimens, — one each of magnesium, aluminum, zinc, tin, iron, 
 nickel, copper, silver, lead, and alloys of copper and zinc, copper and aluminum, and copper and 
 tin. Each set is enclosed with index in a velvet-lined case. 9.85 
 
 31-86 SPECIFIC GRAVITY SPECIMENS for showing that lengths are inversely proportional to specific 
 gravity when comparing substances of same diameter and mass; also, for exact determinations of 
 volume by direct measurements. 
 
 These specimens consist of twelve cylinders, machined to exactly 5 millimeters in diameter and length, 
 adjusted to weigh exactly 10 grams. The set consists of same metals as listed under No. 31-80, 
 enclosed in velvet-lined hinged case, with index on under side of cover.10.85 
 
 31-97 WATERPROOF WOODEN ROD for determination of the specific gravity by the flotation method. 
 
 This is a rod of wood of uniform density, 20 centimeters long, 1 centimeter in diameter, coated with 
 
 paraffine to make waterproof.. .06 
 
 31-100 BRASS SUPPORT for holding No. 31-97 in vertical position. 
 
 This is a spring brass support, designed to clamp securely on the side of a battery jar and to hold 
 
 No. 31-97 in an erect position by means of two aligned round sockets.. .17 
 
 31-105 DENSITY BY FLOTATION APPARATUS consisting of Nos. 31-97 and 31-100 with No. 31-266C 
 
 Glass Jar, complete •. . ..... .63 
 
130 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 31-160 
 
 31-126 SPECIFIC GRAVITY BOTTLE WITH THERMOMETER STOPPER for determination of the 
 specific gravity of a liquid by the weight of a measured quantity; capacity 50 cubic centimeters . 
 31-130 SPECIFIC GRAVITY BOTTLE WITH CAPILLARY STOPPER for determination of the specific 
 gravity of a liquid by the weight of the measured quantity. Capacity 25 cubic centimeters, ac¬ 
 curately adjusted... 
 
 31-131 - —, same as above, capacity 50 cubic centimeters. 
 
 31-132 -, same as No. 31-130, but unadjusted. 
 
 31-136 SPECIFIC GRAVITY BOTTLE. This is a small, glass-stoppered bottle of convenient size frequently 
 
 desired by instructors in preference to the especially adapted types. 
 
 31-140 SPECIFIC GRAVITY BOTTLE WITH CAPILLARY STOPPER, double-walled and evacuated. 
 
 Capacity 25 cubic centimeters... 
 
 31-146 HARE’S BALANCING COLUMNS APPARATUS. This apparatus consists of a support at the top of 
 which is mounted a special lead tube with three branches. To the two outside branches are at¬ 
 tached two lengths of glass tubing; to the central, the tubing through which the air is to be ex¬ 
 hausted from both tubes. 
 
 Complete as illustrated, with clamp, two jars, glass and rubber tubing connections and pinchcock, 
 but without upright support. 
 
 31-146a SPECIAL LEAD PIECE WITH THREE BRANCHES . 
 
 31-146b GLASS TUBES .Per Pair 
 
 31-146c PINCHCOCK . 
 
 31-145d GLASS JARS.Per Pair 
 
 31-146e UPRIGHT SUPPORT AND CLAMP . 
 
 31-145f SUPPORT CLAMP as used in above . 
 
 31-160 SPECIFIC GRAVITY PLUMMETS for Lecture Table use. 
 
 This apparatus consists of twenty-seven plummets indicating by sinking or floating, Specific Gravi¬ 
 ties ranging from .7000 to 2.000 by steps of .0600. 
 
 On the demonstration desk, if placed in a liquid in a tall jar, and other liquids which do not mix are 
 
 carefully placed in this jar, a spectacular result follows.Duty Free 
 
 31-160 DENSITY INDICATING BALL for illustrating the changes in the density of a liquid induced by 
 variations in temperature. 
 
 This is a metal ball 75 millimeters in diameter, nicely adjusted to float in cold water, but which will 
 sink in warm water. 
 
 $2.76 
 
 .67 
 
 .92 
 
 .30 
 
 .10 
 
 2.16 
 
 .96 
 
 .27 
 
 .20 
 
 .20 
 
 .20 
 
 1.76 
 
 48 
 
 9.86 
 
 3.86 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 131 
 
 No. 31-170 
 
 No. 31-227 
 
 No. 31-226 
 
 No. 31-266 
 
 31-170 HYDROMETER (CONSTANT WEIGHT), for finding Specific Gravity of light liquids, 
 
 Beaume’s Scale 70-10, Specific Gravity Scale 0.7000 to 1.000 ..$0.60 
 
 31-171 HYDROMETER (CONSTANT WEIGHT), for heavy liquids, Beaume’s Scale, 0-70, 
 
 Specific Gravity Scale 1.000 to 2.000 . .60 
 
 31-176 HYDROMETER (CONSTANT WEIGHT), for both light and heavy liquids. 
 
 31-226 CONSTANT VOLUME HYDROMETER TUBE, after Millikan, Gale and Bishop’s “Laboratory 
 
 Physics”. 
 
 31-227 CONSTANT WEIGHT HYDROMETER TUBE, after Millikan, Gale and Bishop’s “Laboratory 
 Physics,” for determining the Density of a Liquid by the flotation method. 
 
 31-230 DEMONSTRATION HYDROMETER, illustrating the principle of the hydrometer and the method 
 of determining the specific gravity of liquids by buoyancy. 
 
 This is a paraffined rod, 30 centimeters in length, 1 square centimeter cross section, graduated the 
 entire length to millimeters. Without Jar . .•. 
 
 31-232 
 
 31-240 
 
 31-242 
 
 31-250 
 
 31-266 
 
 with Jar 
 
 NICHOLSON’S HYDROMETER for determining the Density of a Body Heavier than Water. 
 This is a Constant Volume Hydrometer constructed of metal. It consists of a hollow cylinder at¬ 
 tached to the lower end of which is a basket heavy enough to keep the cylinder upright; at the 
 
 upper end is a vertical rod carrying a pan for holding weights. Without Jar. 
 
 _ ; same as above, but made entirely of glass. Recommended for lecture use. Without Jar . . 
 
 CLEAR WHITE GLASS HYDROMETER JARS for use where a tall jar of small diameter is desired. 
 
 Size, inches . 12 X 
 
 Price . . . $0.60 
 
 GLASS JARS, of excellent quality. 
 
 a 
 
 Size, inches . 2\i X 
 
 Price . . . $0.12 
 
 12 X 2 
 
 15 X 2 
 
 15 X 3 
 
 $0.65 
 
 $0.80 
 
 $1.00 
 
 b 
 
 c 
 
 d 
 
 4X5 
 
 6X8 
 
 8 X 12 
 
 $0.26 
 
 $0.40 
 
 $1.60 
 
 18 X 3 
 
 $1.36 
 
 1.26 
 
 .33 
 
 .44 
 
 .20 
 
 .76 
 
 1.95 
 
 2.95 
 
132 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 20 -tol 
 
 No. 20-260 
 
 No. 32-30 
 
 No. 32-36 
 
 20-261 INCOMPRESSIBILITY OF LIQUIDS APPARATUS, IMPROVED DESIGN, for the quantitative 
 
 observation of the incompressibility of liquids. 
 
 This apparatus consists of a tube with indicating capillary. The liquid to be observed should fill 
 the short arm of the tube and should rise in the long arm to near the top of the capillary. If mer¬ 
 cury is poured into the long arm, the liquid, if compressible, will indicate the amount, if any, in the 
 capillary. 
 
 This tube may be mounted on our No. 41-116 Boyle’s Law Stand. Tube only.$2.60 
 
 20-260 SCREW ADJUSTMENT INCOMPRESSIBILITY OF LIQUIDS APPARATUS for showing elas¬ 
 ticity and incompressibility of liquids. 
 
 This apparatus consists of a support which answers the double purpose of supporting a plunger and 
 a bottle as well as that of a clamp. 
 
 In use, the bottle is filled with the liquid, a one-hole rubber stopper placed in the neck, the end of 
 the plunger placed in the hole and the bottle clamped firmly in place by means of a screw ad¬ 
 justment. If the plunger is now thrust into the bottle, the liquid being incompressible, the bottle 
 will burst. 
 
 Complete with three bottles. 1.46 
 
 32-30 UNIFORM PRESSURE SYRINGE OF BRASS for demonstrating that the pressure of liquids is 
 equal in all directions against the sides of the containing vessel. 
 
 This apparatus consists of a metal sphere to which is attached a brass tube with piston. On the 
 surface of this sphere are “bosses” into which glass tubes are sealed in a vertical position. If the 
 apparatus is filled with water, or any other liquid inactive on the metal, any pressure exerted by 
 the piston will be transmitted in all directions against the inner sides of the sphere. As this 
 pressure is equal in all directions, the water will rise from the glass tubes a uniform distance. 
 
 This is a convenient form for the demonstration of the principle involved, and the accuracy of the 
 
 result and the cleanliness of operation make it a valuable addition to a laboratory equipment . . 12.00 
 
 32-36 UNIFORM PRESSURE SYRINGE for demonstrating that the pressure of liquids is equal in all 
 directions against the sides of the containing vessel. 
 
 This is an apparatus similar in design to the above, but made of glass, without the pressure indicating 
 
 tubes. The equality of pressure is illustrated by the spouting liquid. 1.96 
 
 PRESSURE OF LIQUIDS 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 133 
 
 32-50 PRESSURE 
 GAUGE, with 
 Equalizing Tube 
 
 after Cheston, 
 
 Dean and Tim- 
 merman’s 
 “Labora t o rv 
 Manual of 
 
 Physics” (Experiment 4), for measuring directly 
 the pressure of liquids at various depths. 
 
 This apparatus consists of a Pressure Diaphragm in 
 direct connection with a Manometer, the whole 
 mounted on a wooden scale. This form is an im¬ 
 provement over the old types, in that the level of 
 No. 32-50 the liquid in the Manometer may instantly be made 
 
 the same in both branches by allowing an equality 
 of pressure by opening the horizontal tube noted in 
 the illustration at about the central point .... $1.36 
 
 32-60 CHAIN DRIVE PRESSURE GAUGE, HALL’S IMPROVED, for 
 
 demonstrating that pressure upon a surface varies with the depth 
 but not with the angle of inclination. 
 
 This apparatus has been greatly improved to obviate the deteriorat¬ 
 ing quality of the rubber belt as used in former designs, the uni¬ 
 versal movement of the pressure chamber being imparted by a 
 chain and sprocket operated by a small crank. Illustration pic¬ 
 tures also our No. 32-62 Pressure Gauge Attachment, valuable 
 when it is desired to project the indicating globule on a screen. 
 Pressure Gauge only, without Jar or Attachment. 2.80 
 
 Nos. 32-60 and 32-62 
 
 32-62 PRESSURE GAUGE PROJECTION HOLDER, as designed by Dr. Hall, for use in the lantern slide 
 carrier in projecting the indicating globule in Manometer Tube of above. 
 
 This Holder is designed to fit the Standard Lantern Slide Carrier. The Manometer Tube, as il¬ 
 lustrated above, is clamped by two discs eccentrically mounted. The globule shows through the 
 center of the opening. Holder, only.$0.66 
 
 32-66 PRESSURE GAUGE, simple form, consisting of a pressure chamber in con¬ 
 nection with an index tube . .18 
 
 32-66 LIQUID PRESSURE GAUGE, after Millikan and Gale, Figure 4 . .65 
 
 32-70 GLASS MANOMETER TUBE, after Millikan, Gale and Bishop (Experi¬ 
 ment 4)... -27 
 
 32-75 PRESSURE TUBES, after Gage’s “Introduction to Physical Science,” for 
 showing that at same depth pressure is equal in all directions. 
 
 The set consists of four tubes, U form, the shorter arms of which open in 
 different directions, — upward, downward and sideways. 
 
 In use, an equal amount of mercury is placed in the bends and the tubes thrust 
 into a jar filled with the liquid until the openings of the short arms are all 
 brought at the same depth. The pressure indicated by the mercury regis¬ 
 ters the same. 
 
 Per set of four tubes 
 
 .96 
 
134 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 32-100 (Fig. 1) No. 32-100 (Fig. 2) 
 
 32-100 NICHOLS’ UPWARD AND DOWNWARD PASCAL’S VASE APPARATUS for quantitative 
 
 determintaion of the laws governing liquid pressure, both upward and downward, also, that pres¬ 
 sure upon a surface is independent of the shape of the containing vessel. 
 
 The apparatus consists of a standard to which are attached the various supporting arms of which 
 three are used in the experiment. (See Fig. 1 above.) 
 
 DOWNWARD PRESSURE. This apparatus shows the method of assembling when it is desired to 
 measure the downward pressure, its relation to the size of the surface acted upon, the effect of the 
 amount of liquid in the vessel above the surface and the perpendicular height of the liquid. 
 
 If water is then poured into the vessel, the upward pressure will be indicated by the long arm of the 
 lever moving upward. The amount of pressure may be calculated from the factors obtained by 
 the measurements of the two arms of the lever. 
 
 UPWARD PRESSURE. Fig. 2 illustrates how the apparatus is assembled for the study of upward 
 pressure of a liquid on a submerged surface, showing that the upward pressure bears the same 
 relation to the depth as does the downward pressure. 
 
 The apparatus is substantial and beautifully constructed throughout. Attractive dark finish with 
 nickel-plated fittings- The design is such as to permit of exact determinations with the least 
 inconvenience in manipulation. We call especial attention to its compactness, stability, and its 
 cleanliness in operation. 
 
 Complete with all parts 
 
 $ 18.00 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 135 
 
 No. 32-110 
 
 1 
 
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 Ulllllllllll.lllllll.lllllll.lll 
 
 ts* u (n 
 
 iil..il.iil.i.lmliiiliiiil.iili.iliii'iiliiilii. 
 
 —KN Of Tj BOSTON — 
 
 — nu/A'Oicnvjme a — Nu^o*d*Jn>ioc-^rooi^Cn«n'J»*«>o-w < *-^0»d'*® u >o— N<u>uid>jo>Wj 
 
 ulim(niJRniiMlMu!iHiliii!.nilin lm4ifhiiInJmiln>lNii(miki.hnbiu«.iriiiuUiiiluthuibinbiilnnhi.i^lii.ihiiilMnlmiWoliiiiliuiluul.mliutU.iliuilmiluiliiul'.i.uh. l <iir.hmiuiiWli<!iluutKilmi.iiiM 
 
 No. 32-130 
 
 32-110 PASCAL’S VASES WITH BALANCE ARM AND WEIGHT for demonstrating that pressure is in¬ 
 dependent of the shape of the containing vessel. 
 
 The apparatus consists of a casting for supporting the vessels of different shapes, also for a standard 
 which carries at its top a pivoted lever, on the short arm of which may be attached a hanger bear¬ 
 ing a brass disc the surface of which is ground to fit a cylindrical part of the casting above men¬ 
 tioned. 
 
 In use, the hanger is balanced by placing weights on the long arm of the lever. An index attached 
 to the standard indicates the height of the water in the vessel. 
 
 The hanger is attached to the arm of a balance. 
 
 Complete, as illustrated with jar and three vessels of different shapes, balance arm and weights . . $6.35 
 
 32-115 PASCAL’S VASES WITH MERCURY INDICATOR for demonstrating that pressure is independent 
 of the shape of the containing vessel, depending only on the area pressed upon. 
 
 The illustration pictures an instrument made entirely of glass. It consists of three differently 
 shaped vessels, each connected through stop-cocks of equal bore to a common tube terminating at 
 each end in manometer tubes, which, in use, have their bends filled with mercury, which acts as 
 the pressure indicator. 
 
 This instrument has become popular from its quality of being self-contained. Besides its extreme 
 sensibility, its convenience in operating and its cleanliness, this instrument is commended for the 
 
 rapidity with which it can be operated. 6.76 
 
 32-120 BUOYANCY OF LIQUIDS APPARATUS for illustrating vertical upward pressure. 
 
 This apparatus consists of a glass disc the surface of which is ground to fit the lower rim of a glass 
 cylinder. In use, this disc is held in junction to the cylinder by means of a string attached to 
 the center of the disc until a buoyancy pressure sufficient to counteract the weight of the disc is 
 reached. This pressure may be measured by carefully pouring water into the cylinder until the 
 mass equalizes the buoyancy pressure of the liquid on the disc. 
 
 Complete as illustrated, with jar, glass cylinder, disc, and support for cylinder. 1.64 
 
 32-130 LIQUID PRESSURE TUBES, after Chute’s “Physical Laboratory Manual,” Problem 62, for verify¬ 
 ing the Laws of Liquid Pressure. 
 
 These tubes are of glass, 50 centimeters long, of different diameters, graduated into millimeters along 
 
 their entire length, the zero of the scales being at the closed ends.Per Pair 2.76 
 
 32-132 CYLINDRICAL GLASS VESSEL for use with above Liquid Pressure Tubes. 2.50 
 
 32-134 LOADED GRADUATED LIQUID PRESSURE TUBE, after Fuller and Brownlee.36 
 
 32-136 PRESSURE U-TUBES for experiments in Fluid Pressure, consisting of tubes with arms of equal 
 lengths. 
 
 a b c d e 
 
 Length ... 10 12.5 15 30 50 centimeters 
 
 Price . . . $0.14 .16 .18 .30 .60 
 
136 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 32-150 
 
 
 No. 32-160 
 
 - 
 
 
 No. 32-165 
 
 32-160 TORRICELLIAN LAW APPARATUS for determination of the law s equals \/ 2 gh, where 5 equals 
 the speed of efflux, g the value of gravity and h the height of the liquid; also for simple demon¬ 
 stration of variable pressure according to depth below the free surface of the liquid. 
 
 This apparatus consists of a tall glass cylinder with lateral openings, three closed by stop-cock tubes, 
 the fourth terminating in a tube with a vertical branch which may be stopped by rubber tubing 
 and pinchcock. If the liquid is allowed to issue vertically it will rise to nearly the height of the 
 free surface of the liquid in the jar. This height would be the same except for the friction at the 
 orifice, the weight of the falling liquid and the resistance of the air. By turning the stop-cocks in 
 the other lateral tubes, allowing the liquid to issue forth, it will be noted that the pressure varies as 
 the depth of the orifice below the free surface, the paths of the issuing stream following a parabolic 
 curve due to the force of gravity. By observation and calculation it may be determined that the 
 focus of these parabolic curves is as much below the orifice as the surface of the liquid is above it 
 and that the curves are flatter the greater the pressure under which they issue. 
 
 Complete as illustrated.. $7.90 
 
 32-160 MARIOTTE’S BOTTLE, after Hall & Bergen’s “A Text-Book of Physics,” page 44, for the study 
 of Fluid Pressure at varying levels. 
 
 Complete as illustrated, with rubber stoppers and glass fittings.. 3.75 
 
 32-165 EIGHT-IN-ONE APPARATUS, after Gage’s “Introduction to Physical Science” (Experiment 
 32) for the study of the Torricellian Laws, as described under No. 32-160. 
 
 This apparatus, advised for Lecture Table work, consists of a brass cylinder, 6 feet long, surmounted 
 by a reservoir. At various heights along the tube are attached lateral tubes with screw caps. By 
 the successive openings of these screw caps, the paths of the issuing streams are readily observed. 
 
 It will be noted that the stream issuing from the lowest orifice shows flattest, thus showing the great¬ 
 est pressure. The streams issuing from the other orifices all take a curved path, the curvatures, 
 however, depending upon the depths of the orifices below the free surface of the liquid .... 8.76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 137 
 
 No. 32-180 
 
 !2 180 LIQUID LEVEL APPARATUS, IMPROVED FORM, for illustrating the tendency of a liquid to seek 
 its own level. 
 
 This apparatus consists of a cast-iron reservoir with open tubulatures into the top of which are set 
 glass tubes of various shapes and sizes. A liquid poured into the funnel-shaped tube will fill the 
 iron reservoir and rise in the tubes at equal rates and remain at the same height. The U-shaped 
 tube has branches of equal area. 
 
 This apparatus must not be confused with other designs. Our design is of substantial construction, 
 
 handsome in appearance, obviating the inconveniences of less modern types.$3.30 
 
 12-186 LIQUID LEVEL COMMUNICATING TUBES for illustrating the tendency of a liquid to seek its 
 own level. 
 
 This apparatus, constructed entirely of glass, consists of four tubes of different shapes and sizes 
 
 communicating with each other by means of a common connection. .75 
 
 No. 32-205 
 
 No. 32-216 
 
 No. 32-230 
 
 12-200 SIMPLE SIPHON for the qualitative and quantitative study of the principles involved. 
 
 Consists of a glass tube, bent in shape as illustrated. Length of arm, 12 inches.$0.20 
 
 12-206 SIPHON WITH SUCTION TUBE.36 
 
 12-215 TANTALUS CUP OR INTERMITTENT FOUNTAIN, illustrating the principle of Intermittent 
 Springs. 
 
 This standard design is in reality a Siphon, the long arm of which is held in a stopper in the constric¬ 
 tion of the goblet-shaped glass vessel. 
 
 In use, water is led into the goblet. This water will rise in the short arm of the siphon until it reaches 
 the bend, when it will flow down through the long arm of the siphon and continue to flow until 
 the level of the water gets below the end of the short arm. This action will be continuous if the 
 inflow through the siphon is less than the outflow. .70 
 
 >2-230 CARTESIAN DIVER, illustrating the different effects of suspension, immersion, and floating. 
 
 The apparatus as illustrated is instructive and amusing, as the little figure is susceptible to the 
 least movement of the diaphragm, causing it to go through some very peculiar antics. 
 
 Complete as illustrated. .80 
 
 2-231 CARTESIAN DIVER, only.26 
 
138 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 34-10 
 
 34-20 
 
 34-30 
 
 34-40 
 
 T 
 
 • > 
 
 No. 34H0 
 
 No. 34-30 
 
 No. 34-40 
 
 HYDRAULIC POWER PRESS for illustrating the force of a Hydraulic Press. 
 
 The instrument illustrated is more than a model, in that it may be subjected to very severe tests for 
 breaking strengths. It is built of cast iron, bronze and steel throughout, all parts being finished 
 as strikingly as possible. The cylinders are accurately turned and fit perfectly, the large one 
 having an internal diameter of inches, the small cylinder of the force pump being % of an inch. 
 In working our design, or in working any design of Hydraulic Press we advise the use of oil, inas¬ 
 much as this liquid prevents wear of the working parts. 
 
 This instrument has been subjected to very severe strains in our laboratory and each instrument 
 shipped is tested to give the calculated efficiency. 
 
 HYDRAULIC PRESS for the study of the principle involved in the Hydraulic Press. 
 
 This is the standard simple model of glass, the valves of which are colored so that their operation 
 may readily be observed... 
 
 SIX-FOOT WATER HEAD HYDROSTATIC BELLOWS for illustrating an application of Pascal’s 
 Law. 
 
 Our design consists of a strongly constructed bellows 30 centimeters square, supported by legs. 
 Attached to this bellows is a brass tube upright, 6 feet long, terminating at its top in a conical reser¬ 
 voir. This upright is separable into two parts as illustrated. All parts are handsomely finished 
 and designed to withstand reasonable strain, the pneumatic bellows being sufficiently strong to 
 hold a person. 
 
 SEVEN-IN-ONE APPARATUS OR SPIROMETER, GAGE’S IMPROVED, for demonstrating 
 fundamental principles in Pneumatics and Hydraulics. 
 
 This apparatus consists of a seamless brass cylinder, 6 inches in'diameter, mounted on a metal casting, 
 provided with “bosses,” into which rods may be screwed from either side. The cylinder is provided 
 with an ingeniously designed piston which, owing to its construction, has greater efficiency, the 
 longer the use. This construction also obviates the sticking of the washers and leakage around 
 them. Each instrument is provided with our detachable handle in the piston head, a fixed handle 
 with brass stopcock, and nipple. This apparatus, as implied from the name “Seven-in-One,” will 
 illustrate the principle* involved in seven different instruments, as follows: — Hydraulic Lift, 
 Hydraulic Press, Incompressibility of Liquids Apparatus, Pascal’s Law Apparatus, Pneumatic 
 Lift, Hydrostatic Bellows, and Magdeburg Hemispheres. 
 
 It is handsomely finished in nickel plate and is furnished complete with rods for supports . . . . 
 
 $34.60 
 
 1.66 
 
 22.60 
 
 8.90 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 139 
 
 RAMS — PUMPS 
 
 
 
 No. 35-10 
 
 No. 35-15 (Sectional View) 
 
 No. 35-20 
 
 No 35-16 
 
 35-10 HYDRAULIC RAM, illustrating the increase of pressure due to interrupted flow in a stream of water. 
 This model is made entirely of glass, with black glass valve. It is mounted on a wooden base; its 
 size, 17 X 13 inches, is ample for lecture hall demonstration. 
 
 36-16 HYDRAULIC RAM, commercial form. By referring to the sectional view it will be noticed that it 
 consists of an Air Chamber A, the Body B, and the Snifting-Valve for Air Inlet C. The Check 
 or Inlet Valve E is located between the supply pipe and the air chamber. The Impetus Valve F 
 is located at the end of the supply pipe. 
 
 The water flowing through Supply Pipe G passes through the outlet in the impetus valve until the 
 increasing velocity creates sufficient pressure to close the valve checking the flow of water in this 
 direction, and to force open the Check Valve E. The water having passed into the air chamber, 
 is then forced through the Delivery Pipe H by the increased pressure on the air chamber. After 
 forcing the water into the air chamber, the pressure is relieved and the impetus valve opens, only 
 to go through the operation again and again, continually delivering water. A supply of from 2 
 to 3 gallons per minute is required to operate this valve successfully. Size of drive pipe, % inch; 
 discharge pipe, )4 inch diameter; total approximate weight 27 pounds. Capacity 60 to 100 gal¬ 
 lons per hour to a height of 60 feet. 
 
 36-20 COMMERCIAL DEMONSTRATION HYDRAULIC RAM, similar in construction to No. 35-16, 
 yet it has vastly greater pedagogic value in that the air chamber is of glass, permitting view of the 
 working parts in actual operation without in the least taking away from its practical commercial 
 value . 
 
 $3.95 
 
 11.00 
 
 18.00 
 
140 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 No. 36-30 
 
 No. 36-66 
 
 36-30 MODEL OF LIFT PUMP, entirely of glass with colored glass valve, with ground seat. Total length 
 
 15 inches. .$1.60 
 
 36-32 MODEL OF FORCE PUMP, made entirely of glass, with black glass valves, with ground seats . . 1.96 
 
 36-40 FIRE ENGINE PUMP, illustrating the practical application of the simple force pump. 
 
 This pump is in reality a double force pump with a central reservoir having a discharge tube. Its 
 practical application will be found in the walking beam fire engine pump. 
 
 This model is entirely of glass, the valves being constructed of black glass with ground glass seats . . 2.26 
 
 36-60 T-BEAM WATER LIFT PUMP for use with our No. 6-1000 Universal T-Beam Basic Clamp “A.” 
 
 In this design, we present a pump that is patterned after commercial forms, constructed so that all 
 working parts are in full view. Cylinder inches diameter, capable of lifting a large amount of 
 water. 
 
 Without Clamp. 7.86 
 
 36-62 T-BEAM WATER FORCE PUMP for use with our No. 6-1000 Universal T-Beam Basic Clamp “A.” 
 
 This pump has the same commendable features as the above. 
 
 Without Clamp. 7.86 
 
 Note. These Pumps may be used the same as the old form of metal-fitted glass cylinder pumps in case the 
 T-Beam Clamp is not provided. When so used, the attachment serves as a broad, flat base for supporting. The 
 T-Beam Clamps for holding the pumps rigidly to the table will, however, prevent accidental breakage and will be 
 found a wise investment. 
 
 • 
 
 36-66 T-BEAM LIFT AND FORCE PUMPS WITH TANK. This outfit includes the Lift and Force Pumps 
 Nos. 36-60 and 36-62 above and the T-Beam Basic Tank No. 36-67 below. 
 
 Complete outfit . . . .*.-.$21.46 
 
 36-67 T-BEAM BASIC TANK. This tank is the same as furnished in above. It is a special casting with 
 side brackets each with double-beveled lathe-rest slides for the interlocking bases of the pumps. It 
 has a durable black finish and presents a pleasing appearance in the laboratory. 
 
 Its use as a general water tank for many experiments should not be overlooked. 6.76 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 141 
 
 No. 35-76 
 
 36-76 MODELS OF VALVES. In the models above illustrated, we demonstrate the most important valve 
 types, as follows, — butterfly valve, bellows valve, round spring valve, conical valve and oil silk 
 valve. These models are ample in size for lecture work and follow closely the commercial types. 
 
 Each 6 inches in diameter, carefully made and neatly finished. 
 
 Per set of five as above .... .$5.50 
 
 36-12 HERO’S FOUNTAIN, illustrating the raising of water by the elastic force of air. Made entirely of 
 glass, in form as illustrated. 
 
 In operation, the upper bulb is first filled with water, the lower with air. The fountain is started by 
 pouring a small quantity of water into the reservoir. As this flows down, it exerts a pressure on 
 the air contained in the lower bulb. This pressure is transferred to the water in the upper bulb 
 and forces it out through the fountain nozzle.$2.70 
 
 36-30 REACTION APPARATUS, illustrating the reactive force of a laterally escaping stream of liquid. 
 
 The apparatus consists of a glass reservoir with fused-on glass indicator at the bottom and a small 
 opening through which the liquid may flow at the side. If the reservoir is suspended and filled with 
 water, the reactive force of the issuing liquid through the opening above mentioned will cause a 
 movement opposite to that in which the water is flowing. 
 
 Complete as illustrated, with stationary indicating point. 1.00 
 
 36-35 ACTION AND REACTION APPARATUS, after Hall, No. XLV. 1.40 
 
 36-50 REACTION GAS AND FLAME WHEEL for determining the reaction set up by gas escaping from 
 a lateral opening. 
 
 The slightest flow of a gaseous body, from whatever cause, passing through the four horizontal arms 
 will cause a reaction on the same principle as in Barker’s Mill. If the illuminating gas issuing 
 from these four orifices be ignited, the effect is spectacular in the extreme. 
 
 Price complete, as above illustrated. 2.60 
 
 36-75 APPARATUS FOR STUDYING WATER FRICTION IN PIPES, designed by Professor E. H. Hall of 
 Harvard University, for studying the effect of the friction in pipes, tending to impede the flow 
 of liquids. 
 
 As indicated in the diagram, both branches of the liquid tube have the same liquid pressure impressed 
 upon them, pipes being of the same size, differing only in length, while the amount of water which 
 passes through the long pipe is approximately one-half that which passes through the short pipe. 
 Without glasses. 2.26 
 
 36-100 ACTION AND REACTION STRIP, after Hall (Experiment XLVI).95 
 
142 
 
 L . E . KNOTT APPARATUS CO., BOSTON 
 
 WATER TURBINES—WATER WHEELS 
 
 No. 37-30 
 
 No. 37-20 
 
 37-16 DEMONSTRATION MODEL OF A TURBINE. This is an 
 illustrative model for the teaching of the fundamental parts 
 of a Water Turbine. It is substantially constructed of glass 
 and metal, all working parts being in full view. The central 
 No. 37-16 shaft transmits motion through miter gears to a horizontal shaft 
 
 which carries a pulley wheel which may be connected to show 
 power. 
 
 This model is handsomely finished and substantially constructed. It is 42 centimeters high. — ample 
 
 for clear view from all parts of the ordinary lecture room.Duty Free $52.75 
 
 37-20 MODEL OF A WATER TURBINE for connection to a water pump. 
 
 This is of simple construction of glass and brass illustrative of same principles involved in more ex¬ 
 pensive models. 
 
 4.50 
 
 37-30 MODEL OF WATER TURBINE. This model from its design is especially adapted to lecture work. 
 
 It is sufficiently large for class demonstration and yet will develop power for demonstrating the 
 commercial value of a turbine. On the demonstration side it has the feature of a glass front which 
 allows full inspection of all working parts. The model is carefully constructed and handsomely 
 finished, the parts within painted a distinguishable color. It is mounted on a firm supporting base 13.60 
 
 37-50 CAST METAL WATER WHEEL MODEL for study and demonstration of the overshot, undershot, 
 and breast water wheels. In our design, which must not be confused with types on the market, 
 we furnish not only an accurately constructed instrument but one that is durable and handsome 
 in appearance. Our runway is cast of metal and neatly finished. The reservoir, also of cast metal, 
 
 is peculiar in design in that, by the use of one 
 water wheel, we can by changing its position 
 demonstrate either the overshot or undershot 
 wheels. As illustrated, the model is set up for 
 an overshot wheel. If desired to demonstrate 
 an undershot wheel the water reservoir must be 
 moved back to position indicated by dotted line 
 and the water wheel reversed. 
 
 As may be noted from our illustration this model 
 is distinctive in design, scientifically constructed, 
 and we have no hesitancy in claiming for it a 
 place in a catalogue of scientific instruments. 
 Its substantial structure, symmetry of lines, and 
 handsome appearance will recommend it to all . 
 
 6.90 
 
 No. 37-60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 143 
 
 37-60 EXTENSION HEAD BARKER’S MILL for demonstrating the 
 horizontal pressure of a liquid on the containing vessel. 
 
 The design above illustrated has features which obviate all an¬ 
 noyances of the existing types, facilitate the proper cleanly 
 conduct of the experiment, and present a handsome and scien¬ 
 tific appearance. 
 
 This apparatus stands about 3Yi feet high, is handsomely fin¬ 
 ished throughout and ranks well with other scientific instru¬ 
 ments .$4.50 
 
 No. 37-60 
 
 WATER MOTORS 
 
 No. 38-20 
 
 No. 38-26 
 
 38-20 THE IMPROVED WALTHAM COUNTERSHAFT GEARED WATER MOTOR. A Ye H. P. Motor, 
 of more expensive design than the ones listed below, but one which we strongly recommend for 
 the reason that it illustrates most effectively not only the simple water motor, but also the water 
 motor of greatest efficiency, the speed of greatest efficiency, the relation of speed to water flow, 
 the advantages of the direct drive and gear drive, and the application of the prony break to power 
 generators. 
 
 The success of this motor depends upon the following features: 
 
 FIRST. The employment of the well-known reacting bucket-wheel which has proven by a series 
 of scientific tests to give the highest efficiency in a wide range of work. 
 
 SECOND. The reducing gear which enables the wheel to give very much more power, the wheel itself 
 running at its normal speed for greatest efficiency. 
 
 THIRD. A gear which is easily thrown in and out of mesh so that it may be used or not, as desired. 
 
 The motor which we here offer is the first satisfactory attempt at providing a water motor which will 
 give efficient results under a wide variety of conditions. The uses for such a motor in the science 
 laboratory are numerous, taking the place of the whirling table, supplying small power for the 
 small size electric generators, the operating of stirring devices, and the study of the efficiency test 
 by means of the prony break. 
 
 This motor is particularly well adapted to the break-test work in view of the geared driver, enabling 
 two separate and complete series of tests to be made on the same instrument, thus offering a valuable 
 
 series of efficiency tests on both motor and gears.$9.80 
 
 38-26 THE HARCOURT % H. P. DIRECT DRIVE WATER MOTOR, a substantial, attractive, well-built 
 motor of careful design and giving unusual power for its size. Less substantially built motors are 
 sold in the hardware trade, but should not be confused with the class of motor which we here offer. 
 
 Motor complete with 4-inch beveled-face emery wheel, cloth buffing wheel, cake of polish and the 
 grooved wooden pulley. Motor and parts securely packed for shipment in a wooden box . . . 6.00 
 
 38-26 HARCOURT Yi H. P. DIRECT DRIVE WATER MOTOR, same as above described without accesso¬ 
 
 ries, but larger ... 8.00 
 
 38-27 STUD SHAFT to slip over the motor shaft of above motor. This shaft has the same threaded end 
 as the Ys H. P. motor shaft and all the accessories for this motor can be used on the Yi H. P. motor 
 simply by the addition of the stud shaft ... 1.26 
 
 38-29 WATER MOTOR ACCESSORIES, as supplied with our Y% H.P. Motor, No. 38-26. These accessories 
 may be attached to our Yi H. P. Motor No. 38-26 by means of above stud shaft. These accessories 
 are as follows: 
 
 1 Cloth Buffing Wheel 
 1 Beveled-face 4-inch Emery Wheel 
 1 Cake Brass Polish 
 
 1 Grooved Wooden Pulley Per Set 2.00 
 
144 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 39-10 
 
 39-16 
 
 No. 39-10 
 
 No. 39-16 
 
 DEMONSTRATION COMPRESSION BIBB. This is a common type of brass commercial hose 
 bibb cut open to best show interior mechanism and facilitate the demonstration of the operation 
 
 of a standard faucet of compression type. 
 
 DEMONSTRATION FULLER BIBB, — cut away as above to demonstrate the operation of a stand¬ 
 ard faucet of Fuller type. 
 
 $1.26 
 
 1.26 
 
 PNEUMATICS 
 
 ELEMENTARY PROPERTIES OF MATTER 
 
 40-10 BAROSCOPE GLOBE AND BALANCE for demonstrating that air has weight. This apparatus 
 consists of a carefully constructed sensitive balance, to one arm of which is attached a hollow brass 
 globe, 434 inches in diameter; to the other a counterpoise weight, exactly balancing the globe when 
 filled with air. This brass globe is fitted with stop-cock with male screw, provided with hook for 
 attachment to beam of the balance. 
 
 In use, the globe is exhausted by means of some efficient air pump. It is then attached to the beam of 
 the balance, when it will be readily noted that the air which was within the globe had weight, inas¬ 
 
 much as the balance is destroyed. 
 
 Balance complete with brass globe and counterpoise.$6.66 
 
 40-16 -, same as above, except that a glass globe is furnished in place of the brass. 6.30 
 
 40-17 BAROSCOPE BALANCE for use with Weight of Air Globe. 
 
 This balance is the same as used with Nos. 40-10 and 40-16 except that no counterpoise is furnished 3.76 
 40-18 BAROSCOPE GLOBE AND COUNTERPOISE, of brass with stop-cock and hook as used in No. 40-10 2.96 
 
 40-19 -, of glass with stop-cock and hook as used in No. 40-16 . 2.66 
 
 40-22 THE COMBINED BAROSCOPE GLOBE AND BELL IN VACUO, a glass globe 4)4 inches in diam¬ 
 eter fitted with brass cap and stop-cock with hook. In the interior is a small bell. 6.40 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 145 
 
 40-26 BAROSCOPE GLOBE, entirely of glass with hook and stop-cock . . $2,46 
 
 40-36 TWO-LITER BAROSCOPE BELL GLASS for determining the 
 weight of air, also of any gas. 
 
 This consists of a globe connected to a bell glass through a stop-cock. 6.46 
 
 40-66 BAROSCOPE BOTTLE for determining the density of air. This 
 consists of a bottle of about 2-liter capacity, fitted with a two-hole 
 rubber stopper, glass and rubber tubing connections. 
 
 The proper conduct of this experiment requires the use of an air pump, 
 a platform scale with weights, and a barometer, as described in our 
 National Physics Course (Experiment M260). .80 
 
 40-90 OSMOSIS BULB for showing the diffusion of gases. 
 
 This consists of a hollow globular-shaped vessel with neck, constructed 
 of a porous material which permits of rapid diffusion. 
 
 About 70 millimeters diameter., .70 
 
 No. 20-220 
 
 20-200 ENDOSMOMETER for illustrating the phenomena of Endosmose and Osmose. 
 
 The apparatus consists of a glass vessel the lower end of which is covered with a membrane, the 
 upper end of which is connected to a glass tube which carries a scale. This vessel is supported 
 so that the membrane is held under solution during examination. 
 
 All parts complete as illustrated .$3.70 
 
 20-216 STUDENTS’ OSMOSIS APPARATUS for qualitative as well as quantitative 
 work in Osmosis. 
 
 The apparatus consists of an Osmosis Tube of design as illustrated, held ad¬ 
 justably in a nickel-plated clamp which may be clamped to the side of a jar. 
 
 One end of the osmosis tube is closed by a thin porous membrane which 
 may be removed and replaced from time to time as needed. 
 
 Apparatus complete as illustrated . . ..$1.26 
 
 20-220 OSMOTIC PRESSURE TUBE, after specifications by Prof. Thomas B. Freas 
 of the Department of Chemistry in Columbia University, for the rapid il¬ 
 lustration of the phenomenon of Osmotic Pressure. 
 
 This ingenious device consists of an S. & S. Diffusion Shell attached to a glass 
 chamber which ends above in a heavy wall barometer tube 5 feet long. En¬ 
 tering this chamber is another tube with funnel end and stop-cock through 
 which the solution is allowed to flow. 
 
 For rapidity of illustration this apparatus is not excelled and the results ob¬ 
 tained are very noticeable within fifteen minutes from the start. Com¬ 
 plete with Diffusion Shell . ..3.90 
 
 No. 20-216 
 
 20-222 DIFFUSION SHELL, as used in above apparatus 
 
 Each .40 Per Lot of 10 $4.00 
 
146 
 
 L. E . KNOTT APPARATUS CO., BOSTON 
 
 No. 41-60 
 
 No. 41-20 
 
 No. 41-71 
 
 No. 41-70 
 
 41-10 MERCURY STORAGE FUNNEL for storage and delivery of mercury in a cleanly condition. 
 
 Mercury is stored in the reservoir, the unclean, lighter and foreign substances rising to float as a 
 scum. The clean mercury is delivered from the bottom by the pressure of the piston shown in 
 the illustration. 
 
 This instrument, some inches high, will be found of the greatest service in any laboratory where 
 
 clean mercury is in constant demand.$2.00 
 
 41-20 GAS PRESSURE APPARATUS for showing that the pressure upon a gas is transmitted equally in all 
 
 directions. 
 
 If slight pressure is exerted on the rubber diaphragm, this pressure is communicated equally to the 
 open ends of each of the five manometers. 
 
 Complete as illustrated. 6.80 
 
 41-40 HALL'S FRICTION OF AER APPARATUS, designed by Professor E. H. Hall of Harvard Univer¬ 
 sity for showing very clearly the relative friction of air passing through long and short pipes. Com¬ 
 plete as illustrated, including rubber tubing and mouthpiece . .. 2.90 
 
 41-60 PRESSURE GAUGE for steam or air pressure. Enclosed in iron case with nickel-plated ring, diameter 
 
 of dial 3 inches, for pressures up to 150 pounds. 3.76 
 
 41-66 VACUUM GAUGE, same quality as above, tested and graduated to read a vacuum from 0 to 30 inches 
 
 of mercury. Enclosed in iron case with nickel-plated ring, diameter of dial 3 inches. 3.60 
 
 41-70 DEMONSTRATION PRESSURE AND VACUUM GAUGE with silvered metal graduated scale; 
 
 highest quality, glass front permitting full view of the mechanism. May be used under a bell 
 glass or connected directly by tubing to a pressure or vacuum chamber. Diameter 5 inches; grad¬ 
 uated to read 0-75 pounds per square inch (approximately 150 pounds pressure) and 0-30 inches 9.60 
 
 41-71 DEMONSTRATION BOURDON GAUGE. The essential features of the Bourdon Gauge mounted so 
 
 that its working mechanism is instantly understood. Mounted as illustrated. 2.90 
 
 41-72 COMBINATION PRESSURE AND VACUUM GAUGE, enclosed in iron case. Reads 0-75 pounds 
 
 per square inch and 0-30 inches.. 6.60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 147 
 
 No. 41-100 No. 41-105 No. 41-110 
 
 41-100 BOYLE’S LAW APPARATUS for the accurate determination of Boyle’s Law up to ten atmos¬ 
 pheres of pressure. 
 
 This apparatus consists of a frame mounted on an upright support. This frame holds a sensitive 
 manometer with a carefully graduated scale with clear and distinct graduations and figures. 
 
 The pressure is introduced through the stop-cock shown at the left and indicated by the small pressure 
 gauge shown at the top. 
 
 This instrument is handsomely finished, occupies but little space, being but 1 meter high, and is 
 
 capable of very accurate determinations.$24.60 
 
 41-106 ADJUSTABLE SCALE BOYLE’S LAW APPARATUS, after Crew and Tatnall’s “Laboratory 
 Manual of Physics,” Exercise 37, for determining Boyle’s Law of pressures ranging between one- 
 half and two atmospheres. 4.96 
 
 41-106 COMPRESSION PUMP, especially adapted for use with above.26 
 
 HAND AIR PUMP, recommended for use with No. 41-106 Boyle’s Law Apparatus. For description 
 and illustration, see Section 42. 
 
 41-110 FIVE-FOOT ADJUSTABLE BOYLE’S LAW APPARATUS for the determination of Boyle’s Law. 
 
 The apparatus consists of a metal frame with scale mounted on our H Base, the tube carriers consist¬ 
 ing of wooden strips attached to special clamps in such a way that there is a perfect alignment 
 at all times relative to the scale. Each tube is provided with a movable brass indicator for regis¬ 
 tering the heights of the columns of mercury. Instead of the tube with the closed end, we are 
 supplying a tube closed with an air-tight glass stop-cock. This apparatus stands some 150 centi- . 
 meters high, and being mounted on our special design H Base, is extremely rigid. It is hand¬ 
 somely finished in japan and nickel-plate. 
 
 Complete as illustrated.. .•. 9.00 
 
148 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 41-113 
 
 BOSTON 
 
 41-113 KNOTT’S ADJUSTABLE SCALE BOYLE’S LAW AND BAROMETER APPARATUS for deter¬ 
 mining Boyle’s Law. 
 
 This form of apparatus consists of Miller’s Pressure Tube mounted on Adjustable Scale Support 
 as described in the following item, No. 41-115. The use of this apparatus requires some efficient 
 
 form of Air Pump. No. 42-76 is highly recommended. 
 
 Complete as illustrated, with stand.$3.85 
 
 41-114 MILLER’S COMBINATION PRESSURE GAUGE, tube only unmounted. 2.00 
 
 41-116 SIMPLE ADJUSTABLE SCALE BOYLE’S LAW APPARATUS for the derivation of the law that 
 
 the product of the Volume of a Gas by its pressure is a constant quantity. 
 
 In this, our new form, we have striven to correct mistakes of old types and enhance the value of an 
 inexpensive Boyle’s Law Stand. Our stand consists of a finished hardwood backing attached 
 to a casting, which, in turn, is threaded into a neatly finished tripod base. Our improvement obvi¬ 
 ates the use of cumbersome clips, rubber bands, etc. The tube may be attached or removed in an 
 instant from the above-mentioned wooden back, one sliding brass clip, which also answers the 
 
 purpose of an indicator, being the only fastening device. 
 
 Complete with simple J tube, as illustrated. 2.95 
 
 41-116 ADJUSTABLE SCALE BOYLE’S LAW STAND. Stand only, as used in above. 1.96 
 
 41-120 EXTRA HEAVY BOYLE’S LAW TUBE, simple J form, as used in No. 41-116. 1.00 
 
 41-126 BOYLE’S LAW TUBE, unfilled, after Millikan, Gale and Bishop (Experiment 9) .33 
 
 41-130 TRIPOD, ROD, UNIVERSAL CLAMP AND HOLDER after Millikan, Gale and Bishop 
 
 (Experiments 6, etc.). 1.95 
 
 41-155 HEAVY WALLED BAROMETER TUBE, heavy walled glass tube 80 centimeters long, closed at 
 
 one end. .26 
 
 41-167 -, graduated, for use when quantitative measurements are desired. This tube is graduated 
 
 • throughout the entire length to millimeters from zero at the open end of the tube. 2.00 
 
 41-160 GILLEY IMPROVED FORM MERCURY WELL.22 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 149 
 
 AIR PUMPS 
 
 VACUUM PUMPS COMPRESSORS ASPIRATORS 
 
 THE RITCHIE PUMPS 
 Nos. 42-10 and 42-16 
 
 (See next page) 
 
 With the many vast improvements which have, in the past few years, been made in oil-sealed 
 pumps, the question may reasonably be asked why we continue to make the Ritchie Pumps. 
 
 The answer is clear when we consider that the most minute details of construction have been 
 worked out through years of experience and the manufacturer is, therefore, no longer in doubt 
 as to the correct weight and kind of material to use in the valve and other essential parts, the form 
 of the valve seat and method of grinding which will give the best results. Such matters of detail 
 as the fitting of the plunger, the grinding of all internal parts, and a multitude of other points which 
 must be carefully worked out in order to make sure that a pump will give permanent satisfaction, 
 have been reduced to definite manufacturing terms, with the result that we are able to produce, 
 at a definite price, an instrument in which we can guarantee a high degree of efficiency. 
 
 Considering all the conditions, we believe we are justified in claiming that the Ritchie type 
 of pump is worthy of your most careful consideration. Please note that it requires less attention 
 in use; that it gives a sufficiently high degree of vacuum for all practical laboratory purposes; that 
 it may be absolutely relied upon and that no experience nor special precautions are required in its 
 use. 
 
 THE INSTITUTE OIL-SEALED HIGH VACUUM PUMPS 
 Nos. 42-20 and 42-25 
 
 (See next page) 
 
 For work requiring the highest vacuum, the oil-sealed pump has been very generally recognized. 
 The defects as well as the strong points of the old form of oil pump have been very carefully studied 
 during the past two years, with the result that we are able to offer a pump in which the defects of 
 the older pumps have been entirely eliminated. Our new type is rapid in action and guaranteed 
 not to squirt oil from the cylinder. This latter difficulty has been common heretofore in practically 
 all of the oil pumps on the market. Our pump is also capable of an extraordinarily high degree of 
 vacuum. 
 
 TESTS. The test which we have found most practical is the electrical discharge in the ex¬ 
 hausted chamber, and no pump passes our inspection department until it has produced a satis¬ 
 factory X-Ray vacuum. 
 
 OPERATION. The operating part consists of a substantial metal cylinder alternately raised 
 and lowered into a fluid chamber filled with oil of the lowest possible vapor tension. This action 
 results in a Torricellian vacuum being produced in the cylinder at each stroke. At the proper 
 place in the stroke the air is allowed to flow from the chamber being exhausted into the cylinder, 
 and the operation is thus continued. 
 
 It will be noted that we obtain in a single cylinder all the advantages of two cylinders in tan¬ 
 dem frequently used by manufacturers of oil pumps. This is made possible from the fact that 
 air taken from the lower side of the cylinder to produce the Torricellian vacuum in the lower cham¬ 
 ber is forced into the upper chamber, from which it is in turn expelled, a Torricellian vacuum be¬ 
 ing formed in the upper portion of the chamber. 
 
 It will thus be seen that the degree of vacuum depends upon the vapor tension of the fluid 
 used. 
 
 CONSTRUCTION. The simplicity of design enables all parts to be of most substantial 
 construction. The absence of delicate valves to become worn and thrown out of adjustment in¬ 
 sures the continued operation of the pump and its dependable qualities. 
 
L. E. KNOTT APPARATUS CO., BOSTON 
 
 150 
 
 42-10 
 
 42-15 
 
 No. 42-15 
 
 THE RITCHIE PUMPS 
 
 (For description see previous page) 
 
 THE RITCHIE STANDARD PUMP, cylinder 
 
 2J4 inches, stroke 7 inches, plate 10 inches '. . $33.25 
 
 THE RITCHIE SUPERIOR PUMP, same as 
 above, except that the plate is equipped with 
 insulated binding posts as illustrated .... 35.50 
 
 THE INSTITUTE OIL-SEALED PUMPS 
 
 (For description see previous page) 
 
 No. 42-20 
 
 42-20 INSTITUTE OIL-SEALED PUMP “A,” cylinder 234 inches, stroke 5 inches, plate 10 inches . . $26.80 
 42-25 INSTITUTE OIL-SEALED PUMP “B,” cylinder 234 inches, stroke 8 inches, plate 10 inches . . 45.00 
 
 42-45 TORRENTIUM OIL FOR HIGH VACUUM WORK. For the best results with oil-sealed pumps, 
 especially prepared oil having both the right viscosity and vapor tension is required. To meet the 
 requirements of our own Institute Pumps as well as for all oil-sealed pumps, we have arranged 
 to have supplied to us a special oil prepared to meet the most exacting demands of high vacuum 
 work. 
 
 The price is of necessity somewhat higher than for oils of commercial grade, but the amount required 
 
 for each pump is so small that the expense is nominal.. Per Quart 1.26 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 
 151 
 
 42-75 CONDENSING AND EXHAUSTING HAND AIR PUMP 
 WITH SWIVEL for general utility in laboratory practise where 
 a relatively low vacuum or pressure is desired. 
 
 This is a simple pump with valve for both compression and ex¬ 
 haustion and has a cylinder 1 inch in diameter by 113^ inch 
 stroke. The lower end is drilled and tapped to receive our 
 air pump attachment which, in use, requires No. 6-1000 Uni¬ 
 versal T-beam Basic Clamp “A.” This pump attachment is 
 made in two parts and held together by a friction joint which 
 allows the setting of the pump to any angle in one plane. 
 
 It is provided with a nickel-plated T-screw for securing to the 
 Basic Clamp. 
 
 Complete as illustrated, without Basic Clamp.$4.00 
 
 42-76 -, similar to above, but with attached Clamp 
 
 3.60 
 
 42-80 AIR PUMP PLATE, diameter 10 inches, vent hole tapped for all air pump accessories, surface turned 
 true and carefully ground plane. Mounted on substantial tripod base and provided with guard 
 plug and stop-cock. 4.90 
 
 42-82 TEN-INCH HEAVY GROUND GLASS PUMP PLATE. The 
 
 plate consists of ground glass plate which is firmly cemented to 
 a low form of special tripod base. The base is cast in one piece 
 to obviate danger of leakage. It is provided with brass stop¬ 
 cock and brass connecting tube with oil-sealed taps for inlet 
 of air, and manometer.$9.35 
 
 42-100 BOLTWOOD MERCURY PUMP, an inexpensive automatic 
 mercury pump requiring only a small amount of mercury. 
 
 This pump is practically automatic in its action and is con¬ 
 tinuously operated by a small aspirator. It is rapid in action 
 and will exhaust a liter flask sufficient for any ordinary work 
 
 in twenty minutes. 
 
 Mounted on neat wooden stand.11.25 
 
 42-102 -, same as above, without stand. 9.00 
 
 No. 42-100 
 
152 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 42-110 ROTARY COMPRESSOR OR 
 VACUUM PUMP, capacity 15 
 cubic inches per revolution. 
 
 Pulleys, 6 inches in diameter, 
 
 2 -inch face. 
 
 The idea of these rotary pumps 
 is comparatively new, and, 
 from their construction, are de¬ 
 signed to fulfil all the usual re¬ 
 quirements of a compressor or a 
 vacuum pump. For many pur¬ 
 poses they are unexcelled. Be¬ 
 sides presenting a mechanical 
 and handsome appearance, 
 these pumps have the follow¬ 
 ing features which are highly 
 recommended. 
 
 The in-take and delivery of air is 
 continuous and does not depend 
 upon valves or springs of any 
 form. 
 
 The simplicity and facility with 
 which they may be set up and 
 operated. 
 
 The small floor space and the light 
 power required. 
 
 The positive lubrication secured 
 by simple automatic lubricator. 
 
 The efficient cooling by special 
 water jackets. 
 
 The high degree of efficiency 
 possible:—a pressure capacity 
 of 25 to 30 pounds per square 
 inch when used as a compres¬ 
 sor; as a vacuum pump, main- 
 No. 42-110 taining most any vacuum pos¬ 
 
 sible, under local conditions 
 of the atmosphere, up to 90 
 per cent.$56.00 
 
 42-130 HARCOURT ELECTRIC COMPRESSED AIR OUT¬ 
 FIT. Consists of an electric air compressor connected 
 to and mounted on same base as the storage tank. 
 
 The Electric Air Compressor runs from any 110-Volt 
 socket A. C. or D. C., has no exposed electrical parts, 
 gearing, chains, belts, rods, shafts or levers. Is 
 guaranteed to develop 100 pounds air pressure with¬ 
 out overheating. 
 
 Under actual laboratory tests this compressor filled 
 the 5-gallon tank in four minutes with air at 60 pounds 
 pressure, which pressure was increased to 70 pounds 
 in five minutes, 80 pounds in six minutes and 90 
 pounds in seven and one-half minutes. 
 
 Current consumption 160 watts. 
 
 Storage Tank is a 5-gallon galvanized iron tank, guar¬ 
 anteed air-tight and provided with all necessary cocks 
 and pressure gauge. 
 
 Complete as illustrated, with electric cord, and at¬ 
 tachment plug.$69.50 
 
 No. 42-130 
 
 42-135 COMPRESSED AER pUTFIT WITH HAND COMPRESSION PUMP. Similar in general struc¬ 
 ture to above, but with Compound Lever Compression Pump in place of the Electric Air Compres¬ 
 sor. 
 
 Cylinder 3J4 inches, stroke 5^ inches, displacement per stroke 45.6 cubic inches, working pressure 
 about one hundred pounds. 
 
 With this outfit pressures up to 40 pounds can be readily secured. 
 
 Pump, Tank with necessary cocks and Pressure Gauge all connected and mounted on substantial 
 base . 
 
 $36.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 153 
 
 Nos. 42-150 and 42-160 
 
 Nos. 42-162, 
 42-162, and 
 42-177 
 
 Nos. 42-153, 42-163, and 42-178 
 
 No. 42-175 
 
 No. 42-190 
 
 42-160 CHAPMAN’S ASPIRATOR for reduction of air pressure by water aspiration. 
 
 This aspirator is of brass, 4 inches long, inch I. P. size thread, giving a capacity of 5 cubic feet 
 
 per hour.$1.45 
 
 42-162 HYDRANT COUPLING for use in connecting our No. 42-150 to %-inch hose faucet. .30 
 
 42-153 HYDRANT COUPLING for connecting our No. 42-150 to a smooth faucet. These couplings cannot 
 
 leak or be forced off. .50 
 
 42-160 CHAPMAN’S ASPIRATOR, similar to No. 42-150, but with capacity of 18 cubic feet per hour. 
 
 Length 5 inches; inch I. P. size thread. 1.96 
 
 42-162 HYDRANT COUPLING for use in connecting our No. 42-160 to %-inch hose faucet. .30 
 
 42-163 HYDRANT COUPLING for use in connecting our No. 42-160 to a smooth faucet. These 
 
 couplings cannot leak or be forced off. .60 
 
 42-176 RICHARD’S ASPIRATOR, a more powerful and efficient filter pump than Nos. 42-150 and 
 
 42-160. Length 7 inches; % inch I. P. size thread. 1.80 
 
 42-177 HYDRANT COUPLING for use in connecting our No. 42-176 to 
 %-inch hose faucet. 
 
 42-178 HYDRANT COUPLING for use in connecting our No. 42-176 to a 
 smooth faucet. These couplings cannot leak or be forced off . . 
 
 42-190 MUENCKE’S ASPIRATOR, entirely of glass, total length inches. 
 
 As all parts are visible, this is a convenient demonstration instrument 
 
 42- 200 ASPIRATOR DEMONSTRATION TUBES after Hall No. XLVII. Pair 
 
 HIGH PRESSURE AIR STORAGE TANKS for the storage of air or non- 
 corrosive gases under pressure. These tanks are made of heavy galvanized iron 
 and guaranteed to be absolutely air-tight, under a guarantee test of 150 pounds 
 and for a working pressure of 100 pounds. 
 
 43- 110 AIR STORAGE TANK, capacity 2 l A gallons, size 6 inches diameter by 
 
 20 inches high. 
 
 43-111 -, capacity 5 gallons, size 9 inches diameter by 20 inches high . . 
 
 43-112 -, capacity 12 gallons, size 10 inches diameter by 33 inches high . 
 
 PRESSURE GAUGE. See No. 41-60 
 
 Nos. 43-110 to 43-112 
 
154 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 BELL GLASSES 
 
 CLEAR, WHITE GLASS, FLANGES GROUND AND TESTED 
 
 Nos. 43-25 to 43-27 
 ♦ 
 
 Nos. 43-66 to 43-67 
 
 No. 43-70 
 
 No. 43-60 
 
 No. 43-75 
 
 No. 43-80 
 
 43-26 STRAIGHT FORM BELL GLASS, WITH KNOB TOP. Capacity 1 gallon, inside height 11 
 
 inches, diameter 6 inches. 
 
 43-27 - —, same as above, capacity 2 gallons, inside height 15 inches, diameter 7 inches. 
 
 43-35 SWELLED FORM BELL GLASS, WITH KNOB TOP. Capacity 2 gallons, inside height 12 
 inches, diameter 7 inches...* 
 
 43-37 - —, same as above, capacity 3 gallons, inside height 13 inches, diameter inches. 
 
 43-40 - —, same as above, capacity 5 gallons, inside height 15 inches, diameter 10 inches. 
 
 43-50 STRAIGHT FORM BELL GLASS, WITH GLASS STOPPER. Capacity 1 gallon, inside height 
 
 11 inches, diameter 6 inches. 
 
 43-60 STRAIGHT FORM BELL GLASS, NECK FOR CORK STOPPER. Capacity 1 gallon, inside height 
 11 inches, diameter 6% inches. 
 
 43-65 LOW FORM BELL GLASS, WITH KNOB TOP. Inside height 2^ inches, diameter 4 inches . . 
 
 43-67 - —, same as above, inside height 4 inches, diameter 6 inches.*. . . 
 
 43-70 HAND AND BLADDER GLASS, swelled form, both flanges ground and tested, medium size . . . 
 
 43-76 BELL GLASS, special mold, ground flange, re-enforced neck for our No. 30 rubber stopper. Inside 
 height 4 inches. This bell glass is used with a one-hole rubber stopper and a barometer tube to 
 perform the experiment of No. 43-80 . 
 
 43-80 BELL GLASS, straight sides, about 3 feet high, flange ground and tested for use with No. 41-156 Ba¬ 
 rometer Tube and No. 41-160 Well, to show successive diminution in pressure when placed on the 
 plate of an air pump. 
 
 Complete as illustrated, with Barometer Tube and Well. 
 
 43-82 BELL GLASS only, of above. 
 
 $1.45 
 
 2.20 
 
 1.95 
 
 2.90 
 
 6.30 
 
 1.76 
 
 1.45 
 
 .65 
 
 1.00 
 
 1.00 
 
 1.25 
 
 4.25 
 3.75 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 155 
 
 43-140 MANOMETER for attachment to air pump to denote degree of exhaustion. 
 
 This is an instrument carefully constructed and handsomely finished for attachment to the guard or 
 vent hole to denote the degree of exhaustion. It consists of a metal casting, threaded to fit any 
 hole threaded by 16. Attached to this casting is a black oxidized metal scale filled in white, 
 holding a manometer tube. This scale and tube are encased in a heavy glass cover. 
 
 This instrument will be found efficient, rapid, and a valuable accessory in the study of Pneumatics . $6.45 
 
 43-146 MOVABLE SCALE MANOMETER, mounted on neat wooden support stand, to determine the degree 
 
 of exhaustion in experiments in Pneumatics. 
 
 This is an improved form of manometer with glass stop-cock which is mounted with a movable scale 
 
 support supporting the mirror glass scale on a neatly finished wooden stand . 6.26 
 
 43-160 SIMPLE MANOMETER, consisting of a U-tube mounted with scale on a neatly finished wooden 
 
 stand . 1.70 
 
 No. 41-113 
 
 43-160 JAR WITH TWO MANOMETER TUBES, IN¬ 
 LET TUBE and PINCH-COCK, after Milli¬ 
 kan, Gale and Bishop (Experiment 5) ... . $1.25 
 
 43-161 MANOMETER TUBE only.40 
 
 43-165 BALANCING COLUMNS TUBE, after Millikan, 
 
 Gale and Bishop (Experiment 5). .85 
 
 41-113 MILLER’S COMBINATION PRESSURE 
 GAUGE, for registering high pressures. 
 
 This is a tube, 1 meter in height. Our illustration 
 shows it mounted on our No. 41-116 Boyle’s 
 Law stand. One arm of this tube is provided 
 with a stop-cock so that the instrument may 
 be used as a Boyle’s Law Tube as well as a ba¬ 
 rometer. In use as a pressure tube, however, 
 this stop-cock must be left open. In use as a 
 Barometer, the stop-cock is left open until the 
 tube has been completely filled, when it is 
 closed. The mercury will then fall to the 
 point of barometric height. Complete as il¬ 
 
 lustrated, with stand. 3.85 
 
 41-114 MILLER’S COMBINATION PRESSURE 
 
 GAUGE. Tube only, unmounted. 2.00 
 
 43-170 PRESSURE GAUGE, as designed by Messrs. 
 
 Turner and Hersey. 
 
 This gauge has been especially designed for regis¬ 
 tering high pressures, the length facilitating 
 this use. It must be used, however, on some 
 form of stand. Our illustration shows it in 
 use mounted on our No. 41-116, a description 
 
 of which will be found under No. 41-115. 
 
 Complete as illustrated, with stand. 3.30 
 
 43-171 PRESSURE GAUGE. Tube only, unmounted . 1.35 
 
 No. 43-170 
 
156 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 43-200 
 
 No. 43-202 
 
 No. 43-206 
 
 No. 43-240 
 
 No. 43-246 
 
 No. 43-247 
 
 No. 43-260 
 
 No. 43-204 
 
 43-200 BRASS COUPLING, threaded to fit our air pumps and air pump accessories.$0.33 
 
 43-202 BRASS STOP-COCK, double male screw, threaded to fit our air pumps and air pump accessories; 
 
 inch bore. .66 
 
 43-204 BRASS NIPPLE, female screw, threaded to fit No. 43-202 Stop-cock or No. 43-200 Coupling, or any 
 
 of our air pumps and air pump accessories. .33 
 
 43-206 BRASS GUARD PLUG, threaded to fit our air pumps . '.. .33 
 
 43-207 BRASS T-GUARD PLUG threaded to fit our air pumps. .43 
 
 43-210 PUMP OIL AND CAN. This combination will recommend itself to many teachers who require 
 
 an efficient lubricator. Four-ounce size with screw stopper. Filled. .36 
 
 43-216 PHOSPHORUS PENTOXEDE for absorption of moisture in high-vacuum experiments. Sealed 
 
 bottle, containing 1 ounce. .66 
 
 43-217 VACUUM TUBING. This is a specially prepared heavy-walled reinforced rubber tubing, % inch 
 
 diameter, obviating leakage in making air-tight connections.Per Foot .20 
 
 43-220 RUBBER DAM OR THIN RUBBER SHEETING, especially useful in illustrating the crushing 
 
 force of atmospheric pressure.Per Square Foot .33 
 
 43-221 VEGETABLE PARCHMENT, good quality, adapted for demonstrating the crushing force of at¬ 
 mospheric pressure.Per Sheet .10 
 
 43-222 ANIMAL PARCHMENT, good quality.Per Square Foot .60 
 
 43-226 LEATHER WASHERS for use with stop-cocks, plugs, etc., % inch diameter by % inch hole. 
 
 Per Dozen .26 
 
 43-230 RUBBER BAG for experiments in pneumatics. This bag is of light rubber of the best quality and 
 
 is furnished complete with outlet tube and screw pinch-cock. 1.16 
 
 43-240 FOUNTAIN IN VACUO, illustrating atmospheric pressure. In use, the tripod is removed and the 
 apparatus is screwed to the center of the pump plate. The stop-cock is then turned and air ex¬ 
 hausted from the vessel. If the apparatus is again mounted on the tripod and placed in a 
 dish of water the pressure of the atmosphere will force the water into the vessel showing a very 
 vigorous fountain as soon as the stop-cock is opened. 
 
 Complete as illustrated. 6.60 
 
 43-246 DEMONSTRATION SIXTEEN-INCH WATER HAMMER for showing that water or any liquid will 
 
 fall as a solid in a vacuum. 
 
 In use, the air is exhausted from the tube and the end held under water and stop-cock opened. Water 
 is allowed to be forced by atmospheric pressure until about full- If tube is now inverted, the 
 water will fall as a solid mass, the tube emitting a distinct sound as if struck by a blow. 2.80 
 
 43-247 WATER HAMMER, illustrating that water will fall as a solid in vacuo. This consists of a tube, 
 
 30 centimeters in length, partially filled with water in a vacuum. With one bulb. .66 
 
 43-260 TWO-BULB MUSICAL WATER HAMMER, arranged so that the water falling in vacuo will emit 
 
 pleasing tones in addition to the metallic click. 1.10 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 157 
 
 
 No. 43-265 
 
 Nos. 43-276 and 43-277 
 
 No. 34—40 
 
 No. 43-270 
 
 43-266 MAGDEBURG HEMISPHERES for demonstrating atmospheric pressure in all directions. 
 
 The apparatus consists of two cast, hollow hemispheres of meta^ the edges of which are carefully 
 ground smooth to make an air-tight junction. On one is cast a “boss” which is tapped for a brass 
 stop-cock threaded to fit the air pump and also the tripod illustrated. Each hemisphere is pro¬ 
 vided with convenient handles. The whole is durably and handsomely finished.$3.96 
 
 34-40 SEVEN-IN-ONE APPARATUS OR SPIROMETER, GAGE’S IMPROVED for demonstrating 
 fundamental principles in pneumatics and hydraulics. 
 
 This apparatus consists of a seamless brass cylinder 6 inches in diameter, mounted on a metal cast¬ 
 ing, provided with bosses, into which rods may be screwed from either side. The cylinder is pro¬ 
 vided with an ingeniously designed piston which, owing to its construction, has greater efficiency 
 the longer the use. This construction also obviates the sticking of the washers and leakage around 
 them. Each instrument is provided with our detachable handle in the piston head, a fixed han¬ 
 dle with brass stop-cock with nipple, a rubber tube, and funnel. This apparatus, as implied 
 from the name “Seven-in-One,” will illustrate the principles involved in seven different instru¬ 
 ments, as follows: — Hydraulic Lift, Hydraulic Press, Incompressibility of Liquids Apparatus, 
 Pascal’s Law Apparatus, Pneumatic Lift, Hydrostatic Bellows, Magdeburg Hemispheres. 
 
 This instrument is handsomely finished in nickel plate and is furnished complete with three nickel- 
 plated rods. 8.90 
 
 43-270 MODEL OF A DIVING BELL, demonstrating how, in a caisson, air is supplied to keep up life and to 
 keep back the water. 
 
 The design above illustrated demonstrates, in a simple way, the principle of caissons. A conical¬ 
 shaped glass vessel with meta mountings top and bottom has, at its top, a tube for supply of air 
 which is forced into the vessel by means of an air pump. The bottom casting is designed to hold 
 a slow-match as well as to support a weight. The whole is submerged in a jar of water as illus¬ 
 trated. The supply of fresh air through the tube keeps the spark on the slow-match alive. The 
 whole is suspended in the jar by any convenient means. 
 
 Diving Bell complete with weight, slow-match and special jar. 6.76 
 
 43-276 BURSTING SQUARES. When placed under a bell glass on a pump plate and the air exhausted 
 from under the bell glass the expansive force of the air in the bursting square will burst the square 
 with great violence. (See Protecting Shield No. 43-277).Per Dozen 2.16 
 
 43-277 WIRE GUARD for use under a bell glass to protect the bell glass from flying broken parts of the 
 
 bursting squares.Each .46 
 
158 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 
 No. 43-285 No. 43-290 
 
 BELL IN VACUO APPARATUS, illustrating non-transmis¬ 
 sion of sound in a vacuum. 
 
 This apparatus consists of a large-sized bell jar with brass 
 cap, through the center of which slides a brass rod gripped 
 air-tight by means of a packing screw. A bell suspended 
 by a horizontal axis in a stirrup is supported over the vent 
 in the center of the pump plate. This bell is rung by tip¬ 
 ping through the agency of the sliding rod. 
 
 When placed on pump plate, as illustrated, if air is not ex¬ 
 hausted, the bell, if tipped, will emit a distinct tone. If, 
 however, the air is exhausted, the sound, though not abso¬ 
 lutely lost, will be diminished to such an extent as to readi¬ 
 ly illustrate the non-transmission of sound in a vacuum. 
 
 Complete as illustrated, with BelTand Stirrup and Bell Glass with Sliding Rod. All brass parts 
 
 polished and lacquered.;.$6.80 
 
 43-282 BELL IN STIRRUP, as illustrated above 
 
 2.80 
 
 43-283 BELL GLASS WITH SLIDING ROD, as illustrated above 
 
 4.00 
 
 43-285 BELL IN VACUO, illustrating non-transmission of sound in a vacuum. 
 
 This is a self-contained instrument supplied with a small nickel-plated bell suspended by springs to 
 brass binding posts which are sealed into the top of a medium-sized bell glass. As the flange of this 
 bell glass is carefully ground and tested and the vibration of the bell is deadened by suspending 
 on springs, the non-transmission of sound is quite noticeable, the tone being almost lost in the 
 vacuum. 
 
 Complete as illustrated. 2.90 
 
 43-290 MOUNTED ELECTRIC BELL for use in connection with a bell glass and with our No. 42-16 Air 
 Pump with electrical connections, to illustrate non-transmission of sound in a vacuum 
 
 Mounted as illustrated on neatly polished wooden upright. 1.60 
 
 43-26 BELL GLASS, straight form, with knob top, 11 inches high by 6 inches diameter. 1,46 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 159 
 
 No. 40-22 No. 43-310 
 
 40-22 BELL IN BAROSCOPE GLOBE for the illustration of non-transmission of sound in a vacuum; also 
 used to demonstrate the fact that air has weight. 
 
 This is a glass globe, 4J4 inches in diameter, fitted with brass cap and a stop-cock with hook, and 
 has in its interior a small bell. 
 
 To demonstrate that air has weight, this globe is used as an ordinary baroscope globe; to illustrate 
 non-transmission of sound, shaking the globe before and after exhaustion shows that the tinkling 
 
 of the bell is not heard, or heard only dimly, when the globe is in exhausted state.$5.40 
 
 43-310 FREEZING APPARATUS, illustrating freezing by the rapid evaporation of ether or other volatile 
 
 liquids. 1.40 
 
 No. 43-315 No. 43-326 
 
 43-316 DEMONSTRATION NITROGEN FILLED INCANDESCENT LAMP. A heavy glass globe fitted 
 with metal cap and stop-cock, the end of which is threaded to fit the air pump. Binding posts 
 are hermetically sealed and are connected directly to the filament holders. Arranged so that it 
 may be filled with nitrogen to demonstrate nitrogen filled lamps. Complete with one-half dozen 
 special filaments.$3.50 
 
 43-317 DEMONSTRATION INCANDESCENT LAMP FILAMENTS for use with above . Per Dozen .17 
 
 43-325 DEMONSTRATION ARC LAMP for illustrating passage of electric current through rarefied gases. 
 
 This apparatus consists of a bell glass with two lateral openings with brass caps, through the center 
 of which pass the sliding rod carbon holders held in sliding grips by packing screws. These sliding 
 rods are terminated by hard rubber handles and are provided with binding screws for attachment 
 of electric current. As the bell glass is 10 inches in diameter, a pump plate of that size must be 
 used with this instrument. 
 
 This apparatus is carefully made and the experiment, if properly conducted, is exceedingly instruc¬ 
 
 tive and the results spectacular. 
 
 Complete with extra pair of carbon pencils.Duty Free 14.66 
 
 43-326 CARBON PENCILS for use with above.Per Dozen 1.76 
 
160 L. E. KNOTT APPARATUS CO., BOSTON 
 
 BAROMETERS 
 
 The value of the Weather Bureau Type of Barometer has been realized in no small degree 
 because of the large reservoir in which the height of the mercury is adjusted by means of the screw 
 plunger at the bottom, the correct zero being indicated by a pearl white pointer projecting down¬ 
 ward towards the surface of the mercury. This indicator being fixed, and the scale rigidly attached 
 with reference to it, the level of the mercury is readily brought to the correct zero point before 
 each reading. Many other methods of adjustment have been devised, but none have even ap¬ 
 proached this for accuracy and ease of operation. 
 
 / 
 
 45-10 FORTIN SCHOOL BAROMETER, with cistern and method of 
 
 adjustment, same as described above. 
 
 SCALE in both English and Metric systems with clearly indi¬ 
 cated divisions. 
 
 TUBE of generous proportions filled with greatest care. 
 MOUNTING, well seasoned hardwood with rosewood finish, 
 and protecting cap over the reservoir to prevent breakage, 
 so designed as to permit clear view of both pointer and mercury 
 in the reservoir.$9.85 
 
 45-15 FORTIN CISTERN SCHOOL BAROMETER WITH VER¬ 
 NIER, double scale, double vernier, and thermometer. Scale 
 reads from 24 to 32 inches with equivalent metric scale, 
 reading with vernier to % millimeter or Vioo inch.16.80 
 
 45-20 WEATHER BUREAU FORTIN BAROMETER, with extra 
 large mercury tube, cylindrical bulb mounted in oxidized 
 brass, with insulating support and binding screws, thermome¬ 
 ter with graduated stem scale, a thoroughly high grade in¬ 
 strument of a type used in all Weather Bureau Stations . . 40.00 
 
 46-25 MOUNTING BOARD of mahogany, rosewood finish, support¬ 
 ing arm with locknut, dead white plate back of scale and 
 mercury cistern, provided with screws for supporting in a 
 vertical position.4.86 
 
 No. 46-20 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 161 
 
 
 No. 46-30 
 
 No. 46-40 
 
 46-30 DEMONSTRATION ANEROID BAROMETER, desirable for the explanation and illustration of the 
 mechanism of the ordinary Aneroid Barometer. 
 
 This instrument is ample in size for lecture room use and is particularly adapted to such use in that 
 all parts are uncovered and can be distinctly viewed through a glass dome. Parts mounted on a 
 polished hardwood base. Vacuum chamber connected with a length of rubber tubing which can be 
 connected to small capacity air pump or demonstrated more simply by blowing in or drawing out 
 the air through the mouth. The varying pressure is readily shown by means of the indicating 
 hand over the scale. 
 
 This instrument is a beautiful ornament and its construction is accurate enough for barometric ob¬ 
 servations . .$18.26 
 
 No. 46-60 
 
 46-40 ANEROID BAROMETER, adjusted for altitudes 
 up to 3,500 feet, improved form, 4 inches in 
 diameter, mechanism mounted in highly pol¬ 
 ished and nickel-plated brass case. Dial open 
 that mechanism may be in full view. Grad¬ 
 uations read in both the English and the Metric 
 system. 4.26 
 
 46-60 ANEROID BAROMETER, adjusted for altitudes 
 up to 3,500 feet, brass case with closed silvered- 
 metal dial 5 inches in diameter. 
 
 This barometer is improved by a patent altitude ad¬ 
 justment which consists of an auxiliary hand. 
 
 This hand is adjustably attached to the pressure 
 hand and moves with it. While the pressure 
 hand shows the actual atmospheric pressure 
 at the altitude at which the Aneroid is used, the 
 patent adjustment hand may be so regulated 
 as to show also the corresponding sea-level 
 pressure..Each 
 
 46-66 HIGH ALTITUDE ANEROID BAROMETER. 
 
 The movements of this barometer are of good 
 quality and in their general construction are 
 identical to those illustrated in No. 46—40; ad¬ 
 justed for use between 4,900 and 9,500 feet. 
 Mechanism enclosed in polished brass case and 
 open porcelain dial so that mechanism is in full 
 view. 
 
 45-67 -, same as above, but of special design, most 
 
 careful construction, and compensated for 
 changes in temperature. Adjusted for use be¬ 
 tween 5,950 feet and 11,800 feet. Mechanism 
 enclosed in polished brass case with open sil¬ 
 vered metal dial. Mechanism in full view . . 17.26 
 
 8.00 
 
 10.25 
 
L. E. KNOTT APPARATUS CO., BOSTON 
 
 162 
 
 45-65 
 
 45-67 
 
 45- 69 
 
 46- 71 
 
 # 
 
 POCKET MOUNTAIN ANEROID BAROMETER, watch 
 case form. This is a highest quality Aneroid, 1% inches 
 in diameter, compensated for temperature, silvered- 
 metal dial, revolving altitude scale. Enclosed in polished 
 brass case. Adjusted to read to 3,000 feet. Enclosed in 
 neat morocco, plush-lined case . .. .... . ... . 
 
 -. same as above, but adjusted to read to 8,000 feet . . 
 
 -, same as above, but adjusted to read to 10,000 feet . 
 
 4 
 
 -, same as above, but adjusted to read to 16,000 feet . 
 
 $16.00 
 
 17.26 
 
 18.60 
 
 19.75 
 
 CHANG. 
 
 COMPENSATED 
 
 No. 45-67 
 
 No. 45-100 
 
 45-100 RECORDING BAROMETER (BAROGRAPH). Barographs are instruments arranged to record 
 upon a chart all atmospheric changes in pressure, the amount of rise and fall of same, and the time 
 such changes occurred. The mechanism of the ordinary barograph consists of a “pile” or series 
 of vacuum chambers each secured to the other above and below making a greatly magnified 
 sensitive movement. This movement is further magnified and transmitted to an aluminum re¬ 
 cording arm carrying a pen by a series of connecting levers. This pen records the changes in pres¬ 
 sure on a chart which encircles a drum containing a clock movement. As this clock revolves once 
 in seven days, a week’s record can be obtained on the chart. As the top of the chart is divided 
 into seven spaces, each allotted for one day a week and sub-divided into spaces representing two 
 hours, it is possible to tell at what time of any day the atmospheric pressure underwent a change. 
 
 This week’s record will be in the form of a tracing along the chart. By referring to the top of the 
 chart it may be noted at what day and hour a rise or fall of pressure occurred. 
 
 A Barograph, then, is the most reliable form of a barometer and has the further feature that observa¬ 
 tions are recorded, whereas in weather prognostications a single observation of the barometer is 
 of little or no value. 
 
 The instrument listed above has for years been the standard for meteorological work, and its quality 
 in all particulars is unquestioned. In addition to a careful and accurate fitting and adjusting of 
 parts this instrument is handsome in appearance and will be found exceedingly valuable in any lab¬ 
 oratory. Enclosed in mahogany frame glass case cover. 
 
 Complete, with one year’s supply of charts.... $36.75 
 
 45-102 BAROGRAPH CHARTS as used in above instrument. Box containing one year’s supply .... 2 60 
 
163 
 
 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 METEOROLOGICAL THERMOMETERS 
 
 63-10 HOUSEHOLD THERMOMETER, 8 inches long, heavy metal frame, black metal scale with white 
 
 figures, reading from -30° to 120° F.$0.60 
 
 63-12 HOUSEHOLD THERMOMETER, 10 inches long, metal scale on hardwood back, reading from -30° 
 
 to 120° F.96 
 
 46-30 WEATHER BUREAU PATTERN THERMOMETER WITH CERTIFICATE, engraved stem, magni¬ 
 fying mercury tube, cylindrical bulb, porcelain strip at side of tube in which are marked the figures 
 and every fifth degree line of the scale, oxidized black plate, insulating brass support with binding 
 
 screws. Scale range 40° below zero to 120° F. above. 6.45 
 
 46-36 SIX’S MAXIMUM AND MINIMUM SELF-REGISTERING THERMOMETER, black oxidized 
 brass scales, white filled figures, japanned tin case, length 8 inches, scale range 10° to 40° below 
 zero to 120° F. above. Enclosed in box. 3.35 
 
 THERMOMETRIC CONVERSION FACTORS 
 
 F = 9/5 C+32 
 C = 5/9 (F-32) 
 R = 4/9 (F-32) 
 
 F = 9/4 R+32 
 C = 5/4 R 
 R = 4/5 C 
 

 164 L. E. KNOTT APPARATUS CO., BOSTON 
 
 46 40 MAXIMUM AND MINIMUM THERMOMETERS, medium grade thermometers with magnifying 
 
 tubes and black oxidized brass scales, each tube 10 inches long, mounted on a separate plate attached 
 at one end with a thumb screw to the oak back so that the thermometers may be reset as illustrated 
 above . $3.90 
 
 46-50 WEATHER BUREAU MAXIMUM SELF-REGISTERING THERMOMETER, scale range 40° 
 
 below zero to 120° F. above. 
 
 This thermometer has an engraved stem, magnifying tube, cylindrical bulb, porcelain strip at side 
 of tube on which are marked the figures and every fifth degree line of the scale. It is mounted on 
 an oxidized brass plate with insulating brass support with binding screws. Each thermometer is 
 12 inches long and is furnished with a certificate of accuracy. 
 
 Enclosed in box. 6.36 
 
 46-61 WEATHER BUREAU MINIMUM SELF-REGISTERING THERMOMETER, as above described, 
 
 range 20 to 60° below zero to 120° F. above. Each thermometer is 12 inches long and is furnished 
 with a certificate of accuracy. 
 
 Enclosed in box . 5-85 
 
 46-62 WEATHER BUREAU MAXIMUM AND MINIMUM SELF-REGISTERING SET. This outfit 
 consists of the Maximum and Minimum Thermometers above, appropriately mounted on a polished 
 
 mahogany board 17 inches long by 5 inches wide. Each thermometer is furnished with a certificate 
 
 * 
 
 of accuracy. 
 
 The whole, enclosed in a neat box. 12.00 
 
 
 46-70 SOIL THERMOMETER, 16-inch wood frame with handle, brass pointed ferrule, glass cylinder, 
 hand written paper scale. 
 
 1.40 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 165 
 
 No. 46-110 
 
 46-110 RECORDING THERMOMETER (THERMOGRAPH). What has been said of the advantages 
 of the use of a barograph may just as consistently be repeated regarding the advantages of the 
 use of the thermograph. The continuous record of temperature changes is necessary in any inten¬ 
 sive study of Meteorology. 
 
 Our line of Thermographs consists of bi-metallic lamina arranged in such a manner that there are 
 no levers other than the pen arm used in its construction. This construction insures rigidity, 
 overcoming all lag or creep and friction, and in consequence is much more sensitive to slight changes 
 in temperature than the standard mercurial thermometer. 
 
 This instrument is an 8-day cylinder clock, low drum type, chart showing range from 30° below to 
 110° F. above. Movement enclosed in a hinged metal case with padlock. This case is supplied 
 with glass window, well ventilated, and with leather handle for carrying. 
 
 Complete with one year’s supply of charts.•. $36.76 
 
 46-112 THERMOGRAPH CHARTS, as usted in above instrument. Box containing one year’s supply . . 2.60 
 
 No. 46-120 
 
 46-120 BARO-THERMO RECORDER (COMBINED THERMOGRAPH AND BAROGRAPH). The 
 
 above illustration pictures a recent improvement which has been introduced in recording instru¬ 
 ments by combining the Barograph and the Thermograph in the same instrument. The records 
 are given on the same chart, but in different colored inks to prevent confusion (blue for the Baro¬ 
 
 graph and green for the Thermograph). 
 
 Baro-Thermo Recorder. $60.00 
 
 46-122 BARO-THERMO RECORDER CHARTS, one year’s supply, for use with above. 2.76 
 
i66 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 HUMIDITY INDICATORS AND RECORDERS 
 
 No. 47-20 
 
 47-10 “SLING” PSYCHROMETER OR HYGROMETER for obtaining quick and more accurate results 
 than are possible with the stationary wet and dry bulb instruments. 
 
 This instrument consists of two accurate thermoftieters firmly attached to a metal arm swiveled to a 
 wood handle. In use one of these bulbs is covered with a wicking which should be thoroughly sat¬ 
 urated with water. To obtain readings, whirl the instrument fifteen or twenty seconds, holding it 
 well away from the body. Stop and note the wet bulb temperature; continue the operation, whirling 
 and reading until two readings of the wet bulb thermometer are obtained alike or nearly so. This 
 will be the lowest temperature. Tables and full directions are supplied with the instrument to 
 determine the per cent, of relative humidity.Each $2.50 
 
 47-15 MASON’S HYGROMETER (Wet and Dry Bulb), good quality, magnifying mercury tube, silvered 
 brass scales with black filled figures and graduations, mounted on polished oak board 11X5 inches. 
 Enclosed in a box. 3.36 
 
 47-20 WEATHER BUREAU PATTERN HYGROMETER (Wet and Dry 
 Bulb), consisting of two No. 46-30 Standard Thermometers 
 mounted on a polished mahogany board 17 X 5 inches with 
 nickel-plated brass cistern and silk wick. 
 
 This instrument is the United States Standard and may be depended 
 upon for the utmost accuracy. 
 
 Each thermometer is supplied with a certificate of correction. En¬ 
 closed in box . . $11.80 
 
 47-25 SPIRAL HYGROMETER, 80 millimeters diameter. 
 
 This simple little instrument, with handsomely nickeled case, is pro¬ 
 vided with a scale denoting the humidity of the air without refer¬ 
 ence to tables 
 
 No. 47-26 
 
 2.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 167 
 
 No. 47-40 
 
 No. 47-76 
 
 47-40 DIRECT READING HUMIDITY APPARATUS (HYGROPHANT), a simple, convenient, and efficient 
 means of determining both the temperature and humidity of the air with accuracy and without 
 computation. 
 
 This instrument is provided with two standard thermometers, one showing the temperature of the air, 
 the other the temperature due to evaporation. A cylinder upon which is inscribed a series of col¬ 
 umns of figures numbered at their headings from 1 to 22 may be noted between the thermometers. 
 These strips represent the difference in degrees between the indications of the thermometers and the 
 columns exhibiting relative humidity or percentage of moisture in the air for every degree of tem¬ 
 perature indicated by the thermometer. A fixed scale upon the casing in which the cylinder revolves 
 indicates the relative humidity or percentage of moisture in the air. 
 
 In use the cup is filled with pure water into which dips the wicking attached to the wet bulb ther¬ 
 mometer. As soon as this wicking and gauze which covers bulb become wet the instrument is ready 
 for use. In ascertaining the actual temperature, read the indication of the thermometer on the 
 right of the instrument; in ascertaining the temperature due to evaporation read the indications 
 of the wet bulb thermometer. Now note the difference in number of degrees between the two 
 thermometers. Turn the cylinder by means of the knob on the top so as to present to view the 
 column of figures having at its head the number corresponding to this difference. In line then with 
 the division on the fixed scale which corresponds to the degree indicated by the wet bulb thermome¬ 
 ter, may be read the relative humidity or percentage of moisture in the air. 
 
 Complete with full and explicit directions for use.■. . . . 
 
 47-66 RAIN GAUGE, United States Weather Bureau type, diameter 3 inches, height 13 inches, with over¬ 
 flow and measuring stick. 
 
 47-76 REGISTERING RAIN GAUGE. The rain gauge illustrated above is a pattern which is known as 
 the “tilting bucket” gauge. No measurement is necessary as the rain is collected in the 8-inch 
 receiver and is taken through a small pipe and dropped into one side of a bucket. When a given 
 amount of rain has collected in the bucket (0.01 inch) the weight of the rain on the laden side causes 
 it to overbalance, and by a mechanical arrangement the hand moves 0.01 inch at each opera¬ 
 tion. 
 
 The rain still passing through the receiver is collected in the opposite bucket. When that has received 
 the given amount the same operation is repeated. The great advantage of this type of gauge is 
 that it is zero set and is particularly useful when a person wants to keep a record of rainfall by 
 the month or week. The dial registers one inch by 0.01 inch; the second or smaller dial reads up¬ 
 wards of 12 inches. 
 
 Enclosed in metal case 10 X 8 inches 
 
 $9.60 
 
 2.76 
 
 24.76 
 
168 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 48-12 No. 48-30 No. 48-17 
 
 48-10 ANEMOMETER for measuring air currents through tunnels, mines, ventilators of public buildings, 
 etc. The indications are obtained by means of a delicately poised fan wheel, the recordings be¬ 
 ing started by the long hand which traverses the outer circumference of the main dial which indi¬ 
 cates a passage of 100 feet of air. This recording is continued up to 10,000,000 feet by a series of 
 smaller dials, six in number. The disconnector projecting from the band of the instrument opposite 
 the fan wheel serves to throw the mechanism out of gear, arresting its action when required. 
 
 In use the instrument is placed in the current in a number of different positions. Take the number of 
 feet that have passed during a certain time, for example one minute, divide the total by the number 
 of readings and obtain the average. Multiply this average by the square of the opening and the 
 result is the velocity of air in feet passing in a given time. 
 
 Each instrument is enclosed with zero setting attachment in a neat mahogany case.. $24.75 
 
 48-12 - —, same as above, but with four dials reading to 100,000 feet. This instrument is recommended in 
 
 preference to above in that the parts are not so delicate. 24.76 
 
 48-16 BIRAM’S ANEMOMETER for similar use as No. 48-10. In this type of instrument the revolutions 
 are recorded on a dial in the center of the instrument. Each instrument is tested and furnished 
 with a chart of corrections, supplied with patent zero setting attachment in neat mahogany box, 
 diameter 3 inches, two dials reading to 1,000 feet. This instrument will stand a pressure of 1,000 
 feet per minute. 22.60 
 
 48-17 -, similar to above, 4 inches in diameter with four dials reading to 100,000 feet; will stand pressure 
 
 of 3,000 feet per minute. 23.80 
 
 48-30 REGISTERING ANEMOMETER. This simple device for indicating the velocity of the wind in 
 miles consists of a vertical shaft, to the upper end of which are fastened four arms, each carrying a 
 Robinson hemispherical copper cup. These cups turn in one direction, regardless of the direction 
 of the wind, and at a ratio determined by experiment. To the lower end of the shaft is fastened 
 an endless screw which, as the shaft revolves, actuates a wheel which in turn meshes into a series of 
 other wheels; thus the miles are indicated on the registering dial. The dial is so arranged as to show 
 velocities from one-tenth of a mile to 10,000 miles, and then it repeats, commencing at zero. 
 
 To ascertain the rate in miles per hour at which the wind is traveling, make two readings with an in¬ 
 terval of ten minutes and multiply the difference by six. 
 
 This instrument is carefully made and requires but little attention. All parts are interchangeable . 30.00 
 
48-100 
 
 I' 
 
 ■ • 
 
 
 48-102 
 
 HARCOURT STUDENTS’ METEOROLOGICAL EQUIPMENT. This is a complete set of Mete¬ 
 orological instruments of standard quality suitable for all work. The set must not be confused 
 with various types on the market inasmuch as our set comprises standard instruments of medium 
 quality. The set consists of the following, — one 10-inch Thermometer, metal scale on hard¬ 
 wood back; one 10-inch Maximum and Minimum Thermometer, mounted on hardwood back; 
 one Mason’s Hygrometer, mounted on polished oak board 11X5 inches; one 4-inch Aneroid 
 Barometer, open dial, graduations both English and Metric systems, and one 3-inch U. S. Weather 
 Bureau Rain Gauge with Measuring Stick. 
 
 The various instruments cited above, with the exception of the Rain Gauge, may be mounted within 
 the Instrument Shelter as illustrated. This Instrument Shelter is of substantial structure, painted 
 inside and out with a durable coat of lead paint. It is provided with brackets for attachment 
 to wall. 
 
 Instrument Shelter complete as illustrated, with all instruments, including Rain Gauge. 
 
 ■, as above illustrated, but without Rain Gauge 
 
 INSTRUMENT SHELTERS 
 
 48-106 INSTRUMENT SHELTER, as above described in No. 48-100 but without instruments. 
 
 48-116 INSTRUMENT SHELTER. Meteorology and climatology study in our schools has so come to 
 the front during the last few years that it has become almost essential that a shelter for recording 
 instruments be provided for outside use. 
 
 Our instrument is constructed after the latest pattern Weather Bureau Instrument Shelter and may 
 be mounted on legs for use on the school grounds or attached to the side of a wall. It is sufficiently 
 large to hold easily both a Barograph and Thermograph, a Hygrometer and a set of Maximum 
 and Minimum Thermometers, an Aneroid Barometer and a Thermometer. It is constructed of 
 the best quality straight-grained pine with swing door provided with lock and key. We secure 
 perfect circulation of air and obstruction to rain by means of the blind construction usually em¬ 
 ployed in the manufacture of shelters. It is painted outside and in with a durable coat of lead 
 paint. 
 
 Instrument Shelter, complete ready for mounting, but without instruments of any kind. 
 
 169 
 
 $16.26 
 
 12.60 
 
 $6.80 
 
 20.00 
 
170 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 NO. 49-90 
 
 HACKELING TELLURIAN 
 
 Patent No. 868,977, Issued July 2, 1907 
 
 A simplified and improved form of Tellurian, invented by the late Dr. Hermann A. Hackeling. This instru¬ 
 ment was designed with special reference to the needs of the instructor teaching Geography in the last year of the 
 grammar school and the first year in high school, bearing in mind, also, its special usefulness in teaching Physical 
 Geography and General Science in the first and second year of high school work. 
 
 To quote Dr. Hackeling’s own words, his purpose was to “design an educational Tellurian which could be supplied 
 to schools at a comparatively low price and which would make clear to the student the relative positions of the sun, 
 earth, and moon, and the inter-relations resulting from their rotation and revolution.” 
 
 Our designing department has given careful study to Dr. Hackeling’s excellent design and has been able to im¬ 
 prove upon it only to the extent of adapting the design to factory methods of production, thus insuring greater strength 
 of working parts and, at the same time, making it possible to offer the instrument at a lower price. 
 
 As will be noted from the cut, all unnecessary features have been omitted and the essential parts have been sim¬ 
 plified and strengthened. All mechanical parts are exposed to view, these parts being so simplified and strengthened 
 as to insure the instrument not getting out of order. 
 
 Please note that in rotating the earth around the sun, the earth is at the same time given a positive and exact 
 revolution, carrying with it the moon, the position of the moon with reference to the earth and the sun being varied 
 by sliding vertically on the supporting rod. 
 
 Also note that the entire system, by loosening of the T-Screw, may be moved to a horizontal position, without 
 changing the relation previously existing between the three bodies. 
 
 All metal parts are of substantial construction, well finished; the base being made of 5-ply, well seasoned hard 
 wood, neatly finished. 
 
 This instrument has been pronounced by those who have given much study to this important, feature of educa¬ 
 tional work, the only one which produces the desired results in a simple and direct way and so designed mechanically 
 as to insure its not getting out of order. 
 
 $15.00 
 
 Special price will be quoted upon these in dozen lots, where it is desired to place the instrument directly in the 
 hands of the student. . 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 171 
 
 THE NEWELL COLLECTION 
 
 OF 
 
 LANTERN SLIDES IN CHEMISTRY 
 
 Selected and arranged by Lyman C. Newell, Ph.D., Professor of Chemistry, Boston University, Boston, Mass 
 
 The slides in this collection will be found of particular advantage in courses dealing with the historical side of 
 Chemistry. There are 104 slides in the series, each slide, each subject most carefully selected. The series is par¬ 
 ticularly valuable in that it contains so many slides of eminent chemists, — American, Dutch, English, French, Ger¬ 
 man and Italian, all of which are remarkably clear and distinct. The following subjects are stressed, — Alchemy, 
 Atmosphere, Atomic Theory, Atomic Weights, Avogadro’s Hypothesis, Combustion, Electro Chemistry, Elements, 
 Metals, Halogens, and Chemistry in Eighteenth and Nineteenth Centuries. 
 
 Single Slides .Each $0.40 
 
 Any 60 in Regular Lantern Slide Box. .20.00 
 
 A descriptive circular free upon request. 
 
 FIVE HUNDRED AND FIFTY 
 
 LANTERN SLIDES AND STEREOGRAPHS 
 
 Selected and described with Special Reference to 
 STUDY OF PHYSICAL GEOGRAPHY AND GEOLOGY 
 
 BY 
 
 WALLACE W. ATWOOD, PH.D., JANE PERRY COOK, 
 
 Instructor in Physiography and Head of Department of Geography, 
 
 General Geology, University of Chicago. Chicago Normal School. 
 
 This series of slides has been selected and classified according to those topics in Physical Geography and Geol¬ 
 ogy to be found in the best courses of study and in the modern text-books on these subjects. The classification has 
 been systematic and thorough. 
 
 The catalogue of these slides, which may be obtained free upon request, is divided for ready reference into main 
 topics, — Weathering, Sand Dunes, Rivers and River Valleys, Underground Water, Glaciers, Lakes, Shore Lines 
 and Harbors, Vulcanism, Earthquakes, Mountains, Plains, Clouds, Storms and Life Forms in Various Physiographic 
 Environments. Each main topic is logically divided into subdivisions, e. g., 49 pictures have been selected for the 
 study of Glaciers under the following subtopics: — The Study of a Glacier, European Glaciers, Study of Glaciated 
 Valleys and Ascent of Mt. Hood. Each slide has been most carefully selected as best adapted to each particular 
 subtopic. 
 
 The value of this series is further enhanced by brief descriptive matter printed on the back of each stereograph 
 and in the case of slides on slips of heavy book paper. These printed slips are put up in a neat and attractive book¬ 
 let which is sent along with the order. When all the slides of a single topic are ordered the booklet makes a most 
 valuable body of supplementary reading matter on the subject. 
 
 Single Slides .Each $0.40 
 
 Per One Hundred.36.00 
 
 Send for Special Catalogue descriptive of these slides. 
 
172 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • i 
 
 49-100 KULLMER STAR CHART. This new 
 astronomical instrument is based on the 
 principle of the equatorial telescope mount¬ 
 ing, — an arrow taking the place of the 
 telescope. It is so simple and ingenious 
 that it is fascinating to operate. In the 
 cut the instrument is set for February 22, 
 at 9 P.M. Place the arrow wherever you 
 wish, and it will be pointing, when proper¬ 
 ly set, at the star-group shown and named 
 in the opening of the indicator below. 
 
 No. 49-100 
 
 SOME OF THE THINGS IT TEACHES. 
 
 The apparent daily rotation of the whole sky. 
 
 Where stars, sun, moon and planets rise and set and 
 the actual path taken by them. 
 
 The seasons, movement of sun north and south and 
 path at solstices and equinoxes. 
 
 The constellations,—locations and names. 
 
 Sidereal and solar time. 
 
 Right Ascension and Declination. 
 
 Etc., etc., etc. 
 
 Made of nickeled metal with celluloid dial 
 that can be washed when desired. With 
 booklet “Star Maps and Star Facts” in 
 neat leatherette case . 
 
 $5.00 
 
 49-110 SEASONAL TWILIGHT CHART, designed and copy¬ 
 righted 1907 by Miss E. Rebecca Ellis of the Depart¬ 
 ment of Physical Astronomy at Wellesley College, 
 for showing: 
 
 The comparative lengths of day, night and twilight at any place 
 at different seasons of the year. 
 
 The comparative lengths of day, night and twilight at different 
 places at the same season of the year. 
 
 The absolute lengths of day, night and twilight at any place at 
 any season. 
 
 The time of sunrise and sunset at any place at any season. 
 
 The azimuth of sunrise and sunset points at any place at any 
 season. 
 
 The noon elevation of the sun at any place at any season. 
 
 The midnight depression of the sun at any place at any season. 
 
 The phenomena of the midnight sun. 
 
 The diurnal path of the sun at the poles (six months day and six 
 months night). 
 
 The diurnal path of the sun at the equator (days and nights 
 equal: and extremely short twilight). 
 
 No. 49-110 
 
 This chart is the orthographic projection of a globe upon a plane from a due east point in the plane 
 of the horizon. The chart is 12 X 12 inches, divisions and figures distinct and legible and the size 
 ample for use to advantage on the lecture table. The student, however, will gain a much clearer 
 grasp of the whole subject if he works out the various problems with the chart in hand. 
 
 With full directions 
 
 Each Chart $1.00. Per Dozen $9-W 
 
CATALOGUE OF PHYSICAL, INSTRUMENTS 
 
 173 
 
 No. 49-120 
 
 THE B-K SOLAR CALCULATOR 
 
 Invented by FRANK L. BRYANT 
 
 ERASMUS HALL HIGH SCHOOL, BROOKLYN, N. Y. 
 
 No. 49-120 
 
 The object of this ingenious instrument is to provide a simple apparatus for teaching the fundamental ideas of 
 i apparent motion of the sun in relation to any point on the earth’s surface and at any time of the year. It is 
 jecially designed for the use of students in the laboratory for working out certain problems which will be noted 
 low. It is also of value to the teacher in lecture work for all grades of geography instruction from the grammar 
 100 I to advanced work in the college. 
 
 This instrument, about 16 inches high and 16 inches wide, is especially adapted for the lecture table, although it 
 IS primarily designed for individual student use. A special feature in connection with the use of the instrument, 
 d one entirely new, is that the horizon disc may be lowered and adjusted for plotting shadow curves at the time 
 the solstices and equinoxes for different latitudes. This work was practically impossible before the intro- 
 ction of the B-K Solar Calculator. Its value, therefore, will be especially appreciated by teachers of Physical 
 :ography. 
 
 The following exercises may be performed by the use of the instrument: 
 
 1. Find the time of sunrise and sunset at any latitude at any time of the year. 
 
 2. Determine the length of day at any latitude at any time of the year. 
 
 3. Find the relative distribution of insolation over the earth at different times of year. 
 
 4. Find the direction of sunrise and sunset at any latitude at any time of the year. 
 
 5. Find the altitude of the sun at any latitude at any time of the day or year. 
 
 5 . Plot the curves of a shadow cast by an upright post at any latitude at the time of the solstices and equinoxes. 
 
 7. Interpretations of shadow curves. 
 
 8 . Show relation of elevation of celestial pole to latitude. 
 
 9. Show relation of zenith distance of sun to latitude at different times of the year. 
 
 10. Show relation of length of twilight to latitude at different times of the year. 
 
 B-K SOLAR CALCULATOR, brass with oak base 
 irections for use furnished with each instrument. 
 
 Special price in lots of ten. 
 
174 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 THE 
 
 Set for Tropic of Capricorn 
 23S. Lat. 
 
 No. 49-120 
 
 B-K SOLAR CALCULATOR 
 
 Set for Tropic of Cancer, 
 23 N. Lat. 
 
 Set for the North Pole, 90° 
 
 Set for the Arctic Circle 
 66^° N. Lat. 
 
 Set for plotting the Shadow 
 Curves at the Equator 
 
 FORMS OF SHADOW CURVES 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 175 
 
 No. 49-175 
 
 CURTIS NATURALISTIC MODELS 
 
 These models are true scale reliefs, 9X9 inches, representing the forms of the earth’s sur- 
 |ice, durably constructed of a special composition, beautifully colored to reproduce the color scheme 
 f the natural object. They may be handled as readily as a school book and used wherever Geog- 
 aphy is taught. They are especially adapted for work in connection with courses in Physical 
 ieography. This wide range of service is due to the fact that each model is based on well selected 
 ypes taken from actual occurrences in the field, and reproduced in very characteristic forms. 
 
 While it is true that the beginners will get but a small portion of what the advanced student 
 nay obtain, they will lose nothing by the completeness of the subject and what they do gain will 
 jome in the easiest way. 
 
 The set comprises six models, each enclosed in a book-cover case into which the models slide, 
 >ermitting them to be handled and stored like books. The set consists of the following: 
 
 SEACOAST 
 
 No. I. 
 
 SEASHORE BORDERING A PLAIN 
 
176 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 49-175 
 
 CURTIS GEOGRAPHY MODELS 
 
 GLACIERS 
 
 No. I. HEAD OF A GLACIER 
 
 No. II. LOWER END OF A GLACIER 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 177 
 
 
 
 
 No. 49-175 
 
 CURTIS GEOGRAPHY MODELS 
 
 VOLCANOES 
 
 No. I. A FRAGMENTAL CONE 
 
 (VESUVIAN TYPE) 
 
 No. II. AN OPEN CRATER (CALDERA) 
 
178 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 49-175 
 
 CURTIS GEOGRAPHY MODELS 
 
 1 
 
 
 c " *'*. -j 
 
 OC.OCHAPHV 
 
 'AOOCl.!. 
 
 SEACGAST 
 
 No I 
 
 COASTAL 
 PLAIN : 
 
 . v' $*' s . • . r, V 
 
 1 • (,/u 
 
 i' ' OtOCRAPIIV OfOOf\Ar»»Y 
 
 NooeCft noorLs 
 
 SEACOAST VOLCANOES 
 
 No n M 0 j 
 
 MOUNTAIN 
 
 <j«OORA»»HY 
 
 MOMl* 
 
 VOLCANOES CLACK 
 
 lUUN I HU Y nnnf J^ nrrta . A PRATFR HEAD OF 
 
 COAST CINDER CONE ALnAlLlI A GLACIER 
 
 GLACIERS 
 
 Noll 
 
 FOOT or 
 A GLACIER 
 
 SET OF GEOGRAPHY MODELS IN COVERS 
 
 SEACOASTS 
 
 No. I. SEACOAST BORDERING A PLAIN. 
 
 A Plain which borders the sea. 
 
 Rivers which cut the plain and empty into the sea through an estuary. 
 
 A Harbor lying at the head of the bay at the mouth of the largest stream and on its shores. 
 
 A Seaport Town situated on the bay. Vessels may lie at the wharves, load and discharge 
 cargoes well sheltered from storms. 
 
 No. H. EMBAYED MOUNTAIN COAST. 
 
 A Bay reaching up into the mountainous land. 
 
 Mountain Peaks which rise abruptly from the sea. 
 
 A Narrow Valley flanked by steep mountain sides. 
 
 A River flowing through the valley. 
 
 A Delta at mouth of the river and head of the bay. 
 
 VOLCANOES 
 
 No. I. FRAGMENTAL CONE (VESUVTAN TYPE.) 
 
 A Young Volcanic Mountain rising from the sea. 
 
 An Active Volcano at top of mountain; hot stones, ashes, lavas running down the sides of the 
 mountain. 
 
 Lava “Flows” showing as hardened rock. 
 
 An Old Volcanic Mountain. 
 
 No. II. AN OPEN CRATER (CALDERA). 
 
 The Top of a Volcano, showing devastated region about the summit. 
 
 A Deep Crater Pit, a “Caldera.” 
 
 An Old Crater partially filled with lava. 
 
 Fresh Lava. 
 
 GLACIERS 
 
 No. I. HEAD OF A GLACIER. 
 
 Mountain Peaks, sharp topped ridges. 
 
 Lofty Valleys, partially filled with snow and ice, descending steeply. 
 
 Snow Fields, masses of loose and compact snow which feed the Rivers of Ice. 
 
 Glaciers. 
 
 No. II. LOWER END OF A GLACIER. 
 
 The Foot of a Glacier. 
 
 The Head of a River, the melting glacier giving rise to a river. 
 
 An Open Valley. 
 
 An Alpine Village, low huts clustering near the foot of the glacier. 
 
 Complete set of six models, each in Book Cover Case, appropriately labeled, including a 
 
 descriptive manual, a complete text on the subjects covered.$50.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 179 
 
 SOUND 
 
 PROPAGATION OF SOUND 
 
 TUNING FORKS 
 
 • 
 
 In the selection of our TUNING FORKS we have been guided by the demands of the past which we have classi¬ 
 fied. . We have, therefore, eliminated certain types and added forms of greater pedagogic value. Our policy is to 
 furnish the best at the most reasonable prices, offering a line which will give the prospective buyer a range for choice. 
 
 For ordinary work, we recommend our Nos. 61-50 to 61-87. These forks are accurately tested and have, withi n 
 a very small percentage of error, the stated vibration frequencies. For the highest scientific work, we recommend 
 Nos. 61-90 to 51-126. 
 
 All forks are tuned to the Physical Pitch, and, when a fork is mounted on Resonant Case, it must be under¬ 
 stood that the case is accurately tuned in resonance with the fork. 
 
 No. 61-60 
 
 61-60 UNIVERSAL PATENT ADJUSTABLE TUNING FORK, U. S. Standard Pitch, nickel-plated . . $1.10 
 
 No. 51-56 
 
 51-55 TUNING FORK, 12 centimeters long, best polished steel, Pitch A. $0.13 
 
 51-57 -, 12 centimeters long, best polished steel, Pitch C. .13 
 
 Nos. 61-75 to 51-87 
 
 61-65 TUNING FORK, Pitch C = 128 VPS. about 25 centimeters long . $3.10 
 
 61-75 -, Pitch C 1 = 256 VPS. about 22 centimeters long. 1.20 
 
 61-76 -, Pitch D = 288 VPS. about 21 centimeters long. 1.46 
 
 61-77 -, Pitch E = 320 VPS. about 20 centimeters long. 1.45 
 
 61-78 -, Pitch F = 341 1/3 VPS. about 20 centimeters long. 1.45 
 
 51-79 -, Pitch G - 384 VPS. about 19 centimeters long. 1.45 
 
 61-80 -, Pitch A = 426 2/3 VPS. about 19 centimeters long. 1.26 
 
 51-81 -, Pitch B = 480 VPS. about 18 centimeters long. 1.26 
 
 61-82 -, Pitch C 2 = 512 VPS. about 18 centimeters long. 1.10 
 
 51-85 TUNING FORKS, set of four, giving the Major Chord, C 1 , E, G, and C 2 . 6.10 
 
 61-86 MOUNTED TUNING FORKS, set of four, C 1 , E, G, C 2 , as listed above, mounted on resonant cases 12.95 
 
 61-87 TUNING FORKS, set of eight, C 1 to C 2 , giving full Octave. Same forks as Nos. 61-76 to 51-82 9.86 
 
 61-88 RUBBER HAMMER, small.14 
 
 61-89 LARGE LECTURE TABLE PURE GUM RUBBER HAMMER, finely finished handle.66 
 
i8o 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 61-90 NORMAL TUNING FORKS of excellent quality, finely nickel-plated, accurately adjusted. Set 
 of eight forks, from C = 64 VPS. to C = 128 VPS., the largest fork about 40 centimeters long, the 
 smallest about 36}4 centimeters... Duty Free 
 
 61-96 - —, same quality as above, set of fifteen forks, from C = 64 VPS. to C 1 = 256 VPS. The largest 
 fork about 44 centimeters long, the smallest about 23 centimeters .Duty Free 
 
 61-100 -, same quality as above, set of eight forks, from C = 128 VPS. to C 1 =256 VPS. The largest 
 
 fork about 36p£ centimeters long, the smallest about 23 centimeters .Duty Free 
 
 61-106 EXTRA HEAVY TUNING FORK, C = 64 VPS., 44 centimeters long.Duty Free 
 
 61-106 -, C = 128 VPS., 35 centimeters long.Duty Free 
 
 61-116 STANDARD NORMAL TUNING FORKS, highest quality and precision, especially designed for 
 
 research in acoustical phenomena. Set of six large nickel-plated Forks, C = 128 VPS., C 1 = 256 
 
 VPS., C 2 = 512 VPS., C* = 1024 VPS., C 4 = 2048 VPS., and G 4 = 3072 VPS. Each with a vi¬ 
 bration period of 30 seconds. Enclosed in handsome plush-lined case.Duty Free 
 
 61-120 STANDARD NORMAL TUNING FORK, finest, quality, highest precision, worked out of a heavy 
 piece of steel, not cast, with certificate of accuracy from the Physikalische Techniche Reich- 
 sanstalt. Enclosed in neat case.Duty Free 
 
 61-126 FIFTY-CENTIMETER TUNING FORK AFTER BEZOLD, for demonstrating the minimum limit 
 of the normal ear for sound. 
 
 This is a polished steel fork, 500 millimeters long, with a prong 350 millimeters long, each prong 21 X 9 
 millimeters. Each fork has received the most painstaking care in construction and is carefully 
 adjusted. Adjustable ballast weights are provided giving vibration frequencies from 15 to 24. 
 Handsomely polished.Duty Free 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 181 
 
 ELECTRO-SYNCHRONISM-DRIVEN RECORDING FORK 
 
 Nos. 51-135 to 61-140 
 
 Patent Pending 
 
 In our electro-synchronism-driven tuning fork we believe that improvements of the greatest importance have 
 been made in the fundamental instrument, improvements which will give the closest approach to an ideal fork. In 
 our method, an especially designed Microphone is mounted on the base of the instrument. This Microphone picks 
 up the vibrations thrown from the fork, and in turn varies the strength of the electro-magnets which actuate the 
 fork, leaving the prongs free to vibrate unhampered by contacts or springs such as were formerly used. In use the 
 binding posts are connected to the source of current, 4 cells of dry battery being recommended. 
 
 The synchronism that takes place is shown in a very striking manner. Starting with an almost imperceptible 
 vibration, the fork gradually reaches its highest amplitude, when it will continue to give forth a tone of great purity, 
 with absolute freedom from all other foreign sounds or vibrations which have proved so troublesome in forks con¬ 
 structed by ordinary methods. The synchronism method insures the fork giving its actual tone, a result not ob¬ 
 tained by any other method. 
 
 Electrically Driven Tuning Forks in which the electric contact is made directly on the prongs either by a spring 
 attached to one prong or by a platinum contact soldered to it, have the following objections: — 
 
 1. The prong of the fork carrying the contact or spring is dampened, and the fundamental tone of the fork is 
 radically changed thereby. 
 
 2. The vibration of the fork is forced to an unnatural pitch by means of the sudden rush of current due to its 
 intermittent contact. 
 
 3. The contact point emits a sound often sufficient to obscure the fundamental tone of the fork. 
 
 4. An adjustment that will give the natural clear tone of the fork is impossible, owing to the unavoidable noise 
 due to this method of vibration. 
 
 In the Electro-Synchronism-Driven Tuning Fork we justly claim the following features: — 
 
 1. The fork has nothing to carry. 
 
 2. The vibration is absolutely dependent upon the natural period of the fork. 
 
 3. There are no parts of the apparatus to take up vibrations and give any undesirable sounds. 
 
 4. The fork is actuated by a current that varies in strength from maximum to minimum in absolute synchronism 
 with its own period. 
 
 5. The vibrating apparatus is absolutely distinct and unattached to the fork and hence produces no distortion 
 
 I 1 in vibration. 
 
 As the principal object of this apparatus is to maintain for a considerable period a uniform tone and vibration 
 coming from a fork having a definite vibration period, we list the apparatus designed for adjusted forks of 128 and 
 ■ 256 vibrations. We desire to call particular attention to the fact that these forks are of the best quality, furnished 
 
 us by a prominent European manufacturer. , 
 
 61-135 ELECTRO-SYNCHRONISM-DRIVEN RECORDING FORK, including base and imported fork 
 
 No. 61-106, 35 centimeters long, 128 VPS.?17.25 
 
 51-137 -, same as above, but with No. 51-75 fork, 22 centimeters long, 256 VPS. 9.50 
 
 61-140 
 
 
 UNADJUSTED TUNING FORK, large size, for use with No. 51-136. It is frequently desirable 
 to use an electrically driven tuning fork designed so that the stylus for recording the vibrations 
 on a moving surface may be attached; also one in which the mirrors for use in tracing Lissajous’ 
 figures may be used. Where these attachments are added the absolute vibration of the fork 
 cannot, of course, be depended upon, since the prong must carry a load. For this work, there¬ 
 fore, a fork which has not been especially adjusted is entirely adequate. The fork which we 
 furnish under this number is one of unusually substantial construction, approximately 15 inches 
 long, giving about 100 vibrations per second and supplied with threaded holes on the ends of 
 the fork for carrying binding screws which hold the recording stylus, also for carrying the mirrors 
 listed below, used in Lissajous’ experiments .... 
 
 Complete with stylus. 
 
 6.75 
 
 61-141 -, small size for use on No. 51-137 
 
 1.35 
 
 61-142 MOUNTED MIRRORS FOR LISSAJOUS’ CURVES supplied with threaded stems fitting the 
 
 holes of the fork No. 61-140 ..Per Pair 2.50 
 
i 82 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • » 
 
 61-150 
 
 61-166 
 
 61-167 
 
 61-169 
 
 61-161 
 
 Nos. 51-160 to 51-161 
 
 LARGE MOUNTED TUNING FORKS, most careful workmanship, highest accuracy, mounted 
 on synchronized resonant cases. Set includes four large forks from^C 1 = 256 VPS. to C 2 = 512 
 VPS., each mounted on a separate case. With rubber hammer .Duty Free 
 
 ABOVE FORKS SEPARATELY LISTED 
 
 LARGE MOUNTED TUNING FORK, C 1 = 256 VPS.Duty Free . . . 
 
 -, E = 320 VPS. Duty Free . . . 
 
 -, G = 384 VPS.Duty Free . . . 
 
 ——, C 2 = 512 VPS.Duty Free . . . 
 
 51-175 
 
 61-180 
 
 51-190 
 
 61-192 
 
 If 
 
 No. 51-180 
 
 LARGE MOUNTED TUNING FORKS, same quality as above. Set of eight forks, giving the 
 
 Octave, C 1 = 256 VPS. to C 2 = 512 VPS., each mounted on resonant case. Duty Free 
 
 -, same as above, set of thirteen, from C 1 = 256 VPS. to C 2 = 512 VPS.; each mounted on 
 
 synchronized resonant case .. Duty Free 
 
 SYMPATHETIC TUNING FORKS 
 
 for showing sympathetic vibrations, 
 also “beats.” 
 
 Consists of a pair of large tuning forks, 
 accurately adjusted to 256 VPS. per 
 second, mounted on separate syn¬ 
 chronized resonant cases. One of 
 the forks is supplied with a slide to 
 destroy the unison to show “beats.’’ 
 Complete with large 
 rubber hammer, 
 
 Duty Free. 
 
 -, extra large, same 
 
 quality as above, but 
 accurately adjusted 
 forks of 128 VPS., 
 
 Duty Free. 
 
 No. 61-190 
 

 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 183 
 
 THE MORSE SYMPATHETIC VIBRATION APPARATUS, for the study of sympathetic vibra¬ 
 tions in simple pendulums and for determining under what conditions two bodies will vibrate in 
 sympathy. The apparatus clearly shows what is meant by the expression, “natural period of 
 swing.” 
 
 The apparatus consists of a tripod stand on which is mounted the vibration apparatus consisting of 
 four simple pendulums in bi-filar suspensions and a compound pendulum with adjustable disc 
 bob, all suspended from a common swivel support. 
 
 If the compound pendulum is set vibrating the simple pendulum the vibration period of which 
 is synchronous will begin to vibrate. 
 
 Apparatus complete with tripod stand. $8.40 
 
 -, same as above but without tripod stand and support . 5.26 
 
 CHEMICAL HARMONICON or SINGING FLAME, showing that the air in an open tube may 
 be made to give a sound by means of a luminous jet of gas. 
 
 The apparatus consists of a tube about 2 centimeters in diameter of the carefully calculated length 
 to respond to the jet or the burner, also supplied with the apparatus. 
 
 Tube complete with burner. 2.60 
 
 CHEMICAL HARMONICA, similar to No. 61-210, but designed to sound the chord. 
 
 The apparatus consists of four tubes similar in design to No. 61-210, but all mounted on a common 
 stand with special burner. 
 
 Complete as illustrated. 14.60 
 
 GLASS WHISTLE WITH SLIDING PISTON for determining the “fundamentals” of closed pipes. 
 
 This consists of a glass tube in which is a sliding piston and to which is fastened a second tube in 
 such a position that air blown through it will cause the air column in the first tube to emit a tone 
 which may be proved the “fundamental” of the tube. 1.26 
 
 61-206 
 
 
 
 61-206 
 
 61-210 
 
 61-212 
 
 61-250 
 
184 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 61-240 GALTON’S WHISTLE for determining the highest limit of audibility, — calculated vdbrations 
 up to 85,000 per second possible. 
 
 This is an accurately constructed instrument, all dimensions calculated to a scientific nicety. Each 
 part is carefully fitted, neatly polished, and lacquered. Results possible fully warrant its expense. 
 
 61-243 GALTON’S WHISTLE for determining the upper limit of audibility. 
 
 This instrument is similar in appearance to No. 61-240, but designed and constructed by Dr. M. 
 Th. Edelmann. It has an improvement in form of a double adjustment and a large throat. It 
 attains the highest degree of accuracy and is handsomely finished throughout. Complete direc¬ 
 tions and valuable data are furnished with each instrument. 
 
 Enclosed in leather case.Duty Free 
 
 61-276 ALL METAL ORGAN PIPES, set of four giving the Chords, C\ E, G, and C 2 . 
 
 These pipes are carefully constructed from metal, and from actual experimentation are found to give 
 the best results, far in excess of pipes constructed of wood. They are especially constructed for 
 us and we have added to their pedagogic value by the attachment of a Sliding Tuning Tube which 
 is designed to change the tone by lengthening the tube. 
 
 These pipes will be found a valuable addition to any laboratory and their handsome appearance will 
 certainly add to the appearance of the scientific equipment . w . 
 
 61-286 - —, same as above, but a full set of eight pipes sounding the octave from C 1 to C 2 . 
 
 61-290 DEMONSTRATION ORGAN PIPE for showing the vibrating segments and nodes of an organ 
 pipe by means of a membrane. 
 
 This consists of a wooden pipe, one side of which is of glass. Fitting within this pipe is an adjust¬ 
 able membrane, the height of which in the tube can be regulated by means of a rod to which the 
 membrane is attached. 
 
 On lowering the membrane, in the tube, until it reaches a node, a pure tone is produced; but on 
 raising or lowering the membrane a few centimeters, a harsh note is given out. On covering 
 the membrane with a little sand or cork dust and changing its height in the tube, it will be seen 
 that the sand or dust is disturbed at all positions except at the nodes. 
 
 61-295 DEMONSTRATION ORGAN PIPE WITH MOVABLE STOP for sounding two octaves with tones 
 
 and semi-tones distinctly marked on the frame which operates the stop .. 
 
 $9.85 
 
 16.60 
 
 9.60 
 
 18.76 
 
 4.00 
 
 4.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 185 
 
 61-310J MOUNTED TUBE for showing transmission of sound by liquids. 
 
 This apparatus consists of a glass tube with funnel-shaped open end, mounted on resonant case. 
 If stem of vibrating fork is held at open end it may be shown that no sound is transmitted; if, how¬ 
 ever, the tube is filled with water and the stem touches the surface of the liquid, sound is trans¬ 
 mitted.Duty Free 
 
 No. 51-315 
 
 61-316 XYLOPHONE showing musical tones from vibrating wooden bars. Consists of fifteen maple bars 
 mounted on wood frame and accurately tuned to sound two octaves. With two hammers . . 
 
 61-320 METALAPHONE for showing musical tones emitted by vibrating metal. Consists of twelve metal 
 plates’carefully tuned and mounted in ornamented wooden frame. With two hammers .... 
 
 No. 61-325 
 
 $8.60 
 
 $1.25 
 
 1.25 
 
 51-325 TUBEPHONE showing musical tones emitted by vibrating tubes. Consists of fifteen brass tubes 
 
 highly polished, mounted in wooden frame. With two hammers, in cardboard box. $1.95 
 
i 86 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 REFLECTION, REFRACTION AND 
 INTERFERENCE OF SOUND WAVES 
 
 No. 52-10 
 
 62-10 THIRTEEN-INCH UNIVERSALLY ADJUSTABLE TRUE PARABOLIC REFLECTORS for dem¬ 
 onstrating Reflection of Sound, Heat and Light Waves. 
 
 In offering for sale our Improved Reflectors we desire to emphasize the TRUE PARABOLIC SUR¬ 
 FACES. The curves of these surfaces have been accurately calculated and drawn and then by 
 painstaking processes a chuck has been turned to the true parabolic curve. Our Reflectors are 
 all spun from this chuck. The reflecting surface is then highly polished and heavily nickel-plated, 
 presenting an excellent surface without waves. 
 
 The Reflectors are mounted in a two-part circular casting in such a manner as to entirely obviate any 
 danger of distorting the surfaces. This two-part casting is brought together at the bottom, where 
 it makes a swivel junction with a rod which telescopes into the supporting base. 
 
 The holders and attachments are all of special design which allows of both coarse and fine adjustments. 
 We, therefore, secure a tilting movement for the Reflectors, an adjustment for proper height, and 
 universal movements for each attachment. 
 
 In illustrating Reflection of Sound a simple experiment is possible by attaching a watch to one of 
 the carriers at the focus of one reflector; if now one end of a flexible tubing is placed at the focus 
 of the other reflector attached to the carrier and the other end terminating in a large funnel, mega¬ 
 phone, or horn, the ticking of the watch may be heard by the majority of the class. 
 
 The finish of this instrument is fully in keeping with the design. The outer surfaces of the Reflec¬ 
 tors are dull oxidized, the H Base bright japan, and all brass parts polished and nickel-plated. 
 
 Thirteen-Inch Universally Adjustable True Parabolic Reflectors complete as illustrated with at¬ 
 
 tachments . Per Pair $17.60 
 
 52-16 -, same as above, mounted on stand but without attachments or carriers. Per Pair 13.50 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 187 
 
 52-30 SOUND LENS, for experiments on the refraction of sound. 
 
 The apparatus consists of a double-walled rubber diaphragm 
 re-inforced by a rolled metal ring and provided with an 
 outlet for inflating with gas, refractive power of which is to 
 be studied. This outlet is also convenient for regulating 
 the curvature and hence the refractive power of the lens. 
 
 A source of sound is placed in the direction of the axis; the 
 point is then sought on the other side of the lens at which 
 the sound is most distinctly heard. This point will be the 
 focus, and at all other points the sound is scarcely per¬ 
 ceptible, showing that sound has been refracted by the lens 
 in much the same way as light is refracted by a glass lens. 
 
 This apparatus is supported by a simple and effectivelyJ[ de¬ 
 signed base and supporting arm so arranged as to give 
 ample adjustment and full range in the angle of inclination. 
 
 Sound Lens complete, with stand, as illustrated. $9.80 
 
 62-32 SOUND LENS only, ready for mounting on stand .... 6.75 
 
 62-40 EAR TRUMPET, for concentrating sound waves. This|is a 
 neatly finished metal instrument designed to reflect and 
 concentrate sound waves. 2.60 
 
 No. 62-30 
 
 62-76 KUNDT’S INTERFERENCE APPARATUS for the quantitative study of Interference of Sound 
 Waves. 
 
 This apparatus consists of two U-shaped nickel-plated brass tubes, one provided with supporting 
 cross bars; the other has both arms graduated, telescoping into the first. To one of the parallel 
 sides of this interference tube is attached a closed glass tube which in use contains cork dust or 
 lycopodium powder. To the other side is attached a glass tube with supported sliding piston. In 
 use, vibrations are set up in the piston tube with the movable telescoping part of the interference 
 tube pushed home, then with this part so that it represents 1, 2, 3, 4, 5, etc. quarter wave-lengths. 
 
 It will be noted that figures are produced with the even numbers and are not formed with the odd 
 numbers of quarter wave-lengths. Mounted on well finished wood base. $15.00 
 
188 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 62-85 
 
 No. 21-246 
 
 62-80 INTERFERENCE TUBES after QUINCKE for use with C 1 = 512 VPS., in illustrating interference 
 
 of sound waves. 
 
 The apparatus consists of two T-shaped glass tubes of equal diameter connected as illustrated by 
 rubber tubing. 
 
 If a tuning fork is sounded before the open end of the long tube, and the open end of the other tube is 
 held to the ear, there will be no sound heard providing the length of the tube connecting the branches 
 of the T-tube is one-half the wave-length of the note produced by the fork. If, however, this 
 rubber tube be closed by pinching it, the note is at once heard. 
 
 Complete with rubber tubing as illustrated. $0.90 
 
 62-86 HOPKINS’ METAL FORK TUBE after Gage’s “Introduction to Physical Science,” Exp. 255, for 
 study of interference with a Chladni’s Plate (see Nos. 54-126 and 64-134). 
 
 This consists of a forked metal tube with adjustable extension. • 
 
 In use, the plate is bowed so that the two diagonals are distinctly formed. If the fork of the Inter¬ 
 ference T ube is held over two non-contiguous sectors, the sand strewn on the membrane is violently 
 agitated. If the fork is held over two contiguous sectors, the sand is not disturbed. 3.16 
 
 No. 53-40 
 
 21-225 SAVART’S WHEEL, COLOR AND SIREN DISC combined. (See 
 
 Section 21.). 1.50 
 
 21-240 SAVART’S WHEEL for use on Rotator, consisting of four discs of 
 metal in the periphery of which are cut teeth, the number forming 
 a simple ratio to give a harmonic chord. 2.36 
 
 21-242 SAVART’S WHEEL, a single disc for attachment to Rotatqr . . . .48 
 
 21-245 SAVART’S WHEEL for demonstrating that pitch is proportional to 
 the number of vibrations per second. 
 
 The apparatus consists of a heavy cast toothed wheel mounted on steel 
 pinions in a forked stand. This wheel may be rotated by means of 
 a cord. If a card is held lightly against the teeth of the wheel dur¬ 
 ing rotation, a note wall be sounded, the pitch depending on the 
 speed of the wheel . 7.66 
 
 53-40 CAIGNARD-LATOUR SIREN WITH COUNTERS. This is a care¬ 
 fully constructed scientific instrument, a product of a firm well 
 known in Europe for accurate designs of acoustical apparatus. It 
 is handsomely finished throughout .Duty Free . . . 
 
 63-42 CAIGNARD-LATOUR SIREN WITHOUT COUNTERS. This in¬ 
 strument is similar in design to the one above but without counters. 
 
 Duty Free . . . 
 
 63-46 DEMONSTRATION CAIGNARD-LATOUR SIREN WITHOUT COUNTERS. This is a greatly 
 
 simplified form of the above. . 
 
 9.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 189 
 
 SONOMETERS 
 
 Our Sonometers are made from selected well seasoned wood very carefully glued up and finely finished. We 
 list below only those designs which have in actual use given the most efficient service. Each sonometer is sup¬ 
 plied with wires and necessary bridges. On each case beneath the wires, there is a metric scale on which is also 
 indicated the lengths of strings necessary to give both the Diatonic and the Equally tempered scale between C = 
 
 256 VPS. and C = 1024 VPS. 
 
 No. 63-100 
 
 No. 63-116 
 
 63-100 
 
 63-101 
 
 63-102 
 
 63-116 
 
 63-117 
 
 63-126 
 
 63-127 
 
 63-136 
 
 63-137 
 
 63-138 
 
 63-139 
 
 No. 63-136 
 
 SONOMETER. This sonometer is complete as illustrated, requiring no accessory 
 weights, scale pans, etc. Tension is caused by dynamometers, fine adjustment 
 of tension being secured by turning the wing nut sat the end of the slow motion 
 screws to which the wires are attached. Length meters over all. Complete 
 
 as illustrated. ?8.15 
 
 -, without dynamometers. 4.86 
 
 SONOMETER WIRES, set of three wires as used in above.Set .20 
 
 NATIONAL THREE WIRE SCHOOL SONOMETER after Turner and Hersey, 
 
 Exp. No. S040. Requires no accessory weights, scale pans, etc. Three wires 
 attached, each with tension spring of 25 pounds capacity. Fine adjustment of 
 tension secured by piano tension keys. 4.60 
 
 SONOMETER WIRES, set of three as used in No. 63-116.Set .20 
 
 VERTICAL WALL FORM SONOMETER. Recommended in that it takes little 
 space and that the tension is applied direct. With two wires, bridge clamps, 
 etc., as illustrated, but without hangers and weights.11.50 
 
 SONOMETER STRINGS, 0.014 and 0.028 inch diameter as used on above Sono¬ 
 meter .Pair .35 
 
 LEVER TENSION SONOMETER. Tension adjusted by weights sliding on levers, 
 
 fine adjustment by tension keys. Without weights. 7.80 
 
 DIRECT TENSION SONOMETER. Tension secured by means of weights to be 
 
 attached to cords over freely running pulleys. Without weights. 7.80 
 
 DIRECT TENSION SONOMETER, similar to above, but with tension keys and 
 
 complete with necessary hangers and weights.10.60 
 
 KEY TENSION SONOMETER. Tension secured by Keys only. 7.25 
 
 No. 63-125 
 
igo 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 53-200 
 
 61-75 
 
 53-205 
 
 63-216 
 
 63-225 
 
 RESONANCE TUBES 
 
 No. 53-200 
 
 No. 63-206 
 
 KNOTT’S ONE HUNDRED AND FIFTY CENTIMETER RESONANCE APPARATUS, for 
 
 determining the wave length of a tuning fork; also for determining the velocity of sound in air. 
 
 The apparatus consists of a metal upright with metric scale mounted on our H-base. To the rods 
 of this upright are attached the clamps for holding the required accessories. Thus the resonant 
 tube is supported at the left by Nos. 5-887 and 6-089 Clamps, and the reservoir at the right by 
 No. 6-885 Clamp, the fork at the top by one each of our Nos. 6-450 and 6-891 Clamps. The 
 apparatus is designed to support a tube of sufficient dimensions so that with a C 1 = 256 VPS. 
 
 Fork a resonating column of of a wave length is possible. 
 
 Apparatus neatly finished throughout, complete as illustrated but without fork. $8.60 
 
 TUNING FORK, C 1 = 256 VPS. 1.20 
 
 FIVE-FOOT METAL RESONANCE TUBE WITH WATER LEVEL INDICATOR, for determin¬ 
 ing the Velocity of Sound in Air; also for determining the Wave Length of a Tuning Fork. 
 
 This is a metal tube, five feet in height, mounted on our H-base. At the lower end of this tube is 
 a lateral tube with stop-cock, which can serve either as an inlet or as an outlet tube as may be 
 desired. A glass tube of the same length as the metal tube connected to this lateral tube serves 
 as an indicator for registering the length of the resonating air column. 
 
 This design combines advantages of other types, and has the further feature of facility of measure¬ 
 ments of air columns, ease in varying height of water level, and extreme durability. 6.25 
 
 ONE HUNDRED AND FIFTY CENTIMETER RESONANCE APPARATUS, after Ames & Bliss’ 
 “Manual of Experiments in Physics,” Experiment 40. 
 
 This apparatus consists of a long glass tube with a small side tube attached near the open end, 
 the bottom of which is tapered so as to join with a length of rubber tubing connected either with 
 the water tap or as illustrated with a reservoir for water. 
 
 This apparatus is mounted as illustrated on a supporting stand, as described above. 
 
 Complete as illustrated, but without tuning fork. 9.26 
 
 CULLER’S RESONANCE APPARATUS, without support.81 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 191 
 
 53-230 
 
 63-235 
 
 31-250 
 
 No. 63-230 
 
 HORIZONTAL RESONANCE TUBE, for measuring the velocity of sound in air. 
 
 This is a glass tube mounted horizontally on a convenient wooden support. It is provided with a 
 sliding piston for regulating the length of the active air column. This will be found a convenient 
 
 students’ apparatus. 
 
 GLASS RESONANCE TUBES, with smooth ends, for use in resonance experiments. 
 
 a 
 
 Length, centimeters.- 55 
 
 Diameter, centimeters .... 3.5 
 
 Each.$0.85 
 
 b c 
 
 110 110 
 
 3.5 4 
 
 1.20 1.90 
 
 RESONANCE GLASS JARS, for use in resonance experiments. These jars are of clear white glass, 
 with foot and rim. 
 
 a b c d e 
 
 Size, inches . : . 12 X \]/ 2 12X2 15X2 15X3 18X3 
 
 Each. $0.50 .65 .80 1.00 1.35 
 
 $2.25 
 
 STUDY OF SOUND VIBRATIONS 
 
 RECORDING APPARATUS -LISSAJOUS’ CURVES—CHLADNI’S PLATES 
 MANOMETRIC FLAME APPARATUS—SONOGRAPH 
 
 GRAPHIC REPRESENTATION OF SOUND 
 
 64-16 KNOTT’S UNIVERSALLY ADJUSTABLE VTBROGRAPH, for determining the vibration frequency 
 of a tuning fork. 
 
 The results of experience have demonstrated that a Vibrograph built of wood has many objection¬ 
 able features. We have, therefore, discarded wood altogether in this, our new design. Two 
 nickel-plated rods held firmly in end supports form the track along which the carriage bearing the 
 smoked-glass plate moves freely. An upright fastened to one track bears the rod to which is 
 fastened the clamp supporting the pendulum. The tuning fork, to one prong of which must be 
 fastened a bristle, is clamped as pictured at left of illustration in a frame which is adjusted by means 
 of a thumb nut and which in turn adjusts the plane of the fork. 
 
 In addition to the substantiality of this design, our claims for accuracy with a minimum of trouble 
 are fully warranted. The handsome appearance of the instrument will enhance its value as an ac¬ 
 quisition in any well-equipped laboratory. 
 
 Complete as illustrated, but without fork „.. $4.00 
 
 64-16a COATED PAPER. A special coated paper has been provided for use on above Vibrograph. This 
 paper has the property of turning dark whenever rubbed by brase, aluminum or similar metals. 
 
 It will be found valuable in making permanent records.Per Package of 25 Sheets .16 
 
 64-16 VIBROGRAPH TUNING FORK with stylus, low pitch, large amplitude. 1.35 
 
 54-17 EXTRA GLASS PLATES, for use with above VIBROGRAPH.Each .06 
 
 64-26 BRISTLE STYLUS AND FIXATIVE, for use on a Tuning Fork when it is desired to record the 
 
 vibrations on a smoked or coated plate or drum. .25 
 
192 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 VARIABLE SPEED AND MULTIPLE RECORDING KYMOGRAPHS AND 
 
 RECORDING DRUMS 
 
 With Invisible Non-Projecting Thread Feed 
 
 Nos. 64-30, 64-36 and 61-76 
 
 Patent Pending 
 
 No. 54-40 
 
 It has been our purpose in this design to produce an instrument capable of a great variety of uses and of the 
 very highest grade. It may be obtained, operated either by clock movement or arranged for both hand and belt 
 drive. 
 
 The cylinder is 12 yi centimeters in diameter by 16>£ centimeters long, and has a lateral movement of 16 centi¬ 
 meters on a screw with thread so cut and mounted that the. shaft does not extend beyond the bearings more than is 
 shown in the illustration. 
 
 Ample room is provided for the simultaneous use of four tuning forks or six recording pens. One may, there¬ 
 fore, make records of six different operations, no matter where located. 
 
 Features, — 
 
 1. Frictionless rollers on which the shaft is rotated. 
 
 2. The cylinder is mounted so that it may be given a revolving and horizontal movement along 
 
 the shaft without the shaft extending beyond the bearings more than is shown in the 
 
 illustration. 
 
 3. The upright supports are adjustable forward and backward on a lathe rest support. 
 
 4. Vertical adjustment is simplified by means of a clamp and a series of notches in the uprights 
 
 giving a rigidity and range not found in any other instrument of this class. 
 
 5. Screws of different pitches may be obtained for the purpose of adapting the forward movement 
 
 to the nature of the record desired. 
 
 64-30 VARIABLE SPEED KYMOGRAPH with Clock Drive and Invisible Feed. With this clock drive 
 
 two speeds are possible, the change secured by meshing gears in or out, — one revolution in 
 
 , twenty-four hours or one in twelve hours. Clock movement is a standard high grade eight-day 
 
 movement especially adapted to this kymograph. Without tuning fork and marker.$47.50 
 
 54-32 VARIABLE SPEED KYMOGRAPH for both Hand and Belt Drive. Speed may be regulated within 
 
 the limit of the motor or of the relative sizes of the pulleys. Without tuning fork and marker . . 35.00 
 
 64-35 KYMOGRAPH TIME MARKER. This marker is much the same as ordinarily supplied for Kymo¬ 
 graph work and is modified to the extent, only, of securing a better continuous record. 6.50 
 
 54-37 KYMOGRAPH RECORD SHEETS for use with Nos. 64-30 and 64-32 Kymographs. Divisions 
 
 represent ten or five-minute intervals.Per Fifty 2.35 
 
 TUNING FORKS, — any form under ten inches long. See Section 51. • 
 
 54-40 CLOCK RECORDING KYMOGRAPH. This instrument was designed, at the request of Dr. Bovie 
 of Harvard University, to provide a simple easily manipulated, effective device for recording the 
 curve of plant growth in conjunction with the Bovie Auxanometer. 
 
 The recording mechanism, whether it be a pencil or electrical pen, is readily clamped to the sup¬ 
 porting upright as indicated in the illustration. The clock mechanism mounted in the base is a 
 standard twenty-four hour clock movement of heavy construction. 
 
 The cylinder is raised to the upper position by simply releasing the compression clamp and lifting the 
 cylinder bodily. The range of movement and the length of the cylinder is such as to permit three 
 or four records being made at one time. This is made possible because of the position in which 
 the cylinder is mounted, the weight of the cylinder assisting rather than retarding the clock move¬ 
 ment. 
 
 Complete with twenty-four-hour movement.22.25 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 193 
 
 LISSAJOUS’ CURVES APPARATUS 
 
 # 
 
 No. 54-50 
 
 64-60 LISSAJOUS’ CURVES APPA¬ 
 RATUS, IMPROVED MODEL, 
 
 for demonstrations of parallelly 
 and vertically combined vibra¬ 
 tions. 
 
 Mounted on a heavy metal base are 
 the supports for the fork hold¬ 
 ers,— one to support the fork in 
 a horizontal position and the 
 other two in a vertical position, 
 one of the latter capable of being 
 turned backward and forward 
 by means of a small crank. 
 
 The forks supplied with the appa¬ 
 ratus are 250 millimeters in 
 length and have a vibration fre¬ 
 quency of 128 V.P.S. They are 
 substantial in structure and 
 especially designed to give a con¬ 
 tinuous vibration of large am¬ 
 plitude. Each fork is kept in vi¬ 
 bration-fey electro-magnets with 
 which each carrier is supplied. 
 By means of two riders which 
 are furnished with the appara¬ 
 tus the pitch of a fork can be 
 slightly changed for causing 
 beats. 
 
 With addition of a Projection Lan¬ 
 tern and a Lens, the curves can 
 be projected very beautifully on 
 a screen. 
 
 Apparatus complete with two 
 forks.Duty Free 
 
 54^65 LISSAJOUS’ CURVES APPARATUS, same as above, but without the movable upright and crank 
 adjustment. Complete with two forks.Duty Free 
 
 Luminous images on the screen when the Tuning Forks are in unison. 
 
 0 H X Vs ' V Vs X Vs 1 
 
 Luminous images when the difference between the Tuning Forks is an octave. 
 
194 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 Y PENDULUM (SAND PENDULUM). This pendulum 
 consists of a heavy bob suspended by two cords, slid¬ 
 ing along which is a small brass ring the office of which 
 is to vary the length of the stem of the Y, thus modify¬ 
 ing the conditions upon which the relative phases 
 and amplitudes depend. As this bob vibrates, fine 
 sand contained in the funnel-shaped reservoir is al¬ 
 lowed to trickle forth, thus tracing the path of the vi¬ 
 brating pendulum. 
 
 If the bob vibrates in the plane of the paper, the effec¬ 
 tive length is from the adjustable brass ring to the 
 bob; if it vibrates at right angles to this plane, it is the 
 distance from the support rod to the bob. The periods, 
 therefore, will be different and independent. By ad¬ 
 justing the two lengths by means of the ring, the bob 
 may be made to describe various Lissajous’ Figures. 
 
 Y Pendulum only without support of any kind .... 
 
 FIGURES APPARATUS 
 
 Nos. 54-126 to 54-134 
 
 Nos. 5-1000 and 5-1085 
 
 No. 54-142 
 
 $0.90 . 
 
 Vibrating Plates contain nodal lines which vary in number and position according to the form and size of the 
 plate and the point at which they are set in vibration. We list below two forms of plates, each form in two sizes. 
 We also list three different types of clamps, either of which will be found well adapted for use with any of the plates. 
 For those teachers who are provided with T-Beam Basic Clamp No. 5-1000, Interlocking Clamp Attachment No. 
 
 6-1085 will be found the best. 
 
 54-126 ROUND CHLADNI’S PLATE, 6 inches diameter.$1.30 
 
 54-128 -, 10 inches diameter. 1-66 
 
 54-133 SQUARE CHLADNI’S PLATE, 6 inches square. 1.30 
 
 54-134 --, 10 inches square. 1.66 
 
 5-1085 CHLADNI’S PLATE INTERLOCKING CLAMP ATTACHMENT for use on our No. 5-1000 T- 
 
 Bearn Basic Clamp “A”. .60 
 
 5-1000 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “A”.94 
 
 54-141 CHLADNI’S PLATE CLAMP, common type.76 
 
 54-142 -, large size for plates up to 10 inches. 1.95 
 
 54-145 LYCOPODIUM POWDER for use in Kundt’s Tubes and on Chladni’s Plates. Before using this 
 
 powder, we recommend that it be thoroughly dried for best results. Per four-ounce carton . . .45 
 
 54-147 SAND for use on Chladni’s Plate. This is the best quality fine-grained sand carefully sifted. Per 
 
 eight-ounce carton. .22 
 
 57-20 DOUBLE-BASS BOW, recommended for exciting Chladni’s Plates. 1.36 
 
 f 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 195 
 
 MANOMETRIC FLAME APPARATUS 
 
 No. 21-290 _JNo. 21-296 
 
 64-166 MANOMETRIC FLAME APPARATUS for analysis of sound. Composed of No. 21-296 Konig’s 
 Manometric Flame Capsule and No. 21-299 Cubical Mirror. The latter, in use, must be at¬ 
 tached to the socket of a rotator. The Manometric Capsule is constructed of a two-part casting 
 assembled with the sensitive diaphragm between. To one casting is attached the tube and mouth¬ 
 piece, to the other the jet and gas tube, the latter attached to a base forming the support. The 
 cubical mirror consists of a metal box to the sides of which are fastened mirror plates. To the 
 
 lower side of this box is attached a spindle to fit the socket of the rotator. 
 
 Apparatus complete, as illustrated, but without Rotator.$5.90 
 
 21-290 CUBICAL MIRROR, as used in No. 64-166 . 3.16 
 
 21-296 KONIG’S MANOMETRIC FLAME CAPSULE complete, as illustrated above. 2.76 
 
 For ROTATORS, see Section 21. 
 
 64-180 MANOMETRIC FLAME APPARATUS for analysis of sound. 
 
 This apparatus is similar to No. 64-166, but of simpler construction. The revolving mirrors are 
 set in brass frame fitted with spindle for revolving by hand. A simply constructed Manometric 
 Flame Capsule is supplied with rubber tube and mouth-piece. 
 
 Manometric Flame Capsule, complete with Mirror. 4.40 
 
 21-300 REVOLVING MIRROR WITH POSITIVE SPEED GOVERNOR. To meet the repeated demands 
 
 for a mirror which may be revolved at varying 
 speed and of a size sufficiently large for ordinary 
 laboratory work we have, after considerable experi¬ 
 mentation, perfected the design illustrated. 
 
 This mirror is self-contained in that the rotating 
 power is contained in the base in the form of a 
 small motor, with “start” and “stop” key. We 
 secure a positive speed, governed by means of a 
 simple, effectively operating device noted above 
 the mirror shaft and a centrifugal governor 
 mounted within the mirror case. We are able to 
 secure with this structure speeds varying from a 
 few revolutions per minute up to 2,000,—-the 
 maximum speed of the motor. This variation in 
 speed may be made during the revolution of the 
 mirror simply by a movement of the screw over 
 the axle. 
 
 As may be noted, this design consists of a metal 
 housing which serves also as a substantial base. 
 
 Cast to this housing is an upright with project¬ 
 ing arm. The mirror is mounted in metal cast¬ 
 ings carefully centered. The metal housing is 
 provided with binding posts for connections to 
 the motor and also with “start” and “stop” 
 
 No. 21-300 key. The whole is finished in nickel and black No. 21-300 (Sectional View) 
 
 oxidized, presenting a handsome appearance. It 
 
 will be found efficient for all general work for which a rotating mirror is used.$9.76 
 
ig6 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 GRAPHIC ANALYSIS OF SOUND WAVES 
 
 No. 54-200 
 
 “SONOGRAPH” 
 
 No. 54-200 
 
 No. 21-300 
 
 54-200 “SONOGRAPH.” The instrument above illustrated will show in a superior manner all that the 
 manometric flames will show and, in addition, many other interesting experiments. Results are easily obtained, 
 and both simple and complex tones are readily analyzed into their various wave forms, a pure tone depicting in a 
 striking manner the fundamental sine wave. 
 
 The operation of the “sonograph” depends on the compression and rarefactions set up in the air by sound — 
 a spoken word, a note from an organ pipe, a tuning fork, etc., etc. These compressions and rarefactions are com¬ 
 municated to a diaphragm which is set in vibration, the vibrations being greatly magnified by a small mirror, the 
 
 amount of movement being indicated by the tracings of a spot of light on the screen. These tracings will take the 
 
 form of waves if the spot of light be first directed on a rotating mirror. This rotating mirror should be placed between 
 a lens and the screen. Our No. 21-300, illustrated above, described in Section 21, has been especially designed for 
 
 this work. The speed is ingeniously governed for either very high pitch or very low pitch without stopping the 
 
 motor which rotates the mirror. 
 
 To secure the most satisfactory results a strong source of light will be necessary. Sunlight is, of course, the 
 best and when used, a “pencil” of light secured through a small aperture will be found most effective. When a pro¬ 
 jection lantern or any strong artificial source is used, a system of lenses should be provided to render the rays paral¬ 
 lel. With a good arc light or light from the sun, the waves may be easily shown to five hundred students. 
 
 The waves illustrated below are photographic reproductions taken on a revolving film. 
 
 a e i o u 
 
 Wave Forms of Vowels. 
 
 Wave Form of Vowel e. 
 
 “SONOGRAPH” only, without lens, mirror, etc.$26.00 
 
 21-300 ELECTRICALLY OPERATED ROTATING MIRROR, designed especially for use with “Sono¬ 
 graph.” For description see Section 21. 
 
 975 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 197 
 
 
 RESONATORS 
 
 
 65-10 BELL and ADJUSTABLE RESONATOR. 
 
 The apparatus consists of a Bell 15 centimeters in diameter 
 which may be mounted on a stand.—The Resonator consists 
 of a brass tube with close-fitting sliding piston. This tube 
 is of sufficient length to respond to all notes above 256 
 V. P. S. 
 
 Complete as illustrated, with Bell, Resonator, and Stand, but 
 
 without plate.$3.16 
 
 No. 65-32 
 
 No. 65-10 
 
 BRASS HELMHOLTZ RESONATORS. These Resonators are thin brass globes, with wide orifices at one 
 side to receive the exciting waves and narrow orifices to conduct the vibrations to the ear. They are accurately 
 made, neatly polished and lacquered. Fundamental tone, low C = 64 V. P. S. 
 
 55- 30 HELMHOLTZ RESONATORS, set of eleven.Duty Free . . . 
 
 66-32 - —, set of eighteen.Duty Free . . . 
 
 56- 34 - —, set of twenty-five.Duty Free . . . 
 
 No. 55-45 
 
 65- 46 GLASS HELMHOLTZ RESONATORS for the analysis of sound, consisting of a set of four glass 
 
 globes each with a wide orifice at one side to receive the exciting waves and a narrow orifice at the 
 other side to conduct the vibrations to the ear. Will respond to the notes Cs, E4, C4, and Gs . . . $11.50 
 
 66- 60 ACOUSTIC REACTION WHEEL for illustrating Acoustic Repulsion. 
 
 The apparatus consists of four glass resonators fixed upon arms and centered to pivot on a stand. 
 
 In use, the repulsion is so strong as to produce uniform rotation. 
 
 Complete as illustrated 
 
 9.76 
 
198 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 65-70 VIBRATION APPARATUS for showing that sound propagates rarefactions and condensations in the 
 surrounding media. 
 
 This apparatus consists, as illustrated, of two circular discs over one face of Which is attached a plate. 
 Suspended so as to rest against the plate of one is a small ball which is used as an indicator of the 
 sound wave. If now the plate of the second is struck a sharp blow by means of the small hammer, 
 vibrations set up will be communicated in waves to the first, causing the small ball to dance. 
 
 This is a very striking experiment and can be used to advantage in wave study. 
 
 
 $8.25 
 
 66-76 VIBRATION OF ROD APPARATUS for illustrating the vibration of a sounding rod. 
 
 The apparatus consists of a centrally clamped brass rod, one end of which is stroked by resinous cloth 
 or set in vibration by other means. Suspended to an upright frame in bi-filar suspension is a light 
 sphere which is adjusted so as to rest against one of the free ends of the rod. Any vibration, there¬ 
 fore, set up in the rod is communicated to the ball, causing it to rebound from the end of the rod. 
 
 Apparatus complete as illustrated, without Basic Clamp. 2.20 
 
 65-80 TREVELYAN’S ROCKER for illustrating that musical vibrations are maintained by communication 
 of heat. 
 
 The apparatus consists of a brass rod with a V-groove milled lengthwise. To this rod is fastened a 
 metal handle with ball end. When this bar is heated at some point below the melting point of lead 
 and placed so that the edges of the V-groove rest on the lead casting as illustrated, the bar begins 
 to rock, emitting a harsh note. This note may be made to rise in pitch by slightly pressing on 
 the bar. 
 
 Trevelyan’s Rocker with Lead Rest. 2.00 
 
 65-115 TYNDALL’S TUBE for illustrating the transmission of sound in air by wave motion. 
 
 This apparatus consists of a thin metal tube built in sections to three meters in length, the end sec¬ 
 tion terminating cone-shaped. In use this tube is mounted on a simple wooden support. If a 
 lighted candle is placed in front of the conical orifice, and a sharp sound such as that emitted by 
 the clapping together of two sticks is made at the other orifice, the wave motion set up by the 
 sound will be transmitted throughout the whole length of the tube, causing such a disturbance at 
 the conical orifice as to put out the candle flame. 2.96 
 
 21-280 CROVA’S DISC AND SHIELD for illustrating the compressions and rarefactions caused among air 
 
 particles by a sound wave. See Section 21. 2.46 
 
 WAVE MOTION APPARATUS. SECTION 26. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 199 
 
 VELOCITY OF SOUND 
 
 KUNDT’S APPARATUS 
 
 
 inri'T. 
 
 prrrmTrrnTnWnT 
 
 
 
 
 TWTTTTT' 
 
 
 —x 
 
 
 
 
 
 
 .W.uuti.UULLuUUUli.1. 
 
 uUUUWj.UI.iL 
 
 l.i.l.i.UW.i.l.iXifl.iil*iiltiil,ul*iil,i<LhW.,.U 
 
 
 No. 66-20 
 
 No. 66-30 
 
 66-20 KUNDT’S APPARATUS for demonstrating vibrations in a tube closed at both ends; also for measur¬ 
 ing the velocity of sound in air. 
 
 The apparatus consists of a resonance tube, 110 centimeters in length, closed at one end by a tight 
 piston and near the other by a loose-fitting piston at the end of a brass rod. This brass rod, in use, 
 is firmly clamped in a vise. The tight-fitting piston is adjustable within the tube by means of a 
 rod. The whole is compactly mounted on a neat support. 
 
 Complete as illustrated. 
 
 66-30 KUNDT’S APPARATUS, with fittings for the introduction of various gases for the measurement of 
 the velocity of sound in different gases. 
 
 MISCELLANEOUS SUPPLIES 
 
 No. 67-20 
 
 67-10 PIANO WIRE, best quality imported, wound in coils, each weighing approximately \i pound. 
 
 abed 
 Diameter, inch . . .028 .022 .0178 .014 
 
 Per Coil .... $0.40 .46 .46 .66 
 
 67-20 DOUBLE-BASS BOW for setting sounding bodies in vibration. 
 
 This Bow is substantially constructed with a heavy wooden frame. Length 27 inches . . . 
 
 $3.65 
 
 8.60 
 
 $1.36 
 
 57-25 RESIN for use on bows and rods. Best quality French resin. Per cake, in cardboard box ... . 
 
 .06 
 

 200 L. E. KNOTT APPARATUS CO., BOSTON 
 
 HEAT 
 
 GENERAL APPLIANCES FOR HEAT EXPERIMENTS 
 
 BUNSEN BURNERS 
 
 Our selection of BUNSEN BURNERS from the many designs on the market, has been based 
 upon greatest laboratory utility. Thus, there will be found in this list only burners which have 
 given entire satisfaction and which have shown, from experience, that they are well worthy a place 
 in this edition of our catalogue. Each burner is carefully constructed and rigidly tested. The fin¬ 
 ish is durable, and designed to withstand rough usage and the corrosive action of chemicals in the 
 chemical laboratories. We have given a considerable latitude for choice, and there will be found 
 in this list burners to meet every need. 
 
 No. 60-10 
 
 No. 60-12 
 
 No. 60-17 
 
 No. 60-20 
 
 60-10 
 
 60-12 
 
 60-17 
 
 60-20 
 
 60-23 
 
 60-25 
 
 60-27 
 
 60-30 
 
 60-35 
 
 60-38 
 
 NORMAL BUNSEN BURNER for gasoline or illuminating gas, with both gas and air regulation . . 
 
 HARVARD BUNSEN BURNER, with regulation for both gas and air; tube with threaded top for 
 screwing on of star for holding a chimney, a fine adjustment support. 
 
 PILOT LIGHT BUNSEN BURNER for gas. Screw regulation for pilot, stop-cock for shut-off, air 
 regulator. Excellent where intermittent flame is required. Tube 34 inch in diameter. 
 
 SCHOOL BUNSEN BURNER, a serviceable gas burner with air 
 
 regulation; diameter of tube Y inch.$0.25 
 
 CENTRAL DRAFT BURNER with air regulation . .20 
 
 BURNER WING TOP for producing a hot, smoky, wide flame, 
 
 advisable in bending glass tubing . .16 
 
 No. 60-27 
 
 No. 60-30 
 
 No. 60-36 
 
 $ 1.00 
 
 .76 
 
 2.25 
 
 LOW FORM BUNSEN BURNER, upward curved tube, air regulation, height 3 inches, diameter 
 
 of tube A inch.$0.60 
 
 GILLEY LOW FORM BUNSEN BURNER, as regularly used with our Standard Hypsometer No. 
 
 60-360 . 40 
 
 ACETYLENE GAS BUNSEN BURNER, operating efficiently, giving an intense flame. Diameter of 
 
 tube & inch. 1.26 
 
 ANTIMONY RUBBER TUBING for burner connections. This is the best quality antimony tubing, 
 made for the past seventeen years from our own formula. 
 
 a b c : 
 
 Inside diameter, inch . . A A % 
 
 Per Foot .$0.08 .12 .17 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 201 
 
 MISCELLANEOUS BURNERS 
 BLAST LAMPS 
 
 No. 60-40 No. 60-46 
 
 60-40 SEMI-BLAST WYNNE BURNER, supplying either a very hot Bunsen flame or a semi-blast, — in 
 some respects preferable to the ordinary blast flame. 
 
 This burner, substantially constructed of brass and iron, has regulations for both gas and air. Perfect 
 combustion is insured. Air adjustment is secured by regulation of height of tube, gas adjustment 
 by a screw. Possibility of adjustment of flame to any position is also a highly appreciated feature 
 
 of this burner..$1.60 
 
 60-46 ——, similar to above, but adjustment for flame direction is limited .. .90 
 
 Note. — The general form of this burner has been copied by other houses, who are making it of 
 much lighter material, the adjustments of cheaper construction and with no apparent attempt to 
 reproduce the form of the inner gas chamber which has made this burner so efficient. 
 
 No. 60-76 
 
 No. 60-100 
 
 No. 60-110 
 
 60-76 SOLID BUNSEN FLAME STOVE. The advantage of this 
 burner is a broad flame of uniform temperature. It is 
 especially desirable for heating water in quantities; also for 
 
 rapid heating of No. 60-366 Hypsometer. 
 
 60-80 INSTANTANEOUS HOT WATER HEATER. This ap¬ 
 paratus consists of a coiled copper tube enclosed in a 
 Russia iron case. Cold water enters at one end of tube; 
 hot water is delivered at the other end, — instantaneous in 
 action. Illustration pictures apparatus complete with 
 No. 60-80 above stove. 
 
 Complete with Burner. 
 
 60-81 INSTANTANEOUS HOT WATER HEATER without Burner. 
 
 60-100 POLISHED COPPER ALCOHOL BURNER, capacity two ounces. 
 
 This is a small, highly appreciated burner giving a very hot flame. 
 
 With ground-on cap, wick, and wick-holder. 
 
 60-110 ALCOHOL BURNER, glass, capacity 8 ounces. 
 
 Complete with ground-on cap, wick, and wick-holder. 
 
 $2.90 
 
 9.60 
 
 6.60 
 
 .76 
 
 .38 
 
202 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 No. 60-160 No. 60-276 No. 60-300 
 
 60-120 
 
 60-121 
 
 60-136 
 
 60-160 
 
 60-160 
 
 60-276 
 
 60-300 
 
 HOT-BLAST ALCOHOL STOVE. This is a compact stove weighing only 5 ounces. Its efficiency 
 is remarkable. In actual tests water has been heated to boiling point from 0 degree Centigrade 
 in \2 l /v minutes. 
 
 We have no hesitancy in recommending this stove for general use in laboratories not connected with 
 
 gas. 
 
 Complete as illustrated, with tripod support.$ 0.26 
 
 -, same as above, without tripod support. -18 
 
 GASOLENE BURNER. This burner meets all the uses of a Bunsen burner. It is practically 
 automatic in its action, generating its own gas. Air pressure is obtained by small force-pump 
 contained in the handle. Flame is adjustable from very small height to 5 or 6 inches, and will 
 burn for IY hours at full blast from one filling of the reservoir, which holds about Yi pint of gaso¬ 
 
 lene and with one pumping of air pressure. 3.66 
 
 BUNSEN BLAST LAMP, stable and durable in construction, capable of the most exacting service. 
 
 Will produce the maximum intensity of heat with the minimum consumption of gas. Both air 
 and gas pipes supplied with stop-cock. 3.60 
 
 DOUBLE CONCENTRIC BUNSEN BLAST LAMP for illuminating gas only. 
 
 This type of lamp has an inner air jet and an inner tube which may be used either for air or gas, and 
 an external gas tube. The gas and air are changed automatically from the larger to the smaller 
 tube by a slight movement of the lever at the back, the same movement also adjusting both gas 
 and air to each other for each tube. This combination of practically two blowpipes gives a great 
 range of power from a small-pointed jet to a brisk flame, using approximately 35 feet of gas per 
 
 hour .10.00 
 
 FOOT BLOWER for Blast Lamp, Blowpipe, and similar work. 
 
 This is a substantially constructed blower of the latest pattern, with iron legs, producing a steady, 
 powerful blast. Diameter of air reservoir, 9 inches; blast pressure per inch, \Yi pounds; cubic 
 
 feet of air per hour, 330 . 8.76 
 
 HAND BELLOWS. This is a simple inexpensive blower, width 7 inches, capable of efficient ser¬ 
 vice where a not too powerful blast is required. 1.00 
 
 
 
 * 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 203 
 
 HYPSOMETERS 
 
 No. 60-350 No. 60-365 
 
 60-350 
 
 60-30 
 
 60-100 
 
 60-366 
 
 60-390 
 
 GILLEY STEAM BOILER or HYPSOMETER for general use in heat, in generation of steam, in 
 determining the boiling point of a thermometer, or for use where steam is required for the proper 
 conduct of an experiment. 
 
 The apparatus proper consists of a carefully constructed copper boiler mounted on three legs. This 
 boiler is constructed of best quality of material, all joints being sealed in a manner to obviate the 
 danger of destruction due to careless overheating. Entering the sides of this boiler are three 
 tubes, two of which are connected by rubber and glass tubing for showing the water level, the 
 third for attachment of the pressure gauge. The top of this boiler is provided with a screw to 
 which may be attached the screw cap when it is desired to use the boiler merely as a steam generator. 
 This screw must be replaced, however, by a thermometer tube in using the apparatus in determining 
 or in testing the boiling point of a thermometer. In specific heat experiments, this tube is replaced 
 by the dipper in which the solid is heated. 
 
 The apparatus is furnished complete as illustrated without Pressure Gauge or Burner, but including 
 the Steam Boiler, Screw Cap, Thermometer Tube, Dipper, and Water Gauge. 
 
 This form of Hypsometer is recommended for its compactness, stability, and rapidity of heating 
 and ease with which thermometer readings may be made. 
 
 The tall form of apparatus brings the reading portion of the thermometer scale so high that many 
 students are not able to make accurate readings without the use of a stool or some other means of 
 bringing the eye to the right position. The errors of parallax, almost unavoidable in the use of the 
 
 tall form, are a serious drawback to its use.$2.75 
 
 GILLEY LOW FORM BUNSEN BURNER, as illustrated in No. 60-360 above.40 
 
 POLISHED COPPER ALCOHOL BURNER, capacity 2 ounces, giving a very hot flame. Advised 
 
 for use with No. 60-360 when laboratory is not equipped with gas. .76 
 
 STEAM BOILER or HYPSOMETER, as designed by G. M. Turner. 
 
 This form of Hypsometer has received the same careful attention in design and details of structure 
 as our No. 60-350. Its design was first suggested to fill the demand for a hypsometer the steam 
 boiler of which could be detached from the tripod support and which could make use of the ordi¬ 
 nary type of Bunsen burner. As may be noted from the illustration, our design fulfils these re¬ 
 quirements. This form has the further advantage over our No. 60-360 in that it may be used 
 on a stove similar to our Nos. 60-76 and 60-120, the stoves in these cases answering the purpose 
 
 of the tripod support. 
 
 Complete as illustrated, with tripod support, steam boiler, screw cap, dipper and thermometer tube 2.95 
 IMPROVED FORM PRESSURE GAUGE, especially adapted for use with Hypsometer No. 60-360, 
 
 on which instrument it will be found illustrated. .11 
 
204 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 60—430 
 
 No. 61-10 
 
 No. 61-11 
 
 60-326 POLISHED COPPER BEAKER, of heavy polished copper, of extreme utility in a great number of 
 experiments requiring the use of an indestructible utensil for boiler, etc. Capacity 500 cubic 
 
 centimeters ..$0.90 
 
 60-330 POLISHED ALUMINUM BEAKER, similar to above, 500 cubic centimeters capacity. 1.00 
 
 60-400 WATER TRAP, IMPROVED DESIGN, essential in determining the latent heat of steam by pre¬ 
 venting any condensed steam passing into the calorimeter. 
 
 Our design has been improved by the short curved end which entirely obviates any danger of con¬ 
 densed steam passing through into the calorimeter. .36 
 
 60—406 H-K STEAM TRAP, consisting of bottle with glass tubes and stopper arranged to catch any con¬ 
 densed steam as it passes through the bottle. .46 
 
 60-430 GALVANIZED IRON ICE TRAY, designed especially for cooling dry air enclosed in Charles Law 
 
 Tube. With tubulature as illustrated. .76 
 
 60-435 CANVAS ICE BAG for crushing ice into small fragments for calorimetric determinations. .17 
 
 60-440 ICE SHREDDER and SHAVE, coarse or fine shavings. 1.26 
 
 RADIATION, REFLECTION, CONDUCTION 
 
 CONVECTION 
 
 61-10 CROOKE’S RADIOMETER, illustrating attraction and repulsion arising from radiation. 
 
 This instrument consists of a very light vane constructed of thin mica discs fastened at the ends of 
 four arms of aluminum wire, the whole arranged to turn very freely about a vertical axis and en¬ 
 closed in a glass vessel which is highly exhausted. Each of these mica discs is blackened on one 
 side. On exposing the Radiometer to any source of radiant heat the vane revolves in such a direc¬ 
 tion that the blackened faces are always receding. 
 
 Mounted on glass foot.$1.66 
 
 61-11 CROOKE’S DOUBLE RADIOMETER, similar to above, but with two bulbs, in each of which is 
 mounted a vane pivoted independently with its blackened faces opposite to each other. 
 
 Mounted on glass foot ... 
 
 4.00 
 
No. 62-10 
 
 62-10 THIRTEEN-INCH UNIVERSALLY ADJUSTABLE TRUE PARABOLIC REFLECTORS, for dem¬ 
 onstrating Reflection of Sound, Heat and Light Waves. 
 
 
 
 In offering for sale our Improved Reflectors we desire to emphasize the TRUE PARABOLIC SUR¬ 
 FACES. The curves of these surfaces have been accurately calculated and then by painstaking 
 processes a chuck has been turned to the true parabolic curve. Our Reflectors are all spun from 
 this chuck. The reflecting surface is then highly polished and heavily nickel-plated, presenting an 
 excellent surface without waves. 
 
 The Reflectors are mounted in a two-part circular casting in such a manner as to entirely obviate 
 any danger of distorting the surfaces. This two-part casting is brought together at the bottom, 
 where it makes a swivel junction with a rod which telescopes into the supporting base. 
 
 The Holders and Attachments are all of special design which allows of both coarse and fine adjust¬ 
 ments. We, therefore, secure a tilting movement for the Reflectors, an adjustment for proper 
 height, and universal movements for each attachment. 
 
 In demonstrating reflection of heat waves either a candle or a heated metal ball may be used in one 
 of the Carriers at the focus of one reflector; if now a piece of phosphorus be placed at the focus of 
 the other reflector in its Carrier, the heat waves brought to a focus will cause the phosphorus to 
 burn. 
 
 The finish of this instrument is fully in keeping with the design. The outer surfaces of the reflectors 
 are dull oxidized, the H-Base japan, and all brass parts polished and nickel-plated. 
 
 Thirteen-inch Universally Adjustable True Parabolic Reflectors complete as illustrated with Attach¬ 
 ments .. .Per Pair $17.60 
 
 62-16 THIRTEEN-INCH UNIVERSALLY ADJUSTABLE TRUE PARABOLIC REFLECTORS, same as 
 
 above, mounted on stand but without Attachments or Carriers.Per Pair 13.60 
 
206 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • } 
 
 ABSORPTION —RADIATION SCREENS 
 
 No. 61-70 
 
 No. 61-76 
 
 
 No. 61-100 
 
 61-70 ABSORPTION SCREEN for the comparative illustration of the absorptive power of two different 
 substances. 
 
 This is a screen of polished metal with ring of black painted on face, and the back coated with red 
 mercuric oxide. 
 
 If a source of radiant energy is held in front of the face, a ring will be reproduced in yellow on a red 
 ground on the back of the screen. As the mercuric oxide turns yellow at 150 degrees Centigrade, 
 it may be concluded that a black surface has more absorptive power than a polished surface . . $2.86 
 
 61-75 RADIATION SCREENS for comparative illustration of the absorptive power of two different 
 substances. 
 
 This apparatus consists of a pair of screens, 10 inches square, one of polished metal, the other of metal 
 with the face blackened, each screen with small ledges at the back for pieces of phosphorus. 
 
 When placed facing source of radiant energy, it will be noted that the action upon the phosphorus is 
 immediate in the case of the blackened screen, whereas the energy is deflected on the polished 
 screen, demonstrating the absorptive power of a blackened surface and the reflecting power of the 
 polished surface.Per pair 4.26 
 
 61-100 LESLIE’S CUBE for the comparative illustration of the emissive powers of different substances. 
 
 This is a hollow metal cube, 2^ inches on an edge, one face polished, the other three coated with dif¬ 
 ferent substances which have different emissive powers. A tubulature is provided at top for intro¬ 
 duction of hot water and then, if desired, for a thermometer. 
 
 When these surfaces are allowed to radiate in succession against the face of a thermopile or other 
 delicate radiometer, it will be noted that the indications vary, showing the polished metal a very 
 poor radiator, the other substances varying in emissive powers. 
 
 Leslie’s Cube only, without Thermopile and without Stand, with three-sided protective case . . . 1.36 
 
 61-106 -, with four polished faces, each of different metals.$1.65 
 
 THERMOPILES. For illustration and description see Section 64. 
 
 64-15 DIFFERENTIAL THERMOMETER, frequently desired in con¬ 
 nection with Leslie’s Cube. For illustration and description see 
 Section 64 .7.50 
 
 01-135 COOLING CUP, after Turner and Hersey (Experiment No. H100), 
 for comparing the rate of cooling of different substances. 
 
 The apparatus consists of two cooling cups, one nickel-plated, the 
 other blackened, with two wooden covers each with hole for 
 thermometer. 
 
 In use, each is supported in the ring of a Ring Stand on Wooden 
 Support Ring. Hot water is poured into each and curve of rate of 
 cooling is determined by the reading of the thermometers. 
 
 Apparatus complete, with two Cups, one nickel-plated, the other 
 blackened, two Support Rings, and two Covers.1.65 
 
 No. 61-135 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 207 
 
 61-160 
 
 61-160 
 
 61-161 
 
 70-50b 
 
 61-163 
 
 61-176 
 
 61-178 
 
 61-180 
 
 61-183 
 
 61-186 
 
 No. 61-175 No. 61-185 
 
 CONVECTION OF HEAT 
 
 CONVECTIONAL CURRENT APPARATUS for illustrating Convectional Currents in Liquids. 
 
 When the tube is heated in the lower part, currents are set up. These currents will be readily noted 
 by introduction of a few grains of cork dust or addition of some aniline dye.$1.15 
 
 CONVECTIONAL CURRENT APPARATUS for illustrating Convectional Currents in Air. 
 
 By placing a burning candle in the box under one of the chimneys, convectional currents are set up, 
 as may be demonstrated by use of burning Touch Paper or other smoke producers, at the open 
 end of the other chimney. Without candle. 1.90 
 
 CHIMNEYS, straight form.Each .15 
 
 CANDLES, twelves (12 to the pound).Per dozen .20 
 
 TOUCH PAPER.Sheet .10 
 
 CONDUCTION OF HEAT 
 
 HARCOURT COMBINATION VERTICAL CONDUCTOMETER for illustrating relative con¬ 
 ductivities of different solids. 
 
 This apparatus consists of a cored casting into which steam may be led from some steam generator. 
 
 (See Hypsometers Nos. 60-360 and 60-366.) The top of this casting is provided with tubulatures 
 into which are placed the stoppers holding the different metal rods. Each rod is provided with 
 cavities in the upper end for phosphorus and in addition is coated with a heat indicating paint . $3.93 
 
 HEXAGONAL COMBINATION CONDUCTOMETER for illustrating the conductivity of dif¬ 
 ferent metals. 
 
 This conductometer consists of a hexagonal casting, into five faces of which are threaded five rods of 
 different material; into the sixth face is threaded a brass rod terminating in a handle. On each 
 rod at equal distances from the faces are cavities for phosphorus. Each rod in addition is coated 
 
 with a heat indicating paint. 1.60 
 
 PRIMARY CONDUCTOMETER for illustrating conductivity of metals. 
 
 Four rods of different metals fastened to a wooden backing. .35 
 
 CONDUCTIVITY RODS, set of three, 8 centimeters long. .30 
 
 COMPOUND ROD for comparative conductivity illustration. 
 
 This consists of a rod, 5 inches by x /i inch diameter, part of which is wood, part brass. When heated 
 
 at middle and held in hand, the relative conductivity may be readily noted. 35 
 
. 
 
 208 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 61-195 
 
 No. 61-200 
 
 No. 61-210 
 
 No. 61-205 
 
 61-195 CONDUCTIVITY OF WATER APPARATUS, after Millikan and Gale, Figure 198. Without stand 
 
 and dish.$ 0.65 
 
 61-200 DEWAR BULB, illustrating the practically non-conductivity of a vacuum, designed for transport¬ 
 ing liquid air. 
 
 This consists of a double-walled glass vessel, the chamber between walls being exhausted. Capacity 
 
 500 c.c. 3.90 
 
 61-205 UNEXHAUSTED DEWAR BEAKER for study of heat insulating qualities of a vacuum chamber. 
 
 This apparatus consists of a double-walled vessel with tube entering inner chamber for purpose of 
 
 exhausting same. 3.25 
 
 61-210 STEEL ENCASED SOLID ALUMINUM-LINED FIRELESS COOKER. In Manual Training 
 Schools, Vocational Schools, and schools giving courses for young women, the Fireless Cooker 
 has become a prominent and important feature. 
 
 It should be the design of every course in Physics to study the scientific aspects of the Fireless Cooker 
 in its relation to questions of conduction, convection, and temperatures, and time required to 
 produce the fundamental chemical changes occurring in the process of cooking. 
 
 This cooker is of the very best make, worked out upon a scientific basis. The radiator is of soap¬ 
 stone. The cooking compartments are of solid, seamless aluminum, provided with ample heat 
 insulation. The case is of planished steel, provided with legs and castors. Size 2034 inches high, 
 
 1634 inches wide and 1634 inches long. 
 
 Furnished complete with one 12-quart aluminum kettle, two heat radiators, radiator thermometer, 
 one radiator rack, one pair individual pastry and cake shelves, radiator hook and book of di¬ 
 rections .16.00 
 
 Note. — We are prepared to furnish larger sizes than listed above. Prices on application. 
 
 61-215 DAVY’S SAFETY LAMP, illustrating the high conductivity of metal gauze. Valuable in mines 
 against “fire damp,’’ in that although an explosive mixture may burn within the gauze, the flame 
 cannot pass through it to the gas outside.. 2.60 
 
 61-220 LIQUID CONDUCTION TUBE, illustrating the slight conduction qualities of water. W’ater may 
 
 be boiled in upper part while ice remains unmelted at lower end. .15 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 209 
 
 4 
 
 62-10 
 
 62-11 
 
 62-16 
 
 62-16 
 
 PAPIN DIGESTER, illustrating the rise in boiling point by increase 
 in pressure. 
 
 This is a strongly constructed brass boiler about 5 inches high by 
 inches average diameter. With gasket and heavy metal cap, 
 which may be rigidly clamped to boiler. This cap is provided 
 with a hole for thermometer and also with a safety valve. 
 
 Complete as illustrated with Safety Valve and Weight, Tripod Sup¬ 
 port, and Thermometer.$14.00 
 
 -, similar to above, but with addition of Pressure Gauge . . . 17.50 
 
 BOILING POINT OF ALCOHOL TUBE, after Millikan & Gale’s 
 “A Laboratory Course in Physics,” Exercise 23, for determining 
 the boiling point of alcohol by finding the point at which its 
 saturated vapor pressure is equal to the atmospheric pressure. 
 
 This is a simple form of U-Tube, closed at one end. In use it is par¬ 
 tially filled with mercury and alcohol carefully worked around 
 into the closed arm from which the air is altogether driven. The 
 alcohol is vaporized by immersion in a hot bath. When vapor 
 pressure equals atmospheric pressure, the mercury will be at 
 the same height in both arms. The temperature of the water 
 bath at this point will be the boiling point of alcohol. 
 
 Tube oWy, unfilled. 
 
 BEVELED GLASS TUBE, 20 cm., after Turner and 
 
 Hersey Exp. H012.$0.12 
 
 VAPOR PRESSURE TUBE, for determining vapor 
 pressure and boiling point of a liquid. 
 
 This apparatus consists of a U-Tube, one branch of 
 which is provided with stop-cock, an indispensable 
 feature for excluding the air in the closed arm and 
 for the introduction of the liquid; also for the 
 proper cleaning of the tube after use ... 1.45 
 
 .30 
 
 \J) 
 
 KNOTT BOSTON 
 
 No. 62-20 
 
 
 No. 62-62 
 
 of 
 
 VAPOR TENSION APPARATUS, for direct comparison and measurement 
 the vapor tensions of different liquids. 
 
 The apparatus consists of four heavy-walled glass tubes connected through a 
 stop-cock at the top to a small reservoir. These four tubes are held by a 
 special clamp to a metal upright supported on our H-Base. A second clamp 
 trough casting is provided for mercury into which the open ends of the tubes 
 dip. Each tube has an individual trough of its own, thus avoiding expense of 
 an unnecessary amount of mercury. 
 
 Complete as illustrated with four tubes. 
 
 $8.75 
 
 VAPOR TENSION TUBES, as used in above 
 
 Each 1.50 
 
 62-62 
 
 VAPOR TENSION APPARATUS, similar to above, but tubes not provided 
 .with stop-cocks. Each tube is heavy walled with closed end. Complete 
 with four tubes, supporting upright, clamp, and mercury reservoir .... 4.45 
 
 VAPOR TENSION TUBES, as used in above.Each .28 
 
 VAPOR TENSION TUBE with CAPILLARY OF KNOWN VOLUME. This 
 tube may be adjustably mounted in place of air thermometer bulbs as illustra¬ 
 ted under No. 64-55 (see Section 64). At the upper part of the tube there 
 are two stop cocks between which is a capillary of known volume. Most 
 accurate determinations of vapor tension are possible with this tube. Each 3.00 
 
210 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 VAPORIZATION, BOILING, DISTILLING, 
 
 FREEZING, STILLS 
 
 No. 62-70 
 
 62-70 STILL, for distillation of water or spirits. 
 
 This apparatus consists of a heavy tin-lined copper boiler with movable head, connected with the 
 pure block tin condensing worm enclosed in a zinc vessel, provided with proper inlets and outlets. 
 Complete as illustrated. 
 
 a b c d e 
 
 Capacity, gallons . . yi 1 2 3 5 
 
 Each.$10.60 12.40 14.60 19.75 26.60 
 
 No. 62-80 
 
 62-80 ACME WATER STILL. This still is a perfect apparatus for the production of pure water by distil¬ 
 lation. The distillate is cold, and aerated if desired. The apparatus is of first-class workmanship 
 throughout and is made of copper and brass, tin-lined and nickel-plated. The gas and water connec¬ 
 tions are extremely simple. The Acme Water Still runs automatically and there is nothing to get 
 out of order. It is started and stopped in a moment. The “Acme” is comparatively the fastest 
 and most economical Water Still, as it produces a gallon of distilled water in about hours, at 
 a cost of about cents per gallon. It is the most durable still, and will practically last a life¬ 
 time, as the mineral and other matter that remains in the retort is drained off through the flushing 
 outlet, this being done in a moment without any trouble and without displacing the still or taking 
 it to pieces. The combustion of gas with our special burner is perfect and all the heat is fully 
 utilized. Wall space required 4 X 12 inches, extreme width 8 inches, projection 14 inches. 
 
 Still as illustrated with burner for coal or water gas, natural gas, or acetylene. 
 
 $24.50 
 

 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 
 
 
 
 No. 62-120 
 
 No. 62-140 
 
 No. 62-160 
 
 62-90 WOODEN HEAT SHIELD, for use as insulator of heat when it is desired 
 to shield part of an experiment from heat rays emitted from another 
 part, especially when in calorimetry it is desired to use a steam boiler. 
 
 The shield consists of a board, mounted upright on a base. This board is 
 provided with hole for passage of delivery tube for the steam generated 
 in the boiler. 
 
 62-120 LIEBIG’S METAL CONDENSER, for the distillation of liquids. 
 
 This condenser is made of brass and highly polished. Length 30 inches; 
 diameter 1 7/8 inches. This form prevents breakage. 
 
 62-125 LIEBIG’S CONDENSER, entirely of glass, condensing tube fitted to jacket 
 by rubber connection. Length 12 inches . 
 
 62-126 — —, same as above, but 24 inches long. 
 
 HARCOURT ECONOMY MERCURY STILL. See index. 
 
 62-140 FRANKLIN’S PALM or PULSE GLASS, for illustrating influence of pres¬ 
 
 sure on boiling. 
 
 This glass consists of two bulbs joined by a tube which is filled with a colored liquid and from which 
 air has been expelled as completely as possible by boiling the liquid before sealing the tube. There 
 is then in the glass a pressure due to the elastic force of the aqueous vapor which at ordinary tem¬ 
 perature is very small. If, now, one of the bulbs be held in the hand, the heat is sufficient to 
 produce a pressure which drives the liquid into the other bulb and causes it to boil violently, 
 the hand feeling also a sensation of cold. 
 
 $0.46 
 
 2.75 
 
 .85 
 
 1.60 
 
 .35 
 
 62-160 WOLLASTON CRYOPHORUS, illustrating freezing by evaporation. 
 
 In use, the water is introduced into the bulb on the bent neck and the other bulb is placed in a freez¬ 
 ing mixture. The vapor then is condensed in the tube, causing the water in the bulb to evaporate 
 rapidly' in order to yield more vapor. This rapid evaporation causes the water in the bulb to 
 freeze. Without jar . 1.40 
 
 62-166 CARRE’S FREEZING APPARATUS for connecting to an Air Pump, illustrating freezing of water 
 by its own rapid evaporation, at the same time causing ether to boil. 
 
 A few strokes of the piston of the Air Pump cause the water in the flask to evaporate rapidly. The 
 vapor is absorbed at once by the sulphuric acid, causing more rapid evaporation of the water, at 
 the same time increasing its own temperature to such an extent as to cause the ether to boil, and if 
 the tube containing the ether has been lightly stoppered, causing the cork to fly out. 2.16 
 
212 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 < 5 = 
 
 No. 62-160 
 
 No. 62-200 
 
 No. 62-240 
 
 No. 43-310 
 
 62-160 SULPHURIC ACID CRYOPHORUS, for freezing water by its own rapid evaporation. 
 
 When the top bulb has been half filled with water and the middle bulb filled with strong sulphuric 
 acid, the vessel should be clamped in a position as shown in the illustration. The water is then 
 heated until about 1/3 has been driven off in steam. The lower neck is then tightly corked by 
 means of a stopper plug covered with a piece of india rubber tubing, and the burner is removed. 
 
 The water is then cooled by immersing in a cold bath. When sufficiently cooled, the apparatus is 
 turned round a number of times, in such a way that the acid can run in and out of the middle bulb 
 while the water is not allowed to leave the top bulb. The heat generated by the absorption of 
 water vapor drives out any air which may be dissolved in the acid. The stopper is removed and 
 the boiling is continued as described above. After passing the acid several times to and from the 
 middle bulb, the water in the top bulb will be found to solidify. Care must be taken, however, 
 throughout the experiment to prevent any acid passing over into the water bulb, or the experiment 
 will not be a success. 
 
 Cryophorus complete as illustrated with Stopper Plug and Delivery Tube. $1.90 
 
 43-310 FREEZING APPARATUS, illustrating the freezing of water by the rapid evaporization of ether. 
 
 As air is exhausted from bell glass, the ether evaporates very rapidly, causing water in watch glass to 
 freeze. 
 
 Complete as illustrated. 1.40 
 
 62-200 DEW POINT APPARATUS, after Millikan, Gale and Bishop, Exp. 10A, for determining the tem¬ 
 perature at which water vapor begins to condense out of the atmosphere as the temperature is 
 lowered^ 
 
 • In use, the metal tube is filled two-thirds full with ether. Air is forced very gently through this 
 ether by means of the bulb. This process facilitates cooling, since it increases the evaporating 
 surface. The temperature existing within the tube when the first cloudiness begins to appear 
 upon the polished surface is the Dew Point. 
 
 Complete as illustrated. .96 
 
 62-226 MELTING POINT TUBE, for determining the melting point of paraffine, wax, and other substances 
 which, when in solid state, have a color but which turn colorless in liquid state. 
 
 This tube consists of a glass tube with end bent and drawn to a point. While hot, the substance is 
 drawn into the tapered point. It is then allowed to cool when it is immersed into water, the 
 temperature of which is gradually increased until the substance loses color, when temperature is 
 noted by thermometer. This reading will be the melting point of the substance . .,. .16 
 
 62-240 CUBICAL EXPANSION BULB, for determining the point of maximum density of water. This 
 apparatus consists of a bulb' of known volume with graduated capillary neck. 
 
 When filled with water, sufficient to fill the bulb and three quarters of the graduated neck, the bulb 
 is immersed in water, the temperature of which is taken. Freezing mixture is added to bath and 
 continuous readings of thermometer and graduated neck are taken. A point will soon be reached 
 where the reading on the neck does not descend as the temperature decreases but at this point 
 will begin to rise, showing that this is the point of maximum density. This point will be found 
 at about 4 degrees Centigrade. 1.10 
 
 X 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 213 
 
 MEASUREMENT OF INTENSITY OF HEAT 
 
 THERMOMETERS 
 
 No. 63-10 
 
 No. 63-12 
 
 No. 63-16 
 
 63-10 HOUSEHOLD THERMOMETER, 8 inches long, heavy metal frame, reading from -30 
 
 degrees to 120 degrees Fahrenheit...$0.60 
 
 63-12 HOUSEHOLD THERMOMETER, 10 inches long, silvered scale on hardwood back, read¬ 
 ing from-30 degrees to 120 degrees Fahrenheit. 95 
 
 63-16 COMPARATIVE THERMOMETER, three Scale, Fahrenheit, Centigrade, and Reaumur. No. 63-20 
 
 This is a thermometer, 10 inches long, designed to give the student an instrument which 
 will give a reading in all three scales, thus showing direct comparisons. Made of box¬ 
 wood, piano rubbed finish, all graduations and letterings distinct. Bulb protected by 
 metal covering. .80 
 
 63-18 METALLIC THERMOMETER, DEMONSTRATION FORM, with glass back, entire mechanism 
 visible. Diameter 6 inches. This thermometer will be of great pedagogic value in that it shows 
 at a glance the method of multiplying the movement made by two metals soldered together. 
 
 Range from 50 degrees below to 150 degrees Fahrenheit. $4.40 
 
 63-20 GROUND GLASS UNGRADUATED THERMOMETER, 13 inches long, half its circumference 
 etched through its entire length. In calling attention to this thermometer, we request that it be 
 not confused with those on the market. With this thermometer, a student can find and mark 
 in pencil on the etched portion both its zero and boiling points. When these are obtained, it will 
 require very little skill on his part to make a complete thermometer. The etched portion obviates 
 the disagreeable features of rubber bands and otherindicators. Each 50 cents .... Per Doz. 6.76 
 
214 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 CHEMICAL THERMOMETERS 
 
 No. 63-30 No. 63-37 No. 63-60 No. 63-60 No. 63-70 
 
 63-26 CHEMICAL THERMOMETER, paper scale, 8 inches long, with scale reading from -10 to 100° Centi¬ 
 
 grade, enclosed in case. $0.76 
 
 63-26 -, paper scale, 8 inches long, with scale reading from 0 to 220° Fahrenheit, enclosed in case ... .66 
 
 63-30 CHEMICAL THERMOMETER, paper scale, 13 inches long, with scale reading from -10 to 110° 
 
 Centigrade, enclosed in case . 1.00 
 
 63-32 -, paper scale, 13 inches long, with scale reading from -10 to 210° Centigrade, enclosed in 
 
 case. 1.00 
 
 63-36 -, paper scale, 13 inches long, with scale reading from 15 to 220° Fahrenheit, enclosed in 
 
 case. "... 1.00 
 
 63-36 -, paper scale, 13 inches long, with scale reading from 15 to 400° Fahrenheit, enclosed in 
 
 case. 1.26 
 
 63-37 CHEMICAL THERMOMETER, paper scale, 13 inches long, with double scale reading from -10 to 
 110° C. and with equivalent Fahrenheit scale to 220°. 
 
 Enclosed in case. 1.16 
 
 lent Fahrenheit scale to 400°. 
 
 Enclosed in case. 1.36 
 
 63-60 CHEMICAL THERMOMETER, stem scale, white enameled back, 13 inches long, graduated from 
 -10 to 110° C. 
 
 Enclosed in wooden case. 1.16 
 
 63-62 - —, stem scale, white enameled back, 13 inches long, graduated from -10 to 210° C. 
 
 Enclosed in wooden case. 1.26 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 215 
 
 63-55 CHEMICAL THERMOMETER, stem scale, white enameled back, 14 inches long, graduated from 
 
 -10 to 360° Centigrade, enclosed in wooden case.$1.50 
 
 63-67 - —, stem scale, white enameled back, 14 inches long, graduated from 15 to 600° Fahrenheit, en¬ 
 closed in wooden case. 1.50 
 
 63-60 - —, stem scale, white enameled back, 14 inches long, double graduations, from -10 to 110° Centi¬ 
 grade and with equivalent Fahrenheit scale to 220°, enclosed in wooden case. 1.50 
 
 63-62 - —, stem scale, white enameled back, 14 inches long, double graduations, from -10 to 210° Centi¬ 
 grade and with equivalent Fahrenheit scale to 400°, enclosed in wooden case. 1.75 
 
 63-64 - —, stem scale, white enameled back, 14 inches long, double graduations, from -10 to 360° Centi¬ 
 grade, with equivalent Fahrenheit scale to 600°, enclosed in wooden case . 2.00 
 
 63-70 CHEMICAL THERMOMETER, enclosed milk glass scale, 13 inches long, graduated from-10 to 110° 
 
 Centigrade, enclosed in wooden case. 1.25 
 
 63-72 -, enclosed milk glass scale, 13 inches long, graduated from -10 to 250° Centigrade, enclosed in 
 
 wooden case. 1.50 
 
 STANDARD THERMOMETERS 
 
 63-80 STANDARD CHEMICAL THERMOMETER, scale engraved on the stem, white enameled back, 16 
 
 inches long, graduated from 0 to 100° Centigrade by 1/5 degrees, enclosed in wooden case .... $3.00 
 
 63-86 STANDARD CHEMICAL THERMOMETER, scale engraved on the stem, white enameled back, 
 
 25 inches long, graduated from 0 to 100° Centigrade by 1/10 degrees, enclosed in wooden case . . 4.60 
 
 No. 63-146 
 
 63-125 
 
 63-135 
 
 STANDARD THERMOMETERS, Centigrade scale, engraved stem, each with zero and boiling 
 points. Set of four as follows, enclosed in fine leather case: 
 
 0 to 100° X 1/10 100 to 200° X 1/10 
 
 200 to 300° X 1/5 300 to 400° X yi 
 
 Duty Free $19.80 
 
 STANDARD THERMOMETERS, Centigrade scale, after Allihn, enclosed pearl glass scale, set of 
 three about 12 X V± inch, each with zero and boiling points, divided to ]/ 2 degrees. Set as follows: 
 -15 to 100° 100 to 200° 200 to 300° 
 
 In fine leather case, Duty Free 
 
 13.50 
 
 63-146 STANDARD THERMOMETERS, Centigrade scale, after Anschuetz_, enclosed pearl glass scale, 
 about 4 to 6 inches long by inch diameter. Set of seven by 1/5 degrees as follows: 
 
 10 to 60° 40 to 110° 90 to 160° 150 to 220° 200 to 270° 250 to 310° 300 to 360° 
 
 In fine leather case, Duty Free 
 
 14.76 
 
2l6 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 
 MISCELLANEOUS STANDARD 
 THERMOMETERS 
 
 63-155 BECKMANN’S NORMAL DIFFERENTIAL THERMOMETERS, for boil¬ 
 ing or freezing point methods in molecular weight determinations, etc. 
 
 a b 
 
 Range, Degrees C. 1 5 to 6 
 
 Divided, degree . 1/500 1/100 
 Each, Duty Free . $9.80 6.60 
 
 c d 
 
 i 
 
 10 to 12 25 to 30 
 
 1/50 1/20 
 
 6.60 6.25 
 
 e 
 
 50 to 60 
 1/10 
 6.25 
 
 63-166 CALORIMETRIC THERMOMETER, about 20 inches long, scale engraved 
 on pearl glass, from 15 to 25 degrees Centigrade by 1/100 degree Duty Free 
 
 63-170 HYPSOMETER THERMOMETER, scale etched on stem, length about 14 
 inches, 90 to 102° Centigrade by 1/10 degree, with zero and boiling points. 
 
 Duty Free 
 
 63-172 -, same as above, 95 to 102° C. by 1/20 degree.Duty Free 
 
 63-180 HIGH TEMPERATURE THERMOMETERS, Centigrade scale, about 12 to 
 
 14 inches long, in the following ranges by single degrees: 
 
 0 to 130° 100 to 300° 200 to 540° 
 
 Per set of three, in fine leather case. Duty Free 
 
 63-182 - —, same as above, but with certificate of accuracy from Physik-Technische 
 
 Reichsanstalt in Charlottenburg.Duty Free 
 
 63-190 LOW TEMPERATURE THERMOMETER, stem graduation by single 
 degrees, from -50 to 50° Centigrade; without certificate . . . Duty Free 
 
 63-191 - —, same as above, with certificate from Physik-Technische Reichsanstalt 
 
 Duty Free 
 
 63-193 LOW TEMPERATURE THERMOMETER, stem graduation by single de¬ 
 grees, from -100 to 10° Centigrade; without certificate . . . Duty Free 
 63-194 - —, same as above, with certificate from Physik-Technische Reichsanstalt 
 
 Duty Free 
 
 63-196 LOW TEMPERATURE THERMOMETER, stem graduations by single 
 degrees, from -200 to 10° Centigrade, for measuring the temperature of 
 
 liquid air; without certificate .Duty Free 
 
 63-197 - —, same as above, with certificate from Physik-Technische Reichsanstalt 
 
 Duty Free 
 
 No. 63-155b 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 217 
 
 
 SPECIAL THERMOMETRIC INSTRUMENTS 
 
 DIFFERENTIAL THERMOSCOPES 
 
 No. 64-16 No. 64-20 
 
 64-16 UNIVERSAL AIR AND LIQUID DIFFERENTIAL THERMOSCOPE. This design, a modification 
 according to our specifications, may be used equally well for indicating the temperature of liquids, 
 as in comparing temperature of two neighboring places. Thus, as may be noted from our illustra¬ 
 tion, the thermoscope bulbs are bent downward yet opposite the small table which is designed 
 especially for holding the source of radiant energy. The illustration shows our No. 61-100 Leslie’s 
 Cube in position, and comparison of liquids may be demonstrated by use of two vessels containing 
 the liquid, the bulbs dipping into the vessels. The bent U-tube contains the colored liquid, and in 
 a tube which connects the two limbs is a stop-cock by which the liquid in each limb is easily brought 
 
 to the same level. This glass part is mounted in a frame with a scale, the whole mounted on a 
 neat base. 
 
 Without the illustrated Leslie’s Cube. $7.60 
 
 64-20 DIFFERENTIAL THERMOSCOPE, for indicating a difference of temperature between two bulbs. 
 
 The apparatus consists of two bulbs connected by a U-tube, from which air has been expelled by boil¬ 
 ing before sealing, the liquid contained therein as an indicator. This tube with attached bulb is 
 mounted with scale on an upright support. 1.96 
 
 ii 
 
 9 
 
 64-30 AIR THERMOMETER, after Rendtorff, for showing expansion of air by heat. 
 
 This thermometer consists of a bulb into which is sealed a capillary tube, the end of which 
 tube extends nearly to the bottom of the bulb. Through the bulb and sealed into the 
 opposite walls is a wire of v high resistivity. Terminals are left outside the bulb for con¬ 
 nection to batterj r . The whole apparatus is freed from air, before sealing, by boiling the 
 colored liquid contained therein. 
 
 64-36 AIR THERMOMETER, for illustrating gas expansion, of glass, with two-inch bulb . . . 
 
 2.26 
 .1 7 
 
 
 No.64-30 
 
2l8 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 64-65 
 
 64-67 
 
 64-69 
 
 64-66 
 
 64-66 
 
 64-67 
 
 64-70 
 
 AIR THERMOMETERS 
 
 No. 64-66 
 
 No. 64-70 
 
 CONSTANT VOLUME AIR THERMOMETER, for determining the coefficient of expansion of air, 
 or of a gas. 
 
 This apparatus consists of a rectangular frame with the scale mounted on one of our H-bases. The 
 air thermometer, fastened by a protective strip of wood, is adjustably clamped to one rod and 
 the open leveling tube similarly mounted and clamped to the other rod. The open lower ends of 
 each are connected by the finest quality of flexible rubber tubing. 
 
 This instrument is substantially constructed throughout and handsomely finished in nickel-plate and 
 japan. It has been designed that laboratories may have at a reasonable cost an instrument capa¬ 
 
 ble of accurate determinations. We have no hesitancy in recommending it as capable of results 
 attained by instruments of double the cost. 
 
 Complete as illustrated. $8.60 
 
 AIR THERMOMETER BULB, for attachment to above stand to replace breakage. .76 
 
 BOYLE’S LAW TUBE, for use on above stand in determining Boyle’s Law. This tube may be 
 mounted in place of the air thermometer pictured in above illustration. For apparatus complete 
 
 see No. 41-110. 1.26 
 
 AIR THERMOMETER, after Millikan, Gale and Bishop, Exp. 14, for determining the coefficient of 
 expansion of air. 
 
 This is an elementary air thermometer, capable of a fair degree of accuracy. It consists of an air 
 thermometer tube, leveling tube, and scale mounted to a backing which may be adjusted along the 
 rod of the tripod stand by means of a clamp attached to the backing. The lower open ends of the 
 tubes are connected by our finest quality flexible antimony rubber tubing. The apparatus is dur¬ 
 
 ably finished, the metal parts in bright nickel and japan. 
 
 Complete as illustrated. 3.36 
 
 -, without support. 1.66 
 
 AIR THERMOMETER BULB, as used in above apparatus. Each .46 
 
 CONSTANT VOLUME AIR THERMOMETER, highest quality constructed by one of the most 
 
 prominent European manufacturers and extensively used as a precision instrument . . Duty free . . . 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 219 
 
 AN IMPROVED MINERALITE THERMOPILE 
 
 fa 
 
 No. 64-100 
 
 We offer in this series of Thermopiles, instruments of two sizes which cover all ranges in both amperage and 
 voltage, of the Bismuth Antimony type, from the single pair to 120 pair. 
 
 A study of the table below will show the relative strength of our sizes A and B as compared with the Bismuth 
 Antimony Pile of twenty pair, which is usually taken as the standard in Thermo-electric Measurement. 
 
 The advantages of the Improved Mineralite Pile are much greater sensibility, greater mechanical strength, 
 and greater durability. 
 
 In preparing the data given in Table I below, we have used a unit area of metallic surface kept at 100° Centi¬ 
 grade and distant from the Pile 10 centimeters. Deflections in each case are read by a galvanometer of standard 
 D’Arsonval type. In Table II, the source of heat is the direct rays of the sun, the experiment being taken on a 
 typical Boston winter’s day. 
 
 TABLE I 
 
 Unit Area Metallic Surface at 100° Centigrade. Ten Centimeters Distant from Face of Pile 
 
 INSTRUMENT 
 
 TIME 
 
 30 Seconds 
 
 1 Minute 
 
 2 Minutes 
 
 20 pair Bismuth Antimony 
 
 9 Divisions 
 
 11 Divisions 
 
 10 Divisions 
 
 Mineralite A 
 
 30 Divisions 
 
 34 Divisions 
 
 36 Divisions 
 
 Mineralite B 
 
 45 Divisions 
 
 52 Divisions 
 
 55 Divisions 
 
 TABLE II 
 
 Direct Sunlight as Source of Heat 
 
 INSTRUMENT 
 
 TIME 
 
 1 Minute 
 
 
 20 pair Bismuth Antimony 
 
 17 Divisions 
 
 Mineralite A 
 
 83 Divisions 
 
 Mineralite B 
 
 167 Divisions 
 
 64-100 IMPROVED MINERALITE THERMOPILE A with stand .,.$11.76 
 
 64-110 IMPROVED MINERALITE THERMOPILE B;with stand. 14.60 
 
 OTHER RADIOMETERS. Section 61. 
 
220 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 THERMO-ELECTRIC BATTERIES 
 
 No. 64-127 
 
 * 
 
 Thermo-Electricity has been a matter of study for a number of years, but the principal use of a thermo-electric 
 couple or a thermopile has been that of a sensitive radiometer. The new thermo-electric instrument above illus¬ 
 trated is designed for practical use, — that of a thermo-electric battery. These forms are of simplified construc¬ 
 tion, low-priced and with highly efficient output. With the larger sizes, small machinery may be operated, incan¬ 
 descent lamps lighted, storage batteries charged, etc. For experiments in electrolysis, they are, perhaps, unexcelled. 
 From the fact that they may be operated instantly and need no attention, their popularity in this country and 
 abroad has been continually increasing. Each battery is supplied complete with burner. 
 
 64-125 THERMO-ELECTRIC BATTERY, 26 elements, E. M. F. 1.8 to 2.2 volts; current strength on short 
 
 circuit 3 to 4 amperes. 
 
 Complete with Gas Burner ..Duty Free . . . 
 
 64-125a -, same as above, but with Alcohol Burner.Duty Free . . . 
 
 64-126 THERMO-ELECTRIC BATTERY, similar to above, but larger, 38 elements, E. M. F. 2.8 to 3.2 
 
 volts; current strength on short circuit 3 to 4 amperes. 
 
 Complete with Gas Burner .Duty Free . . . 
 
 64-126a -, same as above, but with Alcohol Burner.Duty Free . . . 
 
 64-127 THERMO-ELECTRIC BATTERY, similar to above, but larger, 50 elements, E. M. F. about 4.2 
 volts; current strength about 4 amperes. 
 
 Complete with Gas Burner .Duty Free . . . 
 
 64-127a — —, same as above, but with Alcohol Burner.Duty Free . . . 
 
 64-128 THERMO-ELECTRIC BATTERY, extra large, 100 elements, E. M. F. 4 to 4.5 volts; current 
 
 strength on short circuit 4 to 5 amperes. 
 
 This battery is especially adapted for charging a 7 to 10 ampere storage cell. 
 
 Complete with Gas Burner .Duty Free . . . 
 
 64-128a -, same as above, but with Alcohol Burner.Duty Free . . . 
 
 No. 64-160 
 
 64-160 PORTABLE INDICATING ELECTRIC PYROMETER for indicating temperatures not exceeding 
 
 2000 degrees Fahrenheit (1100 degrees Centigrade). 
 
 This instrument is rugged in structure, durably and handsomely finished. It is furnished with a 
 base-metal Thermo-couple and indicates the temperature within a minute or two after the 
 Thermo-couple has been inserted in the high heat. 
 
 With Thermo-couple and 15 feet of Flexible Cable... 
 
 $ 60.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 221 
 
 EXPANSION OF MATTER 
 
 LINEAR EXPANSION APPARATUS 
 
 No. 65-10 
 
 66-10 COWEN’S LINEAR EXPANSION APPARATUS, for the rapid measurement of linear expansion of 
 solids. 
 
 The apparatus consists of a multiplying device on which the solid in the form of a tube rests. Any 
 movement of the tube lengthwise is greatly multiplied and accurately indicated on a graduated dial. 
 All parts are accurately fitted and handsomely finished. The apparatus occupies a small space, 
 yet from its mechanism presents a highly scientific appearance. 
 
 Results of extensive use have brought out the following features, — SIMPLICITY; no complicated 
 mechanism for clamping the rod and measuring same, the movement lengthwise merely being 
 multiplied by our patented device, the mechanism of which can readily be understood by even the 
 most unscientific mind: ADAPTABILITY; this instrument, taking a tube of any length from 20 
 centimeters up and any diameter desired: ACCURACY; in the shortest time possible and with a 
 minimum of trouble, an accuracy in excess of the ordinary form of linear expansion, is possible 
 with this, our patented design, inasmuch as reasonable errors of observation cause only slight errors 
 
 in final determinations. 
 
 Apparatus complete, including one brass tube.$3.00 
 
 66-11 STEEL TUBE, for use with above. .45 
 
 65- 12 ALUMINUM TUBE, for use with above. .45 
 
 66- 13 BRASS TUBE, as used in above . .40 
 
 65-14 GLASS TUBE, for use with above. .20 
 
 65-16 GLASS RESERVOIR AND STIRRER after Turner and Hersey, Exp. H023 .25 
 
 No. 65-17 
 
 65-17 COWEN COMPENSATION APPARATUS, as designed by George A. Cowen of the West Roxbury 
 High School, to use in connection with apparatus No. 65-10 in demonstrating the effect of multiple 
 bars of different coefficients of linear expansion as used in the Compound Pendulum. 
 
 The apparatus is simple in form, as shown in the cut, the various expanding bars -being held together 
 with two brass clamps on the same principle as the multiple bars are held in the Compensated 
 Pendulum. 
 
 A most interesting phenomenon is observed when the steam enters from the steam boiler. The tube 
 which is reached first by the steam, expands, causing the pointer to make rapid movement toward 
 the left. When the steam reaches the second bar of the system, this being the bar of greatest 
 coefficient of expansion, the pointer moves to the right to and well beyond the starting point. 
 When the steam reaches the third bar of the system, it will again move to the left, reaching the zero 
 point from which it started and there stop, showing successively the relative expansion of the 
 tubes in the order in which the steam strikes them. 
 
 We recommend that this piece of apparatus be placed in the hands of the individual student where 
 possible, although the effect is sufficiently striking to serve well as a lecture table demonstration. 
 
 Complete as illustrated. $5.00 
 
 65-18 COWEN COMPENSATING ATTACHMENT, for use with Cowen’s Linear Expansion Apparatus 
 
 No. 65-10. 2.40 
 
222 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 T-BEAM SERIES LINEAR EXPANSION APPARATUS 
 (LEVER AND MICROMETER FORMS) 
 
 The advantages of this type of apparatus will be readily seen from the cut, — substantial construction, the 
 ends clamped securely to the table avoiding all errors due to the supports not being rigid, the distance between the 
 supports easily varied to meet varying conditions. The metal brace between the two uprights formerly used has 
 been eliminated, doing away with the unavoidable error arising from the expansion of this brace by the heat radi¬ 
 ated from the steam jacket. Please note that the supporting ends of our instruments are attached by the well- 
 known Interlocking T-beam Attachments to the standard Basic Clamps “A,” strong and rigid clamps which hold 
 the apparatus securely to the table top. The uniformly accurate results which these instruments give are due to 
 the fact that all possible sources of error have been carefully worked out and eliminated. 
 
 65-20 
 
 6-1000 
 
 65-22 
 
 T-BEAM SERIES LEVER EXPANSION APPARATUS, complete as illustrated without Basic Clamps 
 
 T-BEAM BASIC CLAMP “A,” two of which are required for above apparatus.Each 
 
 LEVER^FORM LINEAR EXPANSION APPARATUS, similar to No. 65-20, but designed to rest 
 on the table. A nickel-plated metal brace connects the two uprights. Complete with one ex¬ 
 pansion rod. 
 
 $3.25 
 
 .94 
 
 2.65 
 
 
 65-25 T-BEAM SERIES MICROMETER SCREW EXPANSION APPARATUS, complete as illustrated 
 
 without Basic Clamps. $3.85 
 
 6-1000 HARCOURT UNIVERSAL T-BEAM BASIC CLAMP “A,” two of which are required for above 
 
 Each .94 
 
 65-27 MICROMETER SCREW LINEAR EXPANSION APPARATUS, similar to No. 65-25, but de¬ 
 signed to rest on the table. A nickel-plated metal brace connects the two uprights Complete 
 with one expansion rod. 4.60 
 
 THE IMPROVED SPINE-SUPPORTED LINEAR EXPANSION APPARATUS 
 
 In this series of Linear Expansion Apparatus we wish to call particular attention to the improved method of 
 supporting the tube, it being held lengthwise on the top edge of a substantial oak spine, but not in actual contact 
 with the wood. The design is such that the drip from the falling water or the radiated heat from the tube intro¬ 
 duces no error, a very important feature in all designs of apparatus for determining the Coefficient of Linear Ex¬ 
 pansion. 
 
 The apparatus is offered both in the Lever and Micrometer form. 
 
 No. 66-30 
 
 Patented Sept. 7, 1906 
 
 65-30 SPINE-SUPPORTED LEVER FORM EXPANSION APPARATUS, complete, including Brass Rod $4.40 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 223 
 
 66-40 SPINE SUPPORTED MICROMETER SCREW FORM LINEAR EXPANSION APPARATUS, for 
 
 determining the coefficient of linear expansion of a rod. 
 
 This form of expansion coefficient apparatus substitutes a micrometer screw in place of lever for 
 reading the expansion. A lever at the other end of the rod facilitates in the zero readings, indi¬ 
 cating positive contacts of the end of the micrometer screw on the rod, thus avoiding the incon¬ 
 veniences of electrical connections and overcoming absolutely the errors to which the electrical 
 method is liable. 
 
 Mounted on handsomely finished hardwood support 
 
 66-46 ALUMINUM ROD, for use with Nos. 66-20 to 66-40 
 66-46 IRON ROD, for use with Nos. 66-20 to 66—40 
 
 66-70 BRASS TUBE AND POINTER after Millikan, Gale and Bishop, Exp. 15. 
 
 No. 66-80 
 
 No. 66-80 
 
 $4.60 
 
 .46 
 
 .40 
 
 .66 
 
 66-76 COMPOUND BAR, for showing unequal expansion of metal. 
 
 This apparatus consists of two welded pieces of metal, iron and brass, which when heated will show their 
 unequal expansion qualities by bending in the form of an arc, the inner part of which will be the 
 metal of lesser expansibility. 
 
 Complete as illustrated, with handle for comfortable heating. $0.66 
 
 66-80 COMPOUND BAR WITH INDICATOR, for showing the unequal expansion of two metals. 
 
 This is an ingenious device for registering on a dial the expansion of the metal of the greater expansi¬ 
 bility . 4.00 
 
 65-110 GRAVESEND BALL AND RING, for illustrating expansion of metal upon application of heat and 
 contraction upon withdrawal. 
 
 The apparatus consists of a polished metal ball and a ring through which the ball at ordinary tem¬ 
 perature will just pass, each of which is attached to a metal rod with handle end. 
 
 At ordinary temperature, the ball will just pass through the ring, but when heated, it cannot be 
 
 forced through. Cooled below ordinary temperature, it will fit loosely. .98 
 
 17-60 COMPENSATED PENDULUM, illustrating method of time compensation by application of un¬ 
 equal expansion of rods. 12.36 
 
 65-80 TREVELYAN’S ROCKER, for illustrating that musical vibrations are maintained by communi¬ 
 cation of heat. 
 
 The apparatus consists of a brass rod with a V groove milled lengthwise. To this rod is fastened 
 a metal handle with ball end. When this bar is heated at some point below the melting point of 
 lead and placed so that the edges of the V groove rest on the lead casting as indicated, the bar be¬ 
 gins to emit a harsh note. This note may be made to rise in pitch by slightly pressing on the bar. 
 
 Trevelyan’s Rocker with Lead Rest. 2.00 
 
224 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 PACKARD’S 
 
 BREAKING BY EXPANSION AND CONTRACTION APPARATUS No. 65-130 
 
 No. 66-130 
 
 No. 65-130 (Fig. 2) . No. 65-130 (Fig. 3) 
 
 This piece of apparatus has been designed to demonstrate most effectively the power exerted by an 
 expanding or contracting metal bar. The expansion is obtained by a burner in tube form indicated in the 
 illustration. The power exerted by the expanding or contracting rod is presented most strikingly by the 
 breaking of a steel bar placed in the slot in the end and at right angles resting against knife edge supports. 
 
 It will thus be seen that whether the rod be heated by the tube, or allowed to contract in the process 
 of cooling, the bar will be broken and at the instant of breaking the lever will be thrown violently, the results 
 being therefore striking by the breaking of the bar, the sudden rising of the pointer and the noise, leaving no 
 doubt in the student’s mind that great force has been exerted. 
 
 In addition to the above features the instrument makes a most satisfactory lecture table piece for 
 teaching briefly but quickly the principle of expanding by heat. 
 
 The substantial construction, careful workmanship and correct design make this a most satisfactory 
 lecture table demonstration piece. Twelve steel bars for breaking supplied with each instrument. 
 
 Please note that the above instrument serves to teach the force exerted by an expanding rod, force 
 exerted by a contracting rod and the relative amount of expanding and contracting by heat. 
 
 Complete as illustrated 
 
 58.75 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 225 
 
 66-150 
 
 No. 65-160 
 
 No. 62-240 
 
 HOPE’S MAXIMUM DENSITY OF WATER APPARATUS for illustrating the point of Maximum 
 Density of Water, also for explaining reason why the surface of a pond may be covered with ice 
 while underneath is water. 
 
 The apparatus consists of a cylindrical jar in the sides of which, near top and bottom, are drilled 
 holes to contain sensitive thermometers. Around this jar about midway between these holes is 
 sealed a spun copper ice container. 
 
 In use, the jar is filled with water sufficient to immerse the upper thermometer bulb. A freezing 
 mixture is placed in the copper ice container. As the water in the jar cools, the density is in¬ 
 creased, the more dense portion sinking to the bottom, where its temperature will be registered by 
 the lower thermometer. It will be noted that the reading of this thermometer will be lower than 
 that of the upper until 4° Centigrade is reached, at which point the reading will remain stationary, 
 whereas the upper will continue to descend until 0° Centigrade is reached. 
 
 Complete as illustrated, with rubber stoppers for thermometers but without thermometers . . . 
 
 THERMOMETERS. Section 63. 
 
 $5.00 
 
 62-240 
 
 DESPRETZ WATER THERMOMETER for indicating cubical expansion of liquid or for determin¬ 
 ing the maximum density of water. (See Section 62.).. 1.10 
 
 No. 66-175 
 
 i 
 
 No. 65-170 
 
 No. 66-180 
 
 65-170 
 
 65-175 
 
 65-177 
 
 65-180 
 
 65-191 
 
 FREEZING BOMB, illustrating the tremendous expansive force exerted as water freezes. 
 Consists of a cast-iron sphere cored to contain about 2 ounces of water. The throat is tapped 
 to receive a screw plug. 
 
 When filled with water and placed in freezing mixture, although of cast iron, this bomb will 
 burst from the tremendous force exerted from the expansion of water when changing from 
 
 the liquid to the solid state . $0.95 
 
 CHARLES LAW TUBE, after Hall and Bergen, for showing that under constant pressure 
 different gases possess the same coefficient of expansion. 
 
 This consists of two tubes of capillary bore, connected by a flexible rubber tubing. One of 
 these tubes has a closed end and contains dry air which extends part way into the open tube, 
 
 in which is an indicating globule of mercury ... 1.66 
 
 Note. The use of this tube presupposes an equipment consisting of a Bunsen Burner, a Hyp- 
 someter, an Ice Tray, a Meter Rod, and a Barometer. For these instruments, see Index. 
 
 LEVELING TABLE for use with above after Hall No. 52a.1.60 
 
 WATERMAN’S CHARLES LAW TUBE for similar use as above, requiring practically the 
 same accessories. 
 
 The apparatus consists of tube of capillary bore, one end of which is sealed and contains dry 
 air stoppered by a globule of mercury. This tube is mounted on a graduated backing for 
 
 direct measurement of air expansion. 1.75 
 
 VOLUME COEFFICIENT TUBE, after Millikan, Gale and Bishop (Experiment 14a).10 
 
226 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 MEASUREMENT OF THE QUANTITY 
 
 OF HEAT 
 
 CALORIMETERS 
 
 66-10 PARR’S STANDARD CALORIMETER 
 
 for determining the calories of heat de¬ 
 veloped by the combustion of bitumi¬ 
 nous and anthracite coals, lignites, coke, 
 etc. 
 
 The apparatus consists of a cartridge in 
 which is placed the combustible material 
 in the form of a powder and mixed with 
 a chemical compound. This cartridge 
 is placed in a measured quantity of water 
 in an insulated calorimeter can. This 
 calorimeter can is contained within two 
 insulating vessels with air spaces be¬ 
 tween. The pulley noted in the illus¬ 
 tration operates the cartridge and is pro¬ 
 vided with small vanes for causing a 
 constant uniform stirring of the water. 
 
 This pulley may be driven by any con¬ 
 venient means at hand. The illustra¬ 
 tions show it in use driven by Electrical 
 Motor. In use, the coal or combustible substance is ground to pass through a 100 mesh sieve and a 
 weighed quantity is put into the cartridge together with a chemical compound. A measured 
 quantity of water is then placed in the insulated calorimeter can. The stirrer is then set in motion, 
 operated either by water or electric power. After a constant temperature has been obtained, 
 ignition is effected by means of a short piece of hot wire dropped through the stem of the cartridge. 
 Extraction of the heat is completed in from four to five minutes. The maximum reading is taken 
 and the rise of temperature multiplied by a simple factor gives the heat in B. T. U. per pound of coal. 
 
 The complete calorimeter outfit includes a fine thermometer graduated to 14o° F. with certificate 
 of accuracy, a two-liter measuring flask, chemical receptacle, measuring cup, 5-inch 100 mesh 
 brass sieve with bottom, chemicals sufficient for 10 determinations, pincers, ignition wire, read¬ 
 ing lens, and camel’s hair brush . $77.00 
 
 No. 66-10 
 
 No. 66-11 
 
 66-11 PARR’S STANDARD CALORIMETER, same as above, but equipped for electric ignition .... $82.60 
 
 66-12 WATER MOTOR AND SUPPORT. Extra 6.60 
 
 66-13 ELECTRIC MOTOR, Lamp series, as illustrated above. Extra 13.20 
 
 66-14 SUPPORT FOR ELECTRIC MOTOR, as illustrated above. Extra 2.76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 227 
 
 No. 66-35 No. 66-45 No. 66-60 
 
 66-36 CINCINNATI DOUBLE WALL CALORIMETER. Consists of two nickel-plated brass vessels, 
 the smaller resting on a supporting ring within the larger. A cover-with holes for thermometer 
 
 and stirrer is supplied with the outfit. Complete.$1.40 
 
 66-46 DOUBLE WALL CALORIMETER, similar to above but larger, and spun from sheet copper. Heavily 
 nickel-plated inside and out. A cover with holes for thermometei and stirrer is supplied with the 
 outfit. Complete . 2.96 
 
 66-50 CULLER’S CONDENSER ATTACHMENT for use with above or other calorimeters to determine 
 
 Latent Heat of Steam. (See Culler’s “Laboratory Manual of Physics,” Experiment XXHI) ... .96 
 
 No. 61-206 
 
 No. 66-65 
 
 No. 66-75 
 
 61-206 DOUBLE WALL CALORIMETER, of glass. This is a double-walled vessel with outlet for evacuat¬ 
 ing chamber between walls. It will be found invaluable in calorimetric work. $3.26 
 
 60-65 CALORIMETER for general laboratory usage in secondary school work in calorimetry. 
 
 This is the popular nickel-plated brass calorimeter used so frequently in determinations of specific 
 heat, latent heat of melting ice, latent heat of evaporization, and quite frequently for dew point 
 tests. Capacity about 1 liter. .60 
 
 66-70 STIRRER for use with above calorimeters. 20 
 
 66-75 BUNSEN’S ICE CALORIMETER, standard form, consisting of a bulb with sealed-in test tube 
 
 and bent mercury tube.. 1.26 
 
228 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ELECTRIC CALORIMETERS 
 
 No. 66-100 
 
 66-100 THE IMPROVED ELECTRIC CALORIMETER, designed after Stewart & Gee’s “Practical Phys¬ 
 ics,” Lesson 47. This instrument was designed for the purpose of applying Joule’s Law in the 
 determination of the constant of a Galvanometer, consequently the best possible results must be 
 obtained. The calorimeter proper is of the form shown under No. 66-106. This is placed in the 
 secondary chamber as shown in the illustration, the space between the outer chamber and the 
 polished surface of the outer wall of the calorimeter being filled with an insulating compound 
 composed largely of magnesium carbonate. 
 
 Complete as illustrated. $9.90 
 
 66-106 DOUBLE WALL ELECTRIC CALORIMETER, after 
 Millikan & Mills’ “Electricity, Sound and Light,” (Ex¬ 
 periment 4), for testing the calibration of a voltmeter 
 by an absolute determination of potential difference. 
 
 This calorimeter consists of two heavy copper vessels, 
 the inner of about 350 cubic centimeters capacity, 
 insulated from and supported on the outer by a fiber 
 ring. A coil of fine platinum wire is wound on an in¬ 
 sulating strip which is connected to two brass rods. 
 
 These rods extend through the cover and end in 
 binding post terminals. Two holes are provided in 
 this cover, one for a thermometer, the second for a 
 handle of a stirrer, which has heat insulating end. 
 
 Complete as illustrated.$6.86 
 
 No. 66-110 
 
 66-108 HEATING COIL ATTACHMENT, mounted on fiber cover. This attachment is intended for use 
 with No. 66-46 to make up Electric Calorimeter above. Teachers, therefore, who already have 
 No. 66-46 Double Wall Calorimeter need order this attachment only, to obtain Electric Calo¬ 
 rimeter No. 66-106 .$3.90 
 
 66—110 STUDENTS’ ELECTRIC CALORIMETER for determining the number of calories of heat developed 
 in a wire; also for the study of Joule’s Law. 
 
 The apparatus consists of a glass jar, in the neck of which is placed an insulating cover bearing two 
 rods, each terminating in a binding post connected to the ends of a coil of resistance wire. In the 
 center of this cover is a hole for the thermometer. 
 
 Complete as illustrated, without thermometer. 2.10 
 
 No. 66-106 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 229 
 
 JUNKER’S CALORIMETER 
 
 66-125 SIMPLIFIED JUNKER’S CALORIMETER for determin¬ 
 ing the calorific power of combustible gases. In the design 
 above illustrated the heated gases enter the inner chamber of 
 a triple-walled vessel. Within this chamber these gases 
 come in contact with a coil of copper tubing through which 
 a current of water continually flows. The temperature of 
 this water is noted at entering as well as upon issuing from 
 the coil, by the means of the thermometers noted in the 
 illustration. In order to determine the B.T. U., the quan¬ 
 tity of gas consumed and the quantity of water passed 
 through the apparatus must be determined in addition to the 
 difference in temperature. In determining the quantity of 
 gas consumed we advise our No. 66-130 Thorpe Gauge. 
 
 This instrument is substantial in structure, the fundamental 
 part consisting of a casting to which are mounted the two 
 thermometer tubes. On this casting is mounted a double- 
 walled metal chamber surrounded by an insulating compound. 
 The ends of the copper circulating coil supported from above 
 to the inner metal vessel are connected through the casting to 
 the thermometer tubes. The instrument may be mounted 
 on our special stand as illustrated or may be attached to any 
 tripod stand by means of a clamp. 
 
 Simplified Junker’s Calorimeter only. 
 
 $14.40 
 
 No. 66-125 
 
 66-130 THORPE GAUGE for measuring either pressure of gas or rate of gas flow. 
 
 To read pressure of gas screw cap down over outlet at the top and connect gas supply to the inlet. 
 
 Index on left scale gives reading of pressure in inches of water. With cap removed from outlet 
 and gas allowed to flow through the gauge, the indicator registers on right hand scale the rate of 
 flow of the gas in cubic feet per hour . . . .-..$12.00 
 
 SUBSTANCES FOR SPECIFIC HEAT DETERMINATIONS 
 
 66-170 LEAD CYLINDER with CONICAL TOP, weight approximately 650 grams 
 
 $0.66 
 
 66-175 LEAD SHOT .Per Pound .15 
 
 66-177 COPPER SHOT .Per Pound .66 
 
 66-179 ALUMINUM SHOT .Per Pound 
 
 66-181 GLASS BEADS .Per Pound 
 
 66-200 TYNDALL’S SPECIFIC HEAT APPARATUS for qualitative determi¬ 
 nation of the comparative specific heats of different metals. 
 
 The apparatus consists of a tripod on which is supported a disc of paraf¬ 
 fine, 5 balls of different metals with handle for holding balls while 
 heating them, and a tin plate for casting new paraffine discs. The balls 
 may be heated either in boiling water, or by the flame from a Bunsen 
 burner, or spirit lamp at the intersection of the rods bearing the balls. 
 
 Apparatus complete as above described. 
 
 1.05 
 
 1.00 
 
 1.55 
 
 No. 66-200 
 
230 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 MECHANICAL EQUIVALENT OF HEAT 
 
 APPARATUS 
 
 No. 67-20 
 
 The design of the instrument was worked out at the Cavendish Laboratory in Cambridge. 
 In operation it utilizes the principle of heating a given quantity of water by friction, both the water 
 and the friction surfaces being placed in a carefully insulated calorimeter, all sources of error either 
 being eliminated or accurately accounted for. 
 
 Until the outbreak of the European war this instrument was imported from Europe. As a 
 product of our own factory we call particular attention to features of prime importance which 
 have been taken into consideration in its manufacture. 
 
 The vertical shaft is most carefully centered so that the friction unit 
 rotates in a definite plane. 
 
 The tapered surfaces of the hollow truncated cones are hand finished to 
 assure absolute uniform contact. 
 
 To prevent radiations, not only are the cones carefully insulated from the 
 casing, but also an ample air jacket is provided. 
 
 Apparatus complete with detailed laboratory directions and ten feet Round Leather 
 Belting with Patent Belt Fastener. 
 
 $27.80 
 
 For Drive Wheels and Driving Mechanism see Section 21 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 231 
 
 
 No. 67-25 
 
 No. 21-120 
 
 67-25 DOUBLE INSULATION METAL 
 CAPPED MECHANICAL EQUIV¬ 
 ALENT OF HEAT TUBE, after Mil¬ 
 likan, Gale and Bishop (Experi¬ 
 ment 20). j 2jg| 
 
 This tube is a full meter in length, 
 built up from heavy corrugated 
 board covered inside and out with 
 tough wrapping paper, thus afford¬ 
 ing ample air insulation. 
 
 The ends of the tube are closed by 
 cork stoppers and close-fitting metal 
 screw caps. This tube must not be 
 confused with those of the cheaper 
 construction.. $0.70 
 
 21-120 TYNDALL’S HEAT BY FRICTION APPARATUS for illustrating with 
 Rotator the heat caused by friction on a brass tube while it is rotating 
 rapidly . 2.00 
 
 No. 67-50 
 
 67-50 FIRE SYRINGE, illustrating the production of heat by the rapid compression of gases. 
 
 This apparatus consists of a heavy brass cylinder, about 20 centimeters long, provided with tightly 
 fitting piston. On the end of this piston is a holder for a small piece of tinder. This cylinder is 
 mounted on a convenient foot rest. 
 
 In use, a small tuft of tinder is placed in the holder on the piston and moistened with either ether or 
 carbon disulphide that the experiment may be more effective. If now the piston is driven rapidly 
 to the bottom of the cylinder, the compression of the air generates heat sufficient to set fire to the 
 tuft of tinder. 
 
 Complete with piece of tinder. $1.76 
 
 HOT AIR AND GAS ENGINES 
 
 ’ No. 68-15 
 
 68-15 HOT AIR MOTOR for use in schools and colleges in the study of air expansion motors; also readily 
 adapting itself to the operating of small machinery models, etc. 
 
 This is an air-cooled motor with adjustable bearings and runs smoothly and silently. It is 18 inches 
 long by 6 inches diameter, weight about 16 pounds. The fly wheel has a diameter of 6 inches and 
 pulley of \\i inches. 
 
 This engine may be run on either gas or alcohol and either types of burners will be supplied as 
 
 requested .$15.00 
 
 68-30 HORIZONTAL HOT AIR ENGINE. This is a design illustrating, in a similar manner as No. 68-16, 
 the principle of air expansion motors. It is of simple design, but will readily operate from the heat 
 of a small alcohol lamp. 3.75 
 
232 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 68-40 
 
 68-40 GAS ENGINE, illustrating motive power, operated by gas explosion. 
 
 This is a small-sized model made of iron and brass. It is about 6 inches long, 3 inches wide, and weighs 
 3 pounds. Speed varies from 200 to 700 R. P. M.; enameled and nickel-plated. 
 
 This engine will be found an excellent model for demonstration. 
 
 Complete with directions. 
 
 68-60 THE IMPROVED GAS ENGINE WITH SPARK ADVANCING AND SPARK RETARDING DE¬ 
 VICE. The model above illustrated represents in section a four-cycle commercial gas engine. As 
 may be noted, all parts are represented in their proper positions and may be shown in actual oper¬ 
 ation by merely turning a crank, the movement of parts being caused by a succession of gears. 
 
 The model is complete with all essential parts, — exhaust and intake valves, piston head, spark plug, 
 etc., all being shown of sufficient size for classroom demonstration. By an ingenious method of 
 construction partially noted in illustration we are enabled to show the proper moment of ignition 
 giving rise to compression, if the secondary of a Ruhmkorff’s coil be connected in series with the 
 spark plug. 
 
 This engine is of rigid construction, scientific in every detail, and handsomely finished throughout, the 
 finish of the different parts being such as to accentuate the parts desired. It is mounted on a neatly 
 finished hardwood base. 
 
 $3.15 
 
 $7.60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 233 
 
 69-10 
 
 69-20 
 
 69-30 
 
 STEAM ENGINES 
 
 STEAM ENGINE MODELS 
 
 ii'ii 
 
 No. 69-20 
 
 WOLLASTON STEAM ENGINE, a simple model to illustrate the expansive force of steam. 
 
 This apparatus consists of a vessel as illustrated, in the neck of which is provided a close-fitting piston. 
 In use water is placed in the bulb and heated until steam is formed. Steam will force the piston up 
 the tube. If, now, the steam is condensed by plunging the bulb in cold water, the atmospheric 
 pressure will force the piston back. 
 
 STEAM CHEST MODEL. This is an interesting model of a simple steam chest, demonstrating the 
 opening and closing of the port holes by means of the slide valve. 
 
 The apparatus consists of a nickel-plated housing with glass window through which may be seen a 
 working model of a steam chest. By means of a thumb screw at the back, the slide valve may be 
 worked as desired, demonstrating the closing and opening of the port holes. 
 
 This is a handsomely finished instrument constructed on pedagogical lines. It will be found very 
 valuable in the lecture hall in that, during the study of the large engines, this little instrument 
 may be passed around the class. 
 
 SECTIONAL MODELS OF STEAM ENGINES 
 
 No. 69-30 
 
 SECTIONAL MODEL OF A STEAM ENGINE. A complete model of the locomotive showing 
 clearly the movements of slide valve, piston, eccentric, reversal of steam by means of link motion and 
 “cut off.” All parts are carefully fitted and adjusted and have been finished to accentuate the 
 different parts. Though the size is sufficient for class demonstration, it is advised that a pupil use 
 this model for the study of the functions and relations of the different parts. As there is no com¬ 
 plicated mechanism, the pupil’s understanding of the steam engine is complete after a short study 
 of the movements imparted to the different component parts by rotating the fly wheel a few times. 
 
 Mounted on a neatly finished wooden base. 
 
 No. 69-10 
 
 $1.45 
 
 3.25 
 
 $2.65 
 
234 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 69-35 
 
 69-36 THE IMPROVED EIGHTEEN-INCH SECTIONAL MODEL OF A STEAM ENGINE. This 
 model takes the place of the 10-inch model which was formerly made. All the parts are, of course, 
 correspondingly larger and, consequently, of correspondingly greater educational value, since the 
 new model is designed for use on the lecture table. 
 
 Great care has been exercised in making all the parts in a form to resemble as nearly as possible similar 
 parts in the commercial engine of locomotive type. The sectional view, as is indicated in the cut, 
 shows the steam chest, cylinder, piston, and valves in vertical section through the center. Other 
 features are shown sufficiently “off set” not to interfere with their resemblance to the actual 
 working engine. 
 
 The size of this model, being 18 inches long and 9 inches high, renders it particularly well adapted 
 to lecture table work. In order to assist in the easy differentiation of all the essential parts care has 
 been exercised in the proper coloring so as to make the essential features stand out clear and sharp. 
 
 Engine is mounted on a substantial hardwood base, the entire instrument being finished so as to give 
 the most pleasing appearance without interfering with its educational value. 
 
 No. 69-40 
 
 69-40 PROJECTION HORIZONTAL MODEL OF A STEAM ENGINE. The working parts of this model 
 are about the same size as the vertical model shown above, but so designed that they can be 
 projected on the screen by means of the opaque projector, — a valuable feature, particularly in 
 lecture rooms accommodating a larger number of students than can readily examine closely the 
 18-inch model. 
 
 The essential features are carefully differentiated by color effect so as to give the most striking ap¬ 
 pearance and easy differentiation on the screen. 
 
 The mounting is most substantial; workmanship is high grade throughout. 
 
 $6.76 
 
 
 $12.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 235 
 
 No. 69-50 
 
 
 €9-60 4-FOOT MODEL OF A STEAM ENGINE, after design suggested by Mr. F. R. Miller, English 
 High School, Boston, Mass. 
 
 This exceedingly large model has all the working parts of such generous proportions and open con¬ 
 struction that every student in a large lecture hall will be able to see the essential features easily. 
 It will thus be seen that this instrument in demonstration work will do for the large lecture room 
 - what No. 69-36 does for the small one. 
 
 The drive wheel or fly wheel has been omitted from this model, for the reason that it would of neces¬ 
 sity be of such large proportions as to make the entire model altogether too difficult to handle and 
 care for. 
 
 No. 69-66 
 
 69-56 LOCOMOTIVE CHART, designed particularly for hanging permanently on the wall of either lec¬ 
 ture room or laboratory. The parts are so clearly indicated as to serve admirably for a detailed 
 study of the parts of the modern locomotive. The sectional view shows 240 parts all named and 
 numbered. It gives, in addition, complete information regarding the various details of steam 
 engines in general and locomotives in particular. 
 
 Mounted on heavy cardboard with eyelets for hanging. 
 
 $27.60 
 
 $2.26 
 

 236 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 69-75 
 
 No. 69-85 
 
 63-75 WORKING STEAM ENGINE, of small size, for use with Steam Boiler No. 60-366 and consequently 
 designed to work on exceedingly low pressure, operating smoothly without load, on two inches of 
 mercury pressure. 
 
 It is a compact, durably built, and substantial little engine. The factj that practically all schools 
 are provided with inexpensive means of obtaining adequate steam pressure such as the Steam Boiler 
 or Hypsometer above referred to, makes this engine of very wide use. 
 
 The mechanical or power advantage of working as a high or low pressure engine is readily demon¬ 
 strated, the low pressure results being obtained either by connecting the exhaust to a condensing 
 chamber, or working it in connection with the air pump. 
 
 As will be noted from the illustration, the engine is mounted on a substantial iron base, presenting 
 
 very much the appearance of the commercial power engines.. $4.85 
 
 V 
 
 69-85 WORKING MODEL STEAM ENGINE. The model consists of a boiler and an engine both mounted 
 on a nickel-plated iron base the edges of which are polished. This engine runs rapidly and easily, 
 each engine being thoroughly tested before packing and fully warranted. Complete with explicit 
 directions for use and care, in a wooden lock corner box. 7.40 
 
 
 
 
 
 
 
 Nos. 69-116 to 69-117 
 
 69-115 ONE-QUARTER HORSE-POWER HORIZONTAL CORLISS ENGINE, cylinder 1^X2 inches; 
 
 bed 12 inches long by 7 inches wide; fly wheel 6 inches in diameter. $24.60 
 
 69-117 ONE-HALF HORSE-POWER HORIZONTAL CORLISS ENGINE, cylinder 1% X 3 inches; 
 
 bed 23^ inches long by 13)4 inches wide; fly wheel 10 inches in diameter by 2-inch face; approxi¬ 
 mate weight 40 pounds. 66.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 237 
 
 STEAM POWER PLANTS 
 
 No. 69-122 
 
 69-120 STEAM BOILER AND ENGINE. The pedagogic merit of a working demonstration 
 Steam Boiler and Engine of commercial type and of sufficient power to be of practical 
 value will be readily appreciated. Models are excellent and perhaps necessary, but the 
 wide-awake student is not satisfied. He desires an actual operating machine of commer¬ 
 cial type. 
 
 Our outfit, weighing 175 pounds, consists of a commercial 34 H. P. Engine mounted on 
 same base with, and connected to, a commercial 34 H. P. Boiler. 
 
 The Engine is of the standard Corliss Type, cylinder 1J4 inches by 2 inches; bed 12 inches 
 long by 7 inches wide; fly wheel 6 inches in diameter. It is carefully designed, and no 
 efforts are spared in its construction to make a practical engine of pleasing appearance. 
 
 It is provided with attachments to take up wear and maintain adjustments. 
 
 The Boiler is of the Vertical Tubular Type, 10 inches in diameter, height over all 21 inches, 
 with a water jacket fire-box and twenty %-inch seamless drawn brass tubes, each 1034 
 inches long. Shell is of j^-inch wrought iron, lap welded, the upper and lower parts of 
 best grade iron; the casing and the stack are of Russia iron, a thoroughly practical 
 machine tested to 200 pounds per square inch. Steam pressure up to 80 pounds may be 
 utilized. It is equipped with gas burner of ample size, adapted especially to the work. 
 
 (For further description and price see following page). 
 
238 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 The Base is of cast iron of ample dimensions for both Boiler and Engine. It is neatly finished. 
 
 Engine and Boiler are firmly attached and all connections made. The boiler is completely equipped 
 with necessary valves and gauges so that all that is necessary to start operation is to fill the boiler 
 with water to the proper height as seen by the water gauge, connect burner to gas main, and gen¬ 
 erate the steam. 
 
 Illustration is that of No. 69-122 following, but the outfit described under this number is the same 
 
 as illustration except that dynamo is not furnished. $74.50 
 
 69-122 STEAM AND ELECTRIC POWER PLANT. Frequent calls have been made for an outfit which 
 would illustrate the generation of electric power. By referring to the illustration it will be noted 
 that we have attached on the same base with the engine and boiler above listed a generator of 
 sufficient capacity to demonstrate the principles involved. This generator is of commercial type, 36 
 watts capacity (6 volts, 6 amperes). It is direct belted and even with the small pressure of 30 
 pounds may be run to its full speed of 2200 R. P. M. 
 
 Power Plant complete, as illustrated. 88.75 
 
 STEAM BOILERS 
 
 The commercial type engines previously listed, pages 236 and 237, require steam pressure. To satisfy this re¬ 
 quirement we offer one-quarter and one-half H. P. boilers of a convenient size and commercial type selected from 
 this country’s manufactures as having the best educational value. Each boiler is”equipped with a steam gauge and 
 safety valve, a water gauge and three gauge cocks, with valves on steam and water pipes. 
 
 Steam boilers of this type are given a prominent place in laboratories where the practical nature of Physics is 
 stressed. The two sizes below develop energy sufficient to run the ordinary demonstration models. Larger sizes 
 will be quoted and furnished on application. Each boiler is complete with burner all ready for connection to source 
 of gas supply and since they are tested to withstand pressures of practically one hundred per cent, beyond pressures 
 ordinarily required, there is positively no danger in continuous use, especially since each boiler is equipped with a 
 safety valve. 
 
 Installations have been made and these boilers have been found entirely satisfactory in the following ways: 
 
 1. Study of generation of steam and the value of its energy commercially, as the motive force in run¬ 
 
 ning engines, etc. 
 
 2. Study of boiler construction as employed commercially. 
 
 3. Study of functions of each attachment, valves, cocks, gauges, safety valves, etc., and why necessary. 
 
 4. Study of Bourdon Gauge in actual use. 
 
 5. Determining temperature of live steam. 
 
 6. Source of live steam for a great number of practical experiments in Physics, Chemistry and Biology. 
 
 As a source for experiments illustrating rise in boiling point due to increase of pressure, source in 
 determining expansion coefficient, a source for running steam baths in chemistry, in distillations, in 
 evaporations, etc., etc., these boilers will be found of exceptional value. 
 
 69-125 ONE-QUARTER HORSE-POWER BOILER, selected as best adapted not only to furnish steam 
 pressure to run our Steam Engine No. 69-120, but as a boiler of complete adaptability to general 
 purposes. Complete with improved Gas Burner. $37.76 
 
 69-130 ONE-HALF HORSE-POWER BOILER, similar to above. Complete with improved Gas Burner . 63.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 239 
 
 
 No. 70-10 
 
 70-10 HELIOPTICON OR SUNLIGHT PROJECTOR. This instrument consists of a square metal plate 
 in which is fitted a large flat ring to which is fastened a long mirror by special patent hinge. This 
 mirror is arranged for adjustment to any angle with the plate by a large screw which passes through 
 the lower portion of the ring. This ring also carries a condensing lens, in cell, and a metal handle 
 by which the ring and its attachments are turned in a vertical plane. A combination of movements 
 enables the mirror to be adjusted to reflect a beam of sunlight in one direction and keeps it in posi¬ 
 tion with but slight attention. Two parallel tubes pierce the metal plate below the ring and are 
 held firmly by clamping screws. This tube track forms a light but rigid bench for the slide stage and 
 objective carrier. It may also be used for an optical bench. 
 
 Heliopticon as above described, including J^-size objective, one inch condensing lens, and slide 
 
 carrier. $25.00 
 
 70-16 PORTE LUMIERE for securing parallel beams of light. This instrument is a “Sunlight Projector” 9.00 
 
 70-16 ADJUSTABLE SLIT DIAPHRAGM for use with 
 
 heliopticon for securing a rectangular beam of light 1.60 
 
 70-17 CYLINDRICAL DIAPHRAGM for use with heliopticon 
 with five graded openings for securing pencils of 
 light. 1.60 
 
 LIGHT 
 
 SOURCES OF LIGHT 
 
 70-20 
 
 70-22 
 
 UNIVERSALLY ADJUSTABLE HELIOSTAT WITH 
 CLOCK WORK. The instrument illustrated pictures 
 a heliostat capable of universal adjustments to 
 any position. It is manufactured by one of the 
 leading instrument makers of Europe whose guaran¬ 
 tee is sufficient recommendation of its quality. It is 
 handsomely finished throughout and capable of very 
 efficient service. Diameter of mirror 10 centimeters. 
 With each heliostat is furnished a black and a silvered 
 mirror and, in addition, a secondary mirror on stand. 
 
 Duty Free 
 
 HELIOSTAT, same as above, but diameter of mirror 
 5 centimeters .Duty Free 
 
 74.00 
 
 54.00 
 
 No. 70-20 
 
 PARAFFINE CANDLES for use in photometric work as source of light. 
 These candles are of standard quality and are furnished in two sizes: 
 
 70-50a Sixes (six to the pound).Per Dozen .33 
 
 70-60b Twelves (twelve to the pound).Per Dozen .20 
 
 STANDARD CANDLES. See Section 71. 
 

 240 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 70-70 
 
 No. 70-90 
 
 No. 70-92 
 
 70-70 KEROSENE LAMP AND METAL BOUND ASBESTOS CHIMNEY for furnishing source of light 
 
 in photometric experiments. 
 
 This consists of a small brass kerosene lamp, with wick and chimney. In order to furnish merely a 
 beam of light and not diffused rays, an asbestos chimney withjsmall opening is supplied in addition 
 to the glass chimney.$0.50 
 
 70-72 KEROSENE LAMP only, with wick and glass chimney. $0.32 
 
 70-73 METAL BOUND ASBESTOS CHIMNEY, only.18 
 
 70-90 ILLUMINATING BURNER FOR GAS for laboratory tables. Con¬ 
 sists of a burner tube 12 inches high mounted on heavy iron base . .80 
 
 70-92 LOW FORM ILLUMINATING BURNER, curved tube fitted with 
 illuminating tip. 
 
 This burner will be found very convenient for use with optical benches .65 
 
 No. 70-95 
 
 70-96 MONOCHROMATIC FLAME BURNER. Gases of various substances 
 generate in the glass cell and intermingling with the illuminating gas 
 
 give to the Bunsen flame the distinct monochromatic flame desired. 
 
 Complete as illustrated. $2.25 
 
 70-110 ELECTRIC LAMP, table size, adjustable from 12 to 18 inches, made 
 of polished brass, nickel-plated. 
 
 Complete as illustrated. 9.76 
 
 70-112 GAS LAMP, similar to above, but arranged for burning illuminating 
 gas- 
 
 Complete with Argand Burner and six feet of rubber tubing, with 
 
 goose-neck connection, stand adjustable from 12 to 18 inches . . . 9.76 
 
 70-116 KEROSENE LAMP, similar to above, but arranged with reservoir 
 for oil. 
 
 Complete . 9.75 
 
 
 
 No. 70-110 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 241 
 
 LILLIPUTIAN PROJECTING LAMP 
 
 The Lilliputian Projection Lamp was designed for the purpose of giving an intense beam of parallel rays espe¬ 
 cially suited for work in the physical lecture room. It has also been adapted for transparent projections for use where 
 ready and easily operated lantern outfit is desired. The occasion for offering this apparatus arose from the difficulty 
 of handling larger outfits in a way to most readily give desired results in physical experiments. 
 
 A Projection Lantern using from 12 to 15 amperes of current must necessarily require a rheostat of ample pro¬ 
 portions, a housing for the lamp designed to properly care for the heat generated, and a condensing system of sufficient 
 size for producing a picture from 12 to 16 feet in diameter at considerable distance from the lamp. It is apparent 
 that an apparatus designed for this work cannot be readily used on the lecture table where an intense, small parallel 
 beam of light only is required. To meet this requirement, a small lamp with automatic feed is supported with a 
 simple rheostat on an adjustable upright stand. 
 
 The condenser, being small and placed close to the arc, uses a relatively large proportion of the light rays. The 
 rays emerging from the condenser are parallel, forming an intense beam about 3 centimeters in diameter. 
 
 The current required is only 1.5 amperes at 110 volts pressure. The form of lamp above illustrated can only 
 be furnished for direct current. 
 
 The great variety of uses to which such an apparatus can be put will be apparent at once to those who have 
 long felt the need of such a source of light in lecture table work. As may be noted, the instrument is entirely self- 
 contained. The housing is adjustable in height. The necessary resistance is mounted on one of the legs of the 
 tripod base and binding posts for connections to circuit on the other legs. Close observation of scientific requirements 
 has enabled the manufacturers to furnish a lamp that may be readily moved from place to place, — one that al¬ 
 lows of universal adjustment both as to position of lamp and direction of the rays of light proceeding from the ap¬ 
 paratus. 
 
 Although exceedingly compact, renewal of carbons is simple. Their position within the housing is readily noted 
 through the window provided. 
 
 70-126 LILLIPUTIAN PROJECTION LAMP, as illustrated, with resistance on stand for direct current of 
 
 1.5 amperes at 110 volts, with ten extra carbons.Duty Free . . . 
 
 70-126 - —, same as above, but with resistance for 220 volts D. C.Duty Free . . . 
 
242 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 PHOTOMETRIC AND OPTICAL BENCHES 
 
 PHOTOMETERS 
 
 No. 71-10 
 
 71-10 RITCHIE PHOTOMETER for lecture room demonstration. 
 
 So little attention has been given to class demonstrations in Photometry that we believe our design 
 will meet with universal approval. A photometer head is provided with a prism, on the faces of 
 which light from two different sources can fall. A movable ring with^two uprights which support 
 a tilting mirror on horizontal axis may be turned in all directions that pupils in all parts of the 
 room may test the equality of illumination on both faces of the prism. Light shields are provided 
 to obstruct rays from the two sources of light striking the tilting mirror. 
 
 Complete as illustrated, mounted on stand..$9.75 
 
 No. 71-20 
 
 No. 71-30 
 
 71-20 INVERSE SQUARES MODEL for illustrating that the intensity of the illumination at a surface due 
 to a given source of light is inversely proportional to the square of the distance of the surface from 
 the source of light. 
 
 The apparatus consists of a wire frame constructed as illustrated, with a maximum axis of 8 inches. 
 Distances from the source may readily be measured and from the counting of the equal squares the 
 law may readily be formulated. This is a simple pedagogical model which at once brings to the 
 pupil the formulation of a law which oftentimes is particularly abstruse.$1.80 
 
 71-30 CAMERA OBSCURA, or PIN HOLE CAMERA, for illustrating images produced through a small 
 aperture. This camera consists of a rectangular box with pin hole opening in front and a second 
 telescoping box with ground glass plate for receiving the image.65 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 243 
 
 No. 71-40 
 
 • 
 
 71-40 LIGHT-ROOM DIBDIN-BUNSEN PHOTOMETER for determining the relative intensity of two 
 sources of light without the necessity of darkening the room. 
 
 This improved form consists of a light proof box in which at each end within separate compartments 
 are situated the sources of light. Between these sources slides the Dibdin-Bunsen Screen, mounted 
 in substantial holder connected as a part of the eye-shade as noted in the illustration and moving 
 with it. This Eye-shade and Screen Holder are fastened at either end by narrow opaque spring- 
 roller-bands attached to the Photometer Box in such a manner as to prevent light from entering the 
 Box. Doors are provided for access to either source of light or to the Dibdin-Bunsen Screen. 
 
 Without light sources.^.$13.75 
 
 71-50 STUDENT’S PHOTOMETER for determining by direct comparison with a standard the intensity of 
 a source of light. 
 
 The apparatus consists of a graduated rod at one end of which is attached a candle holder; at the other 
 a gas tube with tip. The rod is mounted on metal supports as illustrated in the apparatus of No. 
 
 22-160. 
 
 The photometer box with indicator is fitted with a Bunsen screen, Dibdin’s modification, placed be¬ 
 tween two mirrors fixed at such an angle that both sides of the screen can be viewed simultaneously 
 
 from the front. 
 
 This will be found a typical student’s instrument, capable of a fair degree of accuracy. Complete 
 
 as illustrated..$3.60 
 
 71-52 ELEMENTARY BUNSEN PHOTOMETER, simple form complete with Meter Stick, Supports for 
 same, Simple Bunsen Screen and Holder, Support for one and Support for Four Candles. Com¬ 
 plete . . . 1 -00 
 
 71-53 JOLLY PHOTOMETER HEAD after Fuller and Brownlee (Experiment 37), for use on Meter Stick 2.00 
 
 No. 71-60 
 
 71-80 RUMFORD’S PHOTOMETER for determining the relative intensity of two sources of light. 
 
 This Photometer consists of a wooden base board upon which are mounted two converging meter 
 sticks. At the point of convergence is mounted a blackened rod, designed to cast a shadow on the 
 opaque screen held in the vertical support as illustrated at the extreme left hand side. Two screens 
 fixed vertically on either side of the rod are designed for obstruction of all extraneous light. The 
 sources of illumination are mounted on a base board, one on either side of the light shield. 
 
 Complete as illustrated..$3.60 
 
244 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 GENERAL PHOTOMETRIC OR OPTICAL 
 BENCH ATTACHMENTS 
 
 PHOTOMETERS 
 
 71-100 CAST-ALUMINUM DIBDIN-BUNSEN PHOTOMETER for use as a comparison head in de¬ 
 termining candle power of a source of light. x 
 
 This photometer is a modification of the standard Bunsen Screen. In the Bunsen Screen the trans¬ 
 lucent and opaque portions do not transmit light equally. The grease spot, therefore, even when 
 equally illuminated, is never entirely lost. The Dibdin’s modification consists in exposing a star 
 of translucent paper mounted in heavier paper of the same texture. This screen is mounted be¬ 
 tween two mirrors at such an angle within a cast metal box that both sides of the screen may be 
 seen simultaneously. This cast metal box is mounted on a 10-millimeter rod for use with No. 
 
 5-810 Clamp. It is blackened inside and out. 
 
 The results possible with the Dibdin’s modification are accurate and quickly obtained. We desire 
 
 also to emphasize the advantage of our cast-metal casing over the sheet metal forms.$4.75 
 
 OPTICAL BENCH CANDELABRUM AND DRIP CUP, for use with No. 6-810 Clamp as a candle 
 
 holder on an optical bench “built up” from rods and clamps. 
 
 In the design of our Candelabrum we have overcome the objectionable features of the various types on the mar¬ 
 ket. We are enabled to center candles in groups of one, two, three, and four, almost instantly. 
 
 This design consists of a cast metal trough mounted on a rod of size for use in No. 6-810 Clamp. The Indi¬ 
 vidual Candle Holder is a casting with drip cup that fits into the trough with a sliding fit. Any or all the Holders 
 may be readily moved laterally in the trough to properly center the light. 
 
 CANDELABRUM TROUGH, mounted on a 10-millimeter rod, for use with No. 6-810 Clamp . . $0.60 
 
 INDIVIDUAL CANDLE HOLDER, for holding candles.15 
 
 BRASS KEROSENE LAMP, WICK, AND CHIMNEY, for use on table top No. 71-260 .32 
 
 LUMINOUS BURNER, especially designed for use with No. 71-210 T. & H. Light Box with Wire 
 
 Screen .. .45 
 
 INCANDESCENT LAMP HOLDER, mounted on rod with attachment for connection to the stand¬ 
 ard Edison socket. 
 
 Without lamp cord and Edison plug. .95 
 
 MOUNTED WELSBACH GAS MANTLE. 1.35 
 
 MOUNTED CONVEX GLASS MIRROR. This is a convex mirror, 3 inches in diameter, focus 
 6 inches, adjustably mounted in an improved holder for use with our No. 6-810 Right Angle Clamp 2.60 
 MOUNTED CONCAVE GLASS MIRROR. This is a concave mirror, 3 inches in diameter, focus 
 
 6 inches, adjustably mounted in an improved holder for use with our No. 5-810 Right Angle Clamp 2.60 
 ADJUSTABLE PLANE MIRROR ON ROD, mirror 50 millimeters in diameter, adjustable in 
 stirrup about a horizontal axis, adjustable on rod about a vertical axis. Mounted on nickel- 
 plated rod 15 centimeters long, for use with our No. 5-810 Clamp. 1.95 
 
 71-125 
 
 71-127 
 
 70- 72 
 
 71- 135 
 
 71-140 
 
 71-142 
 
 71-180 
 
 71-182 
 
 5-960 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 245 
 
 OPTICAL BENCHES 
 
 71-190 SCREEN WITH APERTURES. This is a metal screen on which is mounted a revolving disc with 
 apertures of different sizes. By revolving the disc these various sizes of holes center over the 
 large hole on the screen. It is mounted on a rod ready for use with No. 5-810 Clamp.$3.30 
 
 71-195 SCREEN WITH ADJUSTABLE VERTICAL SLIT. This is a metal screen with a two-part metal 
 slide which may be varied at will to secure a slit of any width up to one inch. Mounted on rod 
 ready for use with No. 6-810 Clamp. 3.30 
 
 71-200 SCREEN HOLDER, large size, for holding large pieces of cardboard, sheet gauze, etc. .75 
 
 71-205 SCREEN HOLDER, small size, for holding small pieces of cardboard, sheet gauze, etc. .65 
 
 71-210 T. & H. BOX WITH WIRE SCREEN, for use in determining the conjugate foci of a converging 
 lens. This box is especially designed to hold a source of light. It consists of a metal box in one 
 face of which is a slit covered by a wire screen. It is finished dead black throughout. .90 
 
 71-216 EYE-SHADES, for use on a photometer bench when it is desired to shade the eyes as well as the front 
 of the screen from rays from the sources of light. They consist of a pair of black cloth shades 
 
 suitably mounted for use with No. 5-810 Right Angle Clamp.Pair 1.30 
 
 71-225 GRADUATED CARDBOARD SCREEN, 10 X 10 centimeters, for use with No. 71-200 or 71-206 
 
 Screen Holder . .10 
 
 71-227 BLACK OPAQUE SCREEN, 10 X 10 centimeters, for use with No. 71-200 or 71-205 Screen 
 
 Holder . .20 
 
 71-230 TRANSLUCENT OR OPALESCENT SCREEN, 20 X 20 centimeters, for use with No. 71-200 
 
 Screen Holder. .28 
 
 71-235 CARDBOARD METRIC SCALES for use with No. 71-206 Screen Holder in determining the 
 magnifying power of a convex lens. A 5-centimeter and a 10-centimeter section of a metric scale 
 are mounted on cardboard, the centimeter lines of one ruled in red, in black on the other. Per Pair ■ .10 
 
 5- 970 UNIVERSAL LENS HOLDER for lenses up to 4 inches in diameter. This ingenious holder is ad¬ 
 
 justable by means of the rods and set screws to hold and clamp firmly, in or off center, lenses up 
 to 4 inches in diameter. Handsomely oxidized black with nickel-plated rod. (See illustration, 
 
 Section 6). .88 
 
 6- 975 -, same as above, for holding lenses up to 2 inches in diameter. .78 
 
 71-260 TABLE TOP ON ROD for general use in supporting objects on optical and photometric benches 1.16 
 
 71-255 IMAGE ON ROD for use with No. 6-810 Right Angle Clamp.65 
 
246 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 71-260 No. 71-260 (Sectional View) 
 
 71-260 LUMMER-BRODHUN PHOTOMETER. This is a modification of the grease spot photometer. 
 
 Light from the two sources falls upon the screen ik (see illustration), made of two sheets of paper 
 with tinfoil between, and placed perpendicular to the direction of the optical bench. The diffused 
 light emitted by these screens falls on two totally reflecting prisms and thence on to the faces be 
 and dp of the two prisms A and B. The part rs of the prism A which touches B is plane so that all 
 light falling on rs is transmitted. The eye placed at O thus receives from the side m only light 
 which passes through the ring rs and from the side n only light which is totally reflected from the 
 surfaces ar and bs. The eye thus sees a bright or dark spot within a uniformly bright circle. 
 
 When the photometer is so adjusted that e and f receive the same amount of light, the round 
 circle of light entirely disappears. 
 
 This photometer box is mounted in a frame on rod designed to fit our No. 6-810 clamp for use on an 
 
 optical bench.Duty Free $36.00 
 
 STANDARD SOURCES OF LIGHT 
 
 Nos. 71-269 and 71-270 
 
 71-266 HEFNER LAMP, approved by the Physikalisch-Technischen Reichsanstalt as the German Pho¬ 
 tometric Standard Source of Light, burning amyl-acetate. With flame measure, after regular 
 
 type, wick regulator and shears.. Duty Free $12.60 
 
 71r266 -, same as above, with certificate of the Physikalisch-Technischen Reichsanstalt . . Duty Free 16.60 
 
 71-267 HEFNER LAMP, with Flame Measure after Hefner-Alteneck, wick regulator and shears. Duty Free 12.60 
 
 71-268 -, same as above, with certificate of the Physikalisch-Technischen Reichsanstalt . . Duty Free 16.60 
 
 71-269 HEFNER LAMP, with Flame Measure, after regular type and also after Hefner-Alteneck, wick 
 
 regulator, and shears.Duty Free 19.60 
 
 71-270 -, same as above, with certificate of the Physikalisch-Technischen Reichsanstalt . . Duty Free 24.60 
 
 71-271 AMYL-ACETATE, C. P., for burning in the Hefner Lamp.Per Pound 1.80 
 
 71-272 STANDARD CANDLE, for use as photometric standard, made of sperm, six to the pound, will burn 
 
 120 grains (7.776 grams) per hour.Each .26 
 
 Note. No. 71-260 Table Top on Rod is used as holder for above sources of light. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 No. 98-141 
 
 247 
 
 Nos. 64-100 to 64-110 
 
 No. 98-142 
 
 98-142 MOUNTED SELENIUM CELL. For description see Section 98.$14.00 
 
 98-141 SELENIUM CELL. Same as above but unmounted. For description see Section 98.11.60 
 
 64-100 IMPROVED MINERALITE THERMOPILE “A.” For description see Section 64.11.76 
 
 64-110 IMPROVED MINERALITE THERMOPILE “B.” For description see Section 64.14.60 
 
 6-50d SQUARE SUPPORT ROD, ungraduated, 19 millimeters square X 100 centimeters long .... 2.30 
 
 6-60f , same as above, 19 millimeters square X 200 centimeters long. 4.46 
 
 5- 66a SQUARE SUPPORT ROD, graduated to millimeters, 19 millimeters square X 100 centimeters long 6.60 
 
 6- 66b -, same as above, 19 millimeters square X 200 centimeters long.. 10.76 
 
 6-810 RIGHT ANGLE CLAMP, for holding two rods in same plane but at right angles to each other . .68 
 
 6-376 END SUPPORTS, especially designed for holding bed-rod of optical benches. Extreme care is exer¬ 
 cised in machining these supports so that they will suit all requirements.Each .66 
 
 , PHOTOMETRIC AND OPTICAL BENCH OUTFITS 
 
 (Attachments included in the following outfits are illustrated on pages 244 and 245.) 
 
 For the convenience of those teachers who desire to order their Photometric or Optical Bench Outfits complete, 
 we list the following, which in use have been found most satisfactory. 
 
 71-327 UNIVERSAL TWO-METER PHOTOMETRIC OUTFIT WITH GRADUATED ROD, for use with 
 incandescent lamp as standard, complete as follows: 
 
 1 pair End Supports 1 Incandescent Lamp Holder on Rod 
 
 1 Graduated Two-Meter Rod 1 Welsbach Gas Mantle on Rod 
 
 1 Dibdin-Bunsen Photometer on Rod 3 Right Angle Clamps 
 
 Complete.$20.94 
 
 71-327A -, same as above, but with ungraduated rod.14.64 
 
 71-329 UNIVERSAL ONE-METER PHOTOMETRIC OUTFIT WITH GRADUATED ROD, same as 
 
 No. 71-327, but Graduated Rod is but one meter long.16.69 
 
 71-329A -, same as above, but with ungraduated rod.12.49 
 
 71-331 UNIVERSAL TWO-METER PHOTOMETRIC OUTFIT WITH GRADUATED ROD, complete as 
 
 follows: 
 
 1 Pair End Supports 1 Candelabrum Trough on Rod 
 
 1 Graduated Two-Meter Rod 4 Individual Candle Holders 
 
 1 Dibdin-Bunsen Photometer on Rod 1 Incandescent Lamp Holder on Rod 
 
 1 Pair Eye-Shades 5 Right Angle Clamps 
 
 Complete .23.46 
 
 71-331A -, same as above, but with ungraduated rod.17.16 
 
 71-332 UNIVERSAL ONE-METER PHOTOMETRIC OUTFIT WITH GRADUATED ROD, same as No. 
 
 71-331, bqt Graduated Rod is but one meter long.19.20 
 
 71-332A -, same as above, but with ungraduated rod.16.00 
 
 OPTICAL BENCHES 
 
 The above outfits, with the additions of a few attachments found on pages 244 and 245, will constitute excellent 
 optical benches. 
 
 We recommend the following additions to any of the above outfits. 
 
 71-340 OPTICAL BENCH ATTACHMENTS, consisting of Screen Holder, Graduated Opaque Screen, 
 
 Black Opaque Screen, Translucent Screen, Image on Rod and Lens Holder for lenses up to 4 
 inches in diameter.$3.66 
 
 Lenses, Section 74. Prisms, Section 74. Mirrors, Section 72. Candles, Section 70. 
 
248 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 •» 
 
 71-350 STUDENTS’ OPTICAL BENCH, a simple outfit for optical experiments by students. The apparatus 
 is shipped complete with meter stick, a lens holder, one lens with finished edges, inches diam¬ 
 eter, 15 centimeters focus, a pin holder, pair of metal supports for meter stick, screen holder, and 
 cardboard screen. .. $ 1.10 
 
 SIMPLE PHOTOMETRIC AND OPTICAL ATTACHMENTS 
 
 11-10 METER STICK.$0.28 
 
 71-352 LENS HOLDER.11 
 
 74-121 LENS, 1J4 inches diameter, 6 inches focus.24 
 
 22-160b METAL SUPPORTS FOR METER STICK.Per Pair .25 
 
 71-356 SCREEN HOLDER.08 
 
 71-225 GRADUATED CARDBOARD SCREEN.10 
 
 71-358 PIN HOLDER.08 
 
 71-376 BLOCK AND BENT WIRE for finding real and virtual images in a lens. 
 
 This is the standard piece so frequently called for in the many manuals in use among secondary 
 
 schools . .20 
 
 71-376 WIRE BENT AT RIGHT ANGLES after Hall, No. 73.02 
 
 71-360 MOUNTED CARDBOARD SCREEN.28 
 
 71-362 OPAQUE SCREEN WITH CROSSED OPALESCENT SQUARE OPENING, after Fuller and 
 
 Brownlee (Experiment 40). .30 
 
 71-364 BLACK AND WHITE OPAQUE SCREEN WITH SQUARE OPENING, after Fuller and Brown¬ 
 lee (Experiment 48). .20 
 
 71-366 BUNSEN SCREEN, simple form for use in Holders Nos. 71-356 and 71-368 .10 
 
 71-368 SCREEN HOLDER for use on meter stick, after Turner and Hersey (Experiment L011). .60 
 
 71-370 CANDLE HOLDER FOR ONE CANDLE, for use on meter stick, after Turner and Hersey (Ex¬ 
 periment L011). .30 
 
 71-372 -, for FOUR CANDLES for use on meter stick, after Turner and Hersey (Experiment L011) . .40 
 
 71-380 CARDBOARD DIAPHRAGM WITH ONE CENTIMETER OPENING, after Turner and Hersey 
 
 (Experiments L101 and L105) .06 
 
 71-400 CULLER’S PRINCIPLE FOCUS BOX, after Culler (Experiment XXXV) . 1.26 
 
 71-600 MOUNTED CONVEX LENS AND WIRE SCREEN, after Millikan, Gale and Bishop (Experiment 
 
 46).76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 249 
 
 REFLECTION OF LIGHT 
 
 MIRRORS 
 
 ' Nos. 72-10 to 72-45 
 
 72-10 PLANE GLASS MIRROR for experiments in reflection of light. Best German glass, 6 inches long 
 
 by 2 inches wide.Each $0.08 
 
 72-10a SPRING BRASS CLIPS for holding mirror to a block.Pair .30 
 
 72-10b VERTICAL INDEX BLOCK with white face, after Hall, No. 66.15 
 
 72-12 PLANE MIRROR, similar to No. 72-10, but 6 inches X 4 inches.Each .16 
 
 72-15 BLACKENED PLATE OF GLASS, after Millikan, Gale and Bishop (Experiment 42). .06 
 
 72-20 CONCAVE AND CONVEX CYLINDRICAL MIRROR. This is a cylindrical brass mirror, carefully 
 
 burnished on both sides and heavily nickel-plated. One side is concave and the other convex. Each .60 
 
 72-20a BRASS PLATE with four Projecting Needles, after Hall, No. 67a. .75 
 
 ! 72-20b BRASS PLATE with seven Projecting Needles, after Hall, No. 67b. 1.25 
 
 1 72-26 CONCAVE AND CONVEX SPHERICAL MIRROR. This is a spherical mirror of brass, 3 inches 
 in diameter, 6-inch focus. It is carefully burnished and nickel-plated on each side, one side convex 
 
 and the other concave . .50 
 
 72-35 CONVEX MIRROR. This is a carefully silvered glass mirror with a protective coating. It is 3 
 
 inches in diameter, with a focus of 6 inches. 1.25 
 
 72-37 CONCAVE MIRROR. This is a carefully silvered glass mirror with a protective coating. It is 
 
 3 inches in diameter, with a focus of 6 inches. 1.25 
 
 72-45 MOUNTED CONCAVE AND CONVEX MIRROR. This instrument consists of two mirrors, one 
 
 concave, the other convex, mounted in a circular wooden frame, with handle; diameter 5 inches . . 2.25 
 
250 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 \ 
 
 No. 72-70 
 
 No. 72-60 
 
 72-60 IMPROVED INCIDENCE AND REFLECTION APPARATUS for determining the law of reflection 
 
 of light. 
 
 In use, one arm is set at any desired position. Sighting across the second, this arm is moved until 
 the image of the first and the etched line of the mirror and the sighting edge of the second are in 
 the same straight line. If the positions of these index arms are noted on the graduated arc it will 
 be found that the Angle of Incidence is equal to the Angle of Reflection. $2.25 
 
 72-70 GAGE’S REFLECTION APPARATUS for demonstrating the law of reflection of light. 
 
 By glancing in the mirror through the hole marked “O” an image only of the hole is seen. If the 
 source of light is held before any of the other holes the image in the mirror can be seen only through 
 the hole equally distant on the other side of the normal to the mirror.. 2.45 
 
 22-146 INCIDENCE AND REFLECTION APPARATUS. The apparatus illustrated consists of an attach¬ 
 ment for our Universal Stand No. 22-130. 
 
 In use, the candle is placed in the holder and trimmed so that its flame may be on the plane with 
 the sight hole. It is then lighted. The arm for carrying the sight hole is moved along until the 
 rays of the candle flame are seen through the sight hole. By a glance at the sector line it will be 
 found that this Line of Reflection makes the same angle with the normal to mirror as the Line of 
 Incidence makes with this perpendicular, thus proving that the Angle of Reflection is equal to 
 the Angle of Incidence. 6.66 
 
 No. 72-90 No. 72-96 
 
 72-90 MULTIPLE REFLECTION APPARATUS for illustrating the phenomenon of multiple reflection. 
 
 This apparatus consists of a handsomely finished metal casting on which arc degree lines denoting 
 every ten degrees. Two mirrors, mounted on appropriate metal frames and hinged at the center 
 of the circle, are movable within 180°. In this casting a candle holder is provided for holding the 
 candle in the best possible position. A further advantage of this model is that the mirrors may be 
 unhinged from the center and mounted parallel, thus showing the infinite number of images that 
 may be formed in mirrors mounted parallel to each other. $6.60 
 
 72-96 PLACED IMAGE MULTIPLE IMAGE APPARATUS, after Hall and Bergen’s “A Text-Book of 
 
 Physics,” page 158. 
 
 In use the mirrors are placed upon the board with the reflecting surfaces making an angle of 90°, — in 
 the position as illustrated. The lighted candle should be of such height that its flame will not be 
 above the upper edge of the mirrors and should be exactly over the middle hole in front of the board. 
 
 The positions of the images of the candle should now be noted and pegs placed into the holes be¬ 
 hind the mirrors in such a position that, to an observer placed in front of tne mirrors, the images in 
 the mirrors and the pegs over the mirror will appear to coincide with the images. The experiment 
 should be modified with the mirrors at angles of 60° and 30° also. 2.76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 251 
 
 No. 72-100 
 
 72-100 KALEIDOSCOPE. This apparatus is a design of our own and consists of 3 mirrors, each separately 
 mounted in a metal frame and combined to form a case with mirrors at angles of 60°. One end 
 is closed by a disc of ground glass, the other is provided with a cap with an aperture. Fragments 
 of colored glass are placed at one end between the ground glass discs and the second clear glass disc. 
 
 The objects and their images when viewed through the aperture present themselves in an endless 
 variety of symmetrical forms as the Kaleidoscope tube is turned.$2.76 
 
 72-106 STUDENTS’ KALEIDOSCOPE, similar in design to above, but of simpler construction. 48 
 
 No. 72-126 No. 72-140 
 
 72-125 LUMINOUS CASCADE, used with a strong source of light and a condenser for showing total reflec¬ 
 tion by means of a jet of water. The cylindrical vessel illustrated is placed in front of the source 
 of light in such a way that the glass disc is parallel to, and about 2 centimeters from, the con¬ 
 denser. Water as pure as possible is poured into the vessel and allowed to issue from the jet 
 orifice. The stream of water is then seen to be illuminated for a considerable distance. 
 
 A pleasing modification of this experiment is to insert colored glass plates between the condenser 
 
 and the window of the vessel.$6.40 
 
 72-140 OPTICAL DISC TOTAL REFLECTION APPARATUS for showing total reflection in glass rods; 
 also illustrating the Luminous Cascade. 
 
 The apparatus consists of a dull black board designed for attachment to the face of the Optical Disc 
 as illustrated. On the board are mounted three bent glass rods, one of which is smooth, the other 
 two covered with small chinks of glass. The ends of these rods pass through a diaphragm on which 
 the light falls. Light, therefore, enters these rods through the ends. The effect is readily notice¬ 
 able. The smooth rod remains dark, while the ones with small chinks glisten with bright light. 
 
 The light, however, in the smooth rod, being conveyed further by total reflection, passes out in 
 nearly full strength upon a screen mounted to the face of the board; on the other hand, the spot 
 of light received on the screen from the rod with small chinks is noticeably fainter, inasmuch as the 
 light in the rod has partially passed out through the chinks in the walls causing the glistening 
 bright light. 
 
 This experiment is extremely effective when colored light is used. It has distinct advantages over 
 the Luminous Cascade No. 72-126, in that the observations of the experimenter are not disturbed 
 by the necessity of catching the water and refilling the apparatus. 
 
 Complete ready for attachment to face of Optical Disc.Duty Free . . . 
 
252 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 KOLBE-HARCOURT SELF-CONTAINED 
 
 UNIVERSAL INCLINATION OPTICAL 
 
 DISC 
 
 No. 73-10 
 
 Front View 
 Dial Tilted 
 
 The Optical Disc is doubtless the most satisfactory outfit ever designed for illustrating in simple and concise 
 form the fundamental laws of optics. 
 
 Rays of sunlight, direct or reflected, will show as white paths of light across the face of the dial. When a prism, 
 lens or mirror is placed in these paths, the light is refracted or reflected as may be noticed from the paths traced by 
 the rays of light. Results are clear and positive. They can be viewed by the whole class even across a large lecture 
 room. 
 
 A great many instructive experiments may be demonstrated and the phenomena studied by the entire class. In 
 a special pamphlet which we will send on application, we have suggested a few of these that can be considered as 
 fundamental. Experience will suggest many others. This instrument has been designed particularly for use in a 
 lecture hall. Our new model, the Kolbe-Harcourt Optical Disc, retains the same optical perfection of our original 
 design, yet the following mechanical characteristics greatly enhance its value and will readily serve to distinguish 
 our instrument. 
 
 FEATURES 
 
 1. The apparatus is self-contained in that prisms, lenses, mirrors, etc., are provided for on the in¬ 
 strument itself. 
 
 2. Any conceivable angle of tilt for the dial. 
 
 3. Shade and dial are independently mounted on separate axes and may be rotated independently of 
 each other. 
 
 4. Greater stability secured by our rectangular metal base with forked upright support. 
 
 5. The recessed portion with individual pockets for each optical part enables one to definitely locate 
 any of the parts when operating in a dark room. 
 
 6. The instrument is scientific in structure and appearance. 
 
 7. A 13-inch dial with improved graduations distinctly and clearly brought out by careful differen¬ 
 tiation of lines and figures. 
 
 PRICE, $16.50 
 

 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 
 253 
 
 
 A ray reflected from a plane 
 mirror. Angle of incidence equal 
 to angle of reflection. 
 
 Reflection from a concave 
 mirror. Showing convergence 
 of rays. 
 
 Reflection from a plane mirror. 
 Incident parallel rays are re¬ 
 flected parallel. 
 
 One-half of ray refracted. 
 Showing angle of refraction. 
 
 Total reflection. Showing 
 rays totally reflected at the hy- 
 pothenuse and reversed upon 
 emerging. 
 
 Refraction through double 
 convex lens. Showing con¬ 
 vergence of rays. 
 
 Ray partly reflected, partly 
 refracted. Showing angle of in¬ 
 cidence and refraction. 
 
 Refraction through double 
 concave lens. Showing diver¬ 
 gence of rays. 
 
 Reflection from a convex mir¬ 
 ror. Showing divergence of 
 rays. 
 
 Angle of deviation — mini¬ 
 mum angle of deviation. Show¬ 
 ing an incident ray emerging 
 parallel, since surfaces are par¬ 
 allel. 
 
 Ray totally reflected. By 
 turning disc, critical angle may 
 be determined. 
 
 Send for Special Pamphlet describing experiments suggested above in diagram. 
 

 254 
 
 KNOTT APPARATUS CO., BOSTON 
 
 73-60 DIVERGING RAY ATTACHMENT. This attachment consists of a system 
 of concavo-cylindrical lenses mounted in a frame and adjustably supported 
 in a clamp on a tripod stand. 
 
 In use the concavo-cylindrical surfaces are directed toward the light source. 
 
 Each individual lens sends out a bundle of diverging rays and one ray from 
 each lens will pass through the slit in the screen, forming a system of diverg¬ 
 ing rays which appear to come from the slit as a source and cross the face of 
 the dial. 
 
 Many of the experiments described under the Kolbe-Harcourt Optical Disc 
 should be repeated, using the diverging rays. Better educational results are 
 secured if diverging rays through but two slits are used and the light through 
 one of these slits be made to pass through a colored strip of glass placed 
 under the clips provided on the screen for the purpose. This arrangement 
 enables one to definitely locate the different foci and to trace the formation 
 of real and virtual images. 
 
 Diverging Ray Attachment complete as illustrated.$6.60 
 
 73-76 
 
 No. 73-60 
 
 No. 73-76 
 
 REFRACTION TANK for study of refractions in water and for 
 determining the index of refraction of any liquid inactive upon 
 the metal. 
 
 This attachment, which fastens to the center of the Kolbe Optical 
 Disc, consists of a circular tank with glass front. This glass 
 covers slightly more than one-half circle so that the water level 
 may be used at the 90-90 mark. That results may be quanti¬ 
 tatively made the whole-circle back is graduated. 
 
 In use the tank is attached to the face of the disc and filled to the 90-90 degree line 
 with the liquid to be studied. A ray of light is then allowed to strike the surface of 
 the liquid. This ray traces a path through the liquid which may be read through it. 
 From the Angle of Incidence read from the face of the disc and Angle of Refraction 
 read from the graduated circular back the Index of Refraction of the Liquid may be 
 determined. 
 
 Refraction Tank ready for use on disc. 
 
 $3.36 
 
 No. 73-80 
 
 73-80 POLARIZED LIGHT ATTACHMENT. This device is used in studying the fundamental phenomena 
 of Polarized Light, — uniform reflection of ordinary unpolarized light, polarization by reflection, 
 polarization by multiple refractions, chromatic polarization and many other important phenomena 
 that readily suggest themselves when the instrument is in use. 
 
 All parts of this attachment are fastened to a rectangular metal plate which, in use, is held to the face 
 of the disc by means of thumb screws. At one end of the rectangular metal plate will be found the 
 holder for the polarizers, — the single plate of glass and the bundle of glass plates; at the other end is 
 the analyzer, — a heavy black glass plate held at proper inclination and position in a special holder 
 which permits of rotary motion. To this same holder is attached the projection screen in rotary ad¬ 
 justment. Between analyzer and polarizer is situated the stage provided with a simple holder for 
 specimens for study under polarized light. 
 
 The attachment is fastened to the dial of the Kolbe-Harcourt Optical Disc in the same manner as are 
 the various optical parts in previous experiments, short thumb screws provided with the attachment 
 being used for this purpose. Use the full beam of light through the rectangular opening in the shade 
 
 $8.26 
 
 73-90 THE COWEN N. and F. APPARATUS for use on Optical Disc to illustrate near and far sightedness 1.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 255 
 
 No. 73-101 
 
 HARCOURT IMPROVED STUDENTS’ 
 
 OPTICAL DISC 
 
 
 The Kolbe-Harcourt Optical Disc previously illustrated and described, was designed and especially constructed 
 with universal adjustment for use in lecture work. No. 73-101, above illustrated, is a simplified form utilizing the 
 same optical parts but for use in horizontal position only. The design is particularly adapted to experiments de¬ 
 scribed in our National Physics Direction Sheets Nos. L110 to L118, a full list of these experiments being supplied 
 with each outfit. 
 
 Illustrated above and in our National Physics Direction Sheets Nos. L110 to L118 will be noted our Incan¬ 
 descent Lamp and Shield. This apparatus has been found, a most convenient and satisfactory source of light. 
 
 Direction sheets are furnished and the Students’ Optical Disc is particularly adapted to following experiments:— 
 
 1. With Plane Mirror, — Law of Reflection; Parallel Rays; Diverging Rays; Image of a Point. 
 
 2. With Concave Mirror, — Normal Incidence; Principal Focus; Parallel Beam by Reflection; Spherical 
 Aberration; Caustic Curve. 
 
 3. With Convex Mirror, — Parallel Rays; Principal Focus; Virtual Image of a Point. 
 
 4. With Trapezoidal Glass Plate, — Lateral Aberration; Path of Ray through Prism; Minimum Devia¬ 
 tion; Disperson. 
 
 5. With 45 Degree Right Prism, — Single and Double Total Internal Reflection. 
 
 6. With Convex Lens — Ray through Optical Center; Principal Focus; Spherical Aberration; Conju¬ 
 gate Foci. 
 
 7. With Concave Lens, — Ray through Optical Center; Principal Focus. 
 
 8. With Semi-circular Glass Plate, — Ray passing between Glass and Air; Index of Refraction for Glass; 
 
 Critical Angle; Total Internal Reflection. 
 
 HARCOURT IMPROVED STUDENTS’ OPTICAL DISC without Optical Parts.$8.76 
 
 73-102 OPTICAL DISC GLASS PARTS, complete as described under No. 73-101. 6.26 
 
 Note. One set No. 73-102 will be found sufficient for four groups of pupils. 
 
 73-106 SPECIAL 110-VOLT LIGHT BOX, designed by C. Brooks Hersey of the Masten Park High School, 
 Buffalo, New York, for general laboratory work 
 
 3.26 
 
7 
 
 255 L. E. KNOTT APPARATUS CO., BOSTON 
 
 REFRACTION OF LIGHT 
 
 Nos. 74-50 to 74-62 
 
 74-60 INDEX OF REFRACTION PLATE, GILLEY FORM, for determining the index of refraction of glass. 
 This is a standard glass index of refraction plate, universally described in text-books and manuals. 
 Dimensions, 3X4 inches. Polished edges. 
 
 74-56 EQUILATERAL PRISM, after Millikan and Gale’s “A Laboratory Course in Physics” (Experiment 
 43). This is a triangular prism of heavy glass plate, 75-millimeter edge. Edges polished . . . . 
 
 74-60 GLASS CUBE for the determination of the index of refraction of glass. Polished faces, 30-milli¬ 
 meter edge. 
 
 74-62 - —, same as above, but 50-millimeter edge. 
 
 No. 74-76 No. 74-65 
 
 74-76 GILLEY INDEX OF REFRACTION OF WATER BOARD for determining the index of refraction of 
 
 water. 
 
 This apparatus consists of a thin board attached to a cross-head. The cross-head is of the size and 
 length to hold the board perpendicular in the jar of water. The line of sight as well as the water 
 level is determined by means of pins. Without Jar. 
 
 31-265c GLASS JAR for above, 6X8 inches. 
 
 74-81 BRASS PARTITION with attached clamps according to Hall and Bergen. 
 
 74-82 BRASS CLAMPS with index points according to Hall and Bergen.Each 
 
 74-85 ADJUSTABLE SIGHTING ARM INDEX OF REFRACTION OF WATER APPARATUS, a greatly 
 
 improved design according to Culler’s “Laboratory Manual of Physics” (Experiment XXXIV). Can 
 be clamped on any jar, square or round, — an important feature in that the angle of refraction 
 may be accurately transferred to the note-book page by removing the apparatus from jar and 
 pressing needle points down into the blank sheet. Without jar. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 257 
 
 No. 74-90 No. 74-92 
 
 74-90 PRATT INSTITUTE INDEX OF REFRACTION APPARATUS for determination of Index of Re¬ 
 fraction of Water. 
 
 This instrument consists of a metal casting holding a metal strip with spring grip in each of the four 
 slots. The lower ends of the two inner strips are intended to give the line of water, the strip at right 
 of the illustration to give the angle of incidence. In use the lower end of this strip touches the 
 water line, the line of sight starting over the beveled top. The fourth strip is adjusted to give the 
 line of refraction. Beginning with the strip at the left, then, the line of sight is over the top of the 
 first across the bottom of the second to the bottom of the fourth. When these points are obtained 
 the instrument is taken from the jar and the straight edges placed on a sheet of paper and the line 
 of sight drawn. Index may be determined by ordinary geometrical method or the sines of the angles 
 obtained may be secured from any logarithmic table. 
 
 The simplicity of this instrument will appeal to all. The facility of use, scientific observation of de¬ 
 tails and appearance will doubtless be noted. Without jar.$2.10 
 
 74-92 UNIVERSAL DIRECT READING INDEX OF REFRACTION APPARATUS for determining the 
 index of refraction of any colorless liquid, — acid or alkali. 
 
 This instrument consists of a base on which is mounted a graduated rod. On this rod is fitted a frame, 
 free to move up and down the rod, and which may be clamped wherever desired by means of set 
 screws. To this frame are attached an arc and a side tube with cross-wire. This side tube is swiv¬ 
 eled at the center of the arc. A clear glass jar is held to the base, close up to the frame, by means 
 of spring clips fastened to the base. The side nearest the arc has engraved on its face four lines. 
 
 The opposite side is provided with a metal frame on which slides a screen with movable slit. The 
 line of sight, therefore, is from the cross-wire inside of the tube through the tube through one of 
 the lines engraved on the jar to the slit on the opposite side of the jar. 
 
 The apparatus is accurately constructed, graduations clear and distinct, handsomely finished. 
 
 Three methods of determining the index of refraction of a liquid are possible: 
 
 1. Index of Refraction may be read from the arc, and the sines of the angles from any 
 
 logarithm table. 
 
 2. Length of the sines may be read directly by means of the sliding index on the graduated 
 
 rod. 
 
 3. The index may be determined by the usual geometrical construction of the angles to the 
 
 mensuration of the sines. 
 
 Apparatus complete as illustrated, furnished with simple laboratory directions.4.30 
 
 74-96 REFRACTION TANK for experiments on refraction at plane surfaces. 
 
 This tank consists of a semi-circular vessel of glass, one side 
 of which is curved, and the other side opaque except for 
 the slit through which the light may enter the tank. The 
 reading of the path of the light may be made when the 
 tank is empty. 
 
 This is an interesting and instructive experiment and the 
 apparatus is sufficient in size for use in lecture experi¬ 
 ments .' . . . $8.00 
 
 
 No. 74-96 
 
258 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 DEMONSTRATION LENSES 
 
 Used by express permission of copyright owner 
 
 No. 74-107 
 
 74-107 DEMONSTRATION LENSES. A set of 10 lenses, each 3 inches in diameter. 
 
 These lenses include one each of the following types: 
 
 Double-convex, double-concave Cylindrical-convex, cylindrical-concave 
 
 Plano-convex, plano-concave Sphero-cylindrical, sphero-prismatic 
 
 Periscopic convex, periscopic concave 
 
 The complete set of 10 lenses, 3 inches in diameter.$12.60 
 
 74-110 DEMONSTRATION LENSES. Set including one each of the following lenses: 
 
 Double-convex, double-concave Plano-convex, plano-concave 
 Periscopic convex, periscopic concave 
 
 Set of 6 lenses, 2 inches in diameter, in box. 2.50 
 
 74-112 -, set of 6 lenses, same as above, IK inches in diameter, enclosed in cardboard box . 1.26 
 
 LABORATORY LENSES 
 
 DOUBLE CONVEX LENSES, highest quality, carefully polished, ground edges. 
 
 Number . . 
 
 . 74-118 
 
 74-120 
 
 74-121 
 
 74-122 
 
 74-122a 
 
 74-123 
 
 74-124 
 
 74-125 
 
 74-126 
 
 Diameter . . 
 
 • IK 
 
 IK 
 
 IK 
 
 2 
 
 2 
 
 2 K 
 
 3 
 
 4 
 
 4 inches 
 
 Focus . . . 
 
 . 2 
 
 4 
 
 6 
 
 5 
 
 20 
 
 6 
 
 7 
 
 10 
 
 16 inches 
 
 Each . . . 
 
 . $0.60 
 
 .27 
 
 .24 
 
 .42 
 
 .36 
 
 .60 
 
 .76 
 
 .95 
 
 1.30 
 
 DOUBLE CONCAVE LENSES, highest quality, carefully polished, ground edges. 
 
 Number . . . 
 
 74-160 
 
 74-161 
 
 74-162 
 
 Diameter . . . 
 
 IK 
 
 IK 
 
 2 
 
 Focus .... 
 
 6 
 
 8 
 
 8 
 
 Each .... 
 
 .22 
 
 .22 
 
 .60 
 
 74-163 
 
 3 inches 
 6 inches 
 
 .90 
 
 CONDENSING LENSES, plano-convex, highest quality, carefully polished, ground edges. 
 Number . . . 74-170 74-171 74-172 
 
 Diameter . . . 4J4 4K 5 
 
 Focus .... 6^ 10 8 
 
 Each .... $1.10 ' 1.10 1.70 
 
 74-173 
 
 6 inches 
 10 inches 
 
 6.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 259 
 
 MISCELLANEOUS LENSES 
 
 No. 74-190 No. 74-230 Nos. 74-220 to 74r-225 
 
 74-180 WATER LENS. This is a hollow plano-convex vessel, with opening for introduction of water. 
 
 Diameter 80 millimeters. 
 
 74-182 WATER LENS. This is a hollow double-convex vessel, with opening for introduction of water. 
 
 Diameter 80 millimeters. 
 
 74-190 DEMONSTRATION ACHROMATIC LENS. This lens, in reality, consists of 2 lenses, a concave 
 and a convex lens, each 1 Y 2 inches in diameter, accurately ground to fit each other. Achromatism 
 
 positive. Per Pair 
 
 74-192 ACHROMATIC LENS, consisting of two lenses, a diverging concavo-convex flint glass lens and a 
 double-convex crown glass lens, accurately ground and polished, and perfectly fitted to each 
 
 other. Diameter 2 inches, focus 8 inches. 
 
 74-210 MOUNTED CONDENSING LENS. This is a condensing lens 5-inch diameter, 8-inch focus, mount¬ 
 ed on the Hall Universal Stand, adjustable to height and plane. The stand is of brass and of a 
 design constructed to facilitate in obtaining all positions desired for the lens in laboratory prac¬ 
 tice. Brass parts are polished and lacquered; base is finished in black japan. 
 
 Complete as illustrated. 
 
 74-215 MOUNTED DOUBLE-CONVEX LENS. This is a double-convex lens, 4-inch diameter, 14-inch focus, 
 
 mounted in a universally adjustable stand described under No. 74-210. 
 
 74-220 MOUNTED HOLLOW PLANO-CONVEX LENS. This is an 80 mm. plano-convex water lens, 
 
 mounted as illustrated.! . . . . 
 
 74^-226 MOUNTED HOLLOW DOUBLE-CONVEX LENS. This is an 80 mm. double-convex water lens, 
 
 mounted as illustrated above. 
 
 74r-230 READING LENS. This is a double-convex lens, mounted in a metal frame and provided with 
 handle. Diameter of lens 3 inches. 
 
 $3.90 
 
 3.90 
 
 .75 
 
 4.80 
 
 5.65 
 
 5.25 
 
 5.25 
 
 5.25 
 
 1.00 
 
 74-231 LONG FOCUS LENS with handle.60 
 
 74-236 POCKET MAGNIFIER (LINEN TESTER). This is a small double-convex lens, short focus, 
 
 J/£-inch aperture. It is mounted in a brass piece that may be folded into small compass .... .44 
 
 74-240 KUEHNE’S EYE MODEL for the demonstration 
 and study of the optical construction of the eye, 
 its normal and abnormal condition and the neces¬ 
 sary corrections. 
 
 The apparatus consists of a water-tight rectangular 
 box with various accessories, such as the two cor¬ 
 neas, one of which is fitted with a cylindrical lens, 
 two eye lenses of different foci, three diaphragms, 
 retina and six glasses to be used in front for cor¬ 
 recting errors. 
 
 Apparatus complete as above described, including 
 
 full instructions for use..$28.00 
 
 74-247 MODEL OF HUMAN EYE of plaster of paris. Dis- 
 
 sectible .'. 6.60 No. 74-240 
 
26 o 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 LABORATORY PRISMS 
 
 Used by express permission of copyright owner 
 
 Nos. 
 
 
 74-295 74-297 74-280 
 
 74-282 
 
 74-305 
 
 
 74-316 74-285 
 
 74-307 
 
 74-275 
 
 74-287 
 
 74-276 STUDENTS’ ODD ANGLE GLASS PRISMS for general laboratory use, particularly for deter¬ 
 mining the index of refraction. 
 
 The tendency of pupils to copy results has led to the demand for prisms with odd angles. This set 
 is one that has found favor in the laboratories of Cornell University and we have no hesitancy in 
 recommending its use in any laboratory. The set consists of six prisms about 1 inch high and 
 1 inch face, with the following angles: first prism, 55°, 65°, and 60°; second prism, 48°, 69°, and 
 63°; third prism, 54°, 67°, and 59°; fourth prism, 42°, 74°, and 64°; fifth prism, 43°, 74°, and 63°; 
 sixth prism, 23°, 90°, and 67°. 
 
 Set of six prisms in neat cardboard box. 
 
 74-280 EQUILATERAL PRISM, flint glass, square ends, 30-millimeter face, 4 inches long. 
 
 74-282 EQUILATERAL PRISM, flint glass, square ends, 30-millimeter face, 6 inches long. 
 
 74-285 EQUILATERAL PRISM, flint glass, square ends, 50-millimeter face, optically true surface, 4 inches 
 long .Duty Free 
 
 74-287 EQUILATERAL PRISM, flint glass, square ends, 40-millimeter face, about 2 inches long, surfaces 
 optically true.Duty Free 
 
 74-296 EQUILATERAL PRISM, crown glass, square ends, 25-millimeter face, 1% inches long. 
 
 74-297 EQUILATERAL PRISM, crown glass, square ends, 25-millimeter face, 2 inches long. 
 
 74-305 RIGHT ANGLE PRISM for total reflection, angles of 45 and 90°, sides 25 by 25 millimeters, length 
 
 1 Yl inches. 
 
 74-307 RIGHT ANGLE PRISM for total reflection, angles of 45 and 90°, sides 38 by 38 millimeters, length 
 
 2 inches. 
 
 74-315 FLINT GLASS PRISM, refracting angle of 20°, sides 41 millimeters, length \ l /& inches .....' 
 
 $9.50 
 
 .60 
 
 .76 
 
 14.26 
 
 10.60 
 
 .36 
 
 I 
 
 .48 
 
 .60 
 
 .75 
 
 .50 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 261 
 
 SPECTROSCOPIC PRISMS 
 
 Used by express permission of copyright owner 
 
 ' No. 74-367 No. 74-366 
 
 Nos. 74-360 a-e, to Nos. 74-360 a-e 
 Nos. 74-390 a-c Nos. 74-400 a-c 
 
 74-360 FLINT GLASS EQUILATERAL SPECTRAL PRISMS, optically true surfaces, square ends. 
 
 Refractive Index for D = 1.602; Dispersion C-F — 1° 58'; Minimum for M/D = 55° 20' 
 
 a b c d e 
 
 Side . 25 30 35 40 50 millimeters 
 
 Each, Duty Free . . $4.76 6.26 6.26 7.40 9.76 
 
 Each from Stock . 6.26 
 
 74-360 CROWN GLASS EQUILATERAL SPECTRAL PRISMS, optically true surfaces, square ends. 
 
 Refractive Index for D = 1.517; Dispersion C-F = 41'; Minimum for M/D = 50° 24' 
 
 a b c d 6 
 
 Side . 25 30 35 40 50 millimeters 
 
 Each, Duty Free . . $4.76 6.26 6.26 7.40 9.76 
 
 Each from Stock 6.26 
 
 74-366 CROWN GLASS SPECTRAL PRISM, angles of 45 and 90 degrees, cathetus 25 millimeters. 
 
 Duty Free $6.26 
 
 74-367 CROWN GLASS SPECTRAL PRISM, angles of 45 and 90 degrees, cathetus 50 millimeters. 
 
 Duty Free 9.40 
 
 74r-370 RUTHERFORD’S COMPOUND ACHROMATIC PRISMS, consisting of a flint glass prism luted 
 between two crown glass prisms. 
 
 3. t) C d 6 
 
 Side . 20 30 40 50 60 millimeters 
 
 Each, Duty Free . . $9.76 14.60 23.26 38.60 49.76 
 
 74-380 AMICI’S DIRECT VISION PRISMS, consisting of three prisms so arranged as to give direct vision. 
 
 abed 
 
 Cross-cut . 10 20 30 40 millimeters 
 
 Each, Duty Free . . $4.76 12.26 18.60 39.76 
 
 74-390 EQUILATERAL QUARTZ PRISMS, with the refracting edge perpendicular to the optical axis. 
 
 a b c 
 
 Side . 25 35 45 millimeters 
 
 Each, Duty Free . . $8.60 14.26 22.00 
 
 74-400 EQUILATERAL QUARTZ PRISMS, having the refracting edge parallel to the optical axis 
 
 a b c 
 
 Side . 25 35 45 millimeters 
 
 Each, Duty Free . . $8.60 14.26 22.00 
 
262 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 74-410 
 
 74-420 
 
 74-426 
 
 74-430 
 
 74-432 
 
 74-434 
 
 74-436 
 
 74-438 
 
 MISCELLANEOUS PRISMS 
 
 No. 74-410 No. 74-426 
 
 ACHROMATIC PRISMS, faces polished optically true and carefully fitted. 
 
 a b c 
 
 Aperture . 25 35 50 millimeters 
 
 Each, Duty Free . . . $6.76 7.40 9.80 
 
 WEINHOLD’S DEMONSTRATION PRISMS for explaining dispersion and achromatism without 
 
 deviation of the mean ray. 
 
 Consists of three prisms, two of crown and one of flint glass, ground and polished optically true. 
 
 Set of three, without mounting of any kind.Duty Free $9.76 
 
 POLYPRISM for showing that the angle of deviation increases with the refractive index. 
 
 Each prism consists of four glass parts which are unequally refringent, luted to form a prism. Length 
 of side, 35 millimeters.,.. Duty Free 9.26 
 
 No. 74-430 
 
 No. 74-432 Nos. 74-434 to 74-436 
 
 IMPROVED CAST HOLLOW PRISM. The design illustrated above pictures our new model 
 hollow prism, indestructibly constructed of cast metal with openings in two sides closed in an 
 ingenious manner by optical plate glass. This prism will be found adequate for most laboratory 
 work, and results are entirely satisfactory. 
 
 It is finished with a durable dull black coating. 
 
 OPTICAL GLASS CEMENTED FACE HOLLOW GLASS PRISM, two faces cemented and polished, 
 the third face blackened, ground glass stopper, height 65 millimeters, face 32 millimeters . . . 
 
 HOLLOW GLASS PRISM, equiangular, of best ground and polished crystal plate glass, with ground 
 glass stopper, partition cemented in the middle for two liquids. Mounted on wooden foot, 120 
 millimeters high by 80 millimeters face.Duty Free 
 
 ■, same as above, but 100 millimeters by 60 millimeters wide 
 
 Duty Free 
 
 $3.76 
 
 6.60 
 
 7.60 
 
 6.26 
 
 No. 74-438 
 
 WEDGE-SHAPED TROUGHS, a pair of wedge-shaped troughs each 6 inches long by 2 inches wide, 
 
 refractive angles of 20°.Duty Free $6 60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 263 
 
 MISCELLANEOUS PRISMS 
 
 No. 74-460 
 
 No. 74—460 
 
 74-460 MOUNTED EQUILATERAL PRISM. This is a 4-inch equilateral prism, mounted’on the Hall 
 Universal Stand as illustrated. This stand can be raised and lowered to any desired height or in¬ 
 
 clined to any angle. It is handsomely finished and the base offers a substantial support .... $6.76 
 
 74-462 -, similar to above, but prism 6 inches long. 6.76 
 
 74-466 MOUNTED TOTAL REFLECTION PRISM, consisting of a right angle prism, flint glass, angles of 
 
 45° and 90° mounted on stand as illustrated in No. 74-460 . 6.76 
 
 74-460 WEINHOLD’S DEMONSTRATION PRISM for explaining dispersion and achromatism without 
 deviation of the mean ray. 
 
 This apparatus consists of a set of three prisms conveniently mounted for the greatest utility 
 and ease of adjustment. The lower combination gives an achromatic arrangement, while the upper 
 gives direct vision dispersion. For demonstration, best results are secured by arranging the 
 prisms so that the field is divided into three portions, the center of which is due to the combina¬ 
 tion. (See illustration at right.) 
 
 Complete with three prisms, each separately mounted, with supporting stand .... Duty Free 
 
 No. 74-480 
 
 74-470 DIRECT VISION PRISM, after the original specifications of the 
 late Mr. Eaton of Brooklyn, N. Y., for projection of spectra 
 on a screen. 
 
 This prism consists of a combination of two prisms, one of dense 
 glass, the other a hollow prism which in use is filled with carbon 
 bisulphide, the angles of each of which are very nicely cal¬ 
 culated, giving a direct vision spectrum of large dispersion. 
 At a distance of twenty feet from the screen, with a J^-size 
 objective, it is possible to secure a clear spectrum band 6 feet 
 long by 2 feet wide. 
 
 Mounted on rod telescoping into neat tripod stand. 
 
 74-480 POLYPRISM, illustrating the phenomena of multiple refrac¬ 
 tion. 
 
 This apparatus consists of a cylindrically shaped wooden frame, 
 in one end of which is mounted a prism, the face of which is 
 cut into a series of very small prisms. The other end is pro¬ 
 vided with an aperture, so that an object such as a line may be 
 viewed. 
 
 Curious and interesting modifications of the shape of an object 
 are noted. The apparatus is small, easily handled, and will 
 be found of considerable qualitative value. 
 
264 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 OPTICAL INSTRUMENTS 
 
 TELESCOPES — SEXTANTS 
 
 No. 76-30 
 
 76-30 ACHROMATIC TELESCOPE, extra quality, morocco-covered body, polished brass slides, cap for 
 object glass and sliding cover for eye lens. Length, closed, 534 inches, three draws to 14 inches long, 
 magnifying, power 12 diameters. $3.26 
 
 ASTRONOMICAL TELESCOPES 
 
 
 V,. No. 76-80 
 
 Among the high-grade telescopes now presented to the public no instruments have become so widely or so de¬ 
 servedly popular as the line herewith listed. Due to improved methods of manufacture and the consequent dimin¬ 
 ishing of the manufacturing cost, a high-grade instrument, like an astronomical telescope, has ceased to be the mere 
 instrument of a profession, and the prices have become so reasonable that it is possible for a school or college to num¬ 
 ber one among its equipment. 
 
 The instruments herewith listed are noted for their optical range and capacity. The mechanical features are 
 unexcelled and all accessories are of the same high quality. The policy of the manufacturers has been to make of 
 each telescope an instrument reliable in quality and moderate in price. Each instrument is furnished fully equipped 
 for good work by day or night. 
 
76-60 
 
 76-66 
 
 76-60 
 
 76-66 
 
 76-70 
 
 76-76 
 
 76-60 
 
 76-86 
 
 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 PORTABLE ASTRONOMICAL TELESCOPE. This instrument has been designed light in weight 
 for use on a table or stand. It has the same high optical qualities as have all the models of this 
 manufacturer. Body of telescope, sliding tube for eye-pieces, and tubular support for table tripod, 
 are of polished brass. Feet of tripod are wrought steel, japanned. The instrument has detachable 
 sun-glass, brass cap for protection of object glass, and rack and pinion focusing adjustment. Three 
 eye-pieces are furnished: one terrestrial eye-piece, power 45, and two astronomical eye-pieces, 
 powers 50 and 114. Diameter of object lens, 3 inches; length of tube when closed, about 39 inches, 
 — when extended, about 59 inches. 
 
 Telescope enclosed with table tripod in neat wooden box.Duty Free 
 
 -, same as above, but provided with large hardwood tripod in addition to the table tripod above fur¬ 
 nished. Enclosed in neat wooden box.Duty Free 
 
 ASTRONOMICAL TELESCOPE. This instrument is somewhat more elaborate than the preceding 
 and has a greater focal length. In addition, the tripod is especially designed for stability and 
 strength and is furnished with a simple but effective cranking adjustment for increasing or decreas¬ 
 ing the height of the telescope. It is made of finely finished mahogany. Its construction insures 
 
 • rigidity and affords special steadiness of the telscope. 
 
 Each instrument includes a sun-glass, and three eye-pieces, one terrestrial and two astronomical. 
 The power of the terrestrial eye-piece is 54 and the powers of the astronomical eye-pieces are 60 
 and 120. The size of the object lens is 3 inches; the telescope body with cap is of polished brass; 
 length of tube when closed, about 46 inches, — extended, about 63 inches. 
 
 The instrument is furnished in wooden box with handle, lock, and key.Duty Free 
 
 -, similar to above, except that the object lens is 334 inches in diameter and the telescope is some¬ 
 what larger in size. The magnifying power of the terrestrial eye-piece is 59. The powers of the 
 
 astronomical eye-pieces are 65 and 130. Length of tube closed is about 48 inches, — extended, 
 68 inches. 
 
 In neat wooden box with handle, lock and key.Duty Free 
 
 -, same as above, but provided with a “finder.” This telescope is provided with a sun-glass and 
 
 five eye-pieces: two terrestrial, magnifying 49 and 59 respectively, and three astronomical eye¬ 
 pieces, magnifying respectively 65, 88 and 146 times. 
 
 Enclosed in wooden box.Duty Free 
 
 -, same as above, except that object lens is 3% inches in diameter, and the instrument is fur¬ 
 nished with two terrestrial eye-pieces, powers 55 and 66, and four astronomical eye-pieces, powers 
 74, 99, 147, and 221. Length of tube closed, about 53 inches, — extended, about 73 inches. 
 
 Enclosed in wooden box.Duty Free 
 
 ASTRONOMICAL TELESCOPE (illustrated on preceding page). Uniting all the chief advantages 
 of the types previously listed, this telescope is also provided with still another desirable feature. 
 Each instrument is provided with two slow motions, making it possible for the astronomical observer 
 to control the telescope with greater precision and with the least possible vibration. Tangent 
 screws encased by rods that may be slowly turned by a very slight motion of the hand enable the 
 observer to keep the object in field of view. 
 
 The telescope includes “finder,” sun-glasses for the astronomical eye-pieces and five eye-pieces; two 
 terrestrial eye-pieces, powers 49 and 59, and three astronomical, powers 65, 88 and 146. The 
 size of the object lens is 3)4 inches. Telescope body, etc., are of polished brass, with brass cap to 
 protect the eye lens. The tripod is especially strong and stable, and is constructed of mahogany, 
 and, in addition to the slow motion adjustments already noted, has a special cranking mechanism 
 
 for adjustment of the height. Length of tube when closed, about 48 inches, — extended, about 
 68 inches. 
 
 In wooden box with handle, lock and key.Duty Free 
 
 —, same as above, but larger in size. Object lens 3% inches in diameter. Six eye-pieces: two 
 terrestrial eye-pieces, powers 55 and 66, and four astronomical, powers 74, 99, 147 and 221. Length 
 of tube when closed, about 53 inches, — extended, about 73 inches.Duty Free 
 
 265 
 
266 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 
 These models consist of lenses mounted in holders placed appropriately for the best definition. 
 
 The holders are mounted on a cross-head attached to a neatly finished wood stand. The paths whicl> 
 the rays take are sketched on the flat face of the cross-head. These models will be found instructive and 
 as the magnification and definition are excellent they will be found of great utility. 
 
 
 No. 75-164 
 
 No. .76-150 
 
 76-150 GALILEO’S TELESCOPE MODEL, comprising two lenses, the object glass, and a diverging or 
 double concave eye-piece. This instrument illustrates the common Opera Glass, giving an erect 
 image. .$4.60 
 
 75-151 ASTRONOMICAL TELESCOPE MODEL, consisting of two lenses, one the condensing eye-piece 
 and the other the object glass. In comparison with No. 75-154, Model of the Microscope, it will 
 be seen that this astronomical telescope is analogous to the microscope, differing in the respect 
 that, in the microscope the object being seen through the object glass the image formed must be 
 on the principal focus and is, therefore, greatly magnified, so that both the object glass and the 
 eye-piece magnify, while in the astronomical telescope the heavenly body being at a great distance 
 the rays are parallel and the image formed on the principal focus of the object glass is much smaller 
 than the object. There is, therefore, little magnification except that secured by the eye-piece, 
 which usually is of short focal length. 
 
 The lines which represent the path of the rays bring this out very clearly in object models . . . 6.40 
 
 75-162 TERRESTRIAL TELESCOPE MODEL, consisting of two condensing lenses placed between the 
 object glass and the eye-piece. It will be noted that this telescope differs from the astronomical 
 telescope in that it produces images in their right positions. 7.15 
 
 75-163 TELESCOPE MODELS, as listed above, showing the construction of the principal telescopes, set 
 
 of three i.18.00 
 
 75- 164 MICROSCOPE MODEL, consisting of two lenses, one the objective, the other the eye-piece .... 4.50 
 
 76- 166 DEMONSTRATION MICROSCOPE, after Millikan and Gale’s “A Laboratory Course in Phys¬ 
 
 ics” (Experiment 45), for determining the magnifying power of a microscope. 
 
 The apparatus consists of a brass tube, on either end of which are placed strips with apertures. 
 
 Over one end is fastened a linen tester, No. 74-235. Apparatus complete with two linen testers . 1.05 
 
 75- 166 TUBE only, without linen testers. .20 
 
 « 
 
 76- 161 RULED CARDBOARD STRIP, after Fuller and Brownlee (Experiment 49A).30 
 
 75-163 CARDBOARD INDEX STRIP, after Fuller and Brownlee (Experiment 49A). . .20 
 
 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 267 
 
 
 
 
 76-165 SEXTANT, for measuring the angle between any two distant objects. This is a universal, durably 
 constructed aluminum model, divided on main scale to read to degrees. The vernier on index arm 
 is graduated so that six divisions on vernier equal five on the main scale. 
 
 This model must not be confused with a number of cheap models at present on the market, as this 
 is an accurately working instrument provided with most of the adjustments of an engineer’s 
 and mariner’s expensive metal sextant .$14.00 
 
 76-170 REFLECTING SEXTANT for measuring the angle between any two distant points. 
 
 This is an accurately constructed, brass sextant capable of exact determinations, reading by ver¬ 
 nier to 5 minutes of arc. It is provided with an astronomical telescope of 12 millimeters’ aper¬ 
 ture and with blend glasses as illustrated.Duty Free . . . 
 
 DIFFRACTION OF LIGHT 
 
 
 
 
 « 
 
 No, 77-76 
 
 77-76 SUN SPECTRUM CHART, hand painted on linen, spectrum band about 48 inches long by 7 inches 
 wide. Frauenhofer lines indicated and colors carefully matched and work well executed. Mounted 
 in frame to occupy wall space of about 5X2 feet.Duty Free . . . 
 
 77-80 SPECTRUM CHART, after Kirchhoff and Bunsen, showing beautifully the spectrum of the Sun, 
 
 K, Rb, Cs, Tl, Na, Li, Ca, Sr and Ba. Mounted on linen back with common rollers . . . .... $4.26 
 
 77-82 SPECTRUM CHART, after Kirchhoff and Bunsen, showing the following spectra: In, C, Bo, Mn, Pb, 
 
 Cu, Co, Ni and Fe. Mounted on linen back with common rollers. 4.26 
 
 77-86 SPECTRUM CHART, illustrating the Solar Spectrum. 
 
 This Chart consists of a strip of paper on which the spectrum is beautifully lithographed. It is about 
 
 80 centimeters long and mounted on heavy cardboard. The various Frauenhofer lines are indicated 1.60 
 
 21-210 COLOR DISCS for quantitative work in color mixing and color analysis. 
 
 Set of seven 10-inch discs of primary colors, one each of black and white, and a percentage circular 
 
 protractor for quantitative work. (For illustration, see Section 21). 2.00 
 
 21-225 COMBINATION NEWTON’S COLOR DISC for showing white light when fixed portions of pri¬ 
 mary colors are rapidly rotated. (For description and illustration, see Section 21). 1.60 
 
 77-90 COLORED GLASS PLATES for analysis and study of light. 
 
 These plates are selected colored plates of the best “pot glass” colors. They are furnished 10 centi¬ 
 meters square in the following colors: red, orange, yellow, green, blue, indigo and violet. 
 
 Per set of seven colors. 1.60 
 
268 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 THE VON NARDROFF COLOR APPARATUS 
 
 DESIGNED FOR THE STUDY OF COLOR PHENOMENA 
 
 An Attachment for the Projection Lantern or Porte Lumiere 
 Made under the personal supervision of Mr. F. W. Huntington 
 
 77-100 VON NARDROFF COLOR APPARATUS. This apparatus was designed by Dr. Von Nardroff, 
 Principal of the Stuyvesant High School, New York City, for the convenient and satisfactory study 
 of color phenomena where only one Projection Lantern is available. Our method of mounting is 
 such that it is equally well adapted for use with the Porte Lumiere. 
 
 Briefly, it is an attachment that converts an ordinary Projection Lantern into a triple lantern in which 
 each of the three beams of light is independent both as to intensity and direction. The general form 
 and design will be clearly indicated by the cuts above, showing two positions. 
 
 maxwell’s primary hues. 
 
 Fit. ■ 
 
 Fig. * 
 
 COMPLEMENTARY HUES. 
 F'S J- 
 
 EXPERIMENTS 
 
 Fig. 4. 
 
 A STUDY OF PRIMARIES AND SECONDARIES (see Fig. 1). The red, green, and blue glasses provided 
 with the apparatus are placed in the glass holders shown in the diagram. By a movement of the 
 lens arm these circles of red, green, and blue may be overlapped either in whole or in part as desired 
 and, by means of the diaphragms, the intensity of strength of each color readily regulated. The 
 effect of mixing the primaries in any desired portion, in pairs or in triples, is readily seen. 
 
 FALSE PRIMARIES (see Fig. 2). In this illustration the glasses selected should be the purple, yellow, and 
 blue-green, and by proper manipulation of the diaphragms all possible hues, as well as white, may 
 be obtained. 
 
 COMPLEMENTARY HUES (see Fig. 3) are easily illustrated by carefully choosing the pairs of colored glasses 
 to obtain the desired results. 
 
 “THE GREEN QUESTION” is solved by super-imposing the yellow and blue glasses in the single slide 
 holder of the apparatus and again inserting the same glasses in separate slide holders, adding the 
 beams by over-lapping on the screen, noting that a pure white light is obtained. 
 
 CONTRASTING EFFECTS (see Fig. 4) are strikingly illustrated when a saturated color, such as green, is pro¬ 
 jected and the white disc arranged to partially over-lap turned on; the over-lap, which is really 
 a tint, appearing nearly white, while the remaining white appears strongly colored of the com¬ 
 plementary hue. If the order of projection is reversed, the sudden appearance of the white is 
 very impressive. 
 
 A STUDY OF TINTS is easily made by adding to the white beam a colored beam adjusted for intensity. 
 
 OTHER EXPERIMENTS. Many additional experiments will suggest themselves to the user after he has be¬ 
 come familiar with the apparatus and commences to learn some of its possibilities; such, for in¬ 
 stance, as three equally bright beams being made to partially over-lap. The remaining portions 
 of the beams will present intensities as the ratio of 1: 2: 3. Again, projecting on the screen a com¬ 
 pound white, holding an opaque body in the path of the ray, a very remarkable shadow effect will 
 be produced. 
 
 Price mounted as illustrated. . . $32.00 
 
 ; 
 
 
 ! 
 
 
 
 ! 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 269 
 
 SPECTRAL APPARATUS 
 
 Nos. 77-126 to 77-126 
 
 77-126 DIRECT VISION POCKET SPECTROSCOPE for use in experiments in Spectrum Analysis. 
 
 This instrument consists of a combination of three prisms giving a considerable dispersion. It will 
 show many of the Frauenhofer lines, the bright lines of the metals and gases and the absorption 
 bands in colored gases, crystals, or liquids. It is provided with an adjustable slit operated by a 
 small micrometer screw. This spectroscope has an achromatic lens and is of excellent quality 
 throughout. 
 
 Enclosed in velvet-lined case.$9.00 
 
 77-126 — —, same as above, but fitted with a comparison prism which will show two spectra in the field of 
 view at the same time, so that they may be conveniently compared. 
 
 Enclosed in velvet-lined case.Duty Free 14.60 
 
 77-160 DEMONSTRATION SPECTRAL APPARATUS AND GONIOMETER, — a goniometer or spec¬ 
 trometer of simple design but accurate construction, in which all lenses, diaphragms and slit are 
 separately mounted and arranged for adjustment along nickel-plated graduated metal bars. The 
 prism table and circle is accurately divided on metal to two degrees. 
 
 Although primarily designed for demonstration purposes, it will be found of unusual value as a 
 student’s instrument, in that the student is enabled, not only to use the instrument as a spectral 
 apparatus with a fair degree of accuracy, but also to use it with a correct understanding of con¬ 
 struction of telescope and collimator and, from observation of correct position of parts arranged 
 openly on this simple design, to clearly understand the more complex instruments. 
 
 Constructed of metal throughout, handsomely nickel-plated and oxidized. Complete with Holders, 
 
 Slit and Lenses, but without Prism.$19.80 
 
 77-162 STUDENT’S SPECTROSCOPE. Many teachers have 
 felt the need of an inexpensive instrument capable of 
 demonstrating to students, in a convenient manner and 
 without loss of time, the methods of spectrum analysis. 
 
 The spectroscope illustrated is provided with a set of 
 prisms of high dispersion and yields a wide spectrum, 
 showing a large number of Frauenhofer lines. The ad¬ 
 justment of focal length is secured by means of a small 
 handle sliding along the tube. The fixed slit at one 
 end is covered by a glass plate so as to be completely 
 protected from dust. , The spectrum in consequence 
 will be free from cross-lines. The instrument is mount¬ 
 ed on a neat wooden stand and is provided with holder 
 for test tubes.Duty Free 
 
 No. 77-162 
 
270 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 77-170 ADVANCED SPECTROSCOPE. This 
 instrument is especially designed for 
 high school and elementary college 
 work. It is furnished completely 
 equipped with all essential parts. 
 
 All mechanical details are well con¬ 
 structed and nicely fitted; all optical 
 parts are of the best. The telescope 
 is adjustable, has an aperture of about 
 20 millimeters and a focal length of 
 about 160 millimeters. The collimator 
 is provided with a comparison prism 
 and is of the same dimensions as the 
 telescope. A separate tube contains 
 the scale. The instrument is mounted 
 adjustably in a neatly finished tripod 
 stand. It is furnished with a 60-degree 
 flint glass prism and provided with 
 a cover for same . . . Duty Free 
 
 No. 77-170 
 
 No. 77-175 
 
 77-176 UNIVERSALLY ADJUSTABLE SPECTROMETER, after V. v. Lang. 
 
 The adaptability of this instrument to most spectrometric work has made it one of the most popular 
 spectrometers in use. Constructed by one of the most prominent European manufacturers, it 
 has received every attention in structure. Mechanical parts are accurately constructed and care¬ 
 fully fitted; optical parts calculated to a nicety for the work for which the instrument is intended. 
 
 The circle is 120 millimeters in diameter with graduations on silver to 3^ degree. To facilitate in the 
 reading, the instrument is provided with two verniers with magnifiers which facilitate readings 
 to 60 seconds of arc. The telescope has an aperture of 20 millimeters, is provided with rack and 
 pinion adjustment and may be rotated about the vertical axis. The collimator has same diameter 
 as the telescope and is provided with a slit with micrometer screw adjustment, the extent of open¬ 
 ing being indicated on the graduated drum. The prism table is adjustable in height and may 
 be leveled by three small thumb screws noted in the illustration. The instrument is mounted on 
 a neatly finished tripod base provided with leveling screws. All necessary adjustments for tele¬ 
 scope tube and collimator and locking device for the latter are provided. This instrument will 
 give universal satisfaction.Duty Free 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 271 
 
 
 
 
 
 
 74-360 
 
 74-360 
 
 74-366 
 
 74-367 
 
 74-370 
 
 77-226 
 
 77-226 
 
 77-227 
 
 77-228 
 
 77-236 
 
 77-236 
 
 77-246 
 
 Used by express permission of copyright owner 
 
 No. 74-367 
 
 Nos. 74-360 a-e to 
 Nos. 74-390 a-c 
 
 No. 74-366 
 Nos. 74-360 a-e 
 
 Nos. 74-400 a-c 
 
 FLINT GLASS EQUILATERAL SPECTRAL PRISMS, optically true surfaces, square ends. 
 Refractive Index for D = 1.602. Dispersion C-F — 1° 58'. Minimum for M/D = 55° 20' 
 
 3. 1) c d 0 
 
 Side . 25 30 35 40 50 millimeters 
 
 Each, Duty Free . . $4.76 6.26 6.26 7.40 9.76 
 
 Each from Stock . 6.26 
 
 CROWN GLASS EQUILATERAL SPECTRAL PRISMS, optically true surfaces, square ends. 
 Refractive index for D = 1.517; Dispersion C-F = 41°. Minimum for M/D = 50° 24' 
 
 a b c d e 
 
 Side . 25 30 35 40 50 millimeters 
 
 Each, Duty Free . . $4.76 6.26 6.26 7.40 9.76 
 
 Each from Stock 6.26 
 
 CROWN GLASS SPECTRAL PRISM, angles of 45 and 90 degrees, cathetus 25 millimeters. 
 
 Duty Free 
 
 CROWN GLASS SPECTRAL PRISM, angles of 45 and 90 degrees, cathetus 50 millimeters. 
 
 Duty Free 
 
 RUTHERFORD’S COMPOUND PRISMS, consisting of a flint glass prism luted between two crown 
 
 glass prisms. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 Side . 
 
 20 
 
 30 
 
 40 
 
 50 
 
 60 millimeters 
 
 Each, Duty Free . 
 
 . $9.76 
 
 14.60 
 
 23.25 
 
 38.50 
 
 49.76 
 
 
 Nos. 77-226 to 77-236 
 
 No. 77-246 
 
 GEISSLER SPECTRUM TUBE, filled with carbon dioxide. 
 
 -, filled with hydrogen gas. 
 
 -, filled with nitrogen gas. 
 
 -, filled with oxygen gas. 
 
 GEISSLER SPECTRUM TUBE, most carefully constructed, evacuated, and filled with pure argon gas 
 
 -, same as above, but filled with pure helium. 
 
 GEISSLER SPECTRUM TUBE for exhausting and filling with whatever gas desired. Fitted with 
 two carefully ground glass cocks . 
 
 $6.25 
 
 9.40 
 
 $1.96 
 
 1.96 
 
 1.96 
 
 1.96 
 
 7.76 
 
 7.76 
 
 1.96 
 
272 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ABSORPTION TROUGHS 
 
 No. 77-266 
 
 No. 77-267 
 
 No. 77-270 
 
 77-266 ABSORPTION TROUGH, U-SHAPED, for use as an absorption vessel, light filter or for projec¬ 
 tion of living matter in liquids. 
 
 This trough is durably constructed and the cementing is guaranteed not to leak, being baked in 
 special furnaces at 1000° F. Size 50 millimeters high, 20 millimeters wide, and 4 millimeters 
 deep. . . 
 
 77-267 ABSORPTION TROUGH, square shaped, with round bore, the same careful construction as above. 
 
 Inside measurement 20 X 4 millimeters. 
 
 77-270 DOUBLE ABSORPTION TROUGH for comparing two liquids simultaneously, same careful con¬ 
 struction as above. Inside measurement of each partition, 40 X 25 X 10 millimeters. 
 
 No. 74-438 
 
 74-438 WEDGE-SHAPED TROUGHS, a pair of prism-shaped troughs, each 6 inches long by 2 inches high. 
 
 Refractive angles of 20 degrees.Duty Free 
 
 No. 77-300 
 
 77-300 ADJUSTABLY MOUNTED FRESNEL’S INTERFERENCE MIRRORS for illustrating interference 
 
 of light by reflection. 
 
 The apparatus consists of two optically plane black glass mirrors the polished surfaces of which extend 
 right up to the line of intersection of the two faces. These mirrors are provided with Micrometer 
 Screw Adjustments, so that the angle between them may be varied within short limits. For 
 normal use, these mirrors should be at nearly 180 degrees of angle in order to get proper inter¬ 
 ference. By means of the micrometer screw attachment, however, the complete system of fringes 
 can be caused to pass in succession over any desired part of the screen. The mirror frame is at¬ 
 tached to a rod for use with our No. 6-810 Right Angle Clamp for use on an Optical Bench 
 
 Duty Free 
 
 77-305 MOUNTED FRESNEL’S BI-PRISM for showing interference of light by transmission. Duty Free 
 
 $1.66 
 
 1.45 
 
 4.86 
 
 $6.60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 273 
 
 DIFFRACTION GRATINGS 
 
 77-316 PRISM GRATINGS for spectroscopic and lantern work. Prism Gratings have been designed for 
 obtaining direct vision spectra of great dispersion, while their brilliancy is far greater than plate 
 gratings. They are made of varying angles and sizes to suit requirements and are equal in many 
 cases to 4 to 6 flint prisms, the amount of dispersion being affected by the angle at which the 
 prism is tilted. The surfaces of a, b, and c are accurate to 1/500,000 and of d and e to 1/50,000 
 of an inch. 
 
 a b c d e 
 
 Size of Face . . .61 X 48 38 X 30 28 X 19 64 X 38 28 X 19 millimeters 
 
 Each, Duty Free . ... ... ... ... 
 
 Nos. 77-320 to 77-326 
 
 77-320 TRANSMISSION DIFFRACTION GRATING. These gratings are moulded replicas of Row¬ 
 land’s celebrated metallic gratings of 14,438 lines to the inch. They are mounted on parallel 
 plate glass and are suitable for work of the highest class, both visual and photographic, as well as 
 for projection purposes, and give a brilliant and pure normal spectra. Wave length measurements 
 may be safely taken, as each grating has the number of lines per inch marked on it. Size, 28 X 19 
 millimeters.Dutv Free . . . 
 
 77-322 - —, same quality as above, but 54 X 35 millimeters.Duty Free . . . 
 
 77-326 TRANSMISSION DIFFRACTION GRATING, same size as No. 77-322, but on optically worked 
 
 glass, giving a very brilliant spectrum.Duty Free . . . 
 
 No. 77-360 
 
 77-360 NEWTON’S RINGS for illustrating colors of thin plates, demonstrating interference of light, etc. 
 
 This apparatus consists of two brass rings between which are locked two glasses, one plane and the 
 other convex, of very long focus. The method of locking the two rings is such that by means of 
 the screws, the pressure may be regulated. Diameter of glasses, 1inches. 
 
 If the two surfaces are exposed to ordinary light in front of the window, so as to reflect light, there 
 is seen at the point of contact a black spot surrounded by 6 or 7 colored rings, the tints of which 
 become gradually less strong. If the glasses are viewed by transmitted light, the center of the 
 ring is white and each of the colors is exactly complementary of that of the rings by reflection. 
 If exposed to light from a monochromatic flame, an interesting study of the colored rings presents 
 
 itself.$ 1.45 
 
 77-362 NEWTON’S RINGS, similar to above but of larger size. Diameter, 16 centimeters. Duty Free 13.50 
 77-376 INTERFERENCE OF LIGHT PLATES, after Millikan and Gale, Figure 391.Pair . .46 
 
274 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 POLARIZATION STUDY APPARATUS 
 
 No. 78-40 
 
 78-40 STUDENTS’ POLARIZATION STUDY OUTFIT for study of effects of polarized light. 
 
 There is perhaps no branch of Optics so neglected and yet in which results are so important as that 
 of Polarized Light. The neglect is due in a large measure to the elaborate and costly apparatus 
 designed for this branch. To encourage the study we have secured from our European correspond¬ 
 ents the design above illustrated. 
 
 With this comprehensive outfit, contained in a polished wooden box, each part appropriately mounted 
 and a compartment for each, very beautiful results may be obtained. The Polarizing Black Mirror 
 is mounted at one end, the holder for the Analyzer at the other, a Holder for the different crystals 
 between. The Analyzer consists of a Nicol’s Prism mounted in a brass tube. Four other brass 
 tubes each with different crystals are furnished for use in the mounting with the Analyzer. Various 
 Gypsum Figures and Specimens are furnished for study under polarized light. 
 
 We cannot too strongly urge the use of this simplified Study Outfit. All parts are carefully made 
 and selections of crystals and specimens are those best adapted to study. 
 
 Complete as illustrated.. . .Duty Free . . . 
 
 No. 78-45 
 
 No. 78-75 
 
 78-46 PICKERING POLARISCOPE for study of simple objects under polarized light. 
 
 This is a simple form of polariscope in which the Polarizing Mirror covers the stage. The Analyzer is 
 a Nicol’s Prism 6-millimeter aperture mounted in brass tube. It is provided with pointer and 
 graduated arc. An improved Holder is provided for specimens to be studied.$8.00 
 
 ICELAND SPAR. Iceland Spar is a crystallized mineral which produces two refracted beams of light from 
 one incident ray. 
 
 Iceland Spar comes in many forms, all of which may be reduced by cleavage to the rhombohedron. This min¬ 
 eral comes in many grades of purity and clarity, although the double refraction can be shown by the quality readily 
 obtained, and as generally listed. We recommend our No. 78-76. 
 
 78-76 ICELAND SPAR, best quality, recommended for its remarkable purity and clarity.$0.75 
 
 78-76 ICELAND SPAR, large size, medium quality.30 
 
 78-77 ICELAND SPAR, ordinary quality.25 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 275 
 
 No. 78-85 
 
 Nos. 78-96 to 78-100 
 
 No. 78-87 
 
 TOURMALINE TONGS. Tourmaline is a uni-axial negative crystal in the form of a regular hexagonal prism 
 from which only the “extraordinary” ray emerges, while the “ordinary” is rapidly absorbed. It can, therefore, 
 be used in producing a polarizing light. The optical axis of tourmaline coincides with the prism and for optical 
 purposes the plate is cut from it parallel to the axis. 
 
 In tourmaline tongs used for illustrating and analyzing polarized light, two tourmaline crystals are mounted 
 in discs which are held as illustrated. These discs are each free to move. If the prisms are placed so that their axes are 
 parallel, light emerges as the prisms are turned so that their axes are at an angle. In use, the crystal to be studied 
 under polarized light is placed between the two crystals. 
 
 78-86 TOURMALINE TONGS, simple form, medium size tourmaline prisms, capable of ordinary work . $2.26 
 
 78-87 PARALLELLY ADJUSTABLE TOURMALINE TONGS, superior quality tourmaline plates with 
 improved mounting, which allows of wide separation of the plates; also convenient method of 
 turning the tourmaline holders.Duty Free 11.40 
 
 NICOL’S PRISMS 
 
 The ray of light incident on the crystal of Iceland Spar is split into two rays, the “ordinary” and the “extraor¬ 
 dinary,” each of which travels in a different plane. In order that the incident ray may be transmitted in one plane 
 it is necessary to dispose of either the “ordinary” or “extraordinary” ray. The Nicol’s Prism causes the “ordi¬ 
 nary” ray to be totally reflected, allowing the free transmission of the “extraordinary” ray. 
 
 These types of prisms consist of rhombs of Iceland Spar, each of which is obliquely cross-cut symmetrical to the 
 other. Faces polished and then luted by the cement the index of refraction of which is greater than that of the 
 “extraordinary” ray. This cross cut is of such an angle that total reflection of the “ordinary” ray occurs when 
 the incident ray strikes the luted faces. 
 
 Our Nicol’s Prisms are purchased from one manufacturer and are noted for their large polarizing field and their 
 exceeding clarity. We have no hesitation in recommending either those which are carried in stock or those which 
 we list herewith, free of duty. 
 
 78-96 
 
 78-97 
 
 78-100 
 
 78-110 
 
 NICOL’S PRISMS, luted by Canada Balsam, polarizing field of 22J^ degrees. 
 
 a b c 
 
 Aperture . 6 7 8 millimeters 
 
 Each .$3.30 4.90 6.40 
 
 -, same as above, but larger aperture. 
 
 a b c 
 
 Aperture . 15 20 25 
 
 Each, Duty Free . . $9.26 22.26 46.00 
 
 NICOL’S PRISMS, luted with evaporated linseed oil. Aperture Jjf of length, polarizing field 30 
 degrees. 
 
 & 1) c d 6 
 
 Length . 21 24 27 30 45 millimeters 
 
 Each, Duty Free . . $6.90 7.26 9.80 14.26 37.60 
 
 FOUCAULT’S PRISMS. The Foucault’s Prism is a type of Nicol’s Prism remarkable for its clarity, 
 
 the luting being a stratum of air. Polarizing field 8 degrees. 
 
 abed 
 
 Aperture . 20 25 30 35 millimeters 
 
 Each, Duty Free . . $7.26 14.60 24.00 29.60 
 
276 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 OBJECTS FOR THE POLARISCOPE 
 
 No. 78-140 
 
 78-140 UNANNEALED (IMPERFECTLY ANNEALED) GLASS SPECIMENS. Suddenly cooled glass 
 
 exhibits double refraction. In consequence such specimens will show different patterns under a 
 beam of polarized light. 
 
 Set of eight selected specimens as above illustrated.Duty Free $12.00 
 
 SELENITE DESIGNS EXHIBITING MOST BEAUTIFUL COLORS IN POLARIZED 
 
 LIGHT 
 
 78-163 
 
 78-164 
 
 78-166 
 
 78-166 
 
 78-167 
 
 78-168 
 
 78-166 
 
 78-170 
 
 78-172 
 
 78-174 
 
 78-176 
 
 78-180 
 
 78-181 
 
 78-186 
 
 78-186 
 
 78-190 
 
 78-196 
 
 78-206 
 
 78-207 
 
 78-210 
 
 78-211 
 
 78-220 
 
 78-221 
 
 78-226 
 
 78-226 
 
 FOUR SELENITE PLATES together in four colors. 
 
 CUBE, three colors... 
 
 OCTAHEDRON, four colors.. 
 
 STAR, six colors.‘.. 
 
 BUTTERFLY, most beautiful effects . 
 
 BOUQUET, highly recommended for its many strikingly beautiful colors. Duty Free 
 
 UNCUT MICA, for individual adjustment, set of six plates of different thicknesses. 
 
 MICA PLATE, undulation, 40 millimeter aperture. 
 
 -, J4 undulation, 30 millimeter diameter. 
 
 -, undulation, 12 to 15 millimeter diameter... 
 
 MICA PLATE, l /2 undulation, 12 to 15 millimeter diameter. 
 
 MICA COMBINATION, after Noremberg, collection of six pieces.Duty Free 
 
 -, after Noremberg, in one preparation.Duty Free 
 
 -, after Reusch, plates crossed under 60 degrees, turning right and left.Duty Free 
 
 -, after Reusch, plates crossed under 45 degrees.Duty Free 
 
 MICA WEDGES, two Mica Wedges, eight steps, each wedge arranged, one to turn over the other. 
 
 Per pair..Duty Free 
 
 MICA WEDGES, 16 steps, to 4 undulations, in form of the object bearer, 11 X 70 millimeters. 
 
 Duty Free 
 
 SELENITE PLATE, between two % undulation mica plates, aperture 40 millimeters. Duty Free 
 SELENITE DOUBLE PLATE, between two undulation mica plates, aperture 40 millimeters. 
 
 Duty Free 
 
 SELENITE AND MICA COMBINATION, according to Wright, magnificent colors, collection 
 
 of six pieces..Duty Free 
 
 -, same as above, but collection of eight pieces.Duty Free 
 
 SELENITE PLATE for examining the character of double reflection by uni-axial crystal cuts, 40 
 
 millimeter aperture.Duty Free 
 
 SELENITE PLATE, same as above, but 30 millimeter diameter.Duty Free 
 
 SELENITE PLATES, in x /i, % and % undulations, laid one to the other, giving thirteen different 
 
 steps, for diffused light.. Duty Free 
 
 -, same as above, but for sodium light.Duty Free 
 
 $2.16 
 
 2.70 
 
 3.40 
 5.00 
 
 6.15 
 9.50 
 
 .90 
 
 2.26 
 
 1.60 
 
 1.00 
 
 1.00 
 
 6.25 
 
 7.15 
 
 7.26 
 
 7.40 
 
 7.60 
 
 6.90 
 
 3.25 
 
 3.76 
 
 7.00 
 
 9.76 
 
 6.25 
 
 5.00 
 
 5.40 
 
 5.90 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 277 
 
 PROJECTION APPARATUS 
 
 It is probable that more important changes and improvements have been made during the 
 past few years in Projection apparatus than in any other department of laboratory equipment. 
 
 The various requirements of a well equipped laboratory are so numerous, ranging as they do 
 from simple projection to moving pictures, that it requires long experience and critical judg¬ 
 ment to select the proper equipment for any given laboratory. 
 
 We are prepared to recommend the very latest and best types of projection machines and 
 will do so upon request. When writing to us upon this subject, please inform us of the size of 
 the Class Lecture Room, or Auditorium, the size of the picture desired, whether or not electricity 
 is available and if so the kind and the voltage, and all other local conditions which may assist 
 us. We shall then be pleased to give detailed information as to the combination which we 
 recommend. 
 
278 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 MAGNETISM AND STATIC ELECTRICITY 
 
 MAGNETS 
 
 Our line of apparatus illustrative of Magnetism and its various properties has been selected with great care. 
 Our magnets are of the best quality steel and will retain their m agnetism. 
 
 80-10 LODESTONE or NATURAL MAGNET. As suggested by the name, 
 this magnet is a selected piece of iron ore having magnetic properties. 
 
 It exerts attractive and repulsive force and is readily affected by the 
 earth’s magnetic power.$0.22 
 
 80-11 LARGE DEMONSTRATION TABLE LODESTONE or NATURAL 
 
 MAGNET, highest quality.66 
 
 80-14 SUPPORTING STIRRUP FOR LODESTONE, used in illustrating the 
 action of the earth’s magnetic force. This stirrup will contain either 
 of the lodestones listed above.66 
 
 Nos. 80-10 to 80-11 
 
 
 S 
 
 HORSESHOE MAGNETS WITH KEEPERS 
 
 Numbers . 80-20 80-22 80-24 80-26 80-28 
 
 Length, inches ... 2 3 4 6 8 
 
 Each. $0.08 0.11 0.18 0.48 1.00 
 
 80-30 HORSESHOE MAGNET, special design, 2 inches between poles. Length 5M inches, poles % X M 
 
 inch.$0.35 
 
 80-32 U-SHAPED MAGNET, after Fuller and Brownlee (Experiment 86) .40 
 
 80-36 COMPOUND HORSESHOE MAGNET, demonstrating the intensified magnetic force derived by 
 
 the combination of more than a single magnet. Two magnets firmly clamped together with keeper . 1.70 
 
 80-37 EIGHT-INCH COMPOUND HORSESHOE MAGNET, consisting of four eight-inch single magnets 
 
 firmly clamped together. With keeper. 6.40 
 
 BAR MAGNETS, finest quality steel, excellent retentive quality, neatly polished. 
 
 Numbers .... 80-66 80-67 80-69 80-61 
 
 Size, inches .... 2X^XM 6 X M X M 8 X MX M 12 X 1 X M 
 Price . .Each, $0.18 Per Doz. 1.60 0.20 0.30 0.60 
 
 80-70 BAR MAGNETS, consisting of a pair of 6-inch Bar Magnets in neat wooden box, with keepers . .60 
 
 80-80 ROUND BAR MAGNET, excellent quality polished steel, length 6 inches, diameter % inch ... .26 
 
 80-86 BREAKING MAGNET, illustrating the fact that both polarities of magnetism are present at all parts 
 of the bar, and are not merely at the ends. 
 
 This Magnet is 6 inches long by M inch square, weakened at various points to facilitate in the 
 breaking.22 
 
 80-87 GLASS TUBE and STEEL FILINGS, illustrating the molecular character of magnetism. 
 
 This consists of a small glass tube filled with washed steel filings. If the filings are magnetized by the 
 approach of a bar magnet, each small filing will attain the characteristics of a magnet, attracting 
 and repelling adjacent filings, so that they will all cluster together to form a solid mass. This con¬ 
 dition may be destroyed by violently shaking the tube, thus destroying the magnetism. 30 
 
 80-90 MAGNETIZED STEEL DISC, useful in destroying the conception of the students that magnets must 
 be in the form of rods or bars. 
 
 This disc is 2 inches in diameter and has two distinct magnetic poles 
 
 
 .66 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 279 
 
 80-100 HARDENED STEEL RODS (KNITTING NEEDLES), about % inch diameter by 8 inches long. 
 
 These steel rods are useful in the study of Breaking Magnets. Per set of four. 
 
 80-102 LARGE DARNING NEEDLES. Package of 25 needles. 
 
 80-106 SOFT IRON BAR, for illustrating the action of the earth on magnetic substances; may be used also 
 to illustrate the formation of magnets by enclosing in a solenoid through which passes a current 
 of electricity. 
 
 This bar is of the best quality of soft Norway iron and measures 6 X ^ X . 
 
 80-106 SOFT NORWAY IRON ROD, 20 inches long by inch diameter, for studying the action of the earth 
 on magnetic substances. When this bar is held in the magnetic meridian parallel to the inclination, 
 feeble magnetic polarity is at once noticeable in the bar, the lower extremity being the North Pole, 
 as may be demonstrated by testing with a small magnetic needle. This magnetism is unstable, as 
 may be demonstrated by inverting the bar. The magnetic polarity, however, may be made some¬ 
 what more stable by imparting to the bar a certain amount of coercive force by giving it several 
 sharp blows with a hammer. This coercive force is, of course, very small, and after a time the 
 magnetism entirely disappears. 
 
 89-107 SOFT IRON HORSESHOE CORE, after Millikan, Gale and Bishop (Experiment 30). 
 
 80-108 CYLINDRICAL IRON ARMATURE, after Turner and Hersey (Experiment E011). 
 
 80-109 TWO-PART IRON ARMATURE, after Turner and Hersey (Experiment E011). 
 
 80-110 NICKEL STRIP for illustrating that other substances than iron have magnetic properties. 
 
 This strip is 4 X ]/i inch. 
 
 80-116 MAGNETIC SCREENS for illustrating magnetic transparency, consisting of a set of six screens of 
 different substances, some paramagnetic, others diamagnetic ....... Per set of six 
 
 80-117 PARAMAGNETIC AND DIAMAGNETIC SUBSTANCES .Package 
 
 80-120 MAGNET STIRRUP, for the study of magnetic action in a suspended bar magnet. 
 
 This consists of a wire stirrup with a device for holding magnets and also for attaching to a support 
 by a string. 
 
 $0.05 
 
 .06 
 
 .20 
 
 .40 
 
 .10 
 
 .04 
 
 .04 
 
 .30 
 
 .70 
 
 .40 
 
 .10 
 
 No. 80-123 
 
 No. 80-160 
 
 No. 80-160 
 
 80-123 BLACK’S MAGNET and FRICTION ROD SUPPORT. The magnet or friction rod carrier is con¬ 
 structed of very light weight metal and when balanced as illustrated on the hardened steel sup¬ 
 porting needle, moves with very little inertia. A magnet or friction rod resting on this carrier, there¬ 
 fore, reacts readily to other magnetic or static charges. $1.60 
 
 80-160 MOLECULAR MAGNET MODEL for explaining the distribution of Magnetism in magnetic rods. 
 
 This apparatus consists of twenty-four small magnets about 2 centimeters long, each supported on a 
 point and all placed as illustrated, on an insulated board. These magnets will arrange themselves 
 so that the like poles all point in one direction. If, however, the pole of a strong Bar Magnet be 
 presented to one end, the needles will be immediately deflected. 
 
 Set of twenty-four, mounted as illustrated.Duty Free 9.26 
 
 80-166 FLOATING MAGNETS for illustrating the attraction and repulsion of magnetic poles. 
 
 This apparatus consists of a set of six small magnets each on an individual mount that will float in 
 
 water. Per set of six .20 
 
 80-160 SUPPORTING BOARD for use with a magnet and tracing paper for forming a tracing of the lines 
 of force of a magnet. 
 
 This board, as shown in the illustration, has a groove in the middle into which the magnet is placed, 
 bringing the surface of the magnet flush with the top of the board. 
 
 In use, a sheet of blueprint paper is pinned to the board over the magnet. Iron filings, sifted over this 
 
 sheet, will arrange themselves in the lines of force of the magnet. .46 
 
 80-166 MAGNET SUPPORTS. These supports consist of short strips of wood inch cross-section. They 
 are designed for use with magnets No. 80-66. The blueprint paper is placed on these wooden 
 supports.Per Pair .06 
 
 80-167 SPECIAL MAGNET BLOCK, after Turner and Hersey (Experiment E011). .04 
 
 80-170 GLASS PLATES (6X6 inches), for use in mapping magnetic fields of force. 
 
 These plates may be used to advantage with No. 80-165 Supporting Strips, and No. 80-56 Bar 
 Magnet .'.Each .10 
 
28 o 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 80-180 IRON FILINGS for mapping magnetic lines of force. Selected, fine, soft iron filings. 
 
 Per x /i lb. carton $0.10 
 Per lb. in bulk .20 
 
 80-186 FILINGS SIFTER for evenly distributing filings over a tracing surface. .16 
 
 80-187 CHEESE CLOTH BAG. 10 
 
 80-190 BLUEPRINT PAPER for permanently recording a magnetic field of force of a bar magnet, as indi¬ 
 cated by iron filings. Size, 8H X 10 Yi inches. Per light-proof, sealed package of 100 sheets . . 1.26 
 
 80-200 DIRECT BLACKPRINT PAPER, more desirable than blueprint paper as it gives a black line on 
 white ground. 
 
 This paper is treated like ordinary blueprint paper, except that the print should be left in the bath 
 
 from 10 to 15 minutes.Per 10-yard roll, medium weight, 30 inches wide . 2.75 
 
 80-225 LINES OF FORCE APPARATUS, after Toepler, for show¬ 
 ing the magnetic curves between the poles of an electro¬ 
 magnet. Excellent in projection work. 
 
 This apparatus consists of a glass trough placed between 
 the poles of an electro-magnet. This trough, in use, is filled 
 with glycerine in which fine iron filings have been pre¬ 
 viously mixed. When a current is allowed to pass through 
 the electro-magnet, the small particles of iron will arrange 
 themselves in magnetic curves. This instrument forms 
 an instructive and interesting piece of apparatus .... 
 
 $7.80 No. 80-225 
 
 80-230 MAGNETIC LINES OF FORCE APPARATUS for use with a Vertical Projector in showing on a 
 screen the lines of force about a current. 
 
 This apparatus consists of a set of six slides, each slide being a glass plate set in a wooden frame. 
 Through holes bored in the glass, various forms of wire are set. In projection work, this set will 
 be found invaluable.Per set of six slides $9.75 
 
 No. 80-232 
 
 80-232 MAGNETIC LINES OF FORCE APPARATUS for use with a Vertical Projector in showing on a 
 screen the lines of force about a magnet. 
 
 This apparatus, similar to Set No. 80-230, consists of a set of six slides, each slide consisting of two 
 plates between which are placed thin steel magnets of various forms and differently arranged as 
 illustrated.Per set of six slides $2.50 
 
 80-236 MAGNETIC LINES OF FORCE SLIDES, for illustrating on a screen the fields of force shown by 
 iron filings. 
 
 These slides are direct photographs and are selected from our Miller Collection. The set consists of 
 five slides illustrating the field of: (1) Single Bar Magnet; (2) Two Bar Magnets, Unlike Poles; 
 
 (3) Two Bar Magnets, like Poles; (4) Two Bar Magnets at Right Angles; (5) Ring Magnets. 
 
 Per set of five 2.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 281 
 
 80-260 
 
 80-262 
 
 80-263 
 
 MAGNETOMETERS 
 
 Nos. 80-260 and 80-263 
 
 MAGNETOMETER, after Millikan and Mills’ “Electricity, Sound and Light” (Experiment 2), 
 for determining the magnetic moment (M) and horizontal component of the earth’s magnetic 
 field (H), by first determining the relation M/H and MH. 
 
 This magnetometer is carefully designed to do accurate work. The suspension system consists 
 of five small magnets, cemented to the back of an optically plane glass mirror. This system 
 is held by a silk fibre suspended from the graduated torsion head. The brass housing is so mounted 
 on the tripod that it may be turned about a vertical axis. The outer wall of this housing, with 
 clear, flat glass window, may readily be removed as illustrated, without disturbing the suspension 
 system. 
 
 Magnetometer complete with Suspension System. 
 
 MAGNET AND METER ROD SUPPORTS. In determining the value M/H a bar magnet of 
 a size determined by the diameter of the lower part of the housing and an appropriate support 
 for the same, east and west of the suspended system, are needed. These supports utilize the 
 standard meter stick found in all laboratories. The meter rod is supported by special brass castings; 
 the magnet support is designed to rest on the meter stick wherever desired. An index on the 
 magnet support enables one to make an accurate reading of the distance of the magnet from 
 the magnetometer mirror. 
 
 One pair special brass Meter Rod Supports and Magnet Holder. 
 
 INERTIA ACCESSORIES for use with above Magnetometer, in determining the moment of inertia 
 of the magnet of No. 80-260. 
 
 This system consists of a stirrup to which is attached a plane mirror and which is designed to hold the 
 magnet. That results may be checked, a brass inertia ring is supplied. 
 
 Inertia Ring, Magnet, and Stirrup with Attached Mirror. 
 
 $18.00 
 
 1.40 
 
 3.16 
 
282 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 80-265 
 
 No. 80-300 
 
 
 
 
 f 
 
 80-265 SPRING MAGNETOMETER, after Stewart & Gee’s “Elementary Practical Physics,” Lesson XIII, 
 for determining the distribution of magnetism along a bar magnet. 
 
 In use, the zero point is obtained by substituting for the magnet a piece of wood of the same dimen¬ 
 sions, then turning the milled head until the soft iron piece just touches the surface of the wood. 
 
 Place the magnet in position, and determine the number of divisions through which the milled head 
 must be turned, to detach the iron piece. Readings should always be made from the middle of 
 the magnet toward each end. From a number of such readings, it will be noted that the magnetic 
 strength is directly proportional to the distance from the center. 
 
 Complete with Special Magnet and similar wooden strip. $7.60 
 
 80-270 DEFLECTION MAGNETOMETER for comparing the strength of the poles of a bar magnet. 
 
 The apparatus consists of a polished mahogany base board to the surface of which is fastened a 
 meter rod. Midway between the ends of this rod a delicate magnetic needle is placed, with the 
 50 centimeter division of the rod directly under the supporting pivot of the needle. 
 
 Complete with Magnetic Needle and Bar Magnet. 2.26 
 
 80-280 MAGNETOSCOPE, after Chute’s “Physical Laboratory Manual,” Problems 104 to 106, for measur¬ 
 ing relative magnetic transparencies of various substances; for comparing strength of poles and 
 determining distribution of magnetism along a bar magnet. 
 
 This simple instrument, capable of relatively exact measurements, consists of a heavy jar of special 
 design, mounted on a wooden pedestal. A strongly magnetized permanent magnet is suspended 
 through a stopper plug. .96 
 
 80-300 MAGNETIC POLE ROTATION APPARATUS for demonstrating the tendency of a current and a 
 
 magnet pole to rotate about each other. 
 
 The apparatus consists of a jewel-mounted magnet supported so that the current passes along half 
 the length of the magnet and is carried away at the middle. The magnet is supported at its center 
 on a fine point on top of a post. The current is brought to a mercury cup fitted to the magnet, and 
 a bent copper wire attached to this cup dips into an annular mercury cup, whence it is carried away 
 by the upright support to which the cup is attached. When a strong current is passing (3f$ 
 amperes at 7 volts pressure, at least) one pole will rotate steadily. By reversing the direction of 
 the current, the direction of the rotation is reversed. 
 
 Complete as illustrated. 4.36 
 
 80-116 MAGNETIC SCREENS, set of six screens of different substances, some paramagnetic, others dia¬ 
 magnetic .70 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 283 
 
 80-306 
 
 80-310 
 
 80-326 
 
 
 No. 80-306 No. 80-310 
 
 PARALLEL CURRENT APPARATUS for illustrating mutual actions of parallel currents. The 
 design consists of an insulated stand to the head of which are attached binding posts in electrical 
 connection with two bent copper wires. To these bent wires are suspended two straight copper 
 rods cut to lengths that will allow their free ends to extend within the mercury well set in the base. 
 
 In use it is always best to amalgamate the ends of these copper rods. Success of the experiment 
 depends also upon allowing the rods to just make contact with the surface of the mercury. Parallel 
 currents flowing in the same direction may be secured by connecting both binding posts with one 
 pole of the battery; the other pole should be connected to a binding post (not shown in illustration) 
 fastened to the base and in electrical connection with the mercury well. 
 
 Parallel currents running in opposite directions may be obtained by simply connecting the battery 
 terminals and the binding posts, at the top. 
 
 In the first case, repulsion of the wires will be noted; in the second attraction. 
 
 VIBRATING SPIRAL APPARATUS for illustrating mutual action of parallel currents. 
 
 The apparatus consists of a stand with upright. In the base is set a mercury well in electrical con¬ 
 nection with a binding post. A horizontal rod set into the upright near the top is provided at one 
 end with a binding post and at the other with a binding screw, the latter designed to support one end 
 of a loose copper wire spiral. The other end of this spiral extends within the mercury well. In use, 
 this end should be regulated to just touch the surface of the mercury. When a current is allowed 
 to pass through the spiral, there is an attraction between the convolutions, causing the lower end 
 of the spiral to break the electrical connection with the mercury. The weight of the spiral then 
 causes contact again, which, in turn, sets up attraction of the convolutions. Continual making and 
 breaking contact with the mercury causes this spiral to vibrate up and down. 
 
 No. 80-326 
 
 MAGNETIC DISTRIBUTION APPARATUS, after Stewart & Gee’s “Elementary Practical Phys¬ 
 ics,” Lesson LXXII, for studying the distribution of magnetism along a soft iron bar magnetized 
 by induced currents from a magnetizing helix. 
 
 This apparatus consists of a long, soft, Norway iron bar, mounted on supports as illustrated. At 
 the end are two short pieces of brass of the same diameter as the iron rod, permitting the whole 
 length of the iron rod to be brought under experimentation. For magnetizing purposes a test coil 
 which may be clamped to any part of the bar, is supplied. A small reel wound with fine wire is 
 employed as the induction coil. The range of play and the position of the test coil is determined by 
 two brass guides between which this reel is placed. The guide and reel are each provided with 
 screws for clamping - to the rod. 
 
 Complete as illustrated. 
 
 $1.86 
 
 1.35 
 
 $9.65 
 
284 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • ) 
 
 E QUIPOTENTIAL APPARATUS 
 
 No. 80-350 
 
 80-360 EQUIPOTENTIAL DETERMINATION APPARATUS, after Millikan & Mills’ “Electricity, Sound, 
 and Light” (Experiment 1), for mapping the equipotential surface of an electrical field and drawing 
 the force lines. 
 
 The apparatus consists of a field tray with glass bottom, through which may be seen a sheet of co¬ 
 ordinate paper. This tray is an improved design by C. H. Andrews, South High School, Worcester, 
 Mass. With this design it is impossible for the salt solution to come into contact with the paper, 
 and the whole tray may be thoroughly cleaned without removing the glass plate. It has the further 
 advantage, also, of facilitating the replacing of broken plates. Three bent wires, each with weighted 
 support and binding post, are provided. Two of these are maintained at points of different poten¬ 
 tials and about which it is desired to find equal potential lines which lie in one plane. A constantly 
 varying potential difference is secured by connecting these points to the secondary of an induction 
 coil. A fourth bent wire with insulating handle and binding post is used with the third point as 
 illustrated in locating the points of equipotential. The fourth point may then be considered the 
 equipotential seeker. 
 
 In use, the bottom of the tray is covered with a solution of ammonium chloride or any convenient 
 salt. The bent wires then are located as-illustrated, two connected to the secondary of an induc¬ 
 tion coil the primary of which is connected to a dry cell, the third and the equipotential seeker are 
 connected to telephone receiver. By adjusting the position of the third wire to various points in 
 the plane of the liquid, points of equipotential for these different points may be located by means 
 of the seeker. These points will be found when there is no “buzzing” in the telephone receiver. 
 Results may be transferred to a sheet of co-ordinate paper and equipotential lines and the lines of 
 flow drawn. 
 
 Complete apparatus consists of the Field Tray and the four bent wires, three with weighted supports 
 
 and binding posts, the fourth with insulating handle. Complete. $6.00 
 
 80-361 FIELD TRAY, improved design by Andrews. 4.00 
 
 80-362 BENT WIRE, WITH WEIGHTED SUPPORT AND BINDING POST . . •.Each .60 
 
 80-363 BENT WIRE, WITH INSULATING HANDLE AND BINDING POST.Each .60 
 
 19-67 CO-ORDINATE PAPER, ruled 6X8 inches on sheet 8}^ X lOj^, millimeter ruling, heavy centi¬ 
 meter divisions. v .Per 100 sheets .60 
 
 80-366 INDUCTION COIL, small size with modified hammer, especially adapted to this work. 4.00 
 
 98-100 BIPOLAR DISSECTEBLE TELEPHONE RECEIVER, as above illustrated. 1.46 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 285 
 
 TERRESTRIAL MAGNETISM 
 
 MAGNETIC NEEDLES 
 
 81-10 MAGNETIC NEEDLE, brass capped, agate bearing, neat stand with pinion, needle 6 inches long . . $0.90 
 
 81-12 -, same as above, brass capped only. _60 
 
 81-16 ASTATIC NEEDLE, improved design, brass caps, neat stand with pinion, needle 6 inches long, 
 
 system mounted so that like or unlike poles may be opposite each other. 1.40 
 
 No. 81-60 No. 81-66 
 
 81-60 STUDENTS’ DEMONSTRATION DIP NEEDLE, as designed 
 by W. R. Pyle of Morris High School, New York City. 
 
 This instrument consists of a stand on which may be supported 
 the dipping system. It is intended that this system should be 
 magnetized by the student. For this purpose, there are sup¬ 
 plied four steel rods inch diameter, about 8 inches long. 
 
 Our dipping system consists of a device whereby one of these 
 steel rods may be mounted and balanced unmagnetized and 
 damped in the system. The needle is then magnetized by 
 stroking from the middle toward each end with a strong bar 
 magnet. The dip, then, may be taken and noted. This little 
 instrument has found ready favor in many schools and is highly 
 recommended for its didactic features.$0.96 
 
 No. 81-60 
 
 81-66 DIPPING NEEDLE for showing magnetic dip. 
 
 This design consists of a standard on which is mounted a forked casting. In this forked casting is 
 mounted, in pivotal bearings, a carefully magnetized and balanced needle. A graduated arc, also 
 mounted in this forked casting, gives the magnetic dip.$3.30 
 
 81-60 DIP NEEDLE. This instrument, of the highest quality, and capable of exact determinations, con¬ 
 sists of a horizontal circle mounted on a tripod with leveling screws. Above the circle is a pillar 
 movable about a vertical axis and ending above in a forked stirrup, designed to support the dip 
 system. This system consists of a silvered-metal engine-divided circle fitted between brass stirrups 
 which act as a support for the needle. Set screws fitted with cones and lock nuts carry the hardened 
 steel axis of a delicately balanced needle. The sensitive spirit level mounted on the pillar facili¬ 
 tates leveling.Duty Free 17.60 
 
286 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 49-27 
 
 81-76 
 
 81-76 
 
 81-77 
 
 81-78 
 
 81-86 
 
 81-87 
 
 81-96 
 
 81-100 
 
 81-101 
 
 COMPASSES 
 
 No. 49-27 
 
 MINER’S COMPASS or DIPPING NEEDLE, a serviceable guide to the location of magnetic iron 
 ore. 
 
 In this instrument the magnetic needle is horizontally balanced on an axis within a graduated circle 
 and in which the needle will be found to assume a position inclined to the horizon. When used 
 for tracing ore, the observer should hold the ring in his hand and keep the needle north and south, 
 standing with his face to the west. The inclination of the needle as read on the graduated scale 
 will show the dip. If the compass is held horizontally, it serves as an ordinary compass. This 
 compass is handsomely finished with raised silvered-metal graduated scale, and is inches in 
 diameter. It is provided with a brass cap cover and is enclosed in a neat plush-lined box .... $11.00 
 
 Nos. 81-76 to 81-78 
 
 Nos. 81-86 to 81-87 
 
 No. 81-96 
 
 MAGNETIC COMPASS, consisting of small, delicately balanced needle mounted in polished brass 
 
 case, with card dial, diameter 12 millimeters.Per Dozen $1.40 
 
 MAGNETIC COMPASS, similar to above, but 25 millimeters diameter, and supplied with ring . . .18 
 
 -, same as above, but 35 millimeters diameter . •. .26 
 
 -, same as above, but 50 millimeters diameter. .33 
 
 MAGNETIC COMPASS, superior quality, raised metal dial with 
 full circle divisions, delicately balanced needle with brass-capped 
 agate bearing enclosed in polished brass case, with stop for needle, 
 
 diameter 30 millimeters. $1.06 
 
 -, same as above, but 50 millimeters diameter. 1.30 
 
 MAGNETIC COMPASS, raised metal dial, with full circle divi¬ 
 sions, agate cap needle, with 37-millimeter aluminum pointer, 
 enclosed in polished brass case, with stop for needle, diameter 
 50 millimeters. 1.66 
 
 MAGNETIC POCKET COMPASS, card dial, full circle divisions 
 with cardinal points, needle with brass-capped bearing with stop, 
 inside a polished mahogany box with hinged cover, diameter 
 2 Yi inches. 1.26 
 
 —, similar to above, but silvered-dial and raised ring, needle with 
 brass-capped agate bearing. 3.00 
 
 No. 81-100 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 287 
 
 No. 81-126 
 
 No. 81-130 
 
 81-125 WATCH CASE SIGHT COMPASS, 234 inches in diameter, excellent quality with full circle divi¬ 
 sions on raised dial. Nicely balanced needle, 134 inches long, with agate bearing. Providedjwith 
 folding sights. Spring cover...$6.60 
 
 81-130 BRIDGE SIGHT CLINOMETER COMPASS, for use both as a clinometer and as a sight compass. 
 
 This useful instrument is constructed to fulfill the office of both clinometer and sight compass. The 
 sights are made in the form of a bridge and can be turned on their pivots at right angles. 
 
 The needle of this compass is a hardened and tempered edge bar with needle jeweled center. It is 
 
 mounted within a three-inch bronze case provided with a silvered-metal dial. 7.60 
 
 81-140 MARINE COMPASS, — a compass in which the 
 moving system is floated in alcohol. 
 
 This is a high-grade instrument 5 inches in diam¬ 
 eter. The moving system floating in alcohol is 
 contained in a compensating chamber. It has 
 a standard marine compass dial with line sights. 
 
 The instrument is furnished in a neat mahogany 
 case .11.60 
 
 No. 81-140 
 
 49-26 SUN DIAL AND COMPASS. This little instrument, 2 
 inches in diameter, combines features of both compass 
 and sun dial. It is a pocket compass with raised dial 
 with distinct divisions and figures, and agate center 
 needle. As a sun dial, it is provided with distinct hour 
 lines and may be readily set to any latitude. Case is 
 nickel-plated and provided with hinged cover. 
 
 Duty Free $6.76 
 
 No. 49-26 
 
288 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 UNIVERSAL INCLINATION EARTH INDUCTOR 
 
 No. 81-166 
 
 81-166 UNIVERSAL INCLINATION EARTH INDUCTOR for exact study of the magnetic moment of the 
 
 earth’s pole. 
 
 This improved design consists of a substantial base with uprights to which is swiveled a frame carry¬ 
 ing a ring. The frame carrying the coil may be inclined to any angle within 180 degrees, the 
 inclination being indicated by a pointer moving before a graduated arc. The ring has a groove 
 in which are coiled about 1,000 turns double silk-covered wire. The leads of this wire are heavily 
 insulated and the ends brought to binding posts shown on top of the frame. A positive throw 
 is secured by a simple spring device shown at the bottom of the frame. This device, when set for 
 use, is held by a projecting rod acting against the spring giving to it a tension. A release and stop¬ 
 ping device, actuated by one button, gives to the ring a definite rotation through 180 degrees. This 
 inductor is carefully made and must not be confused with those at a lower price on the market. 
 Our mounting is of the most substantial construction, well finished, making the instrument not 
 only of scientific value, but one in which any laboratory will take pride. 
 
 FEATURES: 
 
 1. Universal inclination in two planes. 
 
 2. Gimbal mounting for varying the angle of inclination. 
 
 3. Graduated arc and pointer for easily determining the same. 
 
 4. Positive spring device for securing a definite rotation through 180 degrees. 
 
 5. A release and stopping device actuated by one button. 
 
 To facilitate in determining the constant of the instrument the B. & S. Gauge No. of wire, the inner 
 and outer diameter of the coil, the number of turns in the coil and the resistance are all perma¬ 
 nently recorded on the instrument. 
 
 $19.60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 289 
 
 GENERATION OF STATIC ELECTRICITY 
 
 FRICTIONAL ELECTRICITY ACCESSORIES 
 
 In listing our line of Frictional Electricity Accessories, we desire to state that we use only the purest materials 
 which, from our experimentation, have proved most satisfactory. Results, therefore, are assured. 
 
 ‘ "SI 
 
 Nos. 82-10 to 82-65 
 
 82-10 
 
 82-16 
 
 82-20 
 
 82-25 
 
 82-30 
 
 82-35 
 
 82-40 
 
 82-60 
 
 82-56 
 
 82-67 
 
 82-60 
 
 82-66 
 
 82-75 
 
 82-77 
 
 AMBER SPECIMEN, illustrating the power of amber in attracting light bodies, when rubbed with 
 
 silk .$0.96 
 
 FRICTION ROD OF GLASS, 12 X H inch, developing a positive charge when rubbed with silk, nega¬ 
 tive when rubbed^with catskin or flannel. .18 
 
 GLASS FRICTION ROD, one-half ground, other half polished, developing both positive and negative 
 charges regardless of the “rubber”. .36 
 
 VULCANITE FRICTION ROD, developing a negative charge when rubbed by catskin, flannel, or 
 
 silk .38 
 
 WAX FRICTION ROD (sealing wax), developing a negative charge when rubbed by catskin, flannel, 
 
 or silk. .10 
 
 CELLULOID STRIP, 12 inches long, developing a negative charge when rubbed by catskin, flannel, 
 
 or silk. .18 
 
 FRICTION ROD, HALF GLASS, HALF BRASS, illustrating rapid conduction of charge from a 
 
 conductor . .95 
 
 SILK EXCITING PAD.40 
 
 FLANNEL EXCITING PAD.25 
 
 FLANNEL CAP WITH ATTACHED SILK CORDS, after Millikan and Gale, Figure 228 . . . .15 
 
 CATSKIN, small size, whole skin. .75 
 
 CATSKIN, large size, whole skin. 1.25 
 
 No. 82-76 
 
 CHARGING ROD. This charging rod has been designed in order to provide a simple and certain 
 means for charging electroscopes. The charges are produced by the friction between a piece of 
 flannel and a resinous rod. The whole is surrounded by a brass case which acts as a guide for the 
 movable flannel ring. The rod can be used to produce either positive or negative charges .... $6.50 
 
 THE IMPROVED POTENTIAL BAR. This bar is designed to maintain a constant potential dif¬ 
 ference of 1,000 volts, mounted in form for convenient and satisfactory use with Electroscopes, 
 Electrometers, Leyden Jars and other high potential electrical instruments. This is undoubtedly 
 the most valuable single instrument obtainable for the study of electrostatic phenomena. Enables 
 the instructor to carry on satisfactory lecture table demonstrations in static electricity regardless 
 of atmospheric conditions. 9-60 
 
290 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ELECTROPHORUS 
 
 82-110 RITCHIE’S LECTURE TABLE ELECTROPHORUS for generation of static charges by the prin¬ 
 ciple of influence. The plate of this electrophorus is 12 inches in diameter, constructed of a 
 special high quality electro-static rubber mounted in a finished metal base. The disc is of heavy 
 brass finely finished, provided with an insulating handle. It is handsomely finished through¬ 
 out and built on a large plan so that it may be used to advantage on the lecture table ..... $9.25 
 
 82-115 CAST-BASE ELECTROPHORUS. In this instrument, above illustrated, we secure a fine-quality 
 instrument capable of striking results. The plate consists of a shallow trough casting in which 
 is moulded a cake of resinous material. The disc is of heavy brass, provided with an insulating 
 handle. The cast metal base insures insulating material against breaking. 2.96 
 
 GEAR DRIVEN INFLUENCE MACHINES 
 
 TOEPLER-HOLTZ — WIMSHURST 
 
 The demonstrator will be gratified to receive the announcement of the application of “gear drive” to influence 
 machines. It is a fact generally recognized by all manufacturers of these machines that the simpler the machine, 
 the better it is electrically, providing, of course, that the mechanism will hold the various parts in their proper po¬ 
 sitions during operation. 
 
 The greatest drawback to obtaining this result has been the “belt drive” with its recognized defects in slip¬ 
 ping, breaking, slipping off the pulley, etc., etc., but which has been universally used because of its low cost of man¬ 
 ufacture. In correcting this defect and to enable us to improve our product, as well as increase the efficiency elec¬ 
 trically, we have selected the self-contained gear drive in which accurately cut gears operate in a case filled with 
 heavy oil, — a form of construction which automobile manufacturers have brought to a high state of perfection. 
 With this mechanism the power is applied at the same rigid support which holds the main axis of the machine. There 
 is, therefore, no tendency to change the relation of the brushes, collectors and plates, as all are mounted on this 
 same central shaft. 
 
 We announce two types of Gear Drive Influence Machines both of which have the same important character¬ 
 istics which will not be found on any other Influence Machine, European or American. 
 
 On the following page we list the Toepler-Holtz Machines, on the second page following, the Wimshurst Ma¬ 
 chines. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 291 
 
 FEATURES —DETAILS OF CONSTRUCTION 
 
 The following important features and details of construction will, we are confident, impress on the prospec¬ 
 tive purchaser the characteristic quality of Knott’s Gear-Drive Influence Machines. 
 
 1. GLASS PLATES of a selected quality of toughened glass, chemically treated and coated with a special 
 
 varnish which gives to the plates a durable, hard and smooth surface. 
 
 2. COLLECTOR COMBS are particularly efficient in collecting the plate charge with little loss. They 
 
 are unusually long and sharp and, since centrally mounted, it is impossible for them to scrape 
 against collector buttons. 
 
 3. COLLECTING BRUSHES will be found a decided innovation. The Brush Holder is of the spring 
 
 clamp type, giving a positive contact and can be attached in an instant. Brushes are readily 
 adjusted in these holders. 
 
 4. POSITIVE GEAR DRIVE, — accurately cut gears operate in heavy oil within the oil-tight gear 
 
 casing. 
 
 5. INSULATION, CONDENSERS and other details of construction have been most carefully considered 
 
 and all details combine to enable the demonstrator to secure a machine particularly well adapted 
 to the most exacting requirements. 
 
 We wish once more to call to attention the unit method of mounting, by which all of the essential parts of the 
 machine, together with the motive power, are attached directly to the rigidly constructed central support. 
 
 KNOTT’S GEAR DRIVE TOEPLER-HOLTZ MACHINES 
 
 No. 82-160 
 
 82-160 KNOTT’S GEAR DRIVE TOEPLER-HOLTZ MACHINE, 12 and 14-inch plates, gear movement 
 in oil tight gear case, no belts to loosen or get out of order, brushes attached by spring contacts, 
 repair bills reduced to a minimum. Spark one-third diameter of plate.$19.00 
 
 82-160 MULTIPLE PLATE GEAR DRIVE TOEPLER-HOLTZ MACHINE, four plates 12 and 14 inches, 
 gear driven. This machine has all the improvements detailed above. 
 
 The value of the multiple plate machine has long been recognized by the manufacturers of X-Ray 
 apparatus, but the cost of construction has been such as to prohibit the general use in educational 
 work. Our method of standardizing construction enables us to furnish this multiple plate ma¬ 
 chine at a cost within the range of laboratory work.32.60 
 
292 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 KNOTT’S WIMSHURST GEAR DRIVEN 
 INFLUENCE MACHINES 
 
 This type of machine is especially recommended for localities where the humidity is frequently high, as it is 
 much less affected by atmospheric conditions than any other type. The drive mechanism is substantially that of 
 the Toepler-Holtz Machines described on the previous pages, except that the case is provided with another set of 
 gears in order to give the revolution in two directions. The advantages of the gear drive in this type of machine 
 are particularly noticeable since it does away entirely with the cross-belt and insures that both plates operate at the 
 same speed, but in opposite directions. With the crossing and necessary slipping of belts, the belt drive cannot ac¬ 
 complish this result. 
 
 Our improved Gear Drive Wimshurst Machines, in addition to the most important manner of drive, has all 
 mechanical features peculiar to our Influence Machines as described on page 291. Applied to the Wimshurst Machine, 
 these features enable us to offer a machine considerably more efficient, of greater durability and more easily operated 
 than has heretofore been offered. 
 
 82-215 KNOTT’S FOURTEEN-INCH TWO-PLATE GEAR-DRIVE WIMSHURST INFLUENCE MA¬ 
 CHINE, glass plates chemically treated and varnished, mounted according to latest structural 
 modifications and with gear drive, insuring a uniform speed of both plates in opposite directions. 
 
 Spark length approximately 5 inches.$20.00 
 
 BELT-DRIVE RUBBER-PLATE WIMSHURST INFLUENCE MACHINE 
 
 No. 82-230 
 
 82-230 EIGHT-INCH TWO-PLATE BELT-DRIVE WIMSHURST INFLUENCE MACHINE. The 
 
 low price at which this machine is offered prohibits the use of our enclosed gear drive. The belt 
 drive will be found entirely satisfactory on a machine of this size. Spark length approximately 
 3 inches. .$10.00 
 
S 8 S S 
 
 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 293 
 
 STATIC ELECTROMETERS 
 
 83-10 PITH BALLS, assorted plain and colored.Per Dozen $0.25 
 
 —12 PITH BALL STATIC ELECTROMETER, attached to silk cord, ready for use . . Each .08 
 
 -15 METALLIC COATED PITH BALL, vastly more sensitive than the uncoated .Each .10 
 
 -17 PITH BALL, one-inch diameter.Each .60 
 
 -33 GOLD-LEAF, PURE GOLD, in book form for electroscope.Per Book .76 
 
 83-36 ALUMINUM-LEAF, in neat, compact roll, especially prepared for electroscope work . Per Roll .36 
 
 83-40 TIN FOIL for Leyden Jar coatings, Condensers, etc.Per Pound 1.26 
 
 
 w 
 
 No. 83-50 
 
 83-50 GILDER’S KNIFE, PAD, AND TIP for cutting gold-leaf. 
 
 Frequent statements have been made us that it is almost impossible to replace broken leaf on electro¬ 
 scopes. This trouble arises, principally, from lack of proper tools. The outfit illustrated above 
 will facilitate in the cutting and handling of even the finest gold-leaf. 
 
 Knife, Pad, and Tip, complete.$2.60 
 
 83-76 PITH BALL ELECTROSCOPE for qualitative demonstra¬ 
 tion of static charges. 
 
 This apparatus consists of a base on which is mounted an 
 insulated support with arm. To this arm are suspended 
 two pith balls, by fine silk fiber.$0.55 
 
 83-100 PITH BALL ELECTROSCOPE, large size for lecture table 
 demonstration. Two pith balls, 1 inch diameter, mounted 
 as illustrated in No. 83-75 . 2.26 
 
 83-106 CHRISTIAN BROTHERS’ ELECTROSCOPE. This simple 
 instrument is in many respects superior to the ordinary 
 electroscope. It is extremely sensitive and acts with readi¬ 
 ness without the aid of drying agents. If desired, one part 
 of it may be charged negatively and another positively, at 
 the same time, and indications are readily observed by all 
 members of the class. 
 
 It consists of an insulating stand on which is pivoted an ebonite 
 needle of most approved size and shape for sensitive work. 
 
 The only directions for care is that the needle should be 
 dismounted when not in use and wrapped in brown paper 
 so as to exclude light. By this means the needle is always 
 in good condition, ready for instant use.80 
 
 No. 83-75 
 
 No. 83-106 
 
 No. 83-110 
 
 83-110 HARCOURT ELECTROSCOPE for demonstrating static charges, also illustrating an electric shield. 
 
 This apparatus consists of a metal plate in the center of which is placed a light mounted indicating 
 needle. A metal screen with insulating handle is provided for placing over the plate. A second 
 mounted needle is provided on top of the metal screen. 
 
 Upon the approach of a spark from a Static Machine or of any static charge it may be demonstrated 
 
 that the upper needle is attracted or repelled while the lower remains unaffected .$1.76 
 
 
2Q4 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 83-136 STUDENT'S ELECTROSCOPE, simple flask form...$ 0.60 
 
 83-142 CAST DRUM GOLD-LEAF PROJECTION ELECTROSCOPE for use as an electrometer for 
 general laboratory work, but especially adapted for use with a projection lantern. The glass 
 front and back are mounted dust-proof, but may be readily removed. The brass rod carrying 
 the gold-leaf strips is insulated with pure amber set in vulcanite. The spun metal cup (shown 
 by dotted lines) which fits loosely over a collar on top of the drum, obstructs radioactive influences. 
 
 The general design and structure of this instrument are such that one is enabled to keep a charge for 
 long periods of time. Under a ten days’ test only a slight loss of initial charge was noted. 
 
 The ball top may be removed when it is desired to use the condenser plate attachment for demon¬ 
 strating that the plates of a galvanic cell are statically charged. 
 
 Electroscope, complete with Plates and spun metal Protecting Cup. 6.26 
 
 83-143 CAST DRUM GOLD-LEAF PROJECTION ELECTROSCOPE, without Condenser Plate At¬ 
 tachment, but with Protecting Cup. 4.00 
 
 83-144 CONDENSER PLATE ATTACHMENT for use with No. 83-143 above, in demonstrating that the 
 plates of a galvanic cell are statically charged. This attachment consists of two plates of polished 
 brass, the lower in illustration to replace the metal ball, the upper with insulating handle. Plates 
 with special dielectric. 2.25 
 
 83-147 FECHNER’S ELECTROMETER, similar to above, but with the metal leaves adjusted between two 
 
 highly polished metal plates. Complete with constant voltage Charging Box.11.60 
 
 83-148 -, without Charging Box .. 9.00 
 
 83-160 BENNETT’S GOLD LEAF ELECTROSCOPE WITH VOLTA’S CONDENSING PLATE AND 
 SAUSSURE’S POINT DISCHARGE. This instrument is intended for sensitive work in testing 
 electrification of a body and in determining the polarity of the same. In our design we use the 
 best quality of electrical glass and further increase the conducting quality of this glass by ground¬ 
 ing it. The jar used is of special mould which allows of the use of the various attachments without 
 disturbing the gold leaves. As a Simple Gold Leaf Electroscope the knob top alone is used. When 
 it is desired to use the Volta’s Condensing Plates, this knob is unscrewed and the bottom plate 
 put in its place. Differing from the usual method of securing a condensing surface on these plates, 
 we furnish with each instrument a special dielectric which greatly increases the condensing power. 
 
 The bottom plate is replaced by the Saussure Point Discharge when it is desired to test the effects 
 of points in discharging electricity from the surface of a conductor. 
 
 This electroscope is of heavy construction and is handsomely finished throughout. It is furnished 
 complete with interchangeable knob, Volta’s Condenser Plates, one with insulating handle, and 
 with Saussure’s Point Discharge. 8.76 
 
 
 S'; 
 
 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 295 
 
 THE WILSON RADIO-ELECTROSCOPE 
 
 DESIGNED FOR RESEARCH WORK IN RADIO-ACTIVITY 
 
 83-165 THE WILSON RADIO-ELECTROSCOPE. 
 
 This instrument, which was originally 
 manufactured at the request of the De¬ 
 partment of Physics of the University of 
 Toronto, instantly met with much favor 
 among all workers in the radio-active field 
 and has for several years been considered 
 standard for high-grade work. 
 
 As the illustration shows, the instrument is 
 especially designed for telescope reading, a 
 special telescope with cross-hair mounting 
 having been designed for the exact measure¬ 
 ment of the angular movement of the gold 
 leaf. The form is such that it also lends 
 itself perfectly to lantern projection. 
 
 INSULATION. The insulation is as perfect 
 as the purest amber can make it, it having 
 remained charged for 48 hours with no fall 
 capable of being detected with telescope 
 reading. 
 
 SELF LEVELING. Owing to the method of 
 supporting the gold leaf member, no care is 
 required in leveling, the gimbal bearing 
 making it perfectly automatic. 
 
 No. 83-165 
 
 METHOD OF USING THE RADIO-ACTIVE MATERIAL. The opening in the base pillar, seen 
 in the illustration, is designed for the ready inserting of the material to be tested. In use, 
 this material is placed in a small watch glass and inserted in the opening, the outside collar then 
 being moved up to exclude all air currents and to keep the conditions within the instrument as 
 nearly uniform as possible. The distance between the radio-active material and the gold leaf 
 is variable and easily determined by the number of discs seen in the illustration, which are 
 placed under the watch glass, thus fixing definitely the distance between the radio-active material 
 and the gold leaf. It will thus be seen that all conditions have been carefully considered and 
 provided for. 
 
 Price, complete.$13.60 
 
 83-170 
 
 No. 83-170 
 
 MOUNTED TELESCOPE FOR RADIO-ACTIVE WORK. This 
 telescope has been designed for rapid and exact measurement 
 of the angular drop of the gold leaf due to the gradual loss of 
 potential under the influence of the radio-active material. A 
 four-inch graduated dial is mounted on the eye-piece of a read¬ 
 ing telescope in such a manner that the dial, eye-piece and 
 cross-hair move as a rigid unit. The angular movement of 
 the cross-hair is therefore easily read by the dial and pointer. 
 
 In use, the eye-piece is rotated until the cross-hair is parallel to 
 the deflected gold leaf. Note the reading on the dial in degrees. 
 After the lapse of a single unit of time, the dial is to be turned 
 again until the cross-hair is again parallel to the gold leaf. 
 The difference in readings on the scale denotes the angular 
 fall. 
 
 Price for telescope with mountings complete, as illustrated, for 
 radio-active work... 
 
 RADIO-ACTIVE ELEMENTS. See No. 83-276 
 
 16.26 
 
2g6 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 83-220 THE RAYBOURN QUADRANT ELECTROMETER, de¬ 
 signed to meet the requirements of a universal instrument. 
 
 By means of the telescoping suspension tube we are able to 
 use any desired length and type of suspension so as to ad¬ 
 just the sensibility of the instrument, within limits, to 
 any desired sensibility. 
 
 As carried in stock it is supplied with a 50-centimeter phos¬ 
 phor bronze suspension ribbon which, while it is extremely 
 durable, will give ample sensibility for most purposes. 
 
 DISTINCTIVE FEATURES. 
 
 1. A quadrant box of open construction affording easy ac¬ 
 cess and view of the needle. 
 
 2. A needle of very light weight, aluminum welded to the 
 axis wire of copper, the upper end of which is bent to 
 form a hook for attaching suspensions. This construc¬ 
 tion greatly lessens the surface resistance of the metal, 
 which, in case of an aluminum hook ordinarily used, is 
 very great. 
 
 No. 83-220 
 
 3. A space beneath the quadrants is ample for placing 
 drying material. 
 
 4. A very light weight optically plane mirror. 
 
 5. Pure amber insulation throughout. 
 
 6. A zero adjustment, simple but most effective and impossible of accidental derangement. 
 
 7. A removable metal protecting case with large rectangular opening covered by a window of 
 uniformly thin flat glass. 
 
 8. Mounted on tripod and held to same by a friction clamp which permits of a rotary movement 
 of the electrometer. 
 
 9. Binding posts and links permit grounding of case or either pair of quadrants. 
 
 10. Suspensions may be readily attached. 
 
 11. A telescoping support allows suspensions of any desired lengths within range of from 30 to 50 
 centimeters. 
 
 12. Inasmuch as degree of sensibility required depends upon the nature of the work, we supply our 
 stock instruments with a metallic suspension 50 centimeters long. These suspensions will be 
 found very durable and sufficiently sensitive for all work except where extreme sensibility is 
 required, in which case we are prepared to furnish other types of suspensions. 
 
 We confidently recommend this instrument for all classes of work where an electrometer of superior 
 sensitiveness and quality is required. 
 
 83-222 CONSTANT VOLTAGE CHARGING BOX, — designed for the easy and convenient charging of 
 Electroscopes and Electrometers, maintaining a constant difference of electrical potential of 
 250 volts. 
 
 
 $39.50 
 
 2.50 
 
 -,- 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 297 
 
 ELECTROSCOPIC ACCESSORIES 
 
 No. 83-250 
 
 83-260 WATER BATTERY. For charging the needles of electrometers and for gauging electroscopes, a 
 battery giving real, constant and well-defined electromotive forces is essential. 
 
 It has 50 cells, mounted on substantial, neatly finished wooden base and is particularly adapted 
 to advanced work when high voltage and low amperage are desired. It will be found a most 
 serviceable battery for all electrostatic electrometer work.$6.25 
 
 83-252 -, same as above, but comprising 100 cells. This battery is a combination of two of the above 12.76 
 
 No. 84-10 
 
 No. 84-15 
 
 82-76 CHARGING ROD for securing either positive or negative charges for electroscopes. For descrip¬ 
 tion, see page 289 .$6.50 
 
 82- 77 THE IMPROVED POTENTIAL BAR. This bar is designed to maintain a constant potential dif¬ 
 
 ference of 1000 volts, mounted in form for convenient and satisfactory use with Electroscopes, 
 Electrometers, Leyden Jars and other high potential electrical instruments. This is undoubtedly 
 the most valuable single instrument obtainable for the study of electrostatic phenomena .... 9.60 
 
 83- 275 RADIO-ACTIVE SUBSTANCES. For the convenience of those who desire to make a study of radio¬ 
 
 activities we list four of the most important substances. They are black uranium oxide, pitch¬ 
 blende, thorium nitrate and uranium nitrate. 
 
 Set of four in sealed glass stoppered bottles. 3.60 
 
 INSULATION AND CONDENSATION OF STATIC ELECTRICITY 
 
 84- 10 INSULATING STOOL, valuable in insuring total insulation from the earth. 
 
 This stool is constructed with a handsomely finished hardwood top, provided with four glazed 
 
 porcelain legs with knob feet, the insulating qualities of which are unexcelled, even by glass . . . 2.50 
 
 84-15 ADJUSTABLE INSULATING STAND, solid in construction, insulating qualities sufficient for all 
 practical purposes. 
 
 Consists of a supporting plate held adjustably by two vulcanite rods to a metal base. 
 
 Complete as illustrated. 2.60 
 
298 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 84-25 No. 84-30 Nos. 84-50 to 84-65 
 
 84-20 PROOF-PLANE, simple disc type with insulating handle.$0.22 
 
 84—25 GUARDED DISCHARGER, simple form, polished brass arc with ball terminals attached to a polished 
 
 ebonite handle with disc ebonite guard. 1.26 
 
 84-30 TWO-HANDLED JOINTED DISCHARGER, two highly polished brass arcs with knob terminals, 
 
 jointed to provide an adjustable gap, each arc with insulating handle of ebonite. 2.76 
 
 84-224 DISCHARGER, lighter construction than above, ordinary grade. .66 
 
 84—40 SHOCKING HANDLES AND CORDS, the standard form used in testing physiological effects of 
 electrical discharges. Two nickel-plated metallic handles, one with insulated carrier; two conducting 
 cords, each cord with connector tips. Per pair with cords. 1.00 
 
 No. 84-60 
 
 84-50 SIX-INCH INDUCTION AND DISTRIBUTION SPHERE 
 
 for showing that -a charge remains on the outer surface 
 and does not penetrate into the interior. 
 
 This sphere is made of spun brass, highly polished, having 
 a hole in the top. It is mounted on a neat, brightly 
 
 japanned base with an insulating ebonite pillar. Diam¬ 
 eter 6 inches. 6.00 
 
 84-55 FOUR AND ONE-HALF INCH INDUCTION AND 
 DISTRIBUTION SPHERE, same as above but 4J£ 
 inches in diameter. 2.75 
 
 84-67 INDUCTION SPHERES, brass, nickel-plated, 5 cen¬ 
 timeters diameter. Mounted on insulating supports 
 so that they can be brought in contact . .Per pair 3.30 
 
 84-60 SIXTEEN-INCH INDUCTION CYLINDER for illus¬ 
 trating electrostatic induction. 
 
 This apparatus consists of a polished brass cylinder, 16 
 inches in length, mounted on an insulated support with 
 tripod base. This cylinder is provided with movable 
 brass supporting arms to which are attached pith balls. 
 
 If a positively charged sphere be brought near one end of 
 the cylinder, that end will become negatively charged 
 
 while the opposite end will be positive. 7.80 
 
 84-66 EIGHT-INCH INDUCTION CYLINDER, similar to 
 
 above, but 8 inches long. 3.50 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 299 
 
 No. 84-70 
 
 84-70 HOLLOW INDUCTION CYLINDER for demonstrating that a 
 charge collects on the surface only. 
 
 This apparatus consists of a polished brass tube supported on an 
 ebonite stem attached to a base. It is provided with a support 
 for pith balls, both within and without the cylinder. When 
 charged, pith balls without the cylinder will fly apart, while 
 those within will remain unmoved, demonstrating that the 
 outside only is charged.$1.95 
 
 84-75 FARADAY’S METAL SHIELD or ELECTRIC SCREEN for 
 
 covering electroscopes, illustrating the Marconi system of 
 selecting electric signal waves; also illustrating the principle 
 of protection from lightning. 
 
 Mount an electroscope on a metal plate placed on a stand or 
 on the table top. Place Screen over electroscope. Allow sparks 
 from a Static Machine to reach the Screen and note leaves of 
 electroscope. Remove screen and metal plate and test leaves 
 by merely approaching a charge to the electroscope. 
 
 Metal Shield only. .46 
 
 1%S!!SSKS&| 
 
 nmsB 
 I isawsg 
 tos^ejt 
 
 BlJSI i li’S.■ 
 
 BSSSSl 
 
 No. 84-75 
 
 No. 84-80 
 
 No. 84-86 
 
 No. 84-90 
 
 84-80 ELLIPSOIDAL CONDUCTOR for demonstrating the tendency of static distribution. 
 
 This design consists of a polished brass ellipsoidal body mounted on an insulated stem with a neatly 
 
 finished base. Size of ellipsoid, inches long, inches in diameter.$4.50 
 
 84-85 BIOT’S HEMISPHERES for demonstrating that a static charge seeks the outer surface of a body. 
 
 This apparatus consists of two polished brass hemispheres with insulating handles. These hemi¬ 
 spheres are designed to fit over No. 84-55 Induction and Distribution Sphere. 
 
 When the globe is electrified and two hemispheres are placed over it, and then removed, it will be 
 found that they have become electrified while the globe has lost its charge. 
 
 Biot’s Hemispheres, only. 2.25 
 
 84-86 BIOT’S HEMISPHERES and NO. 84-65 INDUCTION AND DISTRIBUTION SPHERE, com¬ 
 plete as illustrated. 6.00 
 
 84-90 RITCHIE’S SURFACE AND INTENSITY APPARATUS for showing the variation of electrical den¬ 
 sity on a unit of surface as that surface is diminished or increased. 
 
 This ingenious instructive instrument consists of a special clamp in which fits the roller insulated from 
 the clamp. Around this roller is wound tin foil. An electrometer in metallic contact with the tin 
 foil indicates the quantity of electrical force. 
 
 When the tin foil is rolled up, a charge is imparted to it by which a certain divergence is produced 
 on the balls of the electrometer. On unrolling the tin foil this divergence gradually diminishes but 
 increases as it is rolled up again. 
 
 The clamp of this instrument may be attached to any 19-millimeter rod. 
 
 Without supporting stand. 3.80 
 
300 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 84-100 
 
 
 
 
 84-100 FARADAY’S CONICAL NET. A net 11 inches long by 5 inches diameter on insulating mount for 
 demonstrating that a static charge will always reside on the outside. The apparatus consists of a 
 conical bag of linen gauze, supported on an insulating stand and to which are attached silk strings 
 by which it may be turned inside out. 
 
 In use, this conical bag is charged, which, by tests, may be shown to reside on the outside only. 
 
 When pulled inside out, and tested, it will be found that the charge still is on the outside, having 
 
 passed through the gauze.$1.65 
 
 84-125 BELL CHIMES, illustrating electrostatic attraction and repulsion between electrified bodies. 
 
 This apparatus consists of an insulated stand to the top of which are attached three cross-heads, to 
 the ends of each of which are attached bells suspended by brass chains. The lengths of these 
 chains are adjusted so that all six will be in the same plane as a large bell mounted to the insulat¬ 
 ing support. Also mounted to these cross-heads are six silk cords each holding a small metal ball. 
 
 The lengths of these cords are adjusted so that the balls will lie in the same plane as the bells. 
 
 When this apparatus is electrified, the small balls will be attracted and repelled between the large 
 
 bell and the small bells, causing a continuous jingle. 9.00 
 
 84-130 UNMOUNTED BELL CHIMES, ordinary type.90 
 
 84-165 IMAGE PLATES for illustrating the phenomenon of attraction and 
 repulsion. 
 
 This apparatus consists of two nickel-plated discs suspended one to the 
 other by insulating cords. To the upper disc is fastened a nickel- 
 plated hook for attaching to the Static Machine; the lower is provided 
 with a chain for securing connection with the ground or opposite pole of 
 Static Machine. 
 
 In use the pith images are placed between the two plates. They will dance 
 up and down as they become charged with positive and negative 
 electricity. 1.80 
 
 84-157 PITH IMAGES, a pair of images constructed of pith for use with No. 
 
 84-155 Image Plates.Per Pair .40 
 
 84-176 POLE-TEST PAPER. When two electrical leads are placed close to¬ 
 gether upon a moistened strip of this paper, the negative pole may be 
 distinguished by the pinkish stain which it leaves . . Per Sheet .05 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 301 
 
 ELECTROSTATIC PHENOMENA 
 
 The following accessories will be found interesting for lecture work. With even the smallest size Influence 
 Machine, a great variety of interesting experiments may be performed. The workmanship of each accessory is ac¬ 
 curate and under proper conditions the desired phenomena may be strikingly illustrated. 
 
 As each accessory is designed to fit our No. 84-200 Universal Stand, only one stand will be found necessary. 
 
 84-200 UNIVERSAL STAND. May be used with all accessories listed. $ 1.00 
 
 84-202 PAPER BRUSH. When discharged, paper strips will stand out as illustrated . .65 
 
 84-204 BELL CHIMES, consisting of five harmonically tuned bells which, when connected to Influence 
 
 Machine, will cause small balls to rapidly vibrate back and forth between them. 2.60 
 
 84-206 DANCING BALLS AND HOLDER. Apparatus connected, the balls will dance within the holder 2.70 
 84-208 WHIRL. When connected to Influence Machine, charge will leap rapidly from points, causing a 
 
 rotary motion . .70 
 
 84-210 HOLDER FOR GEISSLER TUBE AND LIGHT¬ 
 NING PLATE.60 
 
 84-212 EBONITE LIGHTNING PLATE. Spectacular 
 
 sparks across gaps in tin foil when connected 
 
 with Influence Machine. 1.20 
 
 84-214 LIGHTNING SPIRAL TUBE. Spectacular spiral 
 of sparks across gaps in tin foil when connected 
 
 with Influence Machine. 1.60 
 
 84-216 BALL RACE. Hollow glass sphere will race rapidly 
 
 around track when connected to Influence Machine 1.66 
 84-218 SMOKE CONDENSATION APPARATUS. The 
 
 smoke from a smoke handle within a glass holder 
 is condensed when connected to an Influence Ma¬ 
 chine, entirely disappearing. 2.70 
 
 84-220 SHOCKING HANDLES for electrifying persons .60 
 
 84-222 LEYDEN JAR, best glass, heavy tin foil covering, 
 
 4 inches high. 1.10 
 
 84-224 DISCHARGER .66 
 
 84-226 CONDUCTOR CHAINS for connecting accessories 
 
 to Influence Machine. .26 
 
 84-230 DEMONSTRATION SET for illustrating electro- 
 statical phenomena. For the convenience of 
 those who desire to order a complete set, we 
 furnish the set as listed above, Nos. 84-200 to 
 84-226, enclosed in a strongly constructed card¬ 
 board box divided into compartments.16.50 
 
302 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 SUPPLEMENTARY DESIGNS 
 
 ELECTROSTATIC PHENOMENA 
 
 No. 84-240 
 
 No. 84-244 
 
 No. 84-250 
 
 No. 84-242 
 
 No. 84-248 
 
 No. 84-246 
 
 No. 84-252 
 
 No. 84-254 
 
 No. 84-256 
 
 No. 84-268 
 
 No. 84r-260 
 
 ELECTROSTATIC MOTOR; the ebonite spider with the metallic balls is rotated rapidly when 
 
 connected to an Influence Machine...$5.25 
 
 GLASS PENETRATING APPARATUS for producing breath pictures and for penetrating glass. 
 
 When connected to an Influence Machine, the imprint of a coin will be invisible until the glass is 
 breathed upon. With this apparatus, also, a glass plate Y% inch in thickness will be penetrated by 
 
 a spark even from the smallest Influence Machine. 3.16 
 
 SAND APPARATUS. Fine glass sand placed in the funnel will emerge through the hole in the 
 bottom in the form of a straight stream. When funnel is electrified, the sand grains will repel 
 each other, causing the stream to spread out and the fine grains will fall with a spattering noise . 1.96 
 
 QUADRANT ELECTROMETER. When not charged, the ball will lie against the metallic rod. 
 
 When charged, the ball will be repelled and according to the strength of the machine to which it is 
 
 connected, will show a large or small deflection... 2.35 
 
 ELECTRIC MORTAR. When connected with an Influence Machine, a spark will jump across the 
 inside of the mortar. The air is suddenly expanded and the ball lying loose on the top is thrown 
 up into the air. If a Leyden Jar is also connected, there will be an explosion and the ball will fly 
 
 a considerable distance. . . 1.36 
 
 BEETZ’ ELECTROSCOPE for demonstrating that a charge collects on the surface only. When 
 apparatus is electrified, the two balls at the top will fly apart while those within the cylinder will 
 
 show no movement._. 1-65 
 
 CANDLE EXPERIMENT for demonstrating that negative electricity will repel a flame and that 
 positive will attract. This apparatus will also show the so-called electric wind, which may be so 
 strong that, when in proper position, the candle is extinguished. An extra ball with a point is 
 supplied to replace one of the balls with hook on the ebonite collar. In performing this experi¬ 
 ment, both balls with hooks must be removed from the pillars. 1.95 
 
 REVOLVING DISC. The ebonite disc which is 
 studded with small colored circles for obtain¬ 
 ing a better visibility is made to revolve rapid¬ 
 ly in consequence of the radiation of the 
 electricity from the points beneath it . . . $2.00 
 
 RADIATION APPARATUS. After the appara¬ 
 tus has been connected to the Influence Ma¬ 
 chine, a luminous circle will be seen in the 
 dark radiating from the disc to the ring . . 1.95 
 
 LIGHTNING CONDUCTOR. A small quan¬ 
 tity of benzine or ether is placed in the small 
 dish. The point resembling a lightning con¬ 
 ductor is unscrewed from the knob mounted 
 on the ebonite pillar. If a spark is now 
 caused to strike this knob, the contents of the 
 dish will be ignited. If point is replaced and 
 grounded by a chain and experiment re¬ 
 peated, there will be no ignition as the spark 
 will be slowly discharged through the point . 2.36 
 
 84-260 IGNITION APPARATUS. By means of a 
 spark from a Leyden Jar, small pieces of 
 ignition paper are ignited. With extra supply 
 
 of ignition paper. 1.76 
 
 84-266 SUPPLEMENTARY DEMONSTRATION SET, 
 consisting of Nos. 84-240 to 84-260 together 
 
 in a strongly constructed wood-reinforced „_____.... 
 
 cardboard box, divided into compartments 19.76 No. 84-266 
 
 84-240 
 
 84-242 
 
 84-244 
 
 84-246 
 
 84-248 
 
 84-260 
 
 84-262 
 
 84-254 
 
 84-256 
 
 84-258 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 303 
 
 STORAGE OF STATIC 
 
 No. 85-10 No. 86-15 
 
 ELECTRICITY 
 
 © 
 
 No. 85-40 
 
 86-10 DEMONSTRATION LEYDEN JAR for demonstrating that an electric charge resides as potential 
 energy in the glass of a Leyden Jar and not in the metallic coatings. 
 
 This is a dissectible Leyden Jar, the outer metallic covering being removable as well as the inner. The 
 inner is provided with a rod with ball terminal for charging. This form must not be confused with 
 the many types on the market. We use a special form of toughened glass for our glass jar and our 
 coatings are of polished brass. The instrument presents a handsome appearance and readily recom¬ 
 
 mends itself in comparison with other makes.$2.90 
 
 85- 16 QUART LEYDEN JAR for storing static electricity. 
 
 This jar is constructed of a special quality of toughened glass, the coatings being smoothly applied. 
 
 Provided with insulating cover through which passes a rod, one end of which is terminated in 
 
 a knob. To the other is attached a chain making connection with the inner coating. 1.60 
 
 86- 20 TWO-QUART LEYDEN JAR, same quality as above. 2.00 
 
 86-26 LEYDEN JAR, as used on our 12-inch Toepler-Holtz Influence Machines. 1.00 
 
 86-30 LEYDEN JAR, as used on our 16-inch Toepler-Holtz Influence Machines. 1.10 
 
 86-40 LUMINOUS LEYDEN JAR for demonstrating optically the distribution of static electricity over 
 the surface of a condenser being charged and discharged. 
 
 This jar is of the same size as our No. 85-20, but is coated inside and out with a tin-foil coating which 
 is not continuous but cut diamond-shaped. 3.15 
 
 LEYDEN JAR BATTERIES 
 
 These consist of a series of Leyden Jars as previously 
 listed, arranged so that their inner coatings are connected 
 to one terminal and their outer coatings to another, thus 
 securing a larger area of coated surface than is contained 
 in one jar. With an arrangement, therefore, of more than 
 one jar connected in this manner it can be demonstrated 
 that the capacity of a condenser is directly proportional to 
 the area of its coated surface. This will be demonstrated 
 by the greater time it takes to charge the battery and 
 the more powerful spark obtained. 
 
 In the form of battery above illustrated we furnish 
 one in which all connections are open to view. The jars 
 are made of the same high quality of di-electric glass as 
 used in all our Leyden Jars. They are placed in a box 
 lined with heavy tin foil which serves to connect the outer 
 coatings with the jars. The inner coatings are connected 
 by means of brass chain. 
 
 85- 60 TWO-JAR LEYDEN BATTERY .... $ 6.80 
 
 86- 66 FOUR-JAR LEYDEN BATTERY . . . 11.70 
 
 86-70 SIX-JAR LEYDEN BATTERY.16.00 
 
 No. 86-65 
 
304 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 86-100 
 
 86-106 
 
 86-110 
 
 PLATE CONDENSERS 
 
 No. 86-100 
 
 DISSECTEBLE DEMONSTRATION PLATE CONDENSER for a study of induction in a condenser. 
 
 This apparatus consists of a neatly finished wooden base on which are mounted three insulating up¬ 
 rights. On the central upright is mounted a glass plate, on each of the others a rod sliding in 
 a hole at the top of the upright. Each rod carries at one end a brass plate, at the other an in¬ 
 sulating handle. All parts are carefully assembled and metal work polished and lacquered. 
 
 By means of a suitable electrometer the density and distribution of a charge under various conditions 
 
 may be readily determined.$9.60 
 
 MOUNTED CONDENSER PLATES, after Millikan, Gale and Bishop (Experiment 27) . . Pair .26 
 
 No. 86-110 
 
 MOUNTED GLASS PLATE CONDENSER for use as a Leyden Jar Battery in accumulating and 
 storing static charges. 
 
 This condenser consists of a neatly finished hardwood frame in which are mounted five condenser 
 plates constructed of the best quality toughened glass and having a total condensing surface area 
 of 1,620 square centimeters. Two parallel conductor rods mounted at the top of the frame over the 
 plates and provided with contact arms for connecting any number of plates desired up to five 
 serve to charge the condenser. 
 
 Complete as illustrated .$14.60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 305 
 
 ELECTRICAL DISCHARGE TUBES 
 
 GEISSLER TUBES 
 
 Our collection of GEISSLER TUBES has been selected with the greatest care, the basis of selection being that 
 of the greatest color effects with didactic illustrative features. These tubes are manufactured by one of the most 
 prominent manufacturers in Europe whose name is a sufficient guarantee of quality. Each tube is provided with 
 strong terminals sealed securely in a manner to obviate frequent breakages at terminal points. 
 
 These tubes are constructed of uranium and white glass formed into various shapes for producing pleasing optical 
 effects. The air is then evacuated and the tubes are sealed. 
 
 86-10 GEISSLER TUBES, plain, set of six different shapes, 6 inches (15 centimeters) long, enclosed in neat 
 
 cardboard case . .$3.00 
 
 86-11 -, same as above.Each .60 
 
 86-15 GEISSLER TUBES, similar to above, but more complicated in form, presenting more pleasing effects, 
 
 set of six, 12 inches (30 centimeters) long, in neat cardboard case. 6.70 
 
 86-16 -, same tubes as contained in above set.Each .95 
 
 No. 86-25 
 
 86-26 
 
 86-26 
 
 86-30 
 
 FLUORESCENT GEISSLER TUBES. These tubes are constructed in a manner similar to above, 
 but filled with fluorescent liquids such as eosine, quinine, kerosene, sesculine, and uranine. 
 
 These tubes present very handsome colors and are highly recommended. Set of six, 6 inches (15 
 
 centimeters) long, enclosed in neat cardboard case. 
 
 -, same tubes as contained in above set.Each 
 
 FLUORESCENT GEISSLER TUBES, similar to above, but more complex in form. Length 12 inches 
 (30 centimeters). Set of six in neat cardboard case 
 
 , same tubes as contained in above set 
 
 $5.40 
 
 .90 
 
 9.90 
 
 1.65 
 
 86-31 
 
 Each 
 
306 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 86-40 
 
 86-46 
 
 FOURTEEN-INCH LECTURE TABLE GEISS¬ 
 LER TUBES. These tubes are designed to 
 illustrate the principal types of Geissler tubes. 
 
 They are 14 inches (35 centimeters) long and 
 give remarkably beautiful results. Set of 
 seven tubes as follows: ■ 
 
 (1) Double Tube, containing two fluores¬ 
 cent liquids. 
 
 (2) Double Tube, containing two phos- 
 
 r horescent substances. 
 
 Highly Evacuated Tube, constructed 
 of uranium and white glass. 
 
 (4) Double Tube, containing two gases. 
 
 (5) Mercury Tube. Will show phosphor¬ 
 escence by shaking mercury in the tube. 
 
 (6) Tube containing a mercury salt which 
 changes colors as heated. 
 
 (7) Tube showing layers of light. 
 
 Set complete, in neat cardboard case .... $14.80 
 
 FLUORESCENT GEISSLER TUBE, containing 
 two fluorescent liquids, illustrating fluorescence 
 of different colored liquids.. 2.36 
 
 No. 86-40 
 
 86-46 PHOSPHORESCENT GEISSLER TUBE, containing two phosphorescent substances.$2.10 
 
 86-47 GEISSLER TUBE, constructed of uranium and white glass, highly evacuated, to illustrate colors 
 
 through different qualities of glass. 2.00 
 
 86-48 GEISSLER TUBE, containing two different gases. 2.00 
 
 86—49 PHOSPHORESCENT MERCURY TUBE. This tube does not require use of Influence Machine 
 or Induction Coil, as phosphorescence of the mercury may be shown by simply shaking it from one 
 end of the tube to the other. 2.60 
 
 86-60 PHOSPHORESCENT GEISSLER TUBE, containing a mercury salt which exhibits different colors 
 
 as it is heated. 2.10 
 
 86-61 GEISSLER TUBE, constructed to show various strata of light. 2.00 
 
 No. 86-60 
 
 No. 86-62 
 
 No. 86-64 
 
 No. 86-66 
 
 86-60 GEISSLER TUBE, improved form, constructed of uranium and white glass and filled with various 
 fluorescent liquids, mounted on glass foot, and provided with strengthened terminals for connec¬ 
 tion to Influence Machine or Induction Coil. Height 6 inches. $1.66 
 
 86-62 GEISSLER TUBE, improved form, as above, but of different shape and more complicated design. 
 
 Height 6 inches (15 centimeters). 1.76 
 
 86-64 GEISSLER TUBE, similar to above, but more complicated design, height 6 inches (15 centimeters) 1.96 
 
 86-66 GEISSLER TUBE. The design illustrated excels in colors. It is designed to show fluorescence of 
 three different colored liquids and two gases, as well as the colors of uranium and white glass. It is 
 mounted on glass foot and is 6 inches (15 centimeters) high. 
 
 2.26 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 307 
 
 No. 86-76 
 
 86-75 UNEQUALLY EVACUATED GEISSLER TUBES for showing effects upon a spark 
 as it passes through tubes filled with unequally attenuated air. 
 
 This apparatus consists of five connected Geissler Tubes, each of which has a dif¬ 
 ferent degree of exhaustion. 
 
 In the least exhausted tube the spark is well defined, but as the vacuum increases, 
 this spark begins to widen out and fill the whole tube, becoming pale in tint 
 and nebulous in form.Per set of five $8.90 
 
 86-86 EXPERIMENTAL BAROMETER VACUUM AND GEISSLER TUBE. The tube 
 illustrated is designed for the purpose of making a critical study of the vacuum 
 in a barometer tube, Geissler tube, Crooke’s tube and X-Ray tube. 
 
 Platinum electrodes are inserted in both the upper and lower end of the tube. The 
 mercury reservoir holds sufficient mercury to fill the entire chamber. The 
 length of the tube is such as to allow ample vacuum space above the mercury 
 under complete exhaustion. The air is exhausted through the tubulature at 
 the top of the tube, while the reservoir is filled through the tubulature in the 
 base. 
 
 For the study of the barometer, the Cooper-Hewitt Lamp, the Geissler tube, the 
 Crooke’s tube, the X-Ray tube and all electrical phenomena under reduced at¬ 
 mospheric pressure, we consider this the most important piece of apparatus that 
 has ever been offered. 3.25 
 
 GEISSLER TUBE ROTATORS 
 
 86-100 
 
 86-102 
 
 86-104 
 
 86-110 
 
 GEISSLER TUBE ROTATOR for rotating Geissler Tubes 
 to increase the spectacular effect. 
 
 Our Rotator consists of a practical motor (not a toy) con¬ 
 structed after designs of the expensive commercial types. 
 
 It is mounted upon a substantial metal pedestal support 
 and is provided with appropriate binding posts, one pair 
 for battery or other current and one pair for induction 
 coil or Influence Machine. The Geissler tube is at¬ 
 tached to the holder, which may be firmly fixed to the 
 spindle of the rotator. This holder is adjustable to 
 take any Geissler tube up to 12 inches in length. 
 
 Motor only, with Geissler tube attachment, motor wound 
 
 for battery current.$12.00 
 
 -, same as above, but motor wound for 110 volts, D. C. 13.25 
 
 -, same as above, but motor wound for 110 volts, A. C. 13.25 
 
 GEISSLER TUBE HOLDER for use with our No. 21-10 
 Mechanical Rotator or our No. 21-30 Motor Rotator, 
 to hold Geissler Tubes for rotation. 
 
 This holder can be firmly attached to the spindle of either 
 of these rotators and is adjustable to hold all sizes of 
 Geissler tubes up to 12 inches long. 2.70 
 
 No. 86-100 
 
3o8 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 SPECTRUM AND VACUUM TUBES 
 
 Nos. 77-225 to 77-236 No. 77-245 
 
 77-225 GEISSLER SPECTRUM TUBE, most careful construction, filled with carbon dioxide.$1.95 
 
 77-226 -, filled with hydrogen gas . 1.95 
 
 77-227 -, filled with nitrogen gas. 1.96 
 
 77-228 -, filled with oxygen gas . 1.95 
 
 77-235 GEISSLER SPECTRUM TUBE, most carefully constructed, evacuated, and filled with pure argon 
 
 gas. 7.75 
 
 77-236 , same as above, but filled with helium. 7.75 
 
 77-245 GEISSLER SPECTRUM TUBE for evacuating and filling with whatever gas desired. Fitted with 
 
 two carefully ground glass cocks. 1.96 
 
 86-150 DE LA RIVES APPARATUS for showing that magnets act on light in Geissler 
 tubes in accordance with the laws with which they act on any other movable 
 conductor. 
 
 The apparatus consists of a highly evacuated bulb sealed into the lower end of 
 which, and extending up into the bulb, is a tube, into which extends a rod of 
 soft iron. This rod, in use, is magnetized by an electro-magnet. 
 
 Terminals of the bulb are connected to an electrostatic current or current from 
 an induction coil, and a beam of light passes from one terminal to the other. 
 
 When the voltaic current is turned through the electro¬ 
 magnet, this beam of light turns slowly about the mag¬ 
 netized rod, sometimes in one direction, sometimes in 
 the other, according to the direction of the induced current 
 or of the induced magnetism. 
 
 Complete with electro-magnet. 
 
 $5.90 
 
 No. 86-150 
 
 No. 86-160 
 
 86-165 
 
 No. 86-170 
 
 86-160 
 
 86-165 
 
 VACUUM TUBE for showing the heating effect of the cathode ray. The negative electrode is in 
 the form of a mirror, designed to focus the cathode ray upon a piece of platinum foil, heating it 
 white hot in a very short time. 
 
 $7.75 
 
 VACUUM TUBE for showing the deflection of a cathode ray. On one side of an evacuated tube is 
 a fluorescent screen with a strip with slit at right angles. This strip absorbs the cathode rays 
 except those which pass through the slit. By holding a magnet to the tube, it may be shown that 
 this beam is deflected as indicated by its path on the fluorescent screen. 6.60 
 
 86-170 VACUUM TUBE for showing the power of a body to interpose the cathode ray. When the dis¬ 
 charge passes, the cathode rays proceed in straight lines. The small cross, however, interposes a 
 number of these molecules and a shadow of the cross is cast on the opposite side of the tube . . . 
 
 7.25 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 309 
 
 ROENTGEN RAY APPARATUS 
 
 X-RAY TUBES 
 
 Nos. 87-40 to 87-50 
 
 The following four tubes are for use with small enclosed Static Machines and Spark Coils operated by battery 
 current which give sparks of from four to six inches in length. We frequently have requests for X-Ray tubes to be 
 used with small unenclosed Static Machines and small Ruhmkorff Coils, but none of these tubes will give satisfactory 
 results and we have not included any in this series. 
 
 87-10 AUTOMATICALLY ADJUSTED X-RAY TUBE, 4 inches in diameter with heavy platinum target 
 
 and with special attachment for maintaining automatically the proper degree of vacuum .... $9.80 
 
 87-15 X-RAY TUBE, 4 inches in diameter with heavy platinum anode the same as above, but without the 
 
 automatic adjuster. 7.50 
 
 87-20 AUTOMATICALLY ADJUSTED X-RAY TUBE, 534 inches in diameter with heavy platinum anode 
 
 and with automatic adjuster.12.25 
 
 87-26 -, 6 inches in diameter with heavy platinum anode and automatic adjuster.16.40 
 
 The following three tubes are for use with large enclosed Static Machines and with large Induction Coils operated 
 by power current with Electrolytic Interrupter. 
 
 87-40 AUTOMATICALLY ADJUSTED X-RAY TUBE, 6 inches in diameter with heavy platinum anode 
 
 and automatic adjuster.$22.00 
 
 87-45 -, 7 inches in diameter with heavy platinum anode and automatic adjuster.27.75 
 
 87-50 -, 8 inches in diameter with heavy platinum anode and automatic adjuster.33.50 
 
 The following two tubes are for use with Tesla and High Frequency Coils. 
 
 87-60 AUTOMATICALLY ADJUSTED X-RAY TUBE, 5J4 inches in diameter with especially constructed 
 
 platinum anode and automatic adjuster.20.40 
 
 87-65 -, 6 inches in diameter with especially constructed platinum anode and automatic adjuster . . 22.60 
 
 (We recommend the use of the above two tubes with our High Frequency Coils, Section 96.) 
 
 The following three tubes are recommended for the very heaviest machines and the most exacting work that 
 can be put upon the X-Ray tube. The anode is of heavy sheet Tungsten which will fuse only at a temperature of 
 3,000 Centigrade, and for X-Ray work*is practically indestructible. These three tubes are the latest and best prod¬ 
 
 uct in X-Ray tube construction. 
 
 87-70 TUNGSTEN X-RAY TUBE, latest construction, 6 inches in diameter.$38.00 
 
 87-75 -, same as above, 7 inches in diameter.44.60 
 
 87-80 -, 8 inches in diameter.49.26 
 
3io 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 87-100 SMALL X-RAY STAND, universal adjustment.$2.50 
 
 87-110 LARGE X-RAY STAND, with heavy iron base. This stand is four feet tall and is arranged for 
 
 adjustment in all directions.11.00 
 
 Nos. 87-126 to 87-146 
 
 Nos. 87-126 to 87-146 
 
 87-126 BARIUM PLATINO-CYANIDE FLUOROSCOPE AND SCREEN, 3X4 inches.$8.26 
 
 87-127 BARIUM PLATINO-CYANIDE FLUOROSCOPE AND SCREEN, 5x7 inches.16.80 
 
 87-130 BARIUM PLATINO-CYANIDE FLUOROSCOPE AND SCREEN, 6X8 inches.19.26 
 
 87-140 CALCIUM TUNGSTATE FLUOROSCOPE AND SCREEN, 5 X 7 inches.12.00 
 
 87-145 CALCIUM TUNGSTATE FLUOROSCOPE AND SCREEN, 6X8 inches.13.60 
 
 No. 87-176 
 
 87-176 PROTECTOR for X-Ray Tube. This Protector is of rubber and will fit over all sizes of tubes up to 
 
 six inches in diameter. .$8.75 
 
 87-180 PROTECTOR for large X-Ray Tubes. This Protector is made of glass containing approximately 
 
 40 per cent, of lead, and should be used with tubes measuring 7 inches and 8 inches in diameter . 13.60 
 
 No. 87-190 
 
 87-190 EYE-GLASS PROTECTOR to be worn by operator when doing X-Ray work . . 
 
 $3.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 90-10 
 
 90-16 
 
 90-20 
 
 90-26 
 
 90-30 
 
 90-36 
 
 90-40 
 
 90-46 
 
 90-60 
 
 90-66 
 
 90-76 
 
 90-80 
 
 90-96 
 
 67-10 
 
 90-100 
 
 90-106 
 
 3U 
 
 ELECTRICITY 
 
 ELECTRICAL SUPPLIES 
 
 COPPER WIRE, bare. 
 B. & S. Gauge . . . . 
 Price per 1 oz. Spool 
 Price per 4 oz. Spool 
 Price per 1 lb. Spool . 
 
 COPPER WIRE, double cotton covered. 
 
 B. & S. Gauge. 
 
 Price per 4 oz. Spool. 
 
 Price per 1 lb. Spool. 
 
 COPPER WIRE, enamel coated. 
 
 B. & S. Gauge. 
 
 Price per 4 oz. Spool. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 Fi 
 
 
 16 
 
 18 
 
 20 
 
 22 
 
 24 
 
 26 
 
 27 
 
 28 
 
 [30 
 
 
 
 
 
 
 
 
 
 
 $0.20 
 
 
 
 
 $0.26 
 
 .26 
 
 .30 
 
 .32 
 
 .36 
 
 .38 
 
 .36 
 
 
 $0.76 
 
 .76 
 
 .80 
 
 .86 
 
 .90 
 
 .96 
 
 1.00 1 
 
 L.10 
 
 
 
 >n covered, 
 
 paraffined. 
 
 B. & S. Gauge No. 
 
 18 
 
 
 
 Per 
 
 ]/2 Pound Coil 
 
 $0.40 
 
 Per Pound Coil 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 i 
 
 J 
 
 16 
 
 18 
 
 20 
 
 22 
 
 24 
 
 26 
 
 27 
 
 28 
 
 30 
 
 36 
 
 
 
 $0.36 
 
 .40 
 
 .46 
 
 .60 
 
 .62 
 
 .66 
 
 .60 
 
 1.16 
 
 $0.90 
 
 .96 
 
 1.00 
 
 1.06 
 
 1.10 
 
 1.36 
 
 1.40 1 
 
 L.60 
 
 
 
 
 
 a 
 
 
 b 
 
 
 c 
 
 
 
 
 $0.75 
 
 28 
 
 $0.86 
 
 30 
 
 1.36 
 
 36 
 
 1.96 
 
 FLEXIBLE WIRE, TINSEL WIRE, covered with green twisted braid.Per Yard 
 
 LAMP CORD, two conductors twisted, B. & S. Gauge No. 18, rubber and cotton insulation. Per Yard 
 THEATRE CABLE for 40 amperes current; advisable for use in lantern projection. This cable con¬ 
 sists of two conductors, flexible, cotton wrapped, rubber covered, braided, twisted together with 
 filler, and finished with two weather-proof braids.Per Yard 
 
 SPRING BRASS WIRE. 
 
 B. & S. Gauge .... 
 Price per 4 oz. Spool . 
 FUSE WIRE. a 
 Amperes ... 
 
 Price per yard . $0.07 
 
 a 
 
 22 
 
 $0.30 
 b c 
 1 3 
 
 b 
 
 24 
 
 .32 
 
 d 
 
 5 
 
 GERMAN SILVER WIRE, 
 
 bare. 
 
 B. & S. Gauge .... 
 
 Price per 4 oz. Spool . 
 
 26 
 
 $0.48 
 
 IRON PICTURE WIRE, No. 1 
 LEAD WIRE, inch diameter 
 
 c 
 
 27 
 
 .36 
 e 
 10 
 
 .18 
 
 18 per cent, alloy, 
 
 a b c 
 28 30 
 
 .64 .60 
 
 .08 .10 .12 
 
 d e 
 28 30 
 
 .40 .60 
 
 f g 
 15 35 
 
 .26 .40 
 
 $0.20' 
 
 .20 
 
 1.60 
 
 alloy. 
 
 90-60 GERMAN SILVER WIRE, 18 per cent, 
 single cotton covered. 
 
 a b bb c d dd 
 
 B. &. S. Gauge . . 18 20 24 28 30 36 
 
 Price per 4-oz. Spool $0.76 1.00 1.10 1.20 2.00 
 Price per 1 lb. Spool $1.76 
 90-70 IRON WIRE, soft drawn, bare. 
 
 abed 
 B. & S. Gauge . . 24 27 28 30 
 
 Price per 4 oz. Spool $0.16 .18 .19 .20 
 
 .Per Package $0.10 
 
 . Per Foot .05 
 
 SPECIAL HIGH RESISTANCE WIRE for use in resistance measurements, — especially valuable in 
 
 determining the effect of temperature on resistance. Per 10 feet .25 
 
 PIANO WIRE, best quality imported, wound in coils, each weighing approximately pound. 
 
 abed 
 
 Diameter, inch. .028 .022 .0178 .014 
 
 Per Coil. $0.40 .46 .46 .66 
 
 PLATINUM WIRE. a b c d e f 
 
 B. & S. Gauge. 20 22 24 26 28 30 
 
 In view of the continual market fluctuations in the price of Platinum, we quote only on application. 
 
 ZINC WIRE, % inch diameter.Per Foot $0.20 
 
312 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 90-150 ARTIFICIAL LIGHT CIRCUIT for reproducing, within the laboratory, conditions similar to those of 
 an actual incandescent lighting circuit as worked out in the Applied Electrical Laboratory of Pratt 
 Institute. 
 
 A wire of known high resistance per mil-foot, resembling in appearance an ordinary incandescent 
 lighting wire, but having an asbestos insulation to avoid danger of fire. In use this.wire is strung 
 along the side of a room or mounted on a movable frame using standard porcelain insulators and 
 cleats, lamp sockets and switches. 
 
 Fiftv-foot Artificial Lighting Circuit complete with special resistance wire, sufficient insulators, cleats, 
 
 lamp sockets and switch, with full directions and diagrams for setting up.$8.76 
 
 THE IMPROVED RAPID BATTERY CONNECTORS 
 
 Patent Pending 
 
 Nos. 90-176 to 90-180 
 
 As will be suggested from the cut, these battery connectors are made of a carefully proportioned spiral spring 
 o fphosphor-bronze wire, the proper size to give sufficient rigidity and at the same time to make them easy of connec¬ 
 tion. 
 
 The spirals being separated by a slight pull, the straight end of the next connector is readily slipped in place, 
 making a secure electric contact which will not accidentally loosen in the course of the experiment. 
 
 These terminals are especially serviceable in laboratory work, since they have the important feature of being 
 connected with equal facility to either an English or American form binding post. For parallel or multiple connec¬ 
 tion they are equally well suited. The use of this connector, therefore, does away with the multiplicity of connectors 
 designed for meeting the conditions of various kinds of binding posts. It frequently happens that one type of instru¬ 
 ment having an English post has to be connected with another having an American post. With the usual form of 
 connectors this condition is very hard to meet. With the “Rapid” this difficulty is entirely overcome. 
 
 Please note the diagram for methods of connecting to English posts, to American posts, and for connecting in 
 multiple and parallel circuits. 
 
 As will be noted from the listing below, these connectors are furnished in pairs or in quantity, without wire con¬ 
 nections, also furnished with wire connections of varying length. 
 
 90-175 
 
 90-177 
 
 THE IMPROVED RAPID CONNECTING TIPS..Per Dozen $0.25 
 
 Per Hundred 2.00 
 
 THE IMPROVED RAPID CONNECTORS, attached to connecting cord 6 inches long, especially 
 
 designed for close connection, such as joining batteries in multiple and in series . . . Per Pair .20 
 
 90-179 THE IMPROVED RAPID CONNECTORS, attached to a con¬ 
 necting cord 2 feet long.Per Pair 
 
 90-180 THE IMPROVED RAPID CONNECTORS, attached to a con¬ 
 necting cord 3 feet long.Per Pair 
 
 CONNECTORS 
 
 90-185 THE “PRIMO” POSITIVE CONTACT LECTURE TABLE 
 CLASPS. These connectors are recommended for rapid con¬ 
 nections in lecture table work. Connections to all styles of 
 binding posts, both bare and insulated wire, can be made in an 
 instant. The grip with teeth makes an excellent contact 
 even through heavily insulated wires.Per Pair 
 
 90-187 THE “PRIMO” POSITIVE CONTACT LECTURE TABLE 
 CONNECTOR. Consists of a pair of No. 90-186 Clasps with 
 a 4-foot length of flexible, heavily insulated copper wire. Each 
 
 $0.30 
 
 .40 
 
 .60 
 
 Nos. 90-186 to 90-187 
 
 .80 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 3i3 
 
 90-190 
 
 * 
 
 90-195 
 
 90-220 
 
 UNIVERSAL CONNECTOR TIP adapted to both English and American types of binding posts. 
 
 To make a convenient laboratory connector, cut a single connecting flexible cord to the desired 
 length. Strip the insulation for one-half inch at each end, leaving the bare wires. Twist the bared 
 wires between the fingers, place in the groove, and bend over with a vise or a pair of pliers until 
 the wire is pinched firmly between the poles of the connector. Some prefer to touch the contact 
 with a drop of solder before bending over.Each $0.05 
 
 No, 90-195 
 
 THE CADY HIGH POTENTIAL CONNECTOR 
 
 THE CADY INSULATED PINCH CONNECTOR, designed for high potential currents to insure 
 safety to the worker and to guard against short circuit. 
 
 Every instructor and wireless worker has had his patience tried with the old-fashioned wire con¬ 
 nectors. They waste time, they fail to grip the smaller sizes of wire and there is constant danger 
 of short circuit and a ground through the operator. 
 
 The Cady Pinch Connector makes all these troubles vanish. There are no screws to turn, only a 
 knob to press. By means of a strong spring inside the connector, a good contact is assured with 
 any size of wire from %2-inch diameter to the thinnest wires and ribbons. The connector is com¬ 
 pletely insulated, being encased in hard rubber, insuring perfect insulation and safety in use. 
 
 These advantages make the Cady Pinch Connector invaluable for general experimental work and 
 for lecture demonstration, especially when frequent changes in connections have to be made. 
 For connecting the fine wires of vacuum tubes and in other high voltage experiments they will be 
 
 found indispensable.Price Each $0.95 
 
 PORCELAIN INSULATING TUBE, after Fuller and Brownlee (Experiment 74).12 
 
 90-221 WOODEN CORES with ATTACHED BINDING POSTS for above 
 
 .25 
 
314 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 •f 
 
 
 BINDING POSTS, CONNECTORS, ETC. 
 
 All of our binding posts, connectors, etc., are manufactured in our own shop, accurately made from the best 
 material, using special tools. By manufacturing in large quantities we are able to supply them at prices which will 
 compare favorably with those commonly charged for similar articles of inferior material and workmanship. We 
 desire to emphasize the fact that all binding posts leaving our factory are finished handsomely, polished and lacquered. 
 
 When ordering binding posts state whether screws and washers are desired or not. If screws are wanted state 
 whether wood or machine, round or flat headed, and length. 
 
 At an additional expense of one cent each a screw of any kind or size, together with either one or two washers, 
 will be supplied. 
 
 Each article herewith illustrated is represented full size. 
 
 No. 90-225 
 Each . $0.90 
 
 No. 90-230 
 Each . $0.90 
 
 No. 90-240 
 Each . $0.55 
 
 No. 90-242 
 Each . $0.46 
 
 No. 90-245 
 Each . $0.58 
 
 No. 90-247 
 Each . $0.26 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 3i5 
 
 No. 90-270 
 Each . $0.46 
 
 No. 90-290 
 Each . $0.18 
 
 No. 90-288 
 Each . $0.12 
 
 No. 90-284 
 Each . $0.16 
 
 No. 90-286 
 Each . $0.12 
 
 No. 90-306 
 Platinum Tipped 
 Each . $0.76 
 
 1MH 
 
 w t % 
 
 gifc 
 
 IHI No. 90-312 
 
 No. 90-296 No. 90-310 Each . $0.10 
 
 Each . $0.16 Each . $0.11 
 
 No. 90-297 
 Each . $0.16 
 
 Each . $0.26 
 
 No. 90-299 
 Each . $0.16 
 
 No. 90-316 Triple Connectors. Each $0.18 
 
 BATTERY CARBON BINDING POSTS, see page 326. 
 
 \ 
 
316 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 SWITCHES 
 
 90-320 CONNECTION BOARD, after Fuller and Brownlee (Experiment 76). $3.00 
 
 90-326 SINGLE POLE, SINGLE THROW KNIFE SWITCH, 15 amperes at 125 volts, mounted on porce¬ 
 lain base. -56 
 
 90-327 SINGLE POLE, DOUBLE THROW KNIFE SWITCH, 15 amperes at 125 volts, mounted on porce¬ 
 lain base. *65 
 
 90-330 DOUBLE POLE, SINGLE THROW KNIFE SWITCH, 15 amperes at 125 volts, mounted on porce¬ 
 lain base. -66 
 
 90-332 DOUBLE POLE, DOUBLE THROW KNIFE SWITCH, 15 amperes at 125 volts, mounted on porce¬ 
 lain base. *90 
 
 90-336 DOUBLE POLE, DOUBLE THROW SWITCH, capacity 50 amperes at 250 volts, heavy construc¬ 
 tion for lantern work. 2.26 
 
 No. 90-340 No. 90-362 No. 90-366 
 
 90-340 POINT SWITCH, wood base, brass terminals, one point. $0.18 
 
 90-342 POINT SWITCH, wood base, brass terminals, two point.. . .22 
 
 90-360 ONE-POINT RUBBER BASE SWITCH, square base, with binding posts on front. .80 
 
 90-362 TWO-POINT RUBBER BASE SWITCH, square base, with binding posts on front. .90 
 
 90-364 THREE-POINT RUBBER BASE SWITCH, square base, with binding posts on front. 1.20 
 
 90-366 FOUR-POINT RUBBER BASE SWITCH, square base, with binding posts on front. 1.46 
 
 90-366 BATTERY RHEOSTAT AND SWITCH, suitable for regulating miniature battery lamps, speed of 
 small motors, etc. 
 
 This switch consists of six steps mounted on a polished wood base with hard rubber handle. Total 
 
 resistance 5 ohms; trimmings nickel-plated. 1.26 
 
 90-370 
 
 No. 90-376 
 
 No. 90-380 
 
 90-370 WOOD PUSH BUTTON, excellent quality, hard rubber button, hardwood antique oak finish . . $0.10 
 
 90-376 DESK PUSH BUTTON, for %-inch hole, nickel-plated trim, light pearl button.28 
 
 90-380 METAL PUSH BUTTON, hard rubber button, ornamented metal case, with screw holes. Diameter 
 
 2 inches. -46 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 317 
 
 No. 90-390 No. 90-392 
 
 90-390 SINGLE CONTACT KEY, hardwood base, open circuit key with two binding posts. $0.78 
 
 90-392 DOUBLE CONTACT KEY, hardwood base, open circuit with pair of binding posts for each circuit 2.60 
 
 No. 90-396 
 
 90-396 DOUGLASS UNIVERSAL DOUBLE CONTACT KEY. With the possible exception of certain 
 classes of condenser measurements, where the highest insulation is required, the Douglass Key 
 will be found to be absolutely satisfactory. 
 
 The key is most universal in character as is shown by the following suggestions, which are a few 
 of the uses to which it may be put. 
 
 The Douglass Key can be used,— 
 
 1. To close a single circuit. 
 
 2. To open a single circuit. 
 
 3. To close two separate circuits. 
 
 4. To close one circuit and open another simultaneously. 
 
 5. To open one circuit and close another. 
 
 6. To open connection with one circuit and close to a second. 
 
 7. To close one circuit, open the second and close the third in one movement. 
 
 It will thus be noted that the Douglass Key serves about every possible use in the laboratory with 
 
 the exception of high capacity condenser work.$4.80 
 
 No. 90-410 
 
 90-410 HIGH INSULATION DOUBLE CONTACT KEY. This is a high-grade key, especially designed 
 where extra high insulation is required. Heavy ebonite blocks and base, extra large binding posts 
 and heavy platinum contact. All metal parts highly polished and lacquered. This is a handsome 
 and serviceable key for general work. $12.00 
 
3i8 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 HIGH TENSION KEYS 
 
 No. 90-430 No. 90-435 
 
 The following keys and switches are recommended whenever one has occasion to use high voltages, to make 
 high resistance measurements or accurate tests on condensers or other apparatus. 
 
 They are mounted on bases of pure ebonite, and where pillars are used the pillars also are of pure ebonite. 
 Extreme care is used in construction, and our line will be found strictly high grade in every respect. The leakage 
 
 factor is very low. 
 
 90-415 SHORT CIRCUIT KEY. $12.00 
 
 90-420 SINGLE PLUG SWITCH, mounted on ebonite pillars, ebonite handle, spring capped plugs to prevent 
 
 blocks being forced apart when plug is inserted. 16.76 
 
 90-425 LAMBERT’S CAPACITY TEST KEY, heavy ebonite blocks and pillars. 22.50 
 
 90-430 RITCHIE REVERSING KEY. 24.50 
 
 90-435 KEMPE’S CHARGE AND DISCHARGE KEYS, ebonite handles. 20.00 
 
 No. 90-460 
 
 90-460 INTERRUPTING WHEEL for interrupting a current. 
 
 It is frequently desired in induction experiments to interrupt the current and also to vary the speed 
 of the interruption. The design above illustrated consists of a toothed wheel mounted on an 
 axle attached to the uprights on a neatly polished base. A spring contact arm rests against the 
 toothed rim of the wheel. This spring contact arm is in electrical connection to one binding post 
 and the pillar supporting the wheel to the other. If, therefore, connections are made to the bind¬ 
 ing posts the current will be interrupted by the teeth of the wheel as it is revolved by means of the 
 crank. These interruptions are positive and the instrument is used to advantage connected in 
 series with the primary of No. 96-40 Primary and Secondary Coil.$1.90 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 319 
 
 COMMUTATORS 
 
 No. 90-470 
 
 No. 90-485 
 
 No. 90-490 
 
 90-470 SIMPLE MERCURY CONTACT POLE CHANGER. This is a simple standard form with improved 
 
 mercury wells and contact. Handsomely finished base with four binding posts.$0.65 
 
 90-476 SPLIT RING POLE CHANGER, consisting of a neatly polished wooden base on which are mounted 
 four binding posts with connected contact arms which make contact with the top of the split ring 
 reversing switch. 
 
 This switch is provided with a neat key-shaped hard rubber piece. All metal parts neatly polished 
 
 and lacquered. I.75 
 
 90-480 PALMER’S PLUG FORM POLE CHANGER. This form consists of a polished base on which are 
 mounted four brass curved blocks, each block provided with a binding post. Current reversal 
 secured by changing the position of the tapered plugs in the tapered holes. Brass parts neatly 
 
 polished and finished. 2.90 
 
 90-486 IMPROVED BLOCK HANDLE POHL’S COMMUTATOR. The simple form above illustrated 
 secures positive current reversals in a cleanly and efficient manner. The design, originated in our 
 laboratories, consists of a polished wooden base with mercury wells, each well connected to a bind¬ 
 ing post with a non-detachable top. The pole changer is of the rocking type, securing instant 
 current reversal by merely tipping from one pair of mercury wells to the other. All metal parts 
 
 are handsomely polished and lacquered. 1.90 
 
 90-490 KNIFE SWITCH POLE CHANGER, mounted on slate base with visible connections. Will carry 15 
 
 amperes. 1.65 
 
 No. 90-480 
 
 No. 90-475 
 
 No. 90-525 
 
 90-546 
 
 90-525 
 
 ELECTRIC BELLS 
 
 DISSECTIBLE IRON BOX BELL. It will 
 ring satisfactorily with one cell of battery 
 and will not stick or buzz with six cells 
 connected. The cover is of light pressed 
 steel, neatly japanned. A slight pressure 
 of the fingers on each side of the cover will 
 disengage it from the clamps opening to 
 view the entire mechanism. Gong 2)4 
 inches in diameter. .$0.45 
 
 DISSECTIBLE IRON-CLAD BUZZER. The No - 90-665 
 
 buzzer listed under this number is in ap¬ 
 pearance the same as No. 90-625 Bell, without the gong, gong extension 
 and striking rod.$0.65 
 
 90-666 SIX-INCH IRON-CLAD WATER-PROOF GONG. This iron-clad bell is designed and constructed 
 to protect the operating mechanism and magnets from dampness, dust, and other outside influ¬ 
 ences. The end of the striking rod is the only part of the working mechanism not contained 
 inside the case and, as this is operated in a straight line, the opening in the case is very small and 
 securely protected. The contact points are of hardened carbon, which permits of the use of a 
 current ranging from 4 to 150 volts with magnets wound for proper resistance. The vibrations 
 are strong, rapid, and regular. 
 
 Iron-Clad Water-proof Gong, resistance 5 ohms, gong 6 inches in diameter. 6.25 
 
320 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 BATTERIES 
 
 No. 91-15 
 
 GILLEY-SKIDMORE BATTERY 
 
 91-10 PORCELAIN MOUNTED GILLEY-SKIDMORE BATTERY STAND for the study of the various 
 
 phenomena of the voltaic cell. This stand has been used for a number of years and its extensive sale 
 has been sufficient recommendation for it. It will be seen that the stand consists essentially of a 
 recessed porcelain base with upright support. To the upright are fastened the two swiveled arms 
 bearing the clamps. To these arms may be attached various accessories for the study of character¬ 
 istics of different types of cells and also, in formulating the laws governing the action and efficiency 
 of a simple single or two-fluid cell. This form of Students’ Battery Outfit is recommended, since 
 the wire leads are attached to the binding posts on the top of the stand, which has a broad base 
 and hence avoids the tipping over of the battery which occurs in other types. 
 
 This cell is admirably adapted for its purpose and excels in simplicity of construction the much more 
 expensive and bulky commercial cells. In the study of the leading types of batteries various 
 accessories may be used to set up the complete cell. The cell is particularly adapted for the study of 
 polarization, internal resistance, effects of different solutions, etc., and readily adapts itself to the 
 construction of the Electro-motive Series. All parts are neatly finished and the battery presents a 
 
 pleasing appearance in any laboratory. 
 
 Porcelain mounted Gilley-Skidmore Battery Stand only, without any accessory parts.$1.20 
 
 91-12 PORCELAIN MOUNTED GILLEY SKIDMORE DEMONSTRATION CELL, complete with jar, 
 
 copper, and zinc element for study of simple single fluid cell. 1.40 
 
 91-15 PORCELAIN MOUNTED GILLEY SKIDMORE BATTERY STUDY OUTFIT. Consists of stand 
 
 complete with all the accessories listed below. 2.40 
 
 SEPARATE PARTS 
 
 91-15a JAR.$0.06 
 
 91-16b POROUS CUP, 3 X 7.5 centimeters inside diameter. .15 
 
 91-15c ZINC PENCIL, % inch diameter.11 
 
 91-15d CARBON PENCIL, % inch diameter.11 
 
 91-16e ZINC ELEMENT, right angle stem.08 
 
 91-16f COPPER ELEMENT, right angle stem.08 
 
 91-15g IRON ELEMENT, right angle stem.07 
 
 91-15h ALUMINUM ELEMENT, right angle stem.10 
 
 91-16i LEAD ELEMENT, right angle stem.07 
 
 91—15j PURE BLOCK TIN ELEMENT, right angle stem.20 
 
 91-16k COPPER CYLINDRICAL ELEMENT.25 
 
 91-26 TURNER AND HERSEY TAPERING ZINC ELEMENT for use with above outfit in the study of 
 
 polarization. .08 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 321 
 
 The GILLEY SKIDMORE BATTERY STAND, with its porcelain base and swiveled arms, overcomes the 
 many inconveniences encountered in the following designs which we offer to meet the demands of individual teach¬ 
 ers. If the following designs are best adapted to individual needs, we wish to assure customers that the quality 
 of material and workmanship is above question. We unhesitatingly recommend, however, our PORCELAIN 
 MOUNTED SKIDMORE OUTFITS. 
 
 No. 91-30 Porous Cup of No. 91-35 No. 91-42 
 
 91-30 GOTHAM DEMONSTRATION CELL. Consists of a Rectangular Glass Jar with a millimeter 
 scale etched on the front for convenience in measuring the separation of the elements. The 
 element holders are of non-corrosive metal and are cast in a most convenient shape for resting 
 on the jar and for clamping and adjusting the elements. 
 
 Complete with a Copper and Zinc Element for study of a simple single fluid cell. $1.40 
 
 91-35 GOTHAM DEMONSTRATION BATTERY STUDY OUTFIT. Consists of the Rectangular Jar 
 with ruled front, a pair of non-corrosive metal Element Holders and the Zinc and Copper Elements 
 of above cell, with the addition of a special Rectangular Porous Cup, round Carbon and Zinc 
 Elements and flat Elements of Aluminum, Carbon, Copper, Iron, Lead, Nickel and Tin. 
 
 Complete.•. 2.10 
 
 91-40 HALL’S IMPROVED DEMONSTRATION CELL. In this design, we have discarded the construc¬ 
 tion using a metal cap for the jar, now using a neat porcelain cap moulded to fit the rim of the 
 jar. To this porcelain cap are attached the special arms which bear the clamps. These clamps 
 wdll hold either the round or flat elements. The method of mounting to the porcelain cap permits of 
 adjusting the distance of the two elements at will. 
 
 Jar, Porcelain Cap with attached Bracket and Clamps and Zinc and Copper Elements for study of 
 
 a simple single fluid cell. . . -66 
 
 91-42 HALL’S IMPROVED DEMONSTRATION BATTERY STUDY OUTFIT. Complete with all 
 
 accessories listed below, including the special copper cylindrical element. 
 
 Complete .. 1-65 
 
 ACCESSORIES 
 
 91-43 JAR. $0.06 
 
 91-44 POROUS CUP, inside measurements 3 X 7.5 centimeters. .15 
 
 91-45 ZINC PENCIL.11 
 
 91-46 CARBON PENCIL.11 
 
 91-47 ZINC ELEMENT, flat.06 
 
 91-48 COPPER ELEMENT, flat.05 
 
 91-49 LEAD ELEMENT, flat .06 
 
 91-60 IRON ELEMENT, flat.05 
 
 91-61 ALUMINUM ELEMENT, flat.05 
 
 91-62 TIN ELEMENT, flat.11 
 
 91-53 COPPER CYLINDRICAL ELEMENT.26 
 
 91-64 CARBON ELEMENT, flat. -11 
 
322 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 91-75 
 
 91-65 LECLANCHE BATTERY, especially adapted for “open circuit” work, most frequently used in bell 
 service. E. M. F. about 1.4 volts. 
 
 Cell complete.. 
 
 91-67 POROUS CUP, sealed. 
 
 91-68 ZINC PENCIL, with binding screw.. . 
 
 91-69 JAR.. 
 
 91-75 GALLON STANDARD DANIELL CELL. This cell has attained the position of a standard labora¬ 
 tory cell, being readily adapted to all kinds of circuit work. Its E. M. F. is about 1.08 volts, this 
 voltage remaining constant throughout the life of the cell. For this reason it may be seen that it 
 is of great value for work in electrical experiments. 
 
 Cell complete, one gallon size, including Jar and Porous Cup, special Copper Cylinder with holder, and 
 
 Zinc Element. 
 
 31-265C JAR .. ... . . 
 
 91-77 POROUS CUP. 
 
 91-79 ZINC ELEMENT. 
 
 91-80 COPPER CYLINDER.. 
 
 91-90 QUART STUDENTS’ DANIELL CELL, complete, including jar not illustrated. 
 
 91-92 POROUS CUP, 2X4 inches.\ . 
 
 91-94 ZINC ELEMENT WITH BINDING POST. 
 
 91-96 COPPER ELEMENT. 
 
 31-266b JAR..'. 
 
 $0.75 
 
 .40 
 
 .10 
 
 .25 
 
 2.60 
 
 .40 
 
 .25 
 
 1.10 
 
 .95 
 
 .95 
 
 .20 
 
 .35 
 
 .15 
 
 .25 
 
 No. 91-105 
 
 No. 91-120 
 
 91-105 
 
 91-120 
 
 CROW FOOT GRAVITY CELL, one of the most popular closed circuit cells, very largely used by 
 telegraph and telephone companies, gallon size, complete 
 91-107 ZINC ELEMENT, crow foot type’ 
 
 91-110 COPPER ELEMENT ... . 
 
 3i-266c jar. ;;;;;;;;;;;;;;;;;;;;;;; 
 
 IMPROVED FULLER CELL, for general laboratory service, open or closed circuits. This cell has 
 unusually high E. M. F., about 2.4 volts, with internal resistance of .4 ohm, gallon size complete. 
 91-122 POROUS CUP, 3X7 inches 
 91-124 ZINC ELEMENT . . 
 
 9i-i35 carbon cylinder. . . . ‘ ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; 
 
 31-265c JAR, 6X8 inches. 
 
 ' 2.10 
 
 1.40 
 
 .30 
 
 .40 
 
 2.65 
 
 .C5 
 
 1.20 
 
 .80 
 
 .40 
 
 
 
 
 mms* 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 323 
 
 
 91-166 BUNSEN CELL, a two-fluid cell for “open circuit” work. E. M. F. approximately 1.9 volts, 
 internal resistance about 1.8 ohms. 
 
 Bunsen Cell complete, one quart size. 
 
 91-166 JAR, 4K X 4 y 2 inches . 
 
 91-167 POROUS CUP, iy 2 X 5 inches . 
 
 91-169 ZINC ELEMENT, special shape with binding post . 
 
 91-170 FLUTED CARBON ELEMENT, with connector and binding post. 
 
 91-180 GRENET BATTERY, especially adapted for experimental and demonstrative work. This battery 
 occupies little space and furnishes a powerful current for a short time. E. M. F. is approxi¬ 
 mately 2 volts at the start with very small internal resistance. 
 
 A further advantage of this type of cell is that the zinc element may be raised from the fluid, thus 
 stopping action of the cell, and preserving the strength of the solution. 
 
 One-pint size complete. 
 
 91-182 ZINC ELEMENT.. 
 
 91-184 CARBON ELEMENT. 
 
 91-186 JAR . 
 
 91-190 GRENET BATTERY, similar to above, but one-quart size, complete. 
 
 91-192 ZINC ELEMENT.. 
 
 91-194 CARBON ELEMENT. 
 
 91-196 JAR. 
 
 91-206 GRENET BATTERY, similar to above, but two-quart size, complete 
 
 91-207 ZINC ELEMENT. 
 
 91-209 CARBON ELEMENT. 
 
 91-210 JAR. 
 
 91-246 FOUR-CELL STUDENTS’ PLUNGE BATTERY. This is a 
 simple combination of Chromic Acid Cells provided with ad¬ 
 justing features which permit of lifting one or more cells from 
 the solutions. It may be used to advantage on the demonstra¬ 
 tion table, but has been designed particularly for students’ 
 experiments. 
 
 Complete as illustrated, four-cell type.. 
 
 91-247 TWO-CELL STUDENTS’ PLUNGE BATTERY, similar to 
 above, but arranged for two cells oaly. 
 
 91-260 COMPLETE ELEMENT, including two carbons 
 and one zinc element with all connections. 
 
 91-262 CARBON ELEMENT. 
 
 91-264 ZINC ELEMENT. 
 
 31-265a SPECIAL BATTERY JAR .. 
 
 $ 2.20 
 
 .60 
 
 .26 
 
 1.26 
 
 .20 
 
 2.10 
 
 .26 
 
 .26 
 
 .95 
 
 2.76 
 
 .28 
 
 .36 
 
 1.16 
 
 4.20 
 
 .36 
 
 .50 
 
 1.75 
 
 6.50 
 
 4.16 
 
 1.45 
 
 .26 
 
 .40 
 
 .12 
 
 
 No. 91-246 
 
324 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 91-225 
 
 91-227 
 
 No. 91-225 
 
 SIX-CELL HIGH SCHOOL PLUNGE BATTERY. Perhaps no source of current for lecture table 
 or general laboratory work has become so desirable as that furnished by the Chromic Acid Cell. 
 In the design illustrated above may be noted a form of portable cell which has found great favor 
 throughout the country. Each cell is a unit in itself delivering about 2 volts and very powerful 
 current for a short time. One or more may be combined in series or parallel to give a large E. M. F. 
 or amperage. 
 
 The type is arranged so that from one to six cells may be used as desired. All six may be placed at 
 one time in the solution. If it is desired that only four be used, as above, two may be suspended 
 to the cross rod. 
 
 This battery is substantially made, provided with every convenience for safe use, and will be found 
 indispensable when once used. 
 
 Complete as illustrated, arranged for six cells . 
 
 FOUR-CELL SCHOOL PLUNGE BATTERY, same as above, but arranged for four cells . . . 
 
 91-229 COMPLETE ELEMENT, including top, two carbon, and zinc elements . 
 
 91-231 CARBON ELEMENT. 
 
 91-233 ZINC ELEMENT.. , . . ; 
 
 91-235 SQUARE BATTERY JAR.,., .'. . 
 
 $27.40 
 
 19.76 
 
 3.00 
 
 .30 
 
 1.30 
 
 .45 
 
 83-260 WATER BATTERY, 50 cells, mounted on substantial neatly finished wooden base. 
 
 This battery is particularly adapted to advanced work when high voltage and low amperage are 
 
 desired. It will be found a most serviceable battery for all electrostatic and electrometer work . $6.25 
 
 83-252 -, same as above, but comprising 100 cells. This battery is a combination of two of the above . 12.75 
 
A* >>•« 
 
 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 325 
 
 . 
 
 
 
 No. 91-280 
 
 No. 91-300 
 
 91-280 MOUNTED H-FORM STANDARD CELL. This cell is furnished appropriately mounted on base 
 provided with binding posts. It is designed that students may assemble their own cells. 
 
 Complete as illustrated .. 
 
 91-282 H-FORM STANDARD CELL, same as above but unmounted, glass part only with sealed-in plati¬ 
 num electrodes. 
 
 91-300 DRY CELL. In our seventeen years’ experience we have experimented with a great number of dry 
 cells. For length of life, high electro-motive force, and low internal resistance we believe that the 
 cell illustrated above is unexcelled. It polarizes slowly and recovers rapidly. We have no hesi¬ 
 tancy in recommending its use for general laboratory work. 
 
 STORAGE BATTERIES 
 
 Nos. 91-325 to 91-330 
 
 Nos. 91-335 to 91-350 
 
 91-315 MOUNTED LEAD PLATES after Millikan and Gale. Fig. 277 .Pair 
 
 91-325 STORAGE BATTERY, LEAD-LEAD TYPE. The plates measure 3J4 inches square, and the glass 
 jar is byi inches high. The cell has a capacity of six ampere hours at an E. M. F. of two volts . 
 
 91-330 - —, same as above, but a much larger cell, and is recommended for such work as operating Ruhm- 
 korff coils, performing electrolysis experiments, and other laboratory work where a heavy current 
 is necessary. The lead plates measure 7j^ inches square and are contained in a glass jar 
 inches high X 9 inches wide X 3^ inches deep. The capacity of each cell is 36 ampere hours at 
 
 an E. M. F. of two volts. 
 
 We recommend either three or four cells as the proper laboratory outfit. 
 
 91-336 PORTABLE STORAGE BATTERY, enclosed in wooden case as shown in the illustration. Capacity 
 60 ampere hours at an E. M. F. of six volts. 
 
 91-340 - —, same as above, capacity 80 ampere hours at an E. M. F. of six volts . 
 
 91-345 - —, same as above, capacity 100 ampere hours at an E. M. F. of six volts. 
 
 91-360 — —, same as above, capacity 80 ampere hourg at an E. M. F. of eight volts. 
 
 $2.30 
 
 1.75 
 
 .40 
 
 $1.50 
 
 2.15 
 
 6.76 
 
 21.00 
 
 27.25 
 
 32.50 
 
 36.00 
 
326 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 BATTERY SUPPLIES 
 
 31-265 BATTERY JARS, of excellent quality. 
 
 a bed 
 
 Size, inches. 2)4 X 3)4 4X5 6X8 8X 12 
 
 Each. $0.12 .25 .40 1.60 
 
 91-380 RECTANGULAR BATTERY JARS, of excellent quality. 
 
 a b 
 
 Size, inches. 2)4 X 4 )4 X 7 
 
 Each. $0.35 
 
 No. 90-185 
 
 91-410 CARBON AND ZINC BATTERY CONNECTORS. 
 
 a b c 
 
 For plates. )4 to % % to K K to 1)4 inches 
 
 Each. $0.20 .35 .42 
 
 THE IMPROVED RAPID BATTERY CONNECTORS 
 
 (For description see page 312) 
 
 90-176 THE IMPROVED RAPID CONNECTING TIPS.Per dozen 
 
 Per hundred 
 
 90-177 THE IMPROVED RAPID CONNECTORS, a six-inch flexible cord with a Connecting Tit 
 
 No. 90-176 at each end.Eacl 
 
 90-179 -, a two-foot flexible cord with a Connecting Tip No. 90-175 at each end.Each 
 
 90-180 -, a three-foot flexible cord with a Connecting Tip No. 90-175 at each end.Each 
 
 90-185 THE “PRIMO” POSITIVE CONTACT LECTURE TABLE CLASPS. (For description see page 
 
 312.) .Per Pair 
 
 90-187 THE “PRIMO” POSITIVE CONTACT LECTURE TABLE CONNECTOR, a four-foot flexible 
 
 cord with a Clasp No. 90-186 at each end.Each 
 
 90-190 UNIVERSAL CONNECTOR TIP for either the English or American Binding Post. (See page 313.) 
 
 Each 
 
 90-196 CADY INSULATED CONNECTOR (See page 313) .Each 
 
 $0.26 
 
 2.00 
 
 .20 
 
 
 .30 
 
 
 .40 
 
 I 
 
 .60 
 
 
 .80 
 
 | 
 
 .06 
 
 .96 
 
 
 No. 91-410a 
 
 No. 91—410b 
 
 No. 91-410c 
 
 Nos. 90-185 to 90-187 
 
 No. 90-195 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 327 
 
 ELECTRO-MAGNETISM 
 
 92-15 AMPERE’S LAW STAND, a 
 
 convenient stand with clamp 
 for holding a No. 10 copper 
 conducting rod; with shelf for 
 arranging small compasses 
 about the conductor and bind¬ 
 ing posts for connecting the 
 lead wires. 
 
 No. 92-15 
 
 92-17 AMPERE’S LAW 
 
 Full directions for the experi¬ 
 ment will be found in the 
 National P h ys ic s Direction 
 Sheets, Experiment E041, a 
 copy of which will be furnish¬ 
 ed with each instrument . . . 
 APPARATUS (Fuller & Brownlee, Exp. 
 
 $1.45 
 
 81). 
 
 No. 92-17 
 
 Complete as illustrated with 
 
 four ssaled-in exploring compasses, but without the larger movable magnetic compass 
 
 $2.65 
 
 No. 92-20 
 
 No. 92-30 
 
 92-20 OERSTED’S LAW APPARATUS, for study of magnetic action of currents and formulating Ampere’s 
 
 rule. 
 
 This apparatus consists of a base to which are mounted two pillars, each provided with two binding 
 posts, one each for the terminals of the parallel conducting wires. A sensitive magnetic needle 
 separately mounted on a base of its own is readily adjusted so that its point of support comes mid¬ 
 way between the parallel wires. This mounted magnetic needle is our No. 81-12 and will not be 
 
 required if already a part of the equipment. $2.85 
 
 92-22 OERSTED’S LAW APPARATUS FRAME, only without mounted magnetic needle. 2.25 
 
 81-12 MOUNTED MAGNETIC NEEDLE, as used in No. 92-20 .60 
 
 92-30 HELIX OERSTED’S LAW APPARATUS, for a study of the directive action which a fixed current 
 exerts at a distance on a magnetic needle, and for formulating Ampere’s Rule. This, our adjustable 
 needle and adjustable helix design, consists of a rectangular metal frame mounted as illustrated 
 on a polished wooden base. The upright parallel sides of this frame are slotted to carry the holders 
 for the movable needle and for the helix. That a study of the effect of a current through a helix 
 on a magnetic needle may be noted, the holders of the helix are provided with a pair of binding 
 posts, one on each end. A pair of binding posts is also furnished for connecting a current to the 
 rectangular frame. Two fixed needles, one over the upper part of the frame and one within the 
 frame over the under side, and a movable needle which may be fixed in any position within the frame 
 indicate the directive action of a current on a magnetic needle. 
 
 All metal parts of this apparatus are finely polished and lacquered and the needles are delicately 
 balanced on steel pivot points. 
 
 Complete as illustrated, with three needles and helix attachment . 6.60 
 
 92-36 SIMPLE ADJUSTABLE NEEDLE OERSTED’S LAW APPARATUS. This design is essentially 
 the same as illustrated and described above. It is, however, furnished without the helix attach¬ 
 ment and without the two fixed needles. As may be readily noted, by means of this movable 
 needle, the holder movable in height and the needle movable along the holder, practically any posi¬ 
 tion within and, if desired, outside the frame may be secured. 3.76 
 
 92-37 HELIX ATTACHMENT, for attachment to above frame in study of the directive action of a current 
 through a helix upon a magnetic needle. 
 
 This attachment is provided with clamps for instant clamping to the slotted upright parallel sides of 
 
 the frame... .85 
 
 92-40 BAR OF IRON and BAR OF WOOD, for placing within helix attachment above for a study of the 
 
 magnetic effects produced .Per Pair .16 
 
328 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 AMPERE’S LAW 
 
 92-50 AMPERE’S FRAME, illustrating various phenomena due to the magnetic effects of an electric current. 
 
 The design, improved in many ways incapable of illustration, consists essentially of a base to which 
 are mounted two metal uprights. At the tops of these uprights are attached arms carrying at their 
 extremities two steel cups for mercury in which are placed the pivoting points of an improved sus¬ 
 pension device carefully balanced by means of a metal ball and provided with sockets and binding 
 screws for attaching the different contact frames. 
 
 These frames are designed to illustrate in a satisfactory manner several interesting and instructive 
 phenomena, each frame interchangeable in the suspension device. Five frames are furnished, — a 
 loop, a rectangle, an astatic rectangle, a rectangular coil, and a solenoid. In addition there is 
 furnished a suspension frame for a bar magnet and a soft iron rod. 
 
 Perhaps no single piece of apparatus designed for the study of magnetism has such wide application 
 as does this time-honored Ampere’s frame. Results are strikingly illustrated with the minimum of 
 annoyance. In our design we have endeavored to obviate the previous sources of difficulty in the 
 old forms and are enabled by our many improvements to guarantee satisfactory results. 
 
 The design is capable of demonstrating in a positive manner: 
 
 1. Mutual Action of Magnets and Solenoids. 
 
 2. Action of Currents on Solenoids. 
 
 3. Directive Action of the Earth on Solenoids. 
 
 4. Directive Action of Magnets on Currents. 
 
 5. “Sucking Effects” of Solenoids. 
 
 6. Action of a Current on a Pivoted Magnet. 
 
 Apparatus complete, as illustrated, including all accessories described above. 
 
 92-60 FLOATING HELIX AND CELL, for demonstrating 
 the magnetic polarity of an electro magnetic 
 solenoid. 
 
 This apparatus consists of a small cell, the leads of 
 which are formed into a horizontal solenoid. In 
 use the elements are placed into the small jar held 
 in a disc of cork, and the whole placed in a jar of 
 water where the combination will float upright. 
 The solenoid will soon take a position so that the 
 axes will point true North and South. From 
 further tests with a bar magnet it will be noted 
 that the solenoid will act the same as a magnetic 
 needle, one end developing South and the other 
 North polarity. 
 
 Cell complete as illustrated. 
 
 
 
 $ 11.00 
 
 1.60 
 
 No. 92-60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 329 
 
 PARALLEL CURRENT 
 APPARATUS 
 
 No. 80-306 No. 80-310 
 
 80-306 P/filALLEL CURRENT APPARATUS, for illustrating mutual actions of parallel currents. The 
 design consists of an insulated stand to the head of which are attached binding posts in electri¬ 
 cal connections with two bent copper wires. To these bent wires are suspended two small 
 straight copper rods cut to the proper length, which will allow their free ends to extend within 
 the mercury well set in the base. 
 
 In use it is always best to amalgamate the ends of these copper rods. Success of the experiment 
 depends also upon allowing the rods to just make contact with the surface of the mercury. 
 
 Parallel currents flowing in the same direction may be secured by connecting both binding posts 
 with one pole of the battery; the other pole should be connected to a binding post (not shown in 
 illustration) fastened to the base and in electrical connection with the mercury well. 
 
 Parallel currents running in opposite directions may be obtained 
 by simply connecting the battery terminals and the binding 
 posts, at the top. 
 
 In the first case, repulsion of the wires will be noted; in the sec¬ 
 ond, attraction. 
 
 80-310 CONTRACTING HELIX, illustrating the mutual action of cur¬ 
 rents. 
 
 This apparatus consists of a spiral of copper wire, one end of 
 which is suspended from a rigid arm, the other end free to dip 
 into a well of mercury located in the base. If current is allowed 
 to flow through the spiral, attraction between the convolutions 
 causes the coil to contract, and the end to be lifted out of the 
 cup of mercury, thus breaking the circuit when current and at¬ 
 traction cease, and the wire dips again into the mercury. A 
 
 rapid and vibratory motion, therefore, is produced. 
 
 92-76 PARALLEL CURRENT REPULSION COILS with BIFILAR 
 SUSPENSION, designed to teach the mutual influence of par¬ 
 allel currents and self-induction. One of the coils when used 
 separately is well adapted for experiments on the Earth’s Mag¬ 
 netic Field. 
 
 The apparatus consists of two carefully constructed form-wound 
 coils of 1000 turns double cotton covered copper wire. Each 
 coil is taped, shellaced and baked. Provided with binding 
 posts for bifilar suspension. 
 
 As the illustration indicates, the coils are suspended by an ad¬ 
 justable clamp fitting a vertical rod of from 13 to 19 millimeters 
 in diameter, the clamp being so designed that the distance be¬ 
 tween the coils may be varied at will. Connections to the coils 
 from the clamp are such that they are readily joined either in 
 multiple or in series according to the current available. The 
 coils are wound for resistance to take 110 volt direct current 
 when running in series. 
 
 Price complete without stand. 
 
 Note. When one of these coils is used for experiments in Earth Induction, we recommend the use of our Lecture Table Galvanometer 
 No. 93-130. 
 
 92-77 COIL FOR MAGNETIC INDUCTION. A form wound coil with connectors and flexible leads. 
 
 When the single coil is connected in series with any sensitive galvanometer, interesting experi¬ 
 ments showing the earth’s magnetic field and other induction phenomena may be performed. 
 
 The purchase of complete apparatus as described above (No. 92-76) for demonstrating also 
 mutual and self induction is recommended.$2.70 
 
330 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 ELECTRO-MAGNETS 
 
 Figs. 7 8 
 
 Nos. 92-110 to 92-130 
 
 9 
 
 92-100 STUDENTS’ ELECTRO-MAGNET, simple electro-magnet capable of complete demonstration of 
 
 magnetic induction. $0.65 
 
 92-110 GILLEY INDUCTION COILS, mounted with binding posts. 
 
 These coils are designed for students’ use in the study of Induction and Electro-magnetism. Care¬ 
 fully prepared students’ directions for their use will be found in the Turner and Hersey series of 
 experiments, E042, E150 and E153. Copies of these experiment sheets are furnished with each 
 pair of coils. 
 
 As the illustration indicates, the coils are form-wound, shellaced and baked so as to make a rigid unit 
 and mounted on a conveniently designed wood base with binding posts, the form of the base 
 being such as to permit the greatest freedom of use in the experiments for which they are intended. 
 
 The hole in the center is of the correct size to take the soft iron armature in the study of electro¬ 
 magnets. Sold by the pair only.Per Pair 1.40 
 
 ACCESSORY APPARATUS FOR THE STUDY OF INDUCTION AND 
 ELECTRO-MAGNETS USING THE GILLEY COILS 
 
 Each of the items listed and illustrated in Figures 2, 3, 4, 5 and 7, are designed for use with the Gilley Coils in 
 performing experiments outlined in the National Loose-Leaf Sheets above referred to. 
 
 92-116 SOFT IRON U-SHAPED CORE, Fig. 3, for study of bipolar electro-magnets. Each $0.20 
 
 92-117 SOFT IRON ARMATURE, Fig. 2, for use with the above core in the study of electro-magnets, Each .10 
 
 92-120 SOFT IRON CORE, Fig. 5, single, for the study of electro-magnets.. Each .10 
 
 92-122 PAIR OF HALF-ROUND CORE PIECES, Fig. 4, for mapping the lines of force in an electro-magnet. 
 
 Per Pair .15 
 
 92-125 PAIR OF SLOTTED CARDBOARDS, Fig. 7, for mapping lines of force. .. Per Pair .08 
 
 Figures 8 and 9 in the illustration show how the above apparatus is used in the study of the Simple Transformer, 
 Induced Currents and Electro-Magnet. 
 
 92-130 COMPLETE GILLEY INDUCTION OUTFIT, supplied in box, with direction sheets. $2.00 
 
 92-136 ELECTROMAGNETIC COILS,—a set of three coils varying 
 in number of turns and character of core, as called for in 
 Brownlee & Fuller’s “Laboratory Exercises,” Exp. 82 . . 1.60 
 
 92-136 -, a set of two coils after Millikan, Gale and Bishop, Exp. 30 
 
 Per Set 1.10 
 

 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 33i 
 
 
 Nos. 92-160 to 92-162 
 
 92-160 INSTITUTE IRON CLAD MAGNET, Commercial Form, 300 lbs. capacity. 
 
 In the design of this magnet careful study has been made of commercial types in use. The defects 
 of previously designed laboratory instruments have been corrected, with the idea of giving the 
 maximum efficiency per pound of weight. We believe this to be the only laboratory lifting mag¬ 
 net on the market in which the cross section area of the shell is equal to that of the core which, of 
 course, is necessary in order to secure the highest efficiency per pound. The success which we 
 have attained may be roughly indicated from the fact that on one cell of dry battery, this mag¬ 
 net will lift approximately thirty times its own weight. ” { 
 
 In actual use, we recommend a voltage of from 4 to 6 volts, the latter emf., of course, giving the 
 best results. 
 
 Size, 4 X 1 Yi inches, weight with armature, 5 pounds, resistance, 1/3 ohm. T.$4.60 
 
 92-162 INSTITUTE IRON CLAD MAGNET, same as above, but smaller in size. 2.26 
 
 No. 92-160 
 
 No. 92-176 
 
 No. 92-186 
 
 92-160 SIX-INCH DEMONSTRATION ELECTRO-MAGNET. This instrument is intended for use on 
 a battery circuit and illustrates in a most striking manner the great magnetic pull obtained from 
 a U-shaped core. 
 
 The two windings of this magnet can be connected either in multiple or in series. Requires five 
 
 or ten volts, depending upon method of connecting coils. 
 
 Core (6 X ^ inches) is of special grade of soft iron. 2.36 
 
 92-166 FOUR AND ONE-HALF INCH HELIX ELECTRO-MAGNET. New York State form. 1.36 
 
 92-176 HELIX AND SEPARABLE MAGNETIC CIRCUIT (HELIX AND RING), for demonstrating mag¬ 
 netization by current. 
 
 This apparatus consists of two symmetrical U-shaped soft iron rods each with a handle. A detach¬ 
 able form-wound helix is fastened to one branch of one of these U-shaped pieces so that when the 
 ends of the U’s are placed together to form a closed magnetic circuit half of the helix will cover 
 one of the branches of one of the U’s and half of the corresponding branch of the other U. 
 
 Before battery is connected no magnetism is noticeable, but as soon as current is allowed to pass 
 through the helix considerable force is needed to separate the U’s. 
 
 Complete as illustrated .. 2.90 
 
 92-186 SOLENOID MAGNET, for illustrating the principle of a solenoid magnet. 
 
 This apparatus consists of a glass tube closed at one end and on which is fastened a helix of wire. If 
 now a bar of soft iron is placed so that it rests on the closed end and the helix is connected to source 
 of current supply, the “sucking” effect of the magnetic force is immediately demonstrated. 
 
 Complete as illustrated with soft iron rod. 1.70 
 
 92-187 HELIX or SOLENOID with MOVABLE COIL. Helix A}4 inches long with connectors. .90 
 
1 
 
 332 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 Upright Position Horizontal Position 
 
 No. 92-195 
 
 92-195 . IMPROVED MOUNTED ELECTRO-MAGNET, useful as a demonstration electro-magnet; also 
 for remagnetizing. In this design mounted for use in the two positions above illustrated we offer 
 not only a design capable of electro-magnetic study but also one inferior to none in appearance 
 and utility. 
 
 This apparatus consists of two 6-inch U-shaped soft iron cores to the branches of which are attached 
 two removable helices. This combination is mounted on a neatly finished support designed for 
 use of the electro-magnet in two positions. Binding posts are provided for connections to battery. 
 Actual tests give the sustaining power of this instrument of from 150 to 200 pounds. 
 
 Electro-magnet mounted as illustrated. 
 
 No. 92-200 
 
 92-200 ONE-HUNDRED-TEN-VOLT LIFTING MAGNET. This 
 
 , magnet more nearly conforms to the conventional type with 
 
 the important modification that it is designed to operate on a 
 110-volt direct current and will easily sustain a load of 300 
 pounds weight. 
 
 As will be noted from the illustration, the magnet is so mounted 
 that it may be easily used in the form shown in the illustration 
 or reversed so that the poles extend vertically upward or sup¬ 
 ported in a horizontal position with the poles extending 
 outward. 
 
 This magnet will be found of particular value in connection 
 with the important series of experiments on magnetic, and 
 diamagnetic materials. 
 
 Stops are provided for limiting the movement of the armature 
 in order to avoid breakage. 
 
 Specifications, — 
 
 Net weight of magnet, without support, 10 lbs. 
 
 Height of the frame, 25 inches. 
 
 Diameter of core, 1 inch. 
 
 Size of winding, X inches. 
 
 Resistance, 220 ohms. 
 
 Ampere consumption, 0.5 amp. 
 
 Voltage recommended, 110 volts. 
 
 Lifting power. 300 pounds,. 
 
 i 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 333 
 
 PARAMAGNETIC AND DIAMAGNETIC 
 STUDY APPARATUS 
 
 No. 92-220 (Fig. 1) No. 92-220 (Fig. 2) 
 
 No. 92—220 (Fig. 3) 
 
 No. 92-220 (Fig. 4) No. 92-220 
 
 92-220 PARAMAGNETIC AND DIAMAGNETIC STUDY OUTFIT for use with Magnet No. 92-200 for 
 
 general electromagnetic study, but especially designed to facilitate the demonstration of para¬ 
 magnetism and diamagnetism. 
 
 The outfit consists of special pole pieces for attachment to the pole faces of Magnet No. 92-200, 
 and the following additional accessories. 
 
 1. Mounted Copper Disc illustrating retarding and stopping of rotation due to the current 
 
 set up in the disc. 
 
 2. Mounted Copper Cylinder illustrating the heating effects in a magnetic field, demon¬ 
 
 strated by the boiling of ether placed in the cylinder. 
 
 3. Mounted Cubical Vessel and Suspension System for illustrating Diamagnetism and 
 
 Paramagnetism, including ten different metal rods, — lead, silver, bismuth, nickel, 
 copper, iron, zinc, tin, aluminum, and antimony, each with a small hook for suspension. 
 
 In using the metals on suspension support the hollow cube is not necessary, as this 
 cube is used to show the magnetization of ferric chloride solution. 
 
 4. Insulation Points with binding screws for illustrating diamagnetism of flames and the de¬ 
 
 flection of the auriole of electric discharges. 
 
 Outfit of accessories complete. $19.00 
 
 92-226 PARAMAGNETIC AND DIAMAGNETIC STUDY APPARATUS. This outfit is complete for the 
 study of paramagnetism and diamagnetism and for general electro-magnetic study. It consists 
 of Magnet No. 92-200 and accessories No. 92-220. It is listed complete for the convenience of 
 teachers who do not already have Magnet No. 92-200 and who desire the complete equipment . 36.00 
 
334 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ELECTRICAL MEASURING INSTRUMENTS 
 
 GALVANOSCOPES 
 
 No. 93-20 
 
 93-12 GALVANOSCOPE, after Millikan & Gale’s 
 “A Laboratory Course in Physics,” pp. 80 
 to 100. 
 
 This instrument has three separate cir¬ 
 cuits, each with two binding posts for 
 connections. One circuit is wound with 
 twenty-five turns of No. 22 wire, an¬ 
 other with one hundred turns of fine 
 wire, and another with a single turn of 
 coarse wire. Thus it may be seen that 
 the sensibility of the instrument can be 
 changed at will depending upon the num¬ 
 ber of turns used in circuit as well as on 
 the position of the compass relative to 
 the current bearing coil. 
 
 Complete as illustrated, but without com¬ 
 pass . . $ 1.20 
 
 COMPASSES. See Section 81. 
 
 ASTATIC GALVANOMETERS 
 
 93-20 ASTATIC GALVANOMETER. This instrument was designed according to the requirements of the 
 National Physics Course, built on the close-coil type, with astatic system in which one needle moves 
 between the coils and one above. Aluminum dial iyi inches, windings of No. 18 copper wire, re¬ 
 sistance approximately one ohm. The instrument is provided with three leveling screws and binding 
 posts. A convenient and sensitive instrument where low voltage only is to be used. $3.60 
 
 93-30 TROWBRIDGE SENSITIVE 
 GALVANOMETER. This in¬ 
 strument is constructed on the 
 close-coil principle in which 
 the magnet is suspended from 
 a light aluminum vane hang¬ 
 ing in front of the coil. Coils 
 of varying resistances may be 
 supplied if desired. The coil 
 with which the instrument is 
 furnished is intended for 
 Wheatstone Bridge work and 
 other experiments where the 
 voltage is exceedingly low. The 
 end of the aluminum vane pro¬ 
 jects into a metal cup under the 
 coil which, for purposes of mak¬ 
 ing the instrument dead-beat, 
 may be filled with glycerine, if 
 desired. The actuating coil is 
 clamped in metal clips and may 
 be easily removed. 
 
 This instrument has the advan¬ 
 tage over the conventional form 
 of Astatic Galvanometer since 
 all the parts are clearly ex¬ 
 posed. The instrument is more 
 nearly dead-beat and by use of 
 
 an outside control magnet, for which the instrument is well adapted, a great variation in sensibility 
 is obtained. 4.26 
 
 No. 93-30 
 
 No. 93-12 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 335 
 
 TANGENT GALVANOMETERS 
 
 Nos. 93-40 to 93-50 
 
 93-40 THE SIX-INCH TANGENT GALVA¬ 
 NOMETER (or GALVANOSCOPE), a 
 
 Tangent Galvanometer of simple con¬ 
 struction, coil of oxidized brass 6 inches 
 in diameter, arranged with binding- 
 posts which connect to 5, 10, and 15 
 turns respectively"51 No. 18 wire. Please 
 note that all connections are exposed so 
 that the student can very easily trace 
 the direction of the current. This is an 
 important feature in students’ work. 
 The compass used may be of varying 
 sizes, brass or jewel bearing, any size of 
 compass being held in the exact center of 
 the coil by means of our double acting 
 spring clips. With the short needle com¬ 
 pass the instrument naturally conforms 
 more nearly to the requirements of the 
 Laws of Tangents. 
 
 No. 93-60 
 
 This is a convenient instrument for such experiments as Tracing the Lines of Magnetic Force, rough 
 experiments in Measurement by Substitution, and a large number of general experiments such as 
 ordinarily given in the first year science courses. The educational value of this form of instru¬ 
 ment we consider far greater than the cheap close-coil instruments sometimes offered. With brass- 
 
 capped compass. 
 
 93-44 STUDENTS’ SIX-INCH TANGENT GALVANOMETER, with agate-bearing compass. 
 
 93-60 STUDENTS’ SIX-INCH TANGENT GALVANOMETER, with large compass and pointer .... 
 
 $ 2.20 
 
 3.00 
 
 3.65 
 
 THE HARCOURT TWENTY-TWO CENTIMETER TANGENT 
 
 GALVANOMETER 
 
 This Galvanometer is designed for High School use. It has all of the essentials of the higher-priced instruments. 
 It is of substantial construction but without unnecessary finish. 
 
 We employ an aluminum ring 22 centimeters in diameter which, with a 2-centimeter magnet, enables the laws 
 of the Tangent Galvanometer to be definitely determined. The coil is 6 millimeters wide, so that errors resulting 
 from this source are reduced to a minimum. Provided with leveling screws and compass box 11 centimeters in di¬ 
 ameter, mirror dial and glass dome. This compass box is easily removable by loosening two set screws shown on 
 the cross bar. With the compass box removed the instrument is readily made use of in a variety of experiments on 
 induction. The instrument is provided with four binding posts connecting consecutively to 5, 10, and 15 turns 
 
 of wire. 
 
 93-60 THE HARCOURT TWENTY-TWO CENTIMETER TANGENT GALVANOMETER, with fiber sus¬ 
 pended needle and long aluminum pointer and mirror dial. $7.16 
 
 93-65 THE HARCOURT TWENTY-TWO CENTIMETER TANGENT GALVANOMETER, with jewel- 
 
 bearing magnet and long aluminum pointer in place of the fiber suspension. 7.15 
 
336 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 TANGENT GALVANOMETERS 
 
 No. 93-75 
 
 93-75 STANDARD TANGENT GALVANOMETER. This is a distinctly higher grade instrument than the 
 preceding. All parts have been made with the greatest care. As will be noted from our illustration 
 it is provided with a Thompson adjustable control magnet with both a vertical and horizontal 
 motion. It slides on a post in a carefully adjustable sleeve. A coil 13 millimeters wide is mounted 
 on a finished brass ring 20 centimeters in diameter. This ring is mounted on a substantial base to 
 the binding posts of which are carried the terminals of the coil'. 
 
 The suspension system consists of a needle 15 millimeters long, suspended by fiber and provided with 
 a convenient and satisfactory lift. The needle is protected by a box 1234 centimeters in diameter, 
 provided with silvered engine-divided dial. 
 
 To meet the conditions of the greatest variety of experiments in practical laboratory work and also 
 for determining the constant in a tangent galvanometer the windings have been carefully worked out 
 as follows: — 
 
 3 turns of coarse wire connected to posts 1 and 2, wound clock-wise. 
 
 12 turns of coarse wire connected to posts 2 and 3, wound counter clock-wise, giving be¬ 
 tween posts 2 and 3, nine turns of coarse wire wound counter clock-wise. 
 
 320 turns of fine wire connected to posts 1 and 4, wound clock-wise. This coil is especially 
 designed for determining the constant of a tangent galvanometer. 
 
 We have no hesitancy in claiming that this is one of the most carefully designed and scientifically 
 
 proportioned galvanometers on the market. $33.00 
 
 93-80 -, same as above, but mounted on polished hardwood base in place of the tripod. 22.50 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 337 
 
 D’ARSONVAL GALVANOMETERS 
 
 The enormous increase in the use of electric current and the employment of iron in the construction of build¬ 
 ings make necessary the use of a type of measuring instrument which is not affected by outside magnetic influences. 
 Of the different types devised the only one which survives by its general fitness is the Deprez-D’Arsonval, usually 
 called the D’Arsonval Galvanometer, but which was first used by Thompson in his work on the Atlantic cable. 
 
 So free is this instrument from magnetic influences that it can be used close to large dynamos and motors. Owing 
 to the method of suspension, the powerful magnetic moment exerted by its moving coil, and the great restoring 
 force of the suspension, it is singularly free from the effects of vibration as compared with the older types of instru¬ 
 ments. In short, a well-designed D’Arsonval Galvanometer is almost the ideal instrument for indicating and meas¬ 
 uring electric currents in laboratories devoted to either educational work or to technical research. 
 
 Development in the D’Arsonval Galvanometer construction has made such rapid progress that exceedingly 
 sensitive instruments, if correctly designed, are now practical for placing in the students’ hands. 
 
 As will be noted from the illustrations on the following pages, we use the D’Arsonval principle on instruments 
 designed both for lecture table demonstration and for students’ individual laboratory work. 
 
 MEASURE OF SENSIBILITY. In the rating of all of our galvanometers we use the “megohm standard,” 
 recognized by the best European manufacturers as the one which conveys most intelligibly the information the user 
 should have at hand. 
 
 MAGNET SYSTEM. Wherever practical we use the laminated magnet for the reason that it gives not only 
 greater magnetic pull per unit area, but more particularly because of its ability to hold its magnetic strength with 
 less loss from rough usage. It will also be noted that we use the closed circuit magnet because of its well-recognized 
 quality of greater strength and permanency. This form of magnet has not heretofore been largely used because of 
 the greater expense involved in properly magnetizing it. The ampere turn method which we use has been recog¬ 
 nized as the only reliable one for magnetizing a magnet designed for use in galvanometer work. The expense, how¬ 
 ever, involved in this method, particularly in the closed circuit type of magnet, is such as heretofore to have dis¬ 
 couraged many manufacturers from using this type of magnet. 
 
 SUSPENSION SYSTEM. We have designed a form of suspension system which is used in practically all of 
 our D’Arsonval types of instruments, both lecture table and students’ type. In this form the entire suspension 
 system can very easily be removed from the magnets, placed on the table in an easily accessible position for the ready 
 interchange of suspension. This will be found of convenience at times, notwithstanding the fact that the liability 
 of breakage of the suspension has been greatly reduced. We supply suspension ribbons and coils with connecting 
 strips which can be attached almost instantly without the aid of either a screw driver or soldering copper. 
 
 COILS. All coils, unless otherwise specified, are of the dead-beat form, but for Capacity and Induction work 
 we supply, when ordered, coils especially adapted to this work for either type of instrument. 
 
 METHOD OF READING. The method of reading employed is such in every case as is best adapted to the 
 particular type of instrument and the use to which it is to be put. On the various types we use the several different 
 systems as here specified: 
 
 A POINTER, reading on either the vertical or horizontal scale. 
 
 MIRROR READING, employing the back target fiducial mark, making it possible to use a front opening wide 
 enough for both eyes to be used in their normal position without errors of parallax. 
 
 THE MIRROR METHOD with the small peek hole front target, designed more particularly for advanced 
 
 students. 
 
 TELESCOPE READING. All of our instruments, except the inexpensive students’ types Nos. 93-198 and 
 93-200, are supplied with mirrors. The regular reading device may be very easily removed and the instrument 
 used as a telescope reading instrument. 
 
 THE TELESCOPE MOUNTING and BRACKET, illustrated under No. 93-246, is designed of such size as to 
 take any of our standard types of instruments. 
 
338 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 LECTURE TABLE GALVANOMETERS 
 
 No. 93-130 
 
 UNIVERSAL LECTURE TABLE GALVANOMETER 
 
 EIGHT INSTRUMENTS IN ONE 
 
 Patent Pending 
 
 Designed for a practical and reliable Lecture Table instrument covering a wide range and giving one division 
 deflection on .002 of a volt. 
 
 The movement is of the commercial D’Arsonval type but slightly modified; the moving coil adjusted for one 
 ohm resistance, making it possible to supply at any time detachable and interchangeable shunts or resistances of 
 any desired range. 
 
 EIGHT INSTRUMENTS IN ONE 
 
 The following eight instruments are therefore available in this one outfit: 
 
 1. A Galvanometer in which one space deflection means .002 of an ampere or .002 of a volt. 
 
 2. A Millivoltmeter in which the entire scale deflection means 25 millivolts in yi millivolt divisions. 
 
 3. A Milliamperemeter in which the entire scale deflection means 25 milliamperes in yi milliampere 
 
 divisions. 
 
 4. A Voltmeter range of 0-5 volts in 1/10 volt divisions. 
 
 5. A Voltmeter range of 0-25 volts in yi volt divisions. 
 
 6. A Voltmeter range of 0-125 volts in 2volt divisions. 
 
 7. An Amperemeter range of 0-5 amperes in 1/10 ampere divisions. 
 
 8. An Amperemeter range of 0-25 amperes in yi ampere divisions. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 339 
 
 DIAL. The dial is twelve inches long with wide and clearly indicated divisions. Note below the reproduction 
 of the scale about 1/5 size. It may easily be read from any part of the lecture room. 
 
 FOR THE INSTRUCTOR’S CONVENIENCE the back of the dial carries a scale with full and explicit direc¬ 
 tions for connecting. On the base is a protecting switch to avoid accidentally burning out the coil by a mis-connection. 
 
 A NEW METHOD OF CONNECTING SHUNTS, which automatically insures the same contact pressure on 
 both the shunt and coil circuit. This eliminates all liability of contact error in the shunt system. 
 
 UNIVERSAL FEATURES. We have produced an instrument in which both the educational and commercial 
 features have been carefully considered and economically solved. 
 
 ACCURACY. The calibration is done in connection with the best standard commercial instruments. All parts 
 are carefully constructed. The magnets are aged by the standard aging method. The jewel bearings are best 
 quality sapphire. In short, we believe this instrument to be the best electrically, mechanically, and educationally, 
 that has ever been offered. 
 
 93-130 UNIVERSAL LECTURE TABLE GALVANOMETER, complete with full set of Shunts and Resist¬ 
 ances giving ranges previously listed.$35.00 
 
 EXTRA SHUNTS AND RESISTANCES. Should an instrument of any other range than that 
 already provided for be desired, the proper shunts and resistances will be furnished on special 
 order at the net price each of. 2.50 
 
 L. E. KNOTT APPARATUS COMPANY 
 Harcourt Street, 
 
 Boston, Mass. 
 
 Gentlemen, — Let me add that your Galvanometer has been a most thoroughly satisfactory instrument and wonderfully sensitive. 
 
 Very sincerely yours, 
 
 (Signed) Harold B. Reed, 
 
 February 21, 1912. Instructor in Physics, 
 
 East High School, 
 
 Cleveland, Ohio. 
 
 Gentlemen, — Your Lecture Table Galvanometer has been a great help in teaching the subject of current electricity to mixed classes. 
 The fact that all connections and moving parts are plainly in view, and the scale large and open, and the ranges large make it an ideal edu¬ 
 cational instrument. 
 
 The use of the ammeter shunts and of the switch shunt and their effects on the deflection of the needle, tend to clear up the subject of 
 divided circuits. 
 
 I have it before my classes during our study of current electricity and use it constantly. It is a usable and extremely satisfactory in¬ 
 strument and one that should be in every Physics lecture room. 
 
 Very truly, 
 
 March 15, 1912. (Signed) Ernest R. Smith, 
 
 North High School, 
 
 Syracuse, N. Y. 
 
 Gentlemen, _The Lecture Table Galvanometer has been received and in good condition. Needless to say I am much pleased with 
 
 it and will make excellent use of it. In fact, it is just about the device I have been looking for and it is probable that I shall order a second 
 unit of this kind for our laboratory, next year. 
 
 Very truly yours, 
 
 March 28, 1912. (Signed) William H. Browne, Jr., 
 
 N. C. Coll, of Agriculture & Mechanic Arts, 
 West Raleigh, N. C. 
 
340 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • i 
 
 No. 93-146 
 
 93-146 LECTURE TABLE GALVANOMETER. As will be noted from the cut, this instrument is mounted 
 vertically, of sufficient height for lecture table use. The scale is large and open so as to be seen 
 across the lecture room, the pointer of aluminum, the bearings jewel, the moving system a \y£- 
 inch magnet. The windings are in three sections, — coarse, medium, and fine wire of varying re¬ 
 sistances and varying ranges. 
 
 This is not designed for an instrument of high sensibility, but rather to cover the widest range feasi¬ 
 ble to attain in an inexpensive lecture table instrument. 
 
 It will be found well adapted for such experiments as polarization, the study of the relative strength 
 of cells either in groups or in multiple, experiments on induction taken in the larger way, and many 
 other experiments which will suggest themselves as adapted to this range of instrument .... 
 
 No. 93-166 
 
 93-166 THE LAMPRA PROJECTION GALVANOMETER. This galvanometer is of the same genera 
 type as used in France and Germany in the early days of the pivotal bearing D’Arsonval. It has, 
 however, been greatly improved by taking advantage of more recent developments in galvanometer 
 construction. 
 
 As will be noted from the illustration, it is especially adapted for projection work, the scale chamber 
 being of the regulation slide holder size with glass both sides of the indicator. The galvanometer 
 movement is encased in a compact box mounted so as to give adequate adjustment for any form 
 of Projection Lantern, the indicator moving over an arbitrary scale. The entire instrument, 
 including the indicator chamber, is sealed for proper protection against dust and air currents. A 
 most effective and convenient demonstration instrument for lantern work. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 34i 
 
 No. 93-175 
 
 THE IMPROVED LAMINATED MAGNET 
 
 LECTURE TABLE GALVANOMETER 
 
 30 MEGOHM SENSIBILITY 
 
 MAGNETS. As the illustration shows, this instrument is made up 
 of four horizontal magnets. Because of the form of the magnet, and 
 the fact that the whole system is laminated, we are able to produce a 
 magnetic pole of a strength at least five times that used in any other 
 Lecture Table Galvanometer on the market. 
 
 COIL. We have employed the cylindrical, close-wound coil recog¬ 
 nized by instrument makers the world over as being the only form in 
 which the deflections bear the proper relation to the current strength. 
 The value of such a coil in a Lecture Table Galvanometer is of especial 
 consideration, as both the lecturer and the students are able to recognize, 
 from the amount of deflection, the relative amperage passing through the 
 coil. 
 
 SCALE. Our instrument is designed or a 60 degree deflection 
 either side of zero, making a total of 120 degrees. Note, also, that the 
 instrument is provided with four scales and double pointer. A vertical 
 scale on both sides of the instrument with coarse divisions, is especially 
 intended for students’ readings. A horizontal finely divided scale on 
 top of the magnet on both front and back is of value to the instructor 
 or students desiring to make closer readings than can easily be made on 
 the coarse scale intended for wide range work. 
 
 NON—PARALLAX READING DEVICE. As will be noted from the illustration, the vertical scale is 
 offset in such a way that the large triangular pointer does not over-lap the scale, but is in the same line with 
 it, making it possible to use the so-called “straight line method of reading,” which avoids all errors of 
 
 parallax. 
 
 ZERO ADJUSTMENT. A convenient and most desirable method of adjusting the pointer to zero 
 has been worked out, using the chain and sprocket, one sprocket being mounted on the upper end of the ver¬ 
 tical shaft passing down the inside of the supporting post. On the other end of this shaft is a milled-edge 
 disc projecting slightly beyond the base to the left in a most convenient and accessible position. With this 
 arrangement the needle is quickly and easily adjusted to zero without raising the glass dome. 
 
 COIL LIFT. For safety in shipping and in handling, the coil is easily raised from the suspension ribbon 
 by a knob conveniently located on the base, on the right of the instrument. 
 
 METHOD OF ATTACHING SUSPENSION RIBBONS. In D’Arsonval Galvanometers, using the 
 steel or phosphor-bronze ribbon, there is some danger of breaking the suspension, owing to carelessness in 
 handling the instrument before the coil is raised to shipping position. As will be noted in the diagram, the 
 upper portion of the coil terminates in a horizontal, close-wound spiral between the turns of which the suspen¬ 
 sion plate is inserted. Should, therefore, breakage accidentally occur, we can furnish a new ribbon with the 
 suspension plates attached, which the customer can insert quickly and easily without the use of a screw driver 
 or soldering copper. This feature makes this lecture table instrument, as well as our complete line of D’Arson¬ 
 val Galvanometers, practical for use by the most inexperienced. 
 
 SENSIBILITY. We have thought it best to adjust this galvanometer to a considerably higher sensibility 
 than is ordinarily furnished for lecture table work, as it permits an entirely new field of experiments not possi¬ 
 ble with the instruments usually supplied. In case, however, it is desired to reduce the sensibility, this can 
 be very easily done by inserting a coil in the form of a shunt. Special coils for this work will be supplied if 
 desired. While it is perfectly feasible, with our methods of construction, to put out an instrument of very much 
 higher sensibility, it has seemed to us that 30 megohms would meet the greatest variety of conditions. This 
 instrument, therefore, will be adjusted to approximately this sensibility. 
 
 THE IMPROVED LAMINATED MAGNET LECTURE TABLE GALVANOMETER, complete as above 
 illustrated.$16.00 
 
342 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 LABORATORY D’ARSONVAL 
 GALVANOMETERS 
 
 No. 93-195 
 
 93-195HORIZONTAL GALVANOMETER, D’Arsonval move¬ 
 ment, jewel bearing, 0 center. This is a commercial 
 type 'of instrument in horizontal or laboratory form. 
 The range is such as to make it of the greatest value in 
 general laboratory practice. Quick action, quick read¬ 
 ing, adapted to a wide range of experiments, such as In¬ 
 duction, Polarization of Cells, Measurements of the 
 Wheatstone Bridge, where an accuracy equal to K 
 millimeter on the bridge is considered sufficient. 
 
 Owing to the form of the pole pieces the scale is propor¬ 
 tional to the amount of current going through, thus 
 giving the instrument a range of usefulness far greater 
 than its sensibility would indicate. 
 
 Jewel bearing, mahogany base, aluminum case. A sub¬ 
 stantial, convenient, well-constructed instrument of 
 the D’Arsonval type. 
 
 No. 93-200 
 
 Patent Pending 
 
 93-198 HARCOURT IMPROVED D’ARSONVAL GALVANOMETER similar to No. 93-200, but single 
 
 magnet type. Designed particularly for “Laboratory Physics” by Millikan, Gale and Bishop. 
 
 93-200 THE TRIPLE LAMINATED MAGNET HIGH SCHOOL GALVANOMETER. The simplicity of 
 construction and ease of use in a students’ laboratory galvanometer are quite as essential as sensi¬ 
 bility. In the instrument above illustrated, simplicity and ease of operation are obtained to an 
 extent which a few years ago was considered impossible. The simplicity of this design will appeal 
 to the practical laboratory instructor. Its sensibility is well within the range which such instru¬ 
 ments are designed to meet. 
 
 Features. The triple laminated magnet gives greater magnetic pull, enabling heavier ribbon sus¬ 
 pensions to be used, thus decreasing the liability of breakage. 
 
 As will be noted, the coil is of the close-wound type, the same as employed in our Galvanometer 
 No. 93-210, a form of peculiar value in an instrument designed for individual laboratory work, as 
 the student should be able to determine from the amount of deflection, the approximate voltage 
 and amperage to which the instrument is subjected. 
 
 The entire suspension system may be removed by loosening a single screw. Should the suspension 
 ribbon be accidentally broken, a new one may be readily inserted in a few seconds by the student. 
 No soldering copper or screw driver is required. 
 
 The zero adjustment is readily made by turning the metal button at the top of the suspension post. 
 
 A most efficient coil lift is provided which raises the coil from its suspension and clamps it rigidly in 
 position, ready for rough handling and for shipping. 
 
 For convenience the readings are taken by a pointer moving over a 3J^-inch horizontal dial grad¬ 
 uated in degrees. 
 
 Sensibility. The rating, according to the standard method, is about thirty megohms, although the 
 construction of the instrument is such as to permit of a higher sensibility should it be deemed 
 desirable to use such in the work for which this instrument was designed. 
 
 Complete. 
 
 $7.50 
 
 $2.75 
 
 4.80 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 343 
 
 93-210 THE LAMINATED VERTICAL MAGNET GAL¬ 
 VANOMETER (The One Ohm per Megohm). 
 
 A laboratory galvanometer designed with 
 special reference to the needs of the individual 
 student will be fully appreciated. It has been 
 our purpose to construct an instrument which 
 can be easily set up, adjusted and kept in ad¬ 
 justment and one in which all working parts 
 are constantly in view. 
 
 The unit suspension system which has been worked 
 out according to the lines noted in the detailed 
 illustration carries the coil, upper and lower sus¬ 
 pension, zero adjustment and lift, all constitut¬ 
 ing a single unit attached to the back brass plate. 
 
 In setting up the instrument this plate is held 
 rigidly between the magnets by means of four 
 screws, removing the thumb nuts from which re¬ 
 moves the entire system for inserting Ballistic 
 Coils, coils of high or low resistance, or for re¬ 
 placing broken suspensions. 
 
 Our suspensions are supplied with metal terminals 
 
 which are easily slipped between the convolutions of the phosphor-bronze spiral with which 
 the coil is supplied, insuring a perfect electrical and mechanical contact. The lower suspension, 
 which has heretofore been replaceable only by a person with much experience, is now even more 
 easily handled than the upper suspension, as each spiral is sent out contained in a sealed glass tube, 
 the terminals passing through the upper and lower ends of the tube. After the coil is set in place 
 and the adjustment made, the seal is cut away; the galvanometer is then ready to use, all without 
 touching the spiral with either tools or fingers. 
 
 We have used on this instrument the modified form of the reading device used on our original stu¬ 
 dents’ D’Arsonval Galvanometer with the very important modification that the user now looks 
 in an inclined position, permitting the galvanometer to be used on the surface of the table and 
 avoiding the necessity of either getting down to the level of the mirror, or of raising the galva¬ 
 nometer to the height of the eye. 
 
 The sensibility of this instrument is equal to all requirements for laboratory work. As ordinarily 
 sent out, these instruments are adjusted for 70 megohms sensibility. A higher sensibility than this 
 is readily obtainable if there be adequate demand for it. 
 
 POINTS OF ADVANTAGE 
 
 The resistance is approximately the same as the sensibility in megohms, — one ohm per 
 megohm. \ 
 
 The unit suspension system. 
 
 The visibility of all parts. 
 
 The readiness of assembling and adjustment. 
 
 The ease of replacing broken suspensions. 
 
 The magnetic strength and permeability due to the laminated magnet. 
 
 A method of reading which is practical in the hands of the most inexperienced. 
 
 The zero adjustment which is effective and easily handled. 
 
 The coil lift, conveniently located and instantly operated by a single movement. 
 
 A sensibility of 70 megohms, being substantially four times that obtained in any other stu- 
 ents’ type of instrument. 
 
 Unusual low resistance, — about 70 ohms. 
 
 93-215 BALLISTIC COIL. The above instrument, No. 93-210, is especially adapted for the use of Ballistic 
 Coils in Capacity and Self-Induction experiments. The most convenient method of inserting the 
 coils is to obtain a unit suspension system with the Ballistic Coil attached. The new system can 
 then be inserted very easily. 
 
 Unit Ballistic System complete ready for attaching. 
 
 $6.45 
 
 6.00 
 
344 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 METHOD OF READING. The method 
 of reading is effective, overcoming er¬ 
 rors of parallax. The reading scale 
 may be easily removed by loosening 
 two thumb nuts. The instrument is 
 then well adapted for telescope reading. 
 When it is desired to use this as a wall 
 form instrument for telescope reading, 
 we recommend telescope, scale, mount¬ 
 ing and bracket. (See Index). 
 
 No. 93-220 
 
 93-230 SIX HUNDRED MEGOHM SELF-LEVELING D’ARSONVAL GALVANOMETER, either wall or 
 table type (see illustration next page). A galvanometer for advanced laboratory work which is 
 both self-centering and self-leveling, used either as a wall or table instrument. The entire in¬ 
 strument is hung from universal gimbals so that both magnet and coil are always in correct re¬ 
 lation. 
 
 93-220 TWO HUNDRED MEGOHM D’ARSON¬ 
 VAL GALVANOMETER, an instrument 
 of high sensibility for use with either 
 scale or telescope reading. 
 
 The method of suspending the coil system 
 will be found of the greatest practical 
 value; the entire system may be taken 
 out by loosening the set screws and re¬ 
 moving the back plate, as noted in the 
 illustration. Broken suspensions may 
 be very easily replaced. 
 
 SENSIBILITY. These instruments are 
 approximately 200 megohms sensibility, 
 of quick movement and practically 
 dead-beat. 
 
 As a wall instrument. This has a great advantage in overcoming the difficulties usually encountered 
 in fastening an instrument to the wall and securing the proper level. 
 
 As a table instrument. The advantages are even more pronounced, as the self-centering permits 
 absolute freedom of movement from one portion of the table to another, with assurance that the 
 instrument will instantly assume a level and be ready for use. 
 
 Telescope mounting and bracket. The supporting stand for the galvanometer was designed to fit 
 our Universal Galvanometer and Telescope Support No. 93-240. When the two instruments 
 are used together, a most convenient and effective galvanometer outfit is obtained. 
 
 Reading Device. A two-color scale mounted in a sliding socket for adjusting to zero, telescope on an 
 adjustable arm with leveling screws which may be removed when not in use. 
 
 The Achromatic Telescope, especially designed for galvanometer work. 
 
 Magnet System. By our method of magnet construction we secure far greater strength and per¬ 
 manency than are obtained in any other galvanometer magnet on the market. The concentration 
 of the lines of force to meet the size and form of the coil has been the subject of much careful 
 
 study. 
 
 » 
 
 $ 16.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 345 
 
 Coil System. A removable coil system insures easy access to all 
 delicate parts and the ready replacement of broken suspensions. 
 
 Extra coil systems designed for special work supplied on request. 
 
 Sensibility. As ordinarily furnished, the instrument is supplied 
 with a coil of 400 ohms resistance, giving a sensibility of over 600 
 megohms, the range which has met with the greatest favor. 
 
 The Mirror is optically plane, yi x % inch. 
 
 Suspensions. By carefully adjusting the weight of the coil to the 
 size of the phosphor-bronze suspension, we have practically elimi¬ 
 nated the zero set, but for those who prefer the steel suspension 
 this will be furnished. 
 
 Complete as illustrated.$32.00 
 
 No. 93-230 
 
 93-232 EXTRA COILS, either Ballistic, low, or high resistance as specified, are furnished for use with the 
 
 above instrument.Each 7.50 
 
 93-235 RADIO MICROMETER. In scientific work the Radio Microm¬ 
 eter has long been recognized as not only the most sensitive, 
 but the most reliable heat indicator produced. In putting this 
 sensitive instrument into practical form, we have used the funda¬ 
 mental parts of the D’Arsonval Galvanometer, — magnet sys¬ 
 tem, mirror and reading device, but with the moving coil replaced 
 by the most sensitive thermo-electric couple which it is possible to 
 construct, with a suspension to hold the couple in position, and 
 designed to introduce the least possible amount of restraining 
 influence. 
 
 Sensibility. In radio-micrometer work, the candle flame at definite 
 distance has been found a convenient standard. It is possible 
 with our instrument to detect an amount of heat equal to that 
 received from a candle flame at a distance of 50 feet, giving clearly 
 indicated readings on the dial. 
 
 Method of Reading. With many radio-micrometers previously 
 constructed, the readings must be taken with the telescope method 
 owing to the fact that the deflections caused by the heat of the No. 93-235 
 
 body make it necessary for the observer to remain at a consider¬ 
 able distance. Much of this difficulty has been overcome by 
 our method of introducing heat to the thermo system. The 
 directing horn is mounted on a movable ring so that the heat may 
 be taken either from one side of the instrument or the other, but 
 not from the front where the observer would naturally stand. 
 
 The moving system being provided with a mirror and the close-reading scales easily removable, the 
 telescope method of reading will be found in some cases more satisfactory. 
 
 Complete instructions for use will be furnished with each instrument. 
 
 Complete as illustrated .$16.00 
 
346 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 UNIVERSAL GALVANOMETER WALL- 
 BRACKET AND TELESCOPE SCALE 
 
 ADAPTED TO ANY TYPE OF INSTRUMENT 
 
 No. 93-246 
 
 93-240 GALVANOMETER WALL-BRACKET and TELESCOPE SCALE. Heretofore sensitive galva¬ 
 nometers have been attached rigidly to the wall, it being necessary to level them with the greatest 
 care. When once attached and adjusted, the galvanometer is allowed to remain on the wall 
 permanently. 
 
 Our rigid wall shelf for galvanometer work, carrying the telescope arm and scale, gives a method 
 of using galvanometers much more satisfactory than has ever before been offered. It was espe¬ 
 cially designed for use with the self-centering instrument No. 93-230, although any of our D’Arson- 
 val instruments may be used on it. For lecture table demonstration this shelf will be found of 
 especial service. For this work we recommend the'use of the bracket only, the light being supplied 
 from the Liliputian Lamp, No. 70-126. 
 
 Wall Bracket, Telescope and Scale.$16.60 
 
 93-242 GALVANOMETER WALL-BRACKET only, without Telescope and Scale. $9.60 
 
 93-246 GALVANOMETER WALL-BRACKET, TELESCOPE and SCALE together with No. 93-230 SELF¬ 
 LEVELING D’ARSONVAL GALVANOMETER complete as illustrated. 48.60 
 
 TELESCOPE. See No. 93-480. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 347 
 
 SHUNTS 
 
 No. 93-350 
 
 93-350 ELEMENTARY AYRTON UNIVERSAL SHUNT. In using a galvanometer of high sensibility it 
 is necessary both for convenience and for protection of the galvanometer to use some device for 
 reducing the strength of the current through the galvanometer. Separate shunts of the proper re¬ 
 sistance may be used to bring the deflection down within the limit of the scale, but where it is desir¬ 
 able to send through the galvanometer at different times several different proportions of the main 
 current the separate shunts become inconvenient. The instrument abotfe illustrated provides 
 in compact form a means of sending small or large fractions of the main current through the 
 galvanometer, merely by a movement of the contact arm. This shunt is suitable for galva¬ 
 nometers with ranges from 50 to 500 ohms resistance. 
 
 Instrument is constructed with the greatest care, coils are accurately tested before shipment, and all 
 parts are handsomely and durably finished. 
 
 No. 93-360 
 
 93-360 UNIVERSAL SHUNT. A great advantage of this shunt over the one preceding is that it can be used 
 with a ballistic galvanometer as well as with a dead-beat instrument. The instrument above 
 illustrated has all the advantages of a universal form and in addition has the latest improved 
 sliding contact which replaces the less convenient plug arrangement. The contact resistance is 
 very low, although this is not a matter of great importance in the ordinary use of the instrument, 
 as the contact resistance does not enter the galvanometer circuit proper.’ The circuit arrangements 
 in our instrument are so arranged that the resistance coils are also available as a “drop wire,” or 
 simple potentiometer for subdividing a potential difference. 
 
 This instrument has received the most painstaking care in its construction as well as design. To 
 protect the ebonite top from air, dust, and sunlight, thus preserving its insulating properties, a 
 brass cover with mahogany top similar in style to the box is provided. It lifts clear away from the 
 box on loosening a bayonet catch and is laid aside while the shunt is in use. 
 
 a b c 
 
 Total Resistance 10,000 20,000 100,000 ohms 
 
 Each .... $28.50 38.00 62.00 
 
 93-370 UNIVERSAL SHUNT, similar to above, but without cover. 
 
 a b c 
 
 Total Resistance 10,000 20,000 100,000 ohms 
 
 Each.$25.00 34.50 68.50 
 
 $7.50 
 
348 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 GALVANOMETER ACCESSORIES 
 
 93-400 PLANE GALVANOMETER MIRROR, optically plane, diameter Y* inch . $1.00 
 
 93-402 ONE-METER CONCAVE GALVANOMETER MIRROR, one-meter focus, diameter 'A inch 1.25 
 
 93-406 TWO-METER CONCAVE GALVANOMETER MIRROR, two-meters focus, diameter A inch . 1.46 
 
 93-416 NICKEL SUSPENSION FILAMENTS. Owing to freedom from oxidation, high fusing point, and 
 the ability to draw it to a fineness suitable for suspensions, nickel as a suspension filament has 
 come into considerable favor. 
 
 3 . be d e 
 
 Diameter.001 .0015 .002 .003 .004 inch 
 
 Per Foot.$0.46 .40 .30 .25 .20 
 
 93-426 PHOSPHOR-BRONZE FILAMENTS. Phosphor-bronze has been used with success as suspensions 
 in the highest grade electrical instruments. Owing to its great tensile strength and non-magnetic 
 qualities, it is of special advantage where high sensibility is desired. 
 
 3 be d e 
 
 Diameter.001 .0015 .002 .003 .004 inch 
 
 Per Foot.$0.46 .40 .30 .25 .20 
 
 93-436 STEEL SUSPENSION FILAMENTS. Steel, as a suspension, is free from “set” and has great 
 
 tensile strength. 
 
 3 be d e 
 
 Diameter.001 .0015 .002 .003 .004 inch 
 
 Per Foot.$0.40 .36 .30 .26 .20 
 
 93-445 
 
 WOLLASTON WIRES, the finest size of platinum wire filament; the wire before drawing, is en¬ 
 closed in a silver sheath and is drawn through a jewel gauge (according to Wollaston) until the 
 smallest size is obtained. The silver film that still remains must be removed chemically before 
 
 the wires are used. 
 
 a 
 
 b 
 
 c 
 
 Diameter of Platinum Core .... 
 
 . . . .00006 
 
 .00008 
 
 .0001 inch 
 
 Approximate External Diameter . . 
 
 . . . .006 
 
 .008 
 
 .0036 inch 
 
 Per Foot . 
 
 . . . $1.26 
 
 1.00 
 
 1.00 
 
 93-460 DIRECT READING ADJUSTABLY 
 MOUNTED LAMP AND SCALE, 
 
 “ Lin-o-Lite ” Lamp, Opalescent 
 Screen, for use with any reflecting gal¬ 
 vanometer to give direct readings of 
 the movement of the coil. 
 
 In the design above illustrated, we mount 
 a single filament incandescent light 
 within a cylindrical tube, the glowing 
 filament showing through only a small 
 opening in the cylinder. This cylinder 
 is provided with a clamp for attach¬ 
 ment to the supporting rod of the stand 
 on which it is readily adjustable. The 
 opalescent screen is mounted in a frame 
 which is provided with a rod telescoping 
 into the supporting rod of the stand. 
 
 This screen has a scale across its entire 
 length with long centimeter divisions 
 and shorter millimeter divisions. This 
 scale reads both ways from zero in the 
 center. All parts of this apparatus 
 are carefully made and the instrument 
 has been of great utility in the many 
 laboratories where it has been adopted. 
 
 Complete as illustrated.$11.25 
 
 No. 93-460 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 349 
 
 
 MOUNTED READING TELESCOPE AND SCALE 
 
 The only distinctive items illustrated above and not elsewhere listed are: 
 
 93-470 READING TELESCOPE SCALE. This scale is printed on glazed bristol board, 50 centimeters long, 
 graduated in long centimeter divisions with shorter millimeter divisions either side from zero at the 
 center, figures inverted. This scale is mounted on a hardwood strip provided with clamp for 
 attachment to any 10-millimeter rod. $1.40 
 
 93-480 READING TELESCOPE WITH CROSS HAIRS, objective 18 millimeters diameter, focus ]/2 to one 
 meter, sliding tube focusing adjustment. This telescope is carefully constructed of the best ob¬ 
 tainable material, the optical parts having been calculated to a nicety. The tubes are beautifully 
 polished and lacquered and the objective is furnished with a brass cap. This telescope is especially 
 
 designed for use in electrical measurements, but may be used equally as well in experiments on 
 
 determining the magnifying power of a telescope. 6.00 
 
 Other apparatus illustrated above, and listed elsewhere is as follows: 
 
 6-242 HARCOURT SPECIAL H-BASE, for 19-millimeter rod . . $1.00 
 
 6-20b SUPPORT ROD, 19 millimeters diameter.52 
 
 6-770 HARCOURT RIGHT ANGLE CLAMP.96 
 
 6-920 TELESCOPE CLAMP.2.45 
 
 5-10b SUPPORT ROD, 10 millimeters diameter.18 
 
 70-110 ELECTRIC LAMP, table size, adjustable from 12 to 18 inches, made of polished brass, nickel-plated. 
 
 Complete as illustrated in Section 70. 9.75 
 
 70-112 GAS LAMP, similar to above, but arranged for burning illuminating gas. 
 
 Complete with Argand Burner and six feet of rubber tubing, with goose-neck connection, stand 
 
 adjustable from 12 to 18 inches. 9.75 
 
 70-115 KEROSENE LAMP, similar to above, but arranged with reservoir for oil. 
 
 Complete. 9-76 
 
 For LILIPUTIAN PROJECTION LAMP, highly recommended as a source of light for galvanometer 
 work, see page 241. 
 
 \ 
 
350 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 D’ARSONVAL TYPE I 
 
 1 
 
 AMMETERS AND VOLTMETERS 
 
 DOUBLE RANGE 
 
 • ' m 
 
 
 This Double Range D’Arsonval line of instruments is offered as a distinctively higher grade line than those 
 which have been commonly used by students in laboratory practice. The D’Arsonval movement, the aging of the 
 magnets, the adjusting of the control spring and jeweled bearing, are features to which special attention has been 
 given by our best instrument makers. 
 
 SCALE. Each instrument is made with two scales so as to cover as wide a range as will be needed in any kind 
 of work. Each scale is individual, calibrated, and hand drawn, the higher range drawn in black, and the lower 
 range in red with binding posts carefully differentiated to avoid burning out by careless connections. The zero of 
 each scale is at the left, giving wide scale divisions. 
 
 93-525 D’ARSONVAL LABORATORY AMMETER, jewel bearings, aluminum case, hand calibrated. 
 
 Range 0-25 amperes, scale drawn in black; 0-5 amperes, scale drawn in red .. $9.40 
 
 93-636 D’ARSONVAL LABORATORY VOLTMETER, jewel bearing, aluminum case, hand calibrated. 
 
 Range 0-120 volts in 2-volt divisions in black, 0-12 volts in 1/5 volt divisions in red. 9.40 
 
 WESTON AMMETERS AND VOLTMETERS, LABORATORY TYPE 
 
 93-660 DOUBLE RANGE AMMETER, 0—25 amperes 
 
 0-5 amperes .$16.26 
 
 93-560 DOUBLE RANGE VOLTMETER, 0-150 volts 
 
 0-15 volts 
 
 16.25 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 351 
 
 THE REMOVABLE SHUNT TRIPLE RANGE 
 
 VOLT-AMMETER 
 
 No. 93-600 
 
 Patent Pending 
 
 Our Universal Voltmeter and Ammeter has been designed to give, in practical working form, all the ranges re¬ 
 quired in such work as is usually taken in technical school and vocational school laboratories, one instrument serv¬ 
 ing the purpose of six of the usual form commercial type. By this means it is possible to supply a complete work¬ 
 ing equipment for an entire laboratory division covering the ranges required for all practical measurements at an 
 expense well within the reach of the average school desiring to give instruction in practical electrical measurements. 
 
 This instrument is of a distinctly high grade and designed for practical work, every possible provision having 
 been made against liability of injury. Should, in the course of rough handling, the pointer be moved slightly from 
 zero, ample provision has been made for ready re-setting, insuring the same degree of accuracy as the instrument 
 originally had. 
 
 The ranges covered are as follows: — 
 
 Voltmeter, 0-150 volts, 
 0-15 volts, 
 
 0-3 volts, 
 
 Ammeter, 0-30 amperes, 
 0-15 amperes, 
 0-3 amperes. 
 
 Voltmeter. The resistances giving the various ranges are permanently attached, each brought out to its ap¬ 
 propriate binding post, and cannot, therefore, be disconnected. 
 
 Ammeter. The various ranges of ampere needs are met by the use of our new form interchangeable shunt, 
 the same as used in our Universal Galvanometer No. 93-130. 
 
 Additional shunts may be supplied, if desired, giving other ranges than those specified. Shunts which are not 
 in use are carried on the inside of the base, as noted in the illustration. 
 
 Mounting. Both the cap and base are of aluminum. The base is made separable to provide carrying space 
 for the shunts not in use. 
 
 Binding Posts. Each binding post is clearly marked, giving use and range for which it is designed, thus avoid¬ 
 ing possibilities of error resulting from wrong connections. 
 
 Scales. Various scales are carefully diSerentiated so that no error may be introduced into the work by care¬ 
 lessness in reading. It will be seen that we have covered in a most satisfactory way the six most important ranges 
 of laboratory instruments and provided against every possible contingency in practical use. 
 
 93-600 THE REMOVABLE SHUNT TRIPLE RANGE VOLT-AMMETER .$20.00 
 
 WESTON TRIPLE RANGE AMMETERS AND VOLTMETERS, 
 
 LABORATORY TYPE 
 
 93-626 TRIPLE RANGE VOLT-AMMETER, laboratory type, covering three ranges of Voltmeters, three 
 ranges of Ammeters, as follows: — 
 
 Volts, 0-150 
 0-15 
 0-3 
 
 Amperes, 0-30 
 0-3 
 
 0-1 # . 29.76 
 
352 
 
 L. E. KNOTT APPARATUS CO , BOSTON 
 
 THE 
 
 No. 93-635 
 
 MULTIPLE RANGE ROTARY METER 
 
 FOR 
 
 DIRECT CURRENT 
 
 Range, 0-30 and 0-3 Amperes, 0-100 Mill Volts (1-10 Volts) 
 0-1-10, 0-3 and 0-30 Volts 
 
 No. 93-636 
 
 The Multiple Range Rotary Meter is a portable universal measuring instrument 4inches X 3 inches X 2 
 inches high, a most convenient size for either instructor’s or students’ use. 
 
 The instrument is provided with six binding posts, clearly differentiated, yet so designed that even after con¬ 
 nections are made to the appropriate posts, no current passes until the body of the instrument is turned in its 
 socket so that the pointer rests on the desired range designated on the graduated surface which surrounds the body 
 of the instrument, thus providing a double protection against accidental injury. 
 
 The base of the instrument contains a commutator which is stationary, mounted in a suitable receptacle having 
 provision for a number of shunts and resistances, connections with which are made through the several segments 
 of the commutator. 
 
 A Milvoltmeter is centrally pivoted to the commutator in such a way that the meter terminal makes connec¬ 
 tion with successive segments of the commutator as the meter is rotated on its axis. A fixed index finger on the 
 side of the knurled meter case shows the position of this terminal and suitable markers on the surface of the com¬ 
 mutator receptacle show the position of the segments. 
 
 No current passes through the meter unless the index finger points to the marker corresponding with the bind¬ 
 ing post connected with the source of current, thus greatly lessening the danger of damaging the instrument by 
 overloading it through a wrong connection. 
 
 This invention practically reduces the problem of making a voltammeter with a number of scales to the sim¬ 
 plicity of a low range single scale voltmeter, and should repairs be necessary, the probability of having to alter the 
 adjustment of the extra shunts or resistances is very remote, a statement that cannot be made concerning the con¬ 
 ventional type of voltammeter. 
 
 In the conventional type of voltammeter where the same moving system is utilized for current and voltage 
 measurements, it is necessary to have two distinct windings on the moving coil and separate means of conducting 
 the current to these windings, or else provide a switch in the moving system circuit to break the ammeter circuit 
 when it is desired to measure voltage, either of which methods introduces complications which are both expensive 
 and unreliable. 
 
 In the Rotary Meter there is but one winding in the moving system and one pair of conductors from the moving 
 system to the contact terminals and these consist of two coil springs which serve the double purpose of carrying 
 the current to the coil and furnish the controlling force of the movable member. All other coils and shunts are con¬ 
 tained in the commutator receptacle each with its own circuit from the binding post to the corresponding segment 
 of the commutator. This appears to be the last word in safety, simplicity and accuracy. 
 
 Instead of a multitude of coils and shunts crowded together in one case and an array of binding posts all con¬ 
 nected permanently to the moving system inviting wrong connections, or a collection of coils and shunts, each sep¬ 
 arate and by itself, an inconvenience that few are willing to tolerate, the Rotary Meter combines in a convenient 
 form the necessary coils and shunts each one in its own compartment and connected with a commutator which makes 
 connection at will with the simplest form of indicating instrument that has yet been devised, and the whole occupy¬ 
 ing a space only 4x 3 x 2 inches. 
 
 Price 
 
 $16.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 353 
 
 VOLT- AMMETERS 
 
 MAGNETIC VANE TYPE 
 
 Volt-ammeters. The line of Volt-ammeters which we list herewith is of the well-known magnetic vane type 
 with zero center which avoids injury in case of wrong connections. This is a type of instrument which will com¬ 
 mend itself to Physics teachers because of the readiness with which the student may obtain results reading directly 
 in the fundamental units of Volts and Amperes, thus learning at the very beginning of his work the significance of 
 the common commercial terms. 
 
 Double scale, jewel bearing, aluminum case with hand calibration, combine to give this instrument a value in 
 laboratory work not equaled by any other medium-priced instrument on the market. 
 
 Ranges. The ranges selected are such as will be of the widest service in laboratory work. 
 
 93-650 VOLT-AMMETER, magnetic vane type, jewel bearing, aluminum mounting, range 10 volts and 10 
 
 amperes. .$6.60 
 
 93-670 VOLT-AMMETER, magnetic vane type, range 120 volts and 15 amperes. 8.60 
 
 NEW LINE OF ALTERNATING CURRENT AMMETERS AND 
 
 VOLTMETERS 
 
 It is doubtless due to the great advance which has been made during the 
 past few years in the production of iron with definite electrical qualities, that 
 the alternating current measuring instrument has now reached its present high 
 state of perfection. It is with pleasure that we call the line we here ofier to the 
 attention of laboratory workers. 
 
 Voltmeter. A thoroughly reliable Voltmeter giving a full scale deflection 
 on 15 volts, a voltmeter of higher resistance than is commonly used in com¬ 
 mercial instruments. 
 
 Ammeter. Our alternating current Ammeters will measure with commer¬ 
 cial accuracy the output of magnetos and even the smallest size alternating current 
 generators. The Ammeters in this class are of much lower resistance than the 
 conventional type of alternating current instruments. 
 
 Mounting. These instruments are mounted in a 7-inch finely finished iron case with nickel trimmings and in 
 the usual switchboard form. See the illustration above. 
 
 93-700 VOLTMETER, 7-inch case, 0-15 volts. $14.00 
 
 93-710 - f 0-125 volts. 14.26 
 
 93-720 -, 0-500 volts. 19.00 
 
 93-740 AMMETER, 7-inch case, 0-1 ampere. 13.00 
 
 93-750 - , 0-5 amperes. 13.60 
 
 93-760 - , 0-25 amperes. 13.50 
 
 93-770 -, 0-100 amperes. 13.76 
 

 354 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ELECTRICAL RESISTANCE APPARATUS 
 
 RESISTANCE COILS 
 
 No. 94-20 No. 94-21 
 
 No. 94-30 
 
 No. 94-60 
 
 94-20 ONE-OHM RESISTANCE, after Millikan and Gale’s “A Laboratory Course in Physics” (Exper¬ 
 
 iment 33). $0.28 
 
 94-21 THOUSAND-OHM RESISTANCE COIL, after Millikan and Gale’s “A Laboratory Course in 
 
 Physics” (Experiments 31 and 32). .45 
 
 94-30 SPOOL RESISTANCES. These spools are practically the same as those which are used in our high- 
 grade resistance boxes. They are guaranteed to be accurate to % of one per cent. 
 
 abcdef ghij klmn o p q 
 
 Resistance 1 2 3 4 10 20 30 40 50 100 200 300 400 1000 2000 3000 4000 Ohms 
 
 Each . $0.50 .55 .65 .55 .60 .62 .65 .68 .76 .80 .85 .95 1.00 1.50 1.75 2.00 2.20 
 
 94-60 TEMPERATURE COIL for use with Wheatstone Bridge in the study of effect of temperature changes 
 
 on the resistance of a coil of wire. 
 
 This instrument consists of a spool of insulating material on which is mounted a coil of high resistance, 
 
 the ends of which are terminated in heavy leads. 
 
 Complete as illustrated.$1.20 
 
 94-61 TEMPERATURE COIL, after Turner and Hersey (Experiment E081). .15 
 
 No. 94-70 
 
 94-70 RESISTANCE COILS, HYDE FORM, for use with Wheatstone Bridges, in determining the resistances 
 of coils; also for formulating laws of resistance in wires. In our new design we have entirely ob 
 viated the danger of the ends of the coil becoming detached from the leads, — a very great ad¬ 
 vantage over the old forms. 
 
 As illustrated, this instrument consists of eight spools, of different lengths and different diameters 
 and two different materials. Each spool is mounted on a pin fixed in a neatly finished baseboard. 
 
 To simplify the deriving of the laws of resistance we furnish eight spools capable of securing the follow¬ 
 ing combinations: — 
 
 2 Spools, same material, same diameter, same length. 
 
 2 Spools, same material, same length, different diameters. 
 
 2 Spools, same material, same diameter, but one double the length of the other. 
 
 2 other Spools which, with combination with those above cited, will allow of comparison, 
 of same diameter and same material, but of lengths as 1: 2: 3: 4: 5. 
 
 1 other Spool of same diameter but different material from one of the above named, but exactly 
 ten times the length. 
 
 Set of eight spools complete, mounted on base as illustrated. 
 
 $3.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 355 
 
 No. 94-80 No. 94-90 
 
 94-80 RESISTANCE SPOOLS. Set of five spools of unknown resistance, all mounted on same spindle 
 on a polished wood base, each with binding posts for connections to each or to all in the series. 
 
 This combination consists of the following spools: Copper Wire— 10 meters, Nos. 22 and 28, and 
 20 meters, Nos. 22 and 28; German Silver— 10 meters, No. 22.Per Set 
 
 94-90 RESISTANCE BOARD, after C. H. Andrews of the South High School, Worcester, Mass. 
 
 This instrument consists of four bobbins, the wire so wound and connected as to make possible com¬ 
 binations as follows: 2 coils of same length and material, but of different diameter; 2 coils of same 
 length and diameter but of different material, and 2 coils, same diameter and material, but of differ¬ 
 ent lengths. 
 
 In the design of this instrument Mr. Andrews has taken pains to select wires the diameters and re¬ 
 sistances of which have convenient ratios to each other and, therefore, best suited for use in parallel. 
 
 The coils have the further advantage that they are so connected to the brass blocks that combina¬ 
 tions in series or parallel of any one or more of the coils may be secured by proper placing of the 
 plugs in their tapered holes. 
 
 This instrument is very carefully constructed; the plugs are nicely tapered and ground to fit the holes. 
 
 Mounted as illustrated on a finished hardwood base. 
 
 94-96 CULLER’S DOUBLE RHEOCHORD. This outfit consists of a pair of Rheochord Boards, finished, 
 provided with wire and binding posts; character, size, length and method of winding the wires as 
 indicated in Culler’s “Laboratory Manual of Physics” (Experiment XLVc).Pair 
 
 94-97 FULLER AND BROWNLEE RHEOCHORD BOARD, as specified in Fuller and Brownlee’s “Labo¬ 
 ratory Exercises” (Experiment 73). , . 
 
 94-98 RHEOCHORD BOARD, as specified in Millikan, Gale and Bishop’s “Laboratory Physics” (Ex¬ 
 periments 32 and 36).). 
 
 STANDARD RESISTANCES. The coil illustrated has been designed for use when¬ 
 ever the highest accuracy is not required, and the inconvenience attending the 
 use of an oil bath can therefore be avoided. Though not intended as the highest 
 standards, the accuracy and compactness make these coils convenient for many 
 purposes. The winding is a matter of great care; the wire used is manganin, 
 and the core on which the coil is wound is of brass. This core is open at each 
 end, giving ventilation as well as preventing changing of temperature; also per¬ 
 mitting the introduction of a thermometer into the interior. The winding is ar¬ 
 ranged in a thin layer on the core and insulated with only sufficient wax to prevent 
 access of the air to the wire. 
 
 The case is of brass; the terminals are heavy copper rods giving ample conductivity 
 and contact surface. The lower ends of these rods are arranged to dip into mercury 
 cups, while the upper ends are equipped with large binding posts screwing into 
 the copper bars and bearing against lugs which give ample clamping surface. 
 These coils are furnished in four different sizes as listed below. They are accu¬ 
 rately adjusted to % of one per cent. With each coil a certificate of accuracy 
 giving the date, temperature, and precise value of the resistance at the final test 
 is included. 
 
 a b c d 
 
 Capacity . 1 10 100 1000 Ohms 
 
 . Each .$10.00 10.60 12.60 16.60 
 
 94-106 STANDARD RESISTANCES, same as above, but adjusted to an accuracy of of one per cent. With 
 these coils the certificate is not furnished. 
 
 a b ' c d 
 
 Capacity. 1 10 100 1000 ohms 
 
 Each. $7.60 8.00 9.60 12.60 
 
 $2.90 
 
 3.90 
 
 6.76 
 
 4.66 
 
 4.65 
 
356 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 STANDARD RESISTANCES 
 
 Nos. 94-116 to 94-117 
 
 94-116 STANDARD RESISTANCES, Reichsanstalt Form, universally accepted for work of high precision. 
 
 These have been evolved as an embodiment of the long experience of the German Government 
 Bureau. The resistance material of these standards is manganin, selected not only for its approved 
 permanence and low temperature resistance coefficient, but also for its small thermo-electro-motive 
 force against copper. The external case is not in connection with the winding and furnishes merely 
 a mechanical support and protection. The standard may be immersed in oil so that the coil is com¬ 
 pletely submerged, and the case, bobbin, and winding are so arranged that the oil has access to all 
 parts of the coil, making it possible to ascertain or control its temperature with certainty. An open¬ 
 ing through the ebonite top permits the insertion of a thermometer into the interior. Case and ter¬ 
 minals are nickel-plated to prevent corrosion. Every operation of the construction of these stand¬ 
 ards, winding, aging, and adjustment, is most carefully carried out. Our standards will there¬ 
 fore be found not merely accurate in adjustment but also permanent in calibration. Each coil 
 is adjusted to Vioo of one per cent, of the value of our copies of the United States Standard. With 
 each resistance sent out is a certificate of accuracy for each coil. 
 
 abed e 
 
 Capacity . 1 10 100 1000 ohms 
 
 Each.$46.00 46.00 46.00 46.00 46.00 
 
 94-117 STANDARD RESISTANCES, Reichsanstalt Form, same accuracy and general struc¬ 
 ture as above, but arranged for air cooling only. 
 
 a b c d 
 
 Capacity . 1 10 100 1000 ohms 
 
 Each.$20.00 20.00 20.00 22.60 
 
 94-126 SINGLE-COIL TENTH MEGOHM. In the construction of this box we use 
 one of the units of our Standard Megohm Box No. 94-226, mounted in a 
 cylindrical brass case with raised terminals, thermometer hole, and offered in 
 form as illustrated. 
 
 Tenth Megohm Coil as illustrated.$36.00 
 
 No. 94-126 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 357 
 
 RESISTANCE 
 
 Nos. 94-152 to 94-155 
 
 BOXES 
 
 No. 94-160 
 
 94-160 SCHOOL RESISTANCE BOX, range 1 to 20 ohms, guaranteed accuracy of 3^ of one per cent. . $3.75 
 
 94-162 SCHOOL RESISTANCE BOX, range 3^ to 111 ohms, guaranteed accuracy of 3 / £ of one per cent. 7.60 
 
 94-165 - —, same as above, but with certificate from our electrical laboratory ..10.00 
 
 94—160 SCHOOL DEMONSTRATION RESISTANCE BOX. This box is the same as above, but supplied 
 with glass front and back that students may see the internal construction of a resistance box. 
 
 By this method the coil connections may readily be observed, and the pupil is enabled to judge 
 
 for himself the structure of an ordinary resistance box. 9.50 
 
 94-170 B-P SWITCH RESISTANCE BOX. The illustration 
 above shows our resistance box fitted with the new 
 B-P Switch in which we believe a great step has 
 been taken in the proper direction, for this simple 
 device comprises the good points of the plug and 
 associates with them the valued features of a switch 
 mechanism. In the design of the switch care has 
 been taken to retain only the good features and it 
 will be found both rapid and dependable in accurate 
 work. 
 
 POINTS OF MERIT 
 
 1. One throw of the hand puts a coil in or out of cir- No. 94-170 
 
 cuit as desired. 
 
 2. The closing of the switch is always accompanied with a wedging rubbing action similar to that 
 
 met with in perfectly fitted plugs. 
 
 3. The resistance of the closed switches is extremely low. 
 
 4. It is not necessary to open the switches when not in use, as the expansion of the rubber upon 
 
 which they are mounted can do no harm. 
 
 5. There arc no loose parts to become lost or mixed. 
 
 6. The values of the coils in or out of circuit can be told at a glance. 
 
 7. The values of the coils are marked upon the switch blade handles, which are always up in plain 
 
 sight when open, so that it is not necessary to get directly over the box to obtain their values. 
 
 8. Portions of the switch device extend through the top of the resistance box and are directly soldered 
 
 to the coil terminals, thereby insuring against unreliable screw contact joints, etc. 
 
 9. The simplicity of construction enables drawn metal of unusually low and uniform resistance to 
 
 be used to advantage. 
 
 10. There is no chance for dirt and filings to lodge and short-circuit the coils. 
 
 11. It is very rapid. 
 
 12. Perfection of contact does not depend upon accurately reamed contact surfaces that may be 
 
 badly injured by use or abuse. 
 
 The coils contained in this box are made and tested by our standard process, and their accuracy is 
 fully equal to that of any box on the market. The coils are each guaranteed accurate to 3^ of one 
 per cent. The total resistance is 111 ohms divided as follows: — 0.1, 0.2, 0.3, 0.4, 1, 2, 3, 4, 10, 20, 
 
 30, 40 ohms.$6.90 
 
358 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 94-180 SUPERIOR ROUND FORM PLUG 
 RESISTANCE BOX. This box is 
 an excellently finished, reasonably 
 priced high-grade instrument. Con¬ 
 tains 13 coils ranging from H to 50 
 ohms, with total resistance of 161 
 ohms. Each instrument is guaran¬ 
 teed accurate to within M to % of 
 one per cent.$7.80 
 
 No. 
 
 No. 94-190 
 
 94-190 
 
 94-196 
 
 TRAVELING PLUG RESISTANCE BOX. This box is provided with extra heavy brass blocks and 
 reinforced ebonite top. Contains 12 coils ranging from 1 to 400 ohms, with total resistance of 
 1110 ohms. The usefulness of the instrument is increased by the addition of two traveling plugs 
 facilitating its use in the comparison of electro-motive force of batteries, and other tests. Guar¬ 
 anteed accuracy of }/i to 3io of one per cent. 
 
 TRAVELING PLUG RESISTANCE BOX, similar to above but constructed for greater range. 
 Contains 16 coils ranging from 1 to 4000 ohms with total resistance of 11,110 ohms. Guaranteed 
 accuracy of K to % of one per cent. 
 
 $26.00 
 
 30.00 
 
 No. 94-200d 
 
 94-200 DECADE RESISTANCE BOX, with sliding contact and connections; best material, highest ac¬ 
 curacy, improved positive contact secured by the laminated contact brushes. 
 
 abed 
 
 No. of Decades ... 3 4 5 6 
 
 Each.$90.00 118.00 140.00 166.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 359 
 
 
 
 MEGOHM BOX 
 
 No. 94-226 
 
 94-225 STANDARD MEGOHM BOX, range 10,000 to 1,000,000 ohms, an arrangement for a megohm re¬ 
 sistance which gives the greatest attainable flexibility and convenience without diminishing the 
 accuracy. 
 
 General Arrangement. Highly insulated binding leads, easily accessible buss bars for changing of 
 the connections. A total resistance of one megohm is obtained by putting 10 coils, each of 100,000 
 ohms, in series. Joining in multiple, a minimum resistance of 10,000 ohms is obtained. Any 
 range between the two in steps of 10,000 ohms is readily obtained. The importance of this ar¬ 
 rangement in accurate comparisons of high resistances cannot be overestimated. 
 
 Insulation. Perfect insulation is a requisite in all high resistance work. As will be noted, the box 
 is made of large proportions, raised ebonite insulated terminals, so designed as to be easily cleaned. 
 
 This feature should not be overlooked in practical work. The box is also provided with a cover, 
 not shown in the illustration. This feature we consider essential in order that the insulating quali¬ 
 ties of the ebonite may be retained. 
 
 Connections. Note the new sliding link running from buss bars to binding posts. This adds greatly 
 to the convenience of connecting, insures against any of the connectors being lost and makes it 
 possible to attain quickly the necessary changes in the least possible room. 
 
 Coils. The coils are wound non-inductively with our special “B” high resistance wire, which we 
 consider for purposes of a megohm box superior to manganin as used in all of our low range boxes. 
 
 Each coil is thoroughly protected from moisture by wax and insulating covering, which also seems to 
 give to each unit ability to withstand mechanical strains. 
 
 Standard Megohm Box.$140.00 
 
 94-230 STANDARD TENTH MEGOHM BOX. We have had frequent calls for a box similar to our No. 
 
 94-226, but utilizing the Wolff method of connecting and other features in its construction, but of 
 lower range. We therefore offer the same box with the same number of coils but of lower unit 
 denomination, making the total resistance of the box J(o megohm. Each coil has a resistance of 
 10,000 ohms; 100,000 ohms may be secured by connection in series, 1,000 ohms by connection if 
 in multiple. 
 
 Standard Tenth Megohm Box.100.00 
 
 Standard Tenth Megohm Coil. See No. 94-126. 
 
360 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 f 
 
 COMBINED BRIDGE AND RESISTANCE 
 
 BOXES 
 
 No. 94-250 
 
 94-250 RATIO BOX. In Wheatstone Bridge work it is essential that easily accessible ratio arms be pro¬ 
 vided. This box has been designed for this particular purpose. It contains six coils as follows: — 
 
 1, 10, 100, 100, 10, and 1 ohms, which will give nine different working ratios. Each coil is guaran¬ 
 teed accurate to of one per cent. It may therefore be seen that with this accuracy the ratio box 
 may be used as a standard resistance of 222 ohms capacity... $10.60 
 
 No. 94-260 
 
 No. 94-270 
 
 94-260 ROUND TYPE PLUG BRIDGE AND RESISTANCE BOX. Contains 13 coils ranging from % ohm 
 
 to 50 ohms, giving a total resistance of 161 ohms, in addition to the bridge coils which have the 
 following resistance of: 100, 10, 1, 1, 10, and 100 ohms. It may therefore be seen that the total 
 range is from .001 ohm to 17,600 ohms. This instrument is recommended as one of great accuracy, 
 giving a wide range. Guaranteed accuracy of % to of one per cent. $18.50 
 
 94-270 IMPROVED COMBINED BRIDGE AND RESISTANCE BOX. Bridge coils are 1, 10, 100, 100, 
 
 10, and 1 ohms. Resistances range from 1 to 400 ohms. Total resistance 1110 ohms. Total range of 
 measurements from .01 ohm to 111,000 ohms. Guaranteed accuracy to % of one per cent. . . 25.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 361 
 
 
 Mr-280 ZIEGLER BRIDGE AND RESISTANCE BOX. This box has been especially designed to meet the 
 constant demands for a reliable and conveniently arranged combined box giving a wide range, yet 
 one which can be furnished at a price within the appropriation of most schools. 
 
 The first row of the resistance box contains nine j^-ohm coils; the second 10 1-ohm coils; the third 
 ten 10-ohm coils. The total range of measurement, therefore, is from .001 ohm to 11,090 ohms. 
 Separate keys properly connected for battery and galvanometer are mounted as illustrated. Coil 
 accuracy guaranteed to 3lo of one per cent. 
 
 No. 94^285 
 
 94-286 ZIEGLER IMPROVED COMBINED BRIDGE AND RESISTANCE BOX. This box is in general 
 similar to No. 94-280. It has, however, a larger capacity and the blocks are extra heavy. The 
 bridge coils are 1000, 100, 10, 1 ,100, 1000 ohms. The resistance box coils range from % ohm up to 
 4,000 ohms. Total resistance 11,111 ohms. Range .0001 ohm to 11,110,000 ohms. Coil accuracy 
 guaranteed to % of one per cent. 
 
 $34.76 
 
 $60.00 
 
362 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 PRECISION RESISTANCE BOX AND BRIDGE 
 
 No. 94-300 
 
 94-300 STANDARD PRECISION RESISTANCE BOX, designed to give the highest degree of precision 
 of which the plug contact form of Wheatstone Bridge is capable; constructed to furnish the best 
 that modern research has produced. 
 
 Range. The one-ohm Ratio Coil can be thrown into either arm desired by means of one of the trav¬ 
 eling plugs supplied with the box. The range of the bridge is, therefore, from .001 to 11,110,000 
 
 ohms. 
 
 Resistance Arms — 
 
 1 
 
 10 
 
 100 
 
 1000 ohms 
 
 2 
 
 20 
 
 200 
 
 2000 “ 
 
 3 
 
 30 
 
 300 
 
 3000 “ 
 
 4 
 
 40 
 
 400 
 
 4000 “ 
 
 Bridge Arms — 
 
 1 
 
 10 
 
 100 
 
 1000 ohms 
 
 Total . . 
 
 10 
 
 100 
 
 1000 “ 
 
 Accuracy. All the features tending to give permanency of calibration as well as accuracy have 
 been studied in every detail. The coils in the ratio arms are adjusted to % of one per cent.; those 
 in the ratio arms to V 20 of one per cent. With a proper handling of this box, results may be secured 
 limited only by the inherent capabilities of the plug contact form. 
 
 For details of construction, see special circular which will be mailed upon request. 
 
 SPECIAL FEATURES 
 
 Coils of manganin wire, aged by our special process, wound on hollow brass bobbins, securing per¬ 
 fect insulation and greater carrying capacity, individually tested, and attached by special arms, 
 permitting new coils to be furnished and attached by user. 
 
 The Insulation is of the very highest quality, interior of box practically moisture proof to insure 
 permanency of insulation. 
 
 Connecting Blocks of unusually large size, of ample clearance and special provision for cleaning. 
 
 Traveling Plugs, — two furnished with each box. 
 
 Coil Plugs, rubber handles, diamond form; tapers designed for constant use without contact error. 
 
 Grid Support, on interior of box to prevent springing of top by excess plug pressure. 
 
 Cover. Dust-tight, provided with each box to insure life of rubber top. 
 
 Standard Precision Resistance Box, as above described. 
 
 $110.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 363 
 
 Patents Pending 
 
 UNIVERSAL LECTURE TABLE RHEOSTAT 
 AND RESISTANCE FRAME 
 
 A Group Cut Illustrating the Following Numbers 
 
 In designing the above apparatus we had two primary objects in mind; first, to make available an easily un¬ 
 derstood, readily controllable rheostat, which could not get out of order, designed for use on 110 volt current; second, 
 a satisfactory method of teaching the effect of different methods of lamp connections in the electrical circuit. 
 
 Should the instructor not care to have the light which comes from the lamps when used as resistances, dark units 
 as illustrated are now available, giving currents of from 0.6 to 5 amperes each, so that combining these in multiple 
 and in series, a wide range of current may be obtained graded in small steps, as the instrument itself will carry from 
 50 to 75 amperes with perfect safety. 
 
 In outfit No. 94-350 lamps only are furnished and the outfit may well be called a Universal Lamp Resistance 
 Board, giving ampere strengths from 0.2 to 6.00 amperes. 
 
 A wide range of ampere values may be secured by using the resistance units in series, multiple or series-multiple 
 arrangement. Outfits Nos. 94-363 to 94-358 are supplied with resistance units only. These outfits are recommended 
 for all laboratory resistance work. 
 
 The fuse plugs have negligible resistances and are used for facilitating connections. 
 
 The value of the apparatus as a practical rheostat of wide ampere ranges is greatly enhanced by its value as an 
 instrument to simplify and demonstrate Ohm’s Law, Three Wire System of Connection, Voltage Drop, Efficiency 
 of Various Types of Lamps and other allied subjects. 
 
 94-350 UNIVERSAL RESISTANCE FRAME, complete with Sockets and Lamps giving ampere strengths 
 
 from 0.2 to 6 amperes. $11.00 
 
 94-363 -, complete with Resistance Units giving ampere strengths from 0.2 to 7.2 amperes by 0.6 ampere 
 
 steps. 18.50 
 
 94-366 -, complete with Resistance Units giving ampere strengths from 0.2 to 18 amperes by 0.6 ampere 
 
 steps. 26.50 
 
 94-368 -, complete with Resistance Units giving ampere strengths from 0.2 to 40.5 amperes by 0.6 ampere 
 
 steps. 42.26 
 
 94-360 MOUNTED D. P. D. T. KNIFE SWITCH, — capacity 50 amperes at 250 volts. Slate base mounted 
 
 on heavy slate sub-base. 2.75 
 
 94-366 RIGID ARM PORCELAIN MOUNTED SOCKET for holding lamps, bridge and fuse plugs. Each .76 
 
 Six 4.00 
 
 94-375 HARCOURT RESISTANCE UNIT, — 6 inches long, 0.6 ampere capacity. 1.60 
 
 94-376 -, 8 inches long, 1.2 amperes capacity. 2.00 
 
 94-377 -, 10 inches long, 2.5 amperes capacity. 2.76 
 
 94-378 -, 12 inches long, 5 amperes capacity. 3.26 
 
 94-380 FUSE PLUG, EDISON BASE, carrying capacity 3 amperes. 10 
 
 94-386 SPECIAL BRIDGE PLUG.60 
 
 Note. — We should be pleased to send a special descriptive circular showing by diagrams many 
 profitable experiments. 
 
 94-390 LAMP BOARD, with 32 C. P. LAMPS, after Fuller and Brownlee (Experiment 77). 9.80 
 
364 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 RHEOSTATS 
 
 This type of Rheostat comprises a layer of high resistance wire wound on an insulating fire-proof slab mounted 
 on a polished wooden base with asbestos shield. They^are fitted with suitable slider and binding posts for connecting 
 in the circuit. Their open construction commendsjthem for general laboratory work. 
 
 In selecting a Rheostat make sure that the ampere capacity is ample to meet the requirements. 
 
 BATTERY RHEOSTATS. The following capacities of the simple type instrument illustrated under No. 94-405 
 will be found well suited to battery or other low voltage circuits, or for use in connection with apparatus that consumes 
 a large proportion of the energy of the power circuit. 
 
 Number 
 
 Voltage 
 
 Maximum 
 
 carrying 
 
 Capacity 
 
 Resistance 
 
 Ohms 
 
 Size 
 
 Inches 
 
 Weight 
 
 Ounces 
 
 Price, Duty Free 
 
 94-400 A 
 
 12 
 
 Amperes 
 
 7 
 
 1.7 
 
 4% X 1%6 X 19 /82 
 
 10 
 
 
 94-400 B 
 
 15 
 
 10 
 
 1.5 
 
 6 B Ae X l%e X le /s2 
 
 14 
 
 
 94-400 C 
 
 24 
 
 3 
 
 8 
 
 4% X 1%6 X 19 /82 
 
 10 
 
 :::: | 
 
 94-400D 
 
 25 
 
 10 
 
 2.5 
 
 8 X 2 X Vi 
 
 42 
 
 SIMPLE RHEOSTATS, 
 
 especially adapted to power circuits. 
 
 
 
 Number 
 
 Voltage 
 
 Maximum 
 
 carrying 
 
 Capacity 
 
 Resistance 
 
 Ohms 
 
 Size 
 
 Inches 
 
 Weight 
 
 Ounces 
 
 Price, Duty Free 
 
 94-406 A 
 
 800 
 
 Amperes 
 
 .3 
 
 2400 
 
 18 X2^X 1 Vs 
 
 137 
 
 94-406B 
 
 112 
 
 .3 
 
 250 
 
 4 % X l 3 /l6 X 19 /82 
 
 10 
 
 .... 
 
 94—406 C 
 
 110 
 
 1 
 
 110 
 
 6 r /lfl X 1%6 X 1 %2 
 
 14 
 
 .... 
 
 94-406 D 
 
 110 
 
 5 
 
 22 
 
 16 X 2 XI 
 
 118 
 
 .... 
 
 DOUBLE 
 
 RHEOSTATS, 
 
 similar to the previous type of instrument, but comprising two wire-carrying mounted 
 
 slabs on a common base. This construction enables a 
 
 much larger capacity to be attained in a given space. 
 
 Number 
 
 Voltage 
 
 Maximum 
 
 carrying 
 
 Capacity 
 
 Resistance 
 
 Ohms 
 
 Size 
 
 Inches 
 
 Weight 
 
 Ounces 
 
 Price, Duty Free 
 
 94-410 A 
 
 100 
 
 Amperes 
 
 10 
 
 10 
 
 12 x 2 y 8 x 1 y 8 
 
 150 
 
 
 94-410 B 
 
 110 
 
 20 
 
 5.5 
 
 18 x 2Vs X 1 V s 
 
 218 
 
 .... 
 
 94-410 C 
 
 140 
 
 7 
 
 20 
 
 12 X 2% X 1% 
 
 150 
 
 .... 
 
 94-410 D 
 
 330 
 
 3 
 
 110 
 
 12 X 2 z /% X lVs 
 
 150 
 
 
 94-410 E 
 
 700 
 
 1 
 
 700 
 
 12 X 2% X 1 Va 
 
 150 
 
 
 94-416 SIX-INCH REGULATING RHEOSTAT. Designed primarily as 
 a fan motor speed regulator, this Rheostat has been modified 
 for use as an adjustable resistance. Maximum watt capacity 
 125. Seven contacts, one “off” point and six running positions 
 of 150 ohms per step. Maximum amperes 10. 
 
 Mounted on marbleized slate panel as illustrated. $3.50 
 
 No. 94-416 
 

 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 365 
 
 I! 
 
 K RESISTANCE UNITS 
 
 No. 94-420 
 
 No. 94-425 
 
 No. 94-430 
 
 No. 94-436 
 
 RESISTANCE UNITS, approximate dimensions % X 4 inches. 
 
 50 Watts Continuous Duty 
 
 Number 
 
 Maximum 
 
 Amperes 
 
 Resistance 
 
 Ohms 
 
 Duty Free, Price 
 
 Number 
 
 94-420 a 
 
 0.45 
 
 250 
 
 
 94-420 h 
 
 - b 
 
 0.6 
 
 125 
 
 
 - i 
 
 - c 
 
 0.8 
 
 75 
 
 
 j 
 
 - d 
 
 1 
 
 45 
 
 
 - k 
 
 - e 
 
 1.25 
 
 32 
 
 
 - 1 
 
 - f 
 
 1.7 
 
 16 
 
 
 - m 
 
 - g 
 
 2.3 
 
 9 
 
 
 - n 
 
 ; RESISTANCE UNITS, approximate dimensions l}/% X 4 % inches. 
 
 86 Watts Continuous Duty 
 
 
 Maximum 
 
 Resistance 
 
 
 
 Number 
 
 Amperes 
 
 Ohms 
 
 Duty Free, Price 
 
 Number 
 
 94-425 a 
 
 0.45 
 
 420 
 
 
 94-425 h 
 
 - b 
 
 0.6 
 
 220 
 
 
 - i 
 
 - c 
 
 0.8 
 
 140 
 
 
 - j 
 
 - d 
 
 1.0 
 
 85 
 
 
 - k 
 
 - e 
 
 1.2 
 
 60 
 
 
 - 1 
 
 - f 
 
 1.6 
 
 32 
 
 
 - m 
 
 - g 
 
 2.2 
 
 18 
 
 
 - n 
 
 RESISTANCE UNITS, approximate dimensions l 5 Ao X 6}4 inches. 
 
 150 Watts Continuous Duty 
 
 Number 
 
 Maximum 
 
 Amperes 
 
 Resistance 
 
 Ohms 
 
 Duty Free, Price 
 
 Number 
 
 94-430 a 
 
 0.45 
 
 800 
 
 94-430 h 
 
 - b 
 
 0.6 
 
 450 
 
 
 - i 
 
 - c 
 
 0.8 
 
 240 
 
 
 — j 
 
 - d 
 
 1 
 
 150 
 
 
 - k 
 
 - e 
 
 1.2 
 
 95 
 
 
 1 
 
 - f 
 
 1.6 
 
 54 
 
 
 - m 
 
 - g 
 
 2.2 
 
 32 
 
 
 - n 
 
 RESISTANCE UNITS, approximate dimensions 1^ X 7 18 /ia inches. 
 
 200 Watts Continuous Duty 
 
 Number 
 
 Maximum 
 
 Amperes 
 
 Resistance 
 
 Ohms 
 
 Duty Free, Price 
 
 N umber 
 
 94-436 a 
 
 0.45 
 
 1100 
 
 
 
 94-435 h 
 
 - b 
 
 0.6 
 
 560 
 
 
 
 - i 
 
 - c 
 
 0.8 
 
 320 
 
 
 
 j 
 
 - d 
 
 1 
 
 200 
 
 
 
 k 
 
 -- e 
 
 1.2 
 
 140 
 
 
 
 1 
 
 — f 
 
 1.6 
 
 72 
 
 
 
 - m 
 
 — g 
 
 2.1 
 
 45 
 
 
 
 - n 
 
 Maximum 
 
 Resistance 
 
 Amperes 
 
 Ohms 
 
 3.3 
 
 4.5 
 
 3.6 
 
 3.9 
 
 5 
 
 2 
 
 6.4 
 
 1.2 
 
 9 
 
 0.6 
 
 12 
 
 0.35 
 
 14 
 
 0.25 
 
 Maximum 
 
 Resistance 
 
 Amperes 
 
 Ohms 
 
 2.8 
 
 11 
 
 3.2 
 
 8 
 
 5 
 
 3.5 
 
 6.2 
 
 2.2 
 
 8.5 
 
 1.1 
 
 11.5 
 
 0.65 
 
 14.4 
 
 0.4 
 
 Maximum 
 
 Resistance 
 
 Amperes 
 
 Ohms 
 
 2.8 
 
 20 
 
 3.2 
 
 13 
 
 5 
 
 6 
 
 6.5 
 
 3.5 
 
 8.5 
 
 2 
 
 12 
 
 1 
 
 14 
 
 0.8 
 
 Maximum 
 
 Resistance 
 
 Amperes 
 
 Onms 
 
 2.8 
 
 27 
 
 3.2 
 
 18 
 
 4.7 
 
 9 
 
 6.3 
 
 5 
 
 8.5 
 
 2.8 
 
 11.5 
 
 1.5 
 
 13 
 
 1.2 
 
 Duty Free. Price 
 
 Duty Free, Price 
 
 Duty Free, Price 
 
 Duty Free, Price 
 
 Nos. 94-420 to 94-435 not furnished from stock. Imported Free of Duty only when ten or more are ordered. 
 
 94-440 GRAPHITE HIGH RESISTANCE. This resistance will 
 be found of great convenience in experimental and test¬ 
 ing work. Its low price and excellent appearance recom¬ 
 mend it for many purposes. Resistance is mounted on 
 polished wood base provided with binding posts for con¬ 
 nections. Capacity 1,000,000 ohms; size of cylinder 4J4 
 X 1% inches. 
 
 94-442 
 
 •, same as above, but 100,000 ohms . 
 
 No. 94—442 
 
366 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 WHEATSTONE BRIDGES 
 
 DEMONSTRATION WHEATSTONE BRIDGES 
 
 Too little attention has been given in schools to a thorough understanding of that basic principle, Fall of Po¬ 
 tential, fundamental to Wheatstone Bridge work. A student’s incomplete understanding of Fall of Potential makes 
 it difficult for him to understand what he is striving to obtain when he uses a Wheatstone’s Bridge. This incom¬ 
 plete understanding is due, perhaps, to the word of mouth descriptions and the lack of adequate illustrative demon¬ 
 strative apparatus. To picture for him the actual Fall of Potential, we heartily recommend the following apparatus. 
 The analogy between hydraulic pressure and electromotive force is often resorted to by teachers, yet the analogy 
 has never been worked out instrumentally except in the following apparatus. 
 
 No. 94-455 
 
 94-455 HYDRODYNAMIC WHEATSTONE BRIDGE for a study of the principles involved by measure¬ 
 ments of resistances by the Wheatstone’s Bridge method, using Fall of Hydraulic Pressure as an 
 analogy to electromotive force. On a polished wooden base board is mounted a system of tubes con¬ 
 nected to form a Wheatstone’s diagram. In the “arms” are reducing valves analogous to resis¬ 
 tances. Pressures in the various arms are indicated by the manometers. In the “bridge” is a 
 pressure indicator analogous to the galvanometer. 
 
 By connecting to one of the nipples noted in the illustration and allowing a flow of water through 
 the apparatus, the fall of pressure through the different arms may readily be noted. By regulating 
 the reducing valves in these arms, a balance may be secured when no indications of pressure can be 
 noted in the “bridge.” The pressures in the arms will then be noted in the manometer. 
 
 The didactic value of this apparatus will readily be noted. The construction is substantial, results 
 possible are positive, parts are carefully fitted and handsomely finished. 
 
 Complete as illustrated. $34.50 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 367 
 
 No. 94-460 
 
 94-460 DEMONSTRATION WHEATSTONE BRIDGE for a study of Fall of Potential and demonstration 
 of the principle of a Wheatstone Bridge. 
 
 This apparatus consists of a vertically-mounted board to which is attached the Wheatstone Diagram. 
 In the “arms” are connected incandescent lamps. In the “bridge” an indicating galvanometer. 
 Binding posts are provided for connecting resistances in shunt with the lamp. By varying the re¬ 
 sistances a point of same potential may be secured. 
 
 As a companion instrument to No. 94-466 Hydrodynamic Wheatstone Bridge, demonstrations of 
 Fall of Potential as utilized in the Wheatstone Bridge are simply and clearly made. 
 
 Complete as illustrated with incandescent lamps. 
 
 No. 94-470 
 
 94-470 WORKING DEMONSTRATION WHEATSTONE BRIDGE, DIAMOND FORM. The merit of a 
 Wheatstone Bridge that may be used equally as well in demonstration as in laboratory practise 
 will at once be recognized. 
 
 The instrument illustrated is constructed so that the arms are arranged as the Wheatstone Diagram. 
 In addition in each of the “ratio arms” are coils of 1, 10, and 100 ohms. The “balance arms” are 
 provided with gaps each with non-detachable binding posts, one pair for the known and the other 
 pair for the unknown resistance. Non-detachable binding posts and key are provided for battery 
 and galvanometer circuits. All parts of this instrument are well made. They are carefully fitted 
 and the instrument is guaranteed to give good satisfaction. 
 
 $26.00 
 
 $6.80 
 
368 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 SLIDE WIRE WHEATSTONE BRIDGES 
 
 No. 94-480 
 
 94-480 WHEATSTONE’S STANDARD METER SLIDE WIRE BRIDGE. In this design, especially 
 
 adapted for students’ laboratory experiments, we furnish an excellent bridge at a reasonable price. 
 Heavy copper leads, non-detachable binding posts, Inanganin wire, improved positive sliding con¬ 
 
 tact key, mounted on polished hardwood base..$ 3.35 
 
 94-482 WHEATSTONE’S BRIDGE, after Millikan and Gale’s “A Laboratory Course in Physics” (Ex¬ 
 periments 32 and 33). 2.00 
 
 No. 94-490 
 
 94-4901WHEATSTONE’S HALF METER BRIDGE, HARCOURT FORM. This bridge is in construction 
 
 similar to No. 94-480, and in quality fully its equal. 
 
 To economize space as well as facilitate its use, it is made in half meter length, but so designed as to 
 carry the full meter length of wire. In accuracy, therefore, it compares favorably with the full- 
 length bridge.•.$ 2.80 
 
 No. 94-495 
 
 94-495 HALF METER WHEATSTONE-CAREY-FOSTER BRIDGE. Extra heavy brass strips, non- 
 
 detachable binding posts, improved sliding knife-edge contact key, improved scale mounted on 
 highly polished base.$9.00 
 
 No. 94-500 
 
 94-500 COWEN COMBINATION BRIDGE. This Bridge was first constructed for the Boston High Schools, 
 but is now generally recognized as a Wheatstone Bridge having unusually valuable educational 
 features. 
 
 It is provided with an especially designed resistance box set in the base, and furnished as a part of 
 the instrument. A horizontal D’Arsonval Galvanometer No. 93-196 is also mounted on the base. 
 Thus it may be seen that a complete measuring unit combining bridge, resistance box, and galva¬ 
 nometer is furnished as a unit system. The necessity, therefore, of all outside connections except 
 those from the battery and unknown resistance is entirely avoided. The permanent connections 
 to the resistance box and the galvanometer are made on top of the bridge in such form that the 
 
 direction of the current can be most easily traced. 
 
 Combination Bridge, Box, and Galvanometer.$22.60 
 
 94-602 COWEN COMBINATION BRIDGE and Box without Galvanometer.16.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 369 
 
 No. 94^625 
 
 94-525 THE UNIVERSITY SLIDE WIRE BRIDGE, adapted for measuring resistances with low E. M. F. 
 
 where the plug form of Resistance Box would be useless. Provided with both mercury cup and 
 binding post contact, the Lattimer-Clark Commutator, tension spiral for bridge wire, contact with 
 rack and pinion and fine adjustment, locking device for holding the contact at any desired point. 
 
 Connecting bars of large cross section, tested for uniform density. Mercury cups of ]/i inch diam¬ 
 eter with bottom finished to give perfect contact. 
 
 Binding posts of large size, provided for each gap in addition to the mercury cup. 
 
 Four gaps are provided for ratio coils and extension coils, which are also available for inserting coils 
 in the conventional Wheatstone Bridge arrangement. The commutator may be removed, leav¬ 
 ing available two extra gaps which may be required in special work. 
 
 Spring Tension insures uniform tension on the resistance wire. Wire supplied for this work will 
 be manganin unless otherwise specified. 
 
 Slider. Combination Rack and Pinion and fine adjustment with push button locking device, makes 
 a most satisfactory method of obtaining a sliding contact. The contact-is entirely enclosed to 
 overcome any possible thermo-electric disturbance due to the presence of the hand of the operator. 
 
 The scale is engine-divided with vernier reading to tenths of a millimeter. 
 
 Base is of three-ply mahogany to prevent warping, oil finished. 
 
 An instrument of the highest accuracy and convenience, substantially and beautifully finished . . $75.00 
 
 No. S4-6S6 
 
 94-535 THE UNIVERSAL CAREY-FOSTER BRIDGE. The Carey-Foster method is recognized as the 
 one suited to the most rapid and accurate work in electrical measurements. It is, in fact, the 
 method which we have found in our own testing department to give not only the most reliable 
 results, but one which permits the largest number of measurements per unit of time. 
 
 The Bridge above illustrated is substantially the one used in our own electrical measurements, and is 
 therefore adapted to a very wide range. The low resistance swinging arms, the mercury contacts, 
 the sliding bridge, the essential features of which are made substantially as in instrument No. 94- 
 526, the micrometer movement on the contact, the heavy insulated low resistance copper leads, the 
 Carey-Foster reversing key, combine to give this instrument a place in high-grade electrical meas¬ 
 urements not filled by any other form. , . . . , , 
 
 The accuracy with which this Bridge is made will perhaps be appreciated when it is known that even 
 the J^-inch copper lead wires and the heavy copper buss bars are carefully tested and adjusted 
 
 • before being set up in the instrument. . . . . . . . . 
 
 The bases are made of three-ply mahogany finished in oil; the finish on the entire instrument is in 
 keeping with that of a thoroughly high-grade, accurate, scientific instrument. 
 
370 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 TRANSFORMING AND INTERRUPTIVE 
 
 APPARATUS 
 
 95-10 FARADAY’S RING AND DEMONSTRATION TRANSFORMER. This simple apparatus is de¬ 
 signed for study of the principles and laws involved in self and secondary induction; also the appli¬ 
 cations of these laws to the step-up and step-down transformer. 
 
 It consists of a closed magnetic circuit within a coil of wire which is tapped and brought to binding 
 posts, dividing itself into four coils of an equal number of turns. The ring and binding posts are 
 mounted on a neatly finished, polished base, making a compact, well worked out instrument in which 
 the ratios of transformation on a unit of voltage are as follows: — 
 
 1:1; 1:2; 1:3; 1:4; 2:1; 2:3; 3:2; 3:1; 4:1.. 
 
 95-16 INDUCTION COIL, after Millikan, Gale & Bishop, Exp. 36. 
 
 This is a simple coil of wire wound on a brass spool.Each 
 
 No. 95-10 
 
 
 
 
 
 $3.25 
 
 
 92-110 GILLEY INDUCTION COILS, Figs. 1 and 6, mounted with binding posts. These coils are described 
 
 on page 330 and are recommended for general experiments in Induction .... Per set of two $1.40 
 
 92-115 SOFT IRON U-SHAPED CORE, Figure 3, for study of bi-polar electro magnets.Each .20 
 
 92-117 SOFT IRON ARMATURE, Figure 2, for use with the above core in the study of electro-magnets. 
 
 Each .10 
 
 92-120 SOFT IRON CORE, Figure 6, single, for the study of electro-magnets .Each .10 
 
 92-122 PAIR OF HALF-ROUND CORE PIECES, Figure 4, for mapping the lines of force in an electro¬ 
 magnet.Per pair .16 
 
 92-125 PAIR OF SLOTTED CARDBOARDS, Figure 7, for mapping lines of force .Per pair .08 
 
 92-130 COMPLETE GILLEY INDUCTION OUTFIT, supplied in box with direction sheets. 2.00 
 
 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 371 
 
 No. 95-30 
 
 THE IMPROVED EDUCATIONAL 
 DISSECTIBLE TRANSFORMER 
 
 ANY VOLTAGE UP TO 115 
 
 Patent Pending 
 
 In the designing of this Transformer we have had in mind an instrument resembling as closely as possible 
 the commercial instrument. In order to make it of the greatest practical use in the laboratory and at the 
 same time serve to teach all of the fundamental forms of Transformers, the dissectible feature is, of course, 
 essential, since a school can hardly afford to buy as many different Transformers as there are types in com¬ 
 mercial use. 
 
 The instrument which we have produced will be found of the greatest use in demonstrating the principles 
 and laws involved in self and secondary induction, also the application in commercial work of the step-up and 
 step-down transformer. 
 
 . CONSTRUCTION. In form and in methods of construction, the regular commercial instrument as used 
 in lighting and power systems has been followed: — laminated core, taped coil, every feature designed to give 
 the greatest efficiency and greatest durability. 
 
 The dissectible feature, which enables the student to take the instrument apart, examine and test each 
 part separately, i$ obtained as follows: — 
 
 The core is of punchings made from the best electrical sheet iron, punchings arranged in groups of ten, 
 each group being held together by riveting, for convenience in assembling. Primary coils are taped^and sup¬ 
 plied with convenient leads. Secondary coils are taped and supplied with leads. These features enable the 
 instrument to be assembled either as a Faraday Ring, Auto Transformer of the shell type, an Auto Trans¬ 
 former of the block or iron-clad type, a Primary and Secondary Transformer of the shell type, a Primary and 
 Secondary Transformer of the block type. 
 
 RANGES IN VOLTAGE. The ratios of the primary to the secondary coils are such that a great variety of 
 transformations may be had. If the primary circuit is 110 volts, the voltages drawn from the secondary in 
 various combinations (fully illustrated by diagrams furnished with each instrument) are 7, 15, 30, 60, 220, 235, 
 and 255 volts. Other ranges may be obtained by using a different voltage in the primary line, the ratios of 
 transformation in each case being as above indicated. 
 
 For convenience in use the instrument is mounted on a mahogany base with six double binding posts as 
 illustrated. 
 
 The instrument serves to teach effectively: — 
 
 1. The influence of iron in the core. 6. Back electro-motive force, and many other funda- 
 
 2. The magnetic hysteresis. mental principles in alternating current practice 
 
 3. Eddy Currents. not possible with any instrument heretofore offered. 
 
 4. Magnetic density. Full directions with descriptive diagrams will be 
 
 5. Self-Induction. supplied with each transformer. 
 
 Complete with full equipment for teaching all of the points above mentioned.$11225 
 
 Note: We should be pleased to send a special descriptive circular showing by diagrams many profitable 
 experiments. 
 
372 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 PRIMARY AND SECONDARY COILS 
 
 96-38 STUDENTS’ PRIMARY AND SECONDARY COIL. Height 7inches. Consists of two hardwood 
 spools, the outer one provided with a base, and the inner one removable. The inner spool is 
 wound with a few turns of coarse wire and is the “primary,” the outer with many turns of fine 
 wire and is the “secondary.” 
 
 Complete with soft iron core. $3.30 
 
 t 
 
 96-40 LARGE PRIMARY AND 
 SECONDARY COLL, for 
 the study of current in¬ 
 duction. This form, with 
 its primary 6 inches 
 by inches and its 
 
 secondary 2 ]A inches by 
 5 inches, must not be 
 confused with the 
 smaller types on the 
 market. We have de¬ 
 sired in this instrument 
 to offer the teacher an 
 instrument capable o f 
 efficient positive results. 
 This can be secured in a 
 satisfactory manner only 
 by using a large number 
 of windings on the sec¬ 
 ondary circuit.' The 
 wire in each circuit is 
 mounted o n separate 
 hardwood spools, and the 
 secondary is mounted on 
 a neatly polished hard¬ 
 wood base. To insure 
 greater rigidity we have 
 added two brass rods 
 connecting the secondary 
 to the base (see illustra- 
 , tion below). The wire 
 used is silk covered, and 
 
 binding posts are neatly polished and lacquered. The soft iron core supplied with the instrument 
 consists of a bundle of soft iron wires tightly moulded by bands to form a nearly solid rod. 
 Primary and Secondary Coil complete with iron core.. 
 
 No. 95-40 
 
 $7.50 
 
 96-45 LARGE PRIMARY AND SEC¬ 
 ONDARY COIL, similar to 
 above, but provided with vi¬ 
 brator mounted on same base 
 with coil. This vibrator is of 
 the simple electromagnetic type 
 and gives positive interruptions 
 to the current, illustrating the 
 simple induction coil. This in¬ 
 strument is of substantial con¬ 
 struction, and all parts are finely 
 polished and finished. 
 
 Complete as illustrated.$10.50 
 
 96-50 MAKE AND BREAK INTER¬ 
 RUPTER. It is frequently de¬ 
 sired to attach a Make and 
 Break Interrupter to an un¬ 
 mounted primary and second¬ 
 ary coil. The type which we 
 furnish is the same as illus¬ 
 trated on the base of the Pri¬ 
 mary and Secondary Coil No. 
 
 96-46. 
 
 The parts are mounted on a neat 
 wooden base ready for attach¬ 
 ment to the terminals of the 
 secondary. 3.00 
 
 INTERRUPTING WHEEL. See No. 90-460. 
 
 No. 96-45 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 373 
 
 INDUCTION COILS 
 
 Nos. 95-75 to 96-80 No. 95-96 
 
 96-76 DEMONSTRATION INDUCTION COIL. This type of coil is of value in the study of the office of 
 the primary in induction coil construction. Both primary and secondary are mounted on a pol¬ 
 ished mahogany box, but the mounting is designed so that the secondary maybe adjusted to enclose 
 varying amounts of the primary. 
 
 This instrument is handsomely finished, all brass parts polished and lacquered, and will give a 
 
 X-inch spark.$6.00 
 
 96-80 -, same as above, but calculated to give a >^-inch spark. 8.26 
 
 96-95 DEMONSTRATION DISSECTIBLE RUHMKORFF COIL. This coil is constructed so that all es¬ 
 sential details of a commercial Ruhmkorff coil may be shown as units and in their relations to the 
 rest of the instrument. Thus the condenser is mounted in a drawer slide. Connections with the 
 secondary are secured through binding posts. The primary may be dissected and taken from the 
 instrument. The make and break and core are of special design calculated to teach the principle, 
 and all connections are fully in the open and may readily be noted at a glance. 37.50 
 
 RUHMKORFF COILS 
 
 Nos. 96-126 to 96-140 
 
 Our small types of Ruhmkorff Coils up to 1-inch spark are construced for us by a prominent European manu¬ 
 facturer. They are of standard quality designed for elementary work. 
 
 Ruhmkorff Coils with a capacity of two inches (see next page) are constructed by us in our own factory. We 
 are, therefore, enabled to furnish a product superior in quality to that ordinarily furnished of European make. We 
 secure a greater efficiency and are enabled to place in the hands of the buyer a more finished instrument. The parts 
 of these coils are of the best proportions to give the maximum efficiency and preserve symmetry. Only the best 
 quality of material is used in construction, and all parts are handsomely finished. 
 
 We are enabled to guarantee our coils up to their full capacity and warrant them against faulty construction. 
 
 EUROPEAN COILS 
 
 96-125 RUHMKORFF COIL, capacity %-inch spark. $4.26 
 
 96-130 -, capacityX-inch spark. £.90 
 
 96-135 -, capacity j^-inch spark. 
 
 96-140 -, capacity 1-inch spark . 21.00 
 
374 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 THE “NEW LINE” INDUCTION COILS 
 
 
 Nos. 95-175 to 95-210 
 
 Because of the great improvements in Induction Coil design during the past three years, it is with especial pleas¬ 
 ure that we call your attention to our series, ranging from 2 to 18-inch discharge. 
 
 These coils are construced according to the latest and best high-tension data. The rigorous demands of 
 X-Ray and Wireless work have rendered valueless coils constructed according to formulae previously used. 
 
 The entire construction of the coil is based on the requirements of heavy discharge rather than length of spark. 
 This is obtained by the use of exceptionally heavy primaries with, of course, the best possible insulation. Every 
 feature has been worked out with the greatest care looking towards the building of a coil which cannot be broken 
 down and which will give the desired results on comparatively low battery power, and in coils designed for use on 
 110-volt current which wall take the rated voltage and amperage without danger. 
 
 TESTING. Each coil is subjected to a rigorous test with an overload of 100% to insure against breaking down 
 with ordinary usage. , 
 
 96-176 £ NEW LINE INDUCTION COIL, guaranteed discharge 2 inches 
 
 
 95- 180 
 
 96- 185 
 
 95- 190 
 
 96- 196 
 96-200 
 96-205 
 96-210 
 
 same as above, guaranteed discharge 4 inches 
 guaranteed discharge 6 inches . 
 guaranteed discharge 8 inches . 
 guaranteed discharge 10 inches 
 guaranteed discharge 12 inches 
 guaranteed discharge 16 inches 
 guaranteed discharge 18 inches 
 
 $37.60 
 
 66.00 
 
 76.00 
 
 100.00 
 
 120.00 
 
 146.00 
 
 200.00 
 
 240.00 
 
 No. 96-230 
 
 LIQUID INTERRUPTING INDUCTION COIL, for a 110-volt current. In connection with our “New Line” 
 Induction Coils above listed we have worked out an instrument for use on the 110-volt current, especially designed 
 to withstand the entire current from Liquid Interrupter No. 96-262. It gives a heavy discharge, admirably suited 
 for Wireless, X-Ray, and general induction coil experiments. It may be used with safety, as these coils are de¬ 
 signed not to burn out on a 110-volt current. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 375 
 
 The 7-inch discharge which these coils are designed to give is such as is found most satisfactoryjfor general all¬ 
 
 round work in X-Ray and Wireless experiments. 
 
 96-225 LIQUID INTERRUPTING INDUCTION COIL, complete with Liquid Interrupter. $73.80 
 
 96-230 -, same as above, without Interrupter . 60.00 
 
 We are listing both coil and interrupter together for the reason that it is somewhat easier to adjust the inter¬ 
 rupter to the coil if both are ordered at one time. This adjustment, however, is not absolutely necessary as a care¬ 
 ful record is made of each coil and the adjustment can be made at a later date. 
 
 THE ELECTROLYTIC INTERRUPTER 
 
 Nos. 96-250 to 96-252 
 
 Patents Pending 
 
 The difficulty with Electrolytic Breaks heretofore used has arisen largely because of the failure of the manu¬ 
 facturers to adjust the size of the gas tube to the line voltage and the amperage which is to be drawn from the break. 
 This difficulty has been fully recognized and satisfactorily met. 
 
 We can supply our new design of Electrolytic Interrupter for any voltage and amperage desired. The two 
 forms selected as being most generally serviceable are listed below and are rated according to the Induction Coil 
 capacity with which they are to be used. Please note that they will operate on a direct or alternating current. 
 
 CONSTRUCTION. Our Interrupter contains a porcelain cylinder in which the size of the opening is carefully 
 adjusted to the amperage of the current to be drawn. In order to avoid breakage this cylinder is carried on a lead 
 shelf, being part of the inner lead cylinder. 
 
 The terminals, as will be noted in the cut, are carried well out on the ends of the long lead bars, bent over and 
 beyond the top of the instrument so as to reduce the objectionable corrosion that is unavoidable when the terminals 
 are above the jar and subjected to the action of the acid fumes thrown off when the Interrupter is in operation. 
 
 METHOD OF COOLING. A substantial iron receptacle is provided which acts as a radiator and serves to 
 keep the liquid from overheating. This receptacle also serves to protect the table, floor, or other apparatus in case 
 
 of accidental breaking of the acid jar. 
 
 96-260 ELECTROLYTIC INTERRUPTER, type A, for coils from 4 to 6-inch spark. $13.80 
 
 96-262 ELECTROLYTIC INTERRUPTER, type B, for coils form 7 to 12-inch spark . 13.80 
 
376 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ELECTRO-DYNAMIC APPARATUS FOR 
 ALTERNATING CURRENTS 
 
 
 
 95-260 ELECTRO-DYNAMIC APPARATUS. This apparatus has been designed for the purpose of showing 
 the repulsion and rotation effects produced by an alternating current. It is designed to operate on 
 a commercial circuit of 110 volts, the alternating current being recommended. It may be used, 
 however, satisfactorily on the direct current if used in connection with our Electrolytic Interrupter 
 No. 96-262. The apparatus is complete, covering a full set of parts for performing a most instruc¬ 
 tive series of experiments. A few of these we note herewith: — 
 
 Diaphragm made to vibrate in unison with the alternations of the current so as to give out a 
 distinct tone. 
 
 Repulsion of a copper disc held in proximity to the iron core on the balance arm. 
 
 The rotation of the copper disc, caused by the revolving field. 
 
 The rotating ball. A copper ball, placed over the exposed end of the iron core and one-half of 
 the core covered with a copper disc, will rotate. By floating the ball in a jar of water, 
 the rotation becomes rapid. 
 
 Lighting of an electric lamp by means of the pulsations given out from the iron core, this be¬ 
 ing accomplished through the glass jar. 
 
 The suspension of a heavy metal ring placed around the iron core. 
 
 The comparative repulsion of copper and aluminum rings. 
 
 Heating effect in a copper ring, shown by the boiling of a liquid. 
 
 These and many other experiments may be performed with the above apparatus. Their strik¬ 
 ing character has caused the outfit to be extensively used as a lecture table set. 
 
 Complete directions for operating and performing many experiments are furnished with the outfit. 
 
 $56.00 
 
 
 i 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 377 
 
 1 
 
 95-300 
 
 OZONE GENERATOR TUBE, a simple glass therapeutical device known 
 as an Ozone Generator Tube. This instrument has been listed, as it has 
 several features of educational value. In operation the central ter¬ 
 minal is connected to a source of High Frequency Current which will 
 fill the air chamber surrounding the central vacuum tube with a fine 
 brush discharge, instantly transforming a portion of the Oxygen of the 
 air into Ozone, which is readily detected by the odor. If desired, Oil of 
 Pine, Starch Solution, or similar Ozone' detecting chemicals may be 
 placed in the upper chamber of the device and the air forced through 
 them by simply pressing the bulb furnished. The instrument being 
 made entirely of glass, all operations are clearly visible . 
 
 $12.50 
 
 No. 95-310 
 
 95-310 SEPARATELY MOUNTED RESONANT LEYDEN JARS, a pair of jars mounted on independent 
 stands, each being fitted with an adjustable discharging circuit, for demonstration of: — 
 
 I. Resonance between Electrical Circuits. 
 
 ' 2. The Oscillatory Character of the Condenser Spark. 
 
 3 Tuning as applied to so-called High Frequency Circuits, Wireless Telegraphy, etc. 
 
 They make an impressive and instructive lecture table outfit. In operation one of the jars should be 
 charged by means of a static machine or induction coil, and at each discharge a simultaneous 
 spark will be obtained from the other jar providing that its loop is adjusted to the same positions as 
 the loop on the first. Changing the size of the loop on either of the jars without altering the other 
 will throw them out of tune, and the charge on one will be much less than on the other When in 
 tune the two parts of the outfit may be removed a considerable distance apart, thus showing in a 
 very clear manner the wonderful sensitiveness of resonsant circuits. , 
 
 The outfit is usually equipped with one-quart Leyden Jars, but jars either larger or smaller may be 
 used if at hand, thereby greatly increasing the educational value of the device, for it can be shown 
 that to obtain resonance the value of the condenser times the inductance or loop must be the same, 
 i. e., a large jar discharging through a small part of the loop of conductor will energize the other 
 or smaller jar through a larger part of its circuit, etc. 
 
 Separately Mounted Resonant Leyden Jars, complete as illustrated. 
 
378 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 HIGH FREQUENCY 
 
 Experimental work with high frequency currents has been impeded by the lack of well-designed apparatus in 
 marketable form. The coils which are listed on the following pages are the results of fifteen years’ experience in the 
 construction of high frequency apparatus, the first coil of this general type being built by us in the early days of high 
 frequency work. It has taken years of careful study, however, to learn how best to combine the elements embodied 
 in these instruments so as to produce a compact, safely handled coil giving adequate power with a range of adapta¬ 
 bility which would especially fit it for a scientific study of high frequency phenomena. 
 
 No. 95-325 
 
 UNI-POLAR HIGH FREQUENCY COIL 
 
 TEN-INCH CONTINUOUS DISCHARGE 
 
 No. 95-325 
 
 This instrument is a most striking outfit for general lecture work and for exhibition. It is built on lines 
 that have proven successful in the highest grade instrument construction. Not only does its peculiar com¬ 
 pact design protect the working parts when not in use, but it 
 also affords an instrument that is readily transportable from 
 place to place. Although when folded it occupies 16^4 X 
 X 9% inches, when open, it is not only large, but all the vital 
 parts are held at a considerable distance apart, so that a very 
 large amount of energy can be handled without overloading or 
 subjecting the various parts to an undue strain. The instru¬ 
 ment is entirely self-contained and after being connected to 
 the lighting circuit by means of a cord and plug, it is ready for 
 use. 
 
 We desire to call particular attention to the construction 
 of this coil. Its design has been the result of careful investiga¬ 
 tion, and the expenditure of a great amount of time and money. 
 
 We believe that there has been attained a perfection not 
 
 reached by any instrument of its class. It comprises no new or untried parts or material. We have watched 
 its development and operation for several years, and when thoroughly convinced of its merits, utility, and 
 “standing-up” qualities, made arrangements with its inventor for its sale in educational institutions. We 
 are enabled to fully guarantee this coil against accidental “break-downs” and against “burn-outs.” 
 
 Designed for alternating current, complete with carrying strap, connecting cords and Edison plug, and 
 with pamphlet descriptive of care and use.$200. 
 
 Showing Coil Folded 
 
 
 
 00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 379 
 
 HIGH 
 
 No. 95-335 
 
 FREQUENCY INDUCTIVE 
 APPARATUS 
 
 No. 95-335 
 
 This instrument represents a radical departure from the types of high frequency coils pre¬ 
 viously offered. By combining the open type of resonator commonly used in European labora¬ 
 tories with the closed core type of transformer and silver spark gap, unusual efficiency is obtained, 
 producing an instrument particularly well adapted to the study of alternating and high frequency 
 
 phenomena. 
 
 Provision has been made for varying the value of both the condenser and inductance. Cur¬ 
 rents of varying frequencies can thus be produced, enabling comparisons to be made between the 
 effects produced by changing either capacity or inductance. 
 
 Both the secondary and the oscillator are easily removed. Also, the entire resonator may be 
 readily taken off from the instrument, permitting experimental apparatus to be attached to the 
 low voltage (approximately 10,000 volts,) high frequency primary current. 
 
 PURPOSE. — This apparatus is designed for a comprehensive study of the high frequency 
 field, including wireless telegraph waves and kindred subjects. It may also be used with great 
 satisfaction to excite all types of vacuum tubes and will produce X-Rays of surprising power and 
 penetration. 
 
 USE. — It is designed to be connected to a commercial alternating current of 110 volts and 
 will furnish a discharge of any desired value up to its full capacity, which is about 12 inches. Its 
 ease of control and great range of usefulness make it of particular value in general laboratory ex¬ 
 periments and experiments on the scientific study of Electro-therapeutics. 
 
 The mounting is mahogany, the condenser of mica and the secondary oscillator is wound 
 on a large mica tube. The highest grade material only is used, — the workmanship the best 
 that mechanical skill can produce.$160.00 
 
38 o 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 No. 95-340 
 
 BI-POLAR HIGH FREQUENCY COIL 
 
 TWELVE-INCH CONTINUOUS DISCHARGE 
 Designed for Alternating Current 
 
 No. 95-340 
 
 96-340 BI-POLAR HIGH FREQUENCY COIL. This coil is designed to furnish a powerful high frequency- 
 discharge, suitable for X-Ray work and general experiments requiring high voltage. It is of ample 
 proportions and entirely self-contained. It is of the bi-polar type, i. e., each terminal is active and 
 throws off an abundance of energy' when in operation. The instrument is fitted with an experi¬ 
 mental circuit for demonstrating the laws and performing the many interesting and instructive 
 experiments pertaining to high frequency phenomena. 
 
 Our coils are built for service, only the best of material being used in their construction. They are 
 built on lines that positively avoid the danger of expensive “break-downs,” such as are met with in 
 the old style of induction coils. Each coil is fully' guaranteed against mechanical and electrical 
 imperfections. 
 
 The instrument is finely' finished throughout and is furnished in a polished magohany case. All 
 metal parts are neatly polished and lacquered. 
 
 Complete with connecting cord and Edison plug and with complete directions for care and use. . $140.00 
 
 95-376 HIGH FREQUENCY PHENOMENA APPARATUS. For the convenience of teachers who desire 
 to give a course in high frequency currents we have designed apparatus capable of performing all 
 the experiments outlined on the following page and many others incapable of adequate illustration. 
 
 This line of apparatus is well made, and finished and guaranteed satisfactory in every respect. 
 
 All the instruments have been tested with the previously listed coils and the instructive and inter¬ 
 esting results obtained have fully warranted a place in our catalogue. 
 
 High Frequency Phenomena Apparatus sufficient for performing all the experiments outlined on the 
 following page. In neat wooden case but without X-Ray Tube. 35.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 38i 
 
 HIGH FREQUENCY PHENOMENA 
 
 ILLUSTRATING TWENTY-FIVE OF THE MANY POSSIBLE 
 
 EXPERIMENTS 
 
 Transformation in¬ 
 to Static Electric¬ 
 ity 
 
 Brush Discharge Brush Discharge Discharge 
 from Hand Ozone Generator from Wire 
 
 Destruction of 
 Dialect ric 
 
 Electric Whirl Effect of Air Blast 
 on Discharge 
 
 Molecular 
 
 X-Rays 
 
 Radiography 
 
 Fluoroscofy 
 
 ' 
 
 
 
 
 Lighting VacuumTube 
 without connection 
 Electro Static field 
 
 Hysteresis 
 Heating Iron 
 
 Self Induction 
 Marked Drop in 
 Voltage 
 
 Stepping up Voltage 
 with forced oscilla¬ 
 tions in self indue 
 tion helix 
 
 Resonance in 
 Helix 
 
 High Voltage <- lir r Ar e Resistance ,J,tra Violet Li 5 ht ,, , v * r y Radiation through 
 
 Resonant Helix Surface resistance Flu0resence High Freq- ~ • 3 
 
 Jcjuency Dialectic 
 
 
382 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 COMMERCIAL WIRELESS APPARATUS 
 
 The educational value of Wireless Telegraphy an<l High Frequency Apparatus cannot be overestimated. Hold- 
 inn the attention of the student and scientist alike with a wonderful fascination, it has been the means of awaken¬ 
 ing an interest in school work where all other devices have failed. 
 
 Tt is not unusual today to hear pupils in the elementary grades speaking in a comprehending manner of wave 
 fronts, vibrations, resonance, attuned circuits, potentiometers, variable condensers, and like subjects and phenomena, 
 that a few years ago were understood only by advanced students of science. It can hardly be realised that stu¬ 
 dents in the grammar schools have been enabled through their interest in this class of apparatus to so master the 
 subject as to be capable not only of designing and building working outfits, but also of reaching such a degree of 
 proficiency in operating them as to be employed as expert operators in commercial stations. 
 
 Wireless apparatus should be installed in every school taking up the study of Physics, for it will be found to be 
 the one set of apparatus in the laboratory that will hold the students’ attention, (.'tubs will be formed, and the 
 students will take the greatest interest in getting into communication with neighboring schools fitted with apparatus, 
 and one and all will endeavor to excel in proficiency and understanding of the subject. 
 
 The installation of apparatus itv extremely simple, requiring but little more thought and time than the installa¬ 
 tion of an ordinary telegraph instrument. In many sections of the country the apparatus is interesting in that it 
 furnishes a ready means of obtaining standard time which is given out daily from the important government sta¬ 
 tions. So much apparatus of purely amateur design and construction has been offered for school work that we feel 
 that the sin cess of the instruction in this field has been seriously handicapped. For this reason we have decided to 
 offer the only standard types of commercial instruments, built by manufacturers of the widest experience in install¬ 
 ing commercial outfits. 
 
 96 400 COMPLETE SENDING OUTFIT. This is a compact 
 outfit comprising Transformer, Condenser, Helix, 
 
 Spark Gap and Key mounted in and on a finely 
 finished mahogany cabinet. It is shipped ready 
 for use and has but to be connected to any conven¬ 
 ient source of 110-volt alternating current and a 
 suitable antenna. 
 
 Complete as above described.$44.00 
 
 No. 96 400 
 
 No. 96-406 
 
 96 406 COMPLETE RECEIVING SET. This is a combination of instruments mounted in a well-finished 
 mahogany cabinet with hinged cover. This set includes a Ferron Detector, a Receiving Trans¬ 
 former, a Fixed Condenser, a Rotary Variable Condenser, and a 2000-ohm Telephone Head set. 
 Binding Posts are provided for antenna, ground and receiving connections. 
 
 1 lie compactness, accessibility and efficiency of this instrument will appeal to any one interested in 
 the subject. 
 
 Complete Receiving Set .... .. 
 
 $40.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 383 
 
 SEPARATE WIRELESS UNITS 
 
 We list below a line of high-grade separate units for the benefit of 
 those who are already partialh equipped or who may wish to construct 
 for themselves a part of their wireless apparatus. The design of the units 
 is of the very latest commercial types and such as will appeal to those 
 desiring to do high-grade work in the wireless field. 
 
 No. 96-410 
 
 SENDING APPARATUS IN SEPARATE UNITS 
 
 96 410 
 
 96-416 
 
 TRANSFORMERS. High efficiency, high power, low heating factors and reliable service. Each 
 instrument is mounted in mahogany cabinet, the secondary sections being instantly removable 
 without injuring the transformer. The primary may also be drawn from the tube without inter¬ 
 fering with the secondary. 
 
 a be 
 
 K H IK. W. 
 
 Each.$33.00 49.00 67.00 
 
 HIGH POTENTIAL CONDENSERS. Each condenser is mounted in a box with separate connec¬ 
 tions brought out from each unit so that the capacity may be varicdTy connecting in various 
 sections. This form of condenser will save an enormous amount of energy which is frequently 
 lost in the condenser system. It will conserve the great power of our transformers as no other 
 condenser can. With this type of condenser the efficiency of a station is often doubled. 
 
 Each 
 
 a 
 
 }-i 
 
 $12.40 
 
 b c 
 
 K 1 K. W. 
 
 24.60 48.00 
 
 No. 95-420 
 
 96-426 
 
 No. 96 430 
 
 96 420 HELIX. This helix is the one employed in No. 
 
 96-400 Transmitting Set. It is simple and 
 rugged in construction, of unusual efficiency, 
 employing us it does edge-wise wound copper 
 strips. The base is of finished mahogany; 
 supported on hard rubber. Three clips un¬ 
 provided for varying the degree of coupling . 
 
 OSCILLATING TRANSFORMER. Our yi, and 1 K. W. sending inductances arc of the in¬ 
 ductively coupled type, having the right amount of coupling to produce a high defined wave and 
 perform close tuning at the receiving station. The primary is of copper ribbon wound spirally. 
 The secondary is of copper ribbon wound on especially prepared drums, lloth circuits have vari¬ 
 able inductances which insure absolute resonance between the two circuits, insuring the radiation 
 of a greater amount of energy in the form of waves, instead of the energy being wasted in heat at 
 the spark gap. This Oscillator is designed for the production of wave lengths of from 600 amperes 
 to 9o0 amperes efficiency. 
 
 a be 
 
 Each 
 
 $ 21.00 
 
 
 21.00 
 
 1 K. W. 
 
 44.00 
 
 96-430 ADJUSTABLE SPARK GAPS. No part of a sending set is more likely to cause loss of energy than a 
 poorly constructed spark gap. In many instances efficiency is cut down one-half through loss at 
 this point. In our instruments we use an especially prepared zinc electrode, capable of with¬ 
 standing heavy currents. 
 
 $6.76 
 
 6.60 
 
384 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 RECEIVING APPARATUS IN SEPARATE 
 
 UNITS 
 
 DETECTORS 
 
 No. 95-435 No. 95-440 
 
 Patented Patented 
 
 95— 435 SILICON DETECTOR. This form of Detector is well known to all who are interested in wireless 
 
 apparatus, and some of the longest records have been made with this type of instrument. It is 
 fully guaranteed and furnished to us by a manufacturer especially licensed by the inventor . . . $6.50 
 
 96- 440 IMPROVED FERRON DETECTOR. The new Ferron Detector is made up of a metallic crystal 
 
 held in a nickeled cup, mounted on the usual form of detector stand. An exceedingly fine adjust¬ 
 ment of pressure is easily obtained by means of a triple spring operated by a milled head rubber 
 rod. Mounted on substantial marble base 5^X3 inches. This Detector is simple and operates 
 best without either Potentiometer or battery. 6.25 
 
 No. 95-446 
 
 95—445 TUNING COIL of the loose couple type. This instrument has been especially designed for educa¬ 
 tional institutions where it is desirable, in order to show the construction of the essential working 
 
 parts, to withdraw entirely the primary from the secondary coil. 
 Special provision has been made for this so that it may be drawn 
 fully from the secondary and inserted without danger of binding. 
 The adjustment is easy and positive. The primary of the coil is 
 of unusual capacity, enabling the shortest and longest wave lengths 
 used by commercial stations to be received with a comparatively 
 small antenna, and without the use of additional inductances or 
 condensers. The secondary is made much larger than is usual and 
 mounted on pivoted wheels. 
 
 95— 450 HEAD BAND RECEIVERS. Double, 2000-ohm resistance . . . 
 
 96— 455 FIXED CONDENSER. The most approved methods of connect¬ 
 
 ing a modern receiving station require a small condenser of fixed 
 capacity in addition to the variable condenser used in tuning 
 purposes. It is mounted in a nickel-plated brass cylinder fitted 
 with hard rubber top carrying binding posts. Its capacity is 
 approximately .003 M. F. 
 
 VARIABLE AIR CONDENSERS. See page 388. 
 
 $15.00 
 
 12.00 
 
 2.30 
 
 No. 95-455 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 385 
 
 ELECTROLYTIC RECTIFIERS 
 
 96-485 ELECTROLYTIC RECTIFIER, Nodon valve type, 
 designed for use on 110-volt alternating current, 
 giving a direct current of the pulsating form, but 
 one in which the negative part of the wave is en¬ 
 tirely cut off, so that for most purposes this trans¬ 
 formed current takes the place of a direct current 
 of equal voltage. The charging of storage batter¬ 
 ies, experiments in electrolysis, charging of electro¬ 
 magnets, complete series of experiments showing 
 the mutual attraction and repulsion of currents, 
 etc., may be performed with this current. 
 
 The valve here illustrated is of substantial construc¬ 
 tion, jars, lead plates, aluminum rods of generous 
 proportions, slate top and connectors, substan¬ 
 tial iron rod support and wooden carrying case. 
 
 Full directions for connections and use furnished 
 with each instrument. 
 
 Large amperage may be drawn from this instrument, 
 but for brief periods only, owing to the fact that 
 no adequate arrangements have been made for 
 radiating the heat. 
 
 Complete.$14.76 
 
 No. 95-486 
 
 96-490 THE NEW MULTIPLE RANGE SELF- 
 COOLING RECTIFIER, with ammeter, 
 designed for use on 110-volt alternating 
 current and to deliver a direct current 
 of varying voltages. As ordinarily 
 furnished, 3, 6, 9, and 12 volts have 
 been provided for, being the ranges 
 most generally useful in laboratory 
 work. In addition to these a 12-volt 
 alternating current may also be drawn. 
 As will be noted from the illustration, 
 the instrument is provided with an 
 ammeter so that the exact consumption 
 on the direct current circuit may be 
 noted constantly. 
 
 The terminals on the top of the case are 
 connected to various sections of the 
 transformer, each clearly marked so 
 that the user can tell at a glance what 
 voltage he is drawing. 
 
 No. 96-490 General construction. Owing to the care 
 
 Patent Pending which has been taken to properly dissi¬ 
 
 pate the heat, large amperage may be 
 drawn from this instrument continuously. The metal case is made with radiating vanes, the 
 case itself serving as one of the electrodes, so that the heat generated is taken care of by con¬ 
 duction and radiation as fast as produced. 
 
 This outfit will be found not only much more convenient to use than the electrolytic rectifiers of 
 the type No. 96-485, but is also much more efficient. The fact that multiple voltages can be 
 drawn enables it to fill a need in laboratory work which has long been felt. These instruments 
 should be provided in every laboratory where a direct current of low voltage is not already pro¬ 
 vided for. 
 
 Complete directions furnished with each instrument. 
 
 Complete with ammeter, mounted as shown in the illustration 
 
 $38.00 
 
 =jiitl& 
 
386 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ROTARY CONVERTERS 
 
 Nos. 95-500 to 95-506 
 
 Our Rotary Converters are of the same high quality as are our Generators and Motorsilisted in Section 97. The 
 conversion of the Direct to the Alternating current is accomplished with the highest efficiency output. They are 
 guaranteed against mechanical and electrical imperfections. 
 
 Prices include Automatic No-voltage Release Starting Box. 
 
 Price 
 
 
 Output 
 
 Watts Speed 
 
 no 
 
 Volts 
 
 Input 
 
 220 
 
 95-600 
 
 75 
 
 3600 
 
 $50.00 
 
 
 $53.00 
 
 95-602 
 
 100 
 
 3600 
 
 52.50 
 
 
 56.50 
 
 95-604 
 
 150 
 
 3600 
 
 56.00 
 
 
 68.00 
 
 96-606 
 
 250 
 
 1800 
 
 60.00 
 
 
 64.00 
 
 MOTOR GENERATORS 
 
 LC.KNOTT APPARATUS CO. 
 HOST ON 
 
 Nos. 95-610 to 95-620 
 
 These Motor Generators are intended for those schools which have an available Alternating Current and which 
 desire a Direct Current. Our line listed below is of standard quality guaranteed against mechanical and electrical 
 defects. 
 
 Prices include suitable rheostat when needed. 
 
 
 A. C. Motor. 
 
 60 cycle, single phase 
 
 1740 RPM, 110 or 220 volts 
 H. P. 
 
 Generator 
 
 Watts 
 
 Price 
 
 95-510 
 
 % 
 
 60 
 
 $80.00 
 
 95-512 
 
 V4 
 
 120 
 
 96.00 
 
 95-616 
 
 y 2 
 
 175 
 
 142.00 
 
 95-517 
 
 % 
 
 250 
 
 165.00 
 
 96-620 
 
 i 
 
 500 
 
 216.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 387 
 
 INDUCTANCE AND CAPACITY APPARATUS 
 
 Nos. 96-10 to 96-40 Nos. 96-60 to 96-62 
 
 STANDARD SELF-INDUCTION COILS. The knowledge of exact measurements in the matter of self-induction 
 and capacity is of the greatest importance in setting up and in the use of machines, measuring instruments, and 
 apparatus operated by alternating currents, as in installing of telegraph and telephone apparatus, cables, and cir¬ 
 cuits of all kinds. By the use of standard self-induction coils and simple measuring appliances it is possible to de¬ 
 termine these values very exactly. 
 
 The self-induction coils below listed have been prepared in accordance with the principles laid down by the 
 Reichsanstalt. They are spools of wire of known self-induction wound upon cylinders of serpentine, wholly free 
 from iron and immovably fixed upon these cylinders. 
 
 These spools are so encased in a vulcanized rubber covering that they are protected against injury from the 
 outside. By avoiding all metal parts except very small clamps, and by the divisions of the turns of the coil the pres¬ 
 ence of eddy currents is effectually avoided. 
 
 The standards are tested with great care to .002 of their stated value. 
 
 96-10 STANDARD SELF-INDUCTION COIL, capacity 1 Henry .Duty Free . . . 
 
 96-12 -, capacity 0.5 Henry . .. “ “ . . . 
 
 96-14 -, capacity 0.1 Henry. “ “ . . . 
 
 96-16 -, capacity 0.01 Henry. “ “ ... 
 
 96-17 -, capacity 0.001 Henry. “ “ ... 
 
 96-19 -, capacity 0.0001 Henry. “ “ ... 
 
 96-30 STANDARD SELF-INDUCTION SPOOLS, same as above, but wound on marble spools; capacity . . . 
 
 1 Henry.Duty Free . . . 
 
 96-32 -, capacity 0.5 Henry. 
 
 96-34 -, capacity 0.1 Henry. 
 
 96-36 -, capacity 0.01 Henry.Duty Free 
 
 96-38 -, capacity 0.001 Henry. “ “ 
 
 96-40 -, capacity 0.0001 Henry. “ “ 
 
 96-60 AYRTON and PERRY’S VARIABLE STANDARD OF SELF-INDUCTION, 
 
 reading directly to Millihenrys, range from 4 to 40 Millihenrys. Wood 
 mounting.Duty Free 
 
 96-62 - —, same as above, but constructed of ebonite. “ “ 
 
 96-60 ADJUSTABLE INDUCTANCE. These inductances are made up of copper 
 wire wound on a threaded hard rubber tube, — a construction that has 
 been found to give excellent results both mechanically and electrically. 
 
 A smooth-acting slide permits any desired amount of the wire to be placed 
 in circuit, and a scale on the slide support gives the value of the portion 
 in use. 
 
 These inductances will be found well suited and convenient to use in con- 
 necton with High Frequency currents and Wireless Telegraph outfits. 
 
 Capacity 1000 Microhenrys.$1 
 
 96—66 -, same as above, capacity 5000 Microhenrys. 26.00 Nos. 96-60 to 96-66 
 
388 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 96-106 
 
 96-110 
 
 96-116 
 
 96-117 
 
 96-125 
 
 96-136 
 
 • » 
 
 CONDENSERS 
 
 Nos. 96-136 to 96-140 
 
 CONDENSERS, paper and tinfoil rolled type. These condensers have a guaranteed capacity, and 
 the average insulation resistance of 100 megohms and not less than 50 megohms per micro-farad. 
 
 a b c 
 
 Capacity. 1 2 M. F. 
 
 Each . $1.20 1.30 2.10 
 
 SUBDIVIDED PAPER CONDENSER, V 2 to 2 M. F. by y 2 M. F. steps. Enclosed in polished 
 
 wooden case . 
 
 SUBDIVIDED PAPER CONDENSER, excellent grade, capacity one micro-farad, subdivided into 
 four steps, — 0.1, 0.2, 0.2 and 0.5 M. F. Enclosed in polished wood case as illustrated under 
 No. 96-117. 
 
 -, same as above, but capacity 2 M. F. subdivided into five steps, — 0.1, 0.2, .0.5 and 1 M. F. 
 
 MICA CONDENSERS. These condensers are constructed by an improved process in which the 
 mica leaves are silvered on both sides. This direct deposit of metal without any foreign sub¬ 
 stance permits of the full dielectric properties of the mica. It will be noted also that the deposit 
 of silver adhering so closely to the mica forms a perfect condensing surface. It will be found by 
 actual tests that the stated capacities remain constant. 
 
 a b c d 
 
 Capacity. 0.1 0.2 0.5 1 M. F. 
 
 Each, Duty Free ........ $22.40 30.00 38.50 69.00 
 
 VARIABLE AIR CONDENSER. This is a standard instrument constructed of the highest quality 
 material and of first-class workmanship throughout. The vanes are of aluminum, and the moving 
 system works perfectly without interference of the plates or other objectionable features commonly 
 met with in instruments of cheaper construction. The top is of the best grade hard rubber, insuring 
 high insulation and durability. A binding post is provided connecting to the case for grounding in 
 experiments where the utmost accuracy is required. These condensers will be found of great use¬ 
 fulness in wireless telegraphy and in experiments with currents of high frequency. Capacity .001 
 M. F. 
 
 $6.75 
 
 32.40 
 
 40.00 
 
 28.00 
 
 96-140 
 
 , similar to above, but with a capacity of .005 M. F 
 
 42.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 389 
 
 ELECTRO-DYNAMIC APPARATUS 
 
 DYNAMOS AND MOTORS 
 
 No. 97-10 
 
 No. 97-25 
 
 No. 97-30 No. 97-40 
 
 97-10 MOTOR PARTS, complete parts for assembling a working motor. The popularity of the outfit 
 above illustrated has demonstrated its efficiency as a pedagogic instrument. All parts ready to 
 wind and assemble are enclosed with simple directions in a neat cardboard box. These parts and 
 directions may be placed in the hands of any ingenious pupil who may readily assemble a motor 
 for himself. $1.26 
 
 97-15 SIMPLE MOTOR. This motor though simple is well and substantially made. It is finished in black 
 enamel with nickel-plated trimmings; mounted on polished wood base. It weighs about 1 pound 
 and occupies a space 3 X 334 X 4 inches. 
 
 It will run efficiently on a single battery cell. 1.60 
 
 97-17 SERIES WOUND DYNAMO, same simple and substantial structure as above. Effectively used 
 
 with above in combining a simple Motor Generator. 2.00 
 
 97-26 STANDARD MOTOR. This motor is built for efficiency. It is designed to operate on two or three 
 cells of battery. Will run about 2200 R. P. M. with average load on a current of 2 amperes at 4 
 volts. 
 
 Finished in black enamel with brass terminals. Weighs about 134 pounds; occupies a space about 
 
 334 inches square . 3.25 
 
 97-30 REVERSING LEVER MOTOR. This motor is similar in design to No. 97-40, though built on a 
 smaller plan. It is wound for battery current only and runs to full efficiency on two or three dry 
 cells. Stands about 334 inches high and weighs about 15 ounces. 
 
 A feature of this motor is the reversing lever designed to start, stop, and reverse the motion of the 
 armature. . 3.75 
 
 97—40 AIR-COOLED MOTOR. This small motor, standing 3% inches high and weighing 20 ounces, is built 
 on the lines of large machines. With the exception of the base no cast iron is used in its construction. 
 
 The field is made of the best charcoal iron, annular field coil carefully taped and shellaced. The 
 armature is laminated and slot wound. It is provided with self-lubricating bearing so constructed 
 as to always be in perfect alignment, the cups having covers. The commutator segments are of 
 hard copper carefully insulated with mica. Brushes are self-adjusting. Steel armature shaft 
 fitted with grooved brass pulley % inch in diameter. This motor is handsomely finished through¬ 
 out, the frame and base being finished in black enamel. It is highly recommended as a most power¬ 
 ful battery motor. 4.60 
 
390 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 97-60 
 
 97-60 STUDENTS’ MOTOR GENERATOR for the study of the construction and operation of a simple 
 dynamo and motor. This is a complete power station in the smallest practical size for students’ 
 laboratory work. The general design is such as all doubtless are already familiar with, but made of 
 much higher quality of workmanship, and consequently more efficient. 
 
 The motor is wound for a 4-volt battery current, the dynamo is series wound, and proportioned to 
 give the best possible results as a generator, notwithstanding its small size. The dissectible features 
 of both dynamo and motor are important for both laboratory instruments. They will be found 
 valuable educational instruments in studying the complete transformation of electrical energy from 
 the battery through the motor, dynamo, and galvanometer. \ 
 
 Both instruments are mounted and clamped to a neatly polished wooden base and direct connected by 
 a short belt. With the use of this combination a student is able to compare the parts of the dynamo 
 with the corresponding parts of the motor, to observe points of similarity and points of difference. 
 
 The instrument utilizes our popular Turner Base and Clamp which binds both motor and dynamo in 
 
 correct alignment in a simple and efficient manner. $3.95 
 
 97-62 TURNER AND HERSEY BED CLAMP for small power station. This base, as supplied in above 
 apparatus, is designed for easy and effective coupling of a motor and dynamo. In students’ ex¬ 
 perimental work it is necessary that the two units be held rigidly in position, but that sufficient ad¬ 
 justment be allowed for readily tightening the belt. The metal clamps provide an easy and ef¬ 
 fective method of regulating the distance and of tightening the belt. 
 
 Complete. 46 
 
 97-70 DYNAMO-MOTOR, field of soft gray iron, armature — eight sections of the laminated tunnel 
 drum pattern, shunt wound with silk enameled wire, commutator eight sections amply insulated 
 with large carrying capacity, brushes of best pattern and quality, bearings of brass with large 
 
 oil cups, finish bright enamel and nickel-plate, 
 mounted on polished wood base 4% X 5H 
 inches. 
 
 As a Dynamo its output at full speed of 3.000 
 to 3200 R. P. M. is about 30 watts (12 volts 
 and 2.5 amperes). It will be found very use¬ 
 ful for furnishing current for many experi¬ 
 ments in the study of Electricity and Mag¬ 
 netism. It will charge a six-volt 40-ampere- 
 hour storage battery in 12 hours. 
 
 As a Motor it operates on 6 to 12 volts of 
 battery current, giving about 1800 R. P. M. 
 at 8 volts and 2500 R. P. M. at 12 volts. It 
 will develop about %6 H. P. 
 
 This Dynamo-Motor is furnished with a pulley 
 1 Y 2 inches in diameter, V-groove for a %o-inch 
 round belt.. 
 
 V 
 
 
 
 No. 97-70 
 
 7.76 
 
 __ 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 391 
 
 I 
 
 
 
 No. 97-100 
 
 vJ 
 
 t... SET-UP WITH 4-POlE ARMATURC 
 
 K--.V.V.-v.. 
 
 Fields 
 
 Arm with 
 
 Brushes 
 
 e-Pole Field 
 
 No. 97-100 (Fig. 1) 
 
 
 
 2-POLE ARMATURE 
 
 Fig. 2 
 
 3- POLE ARMATURE 
 
 Fig. 3 
 
 .•POLE ARMATURE 
 
 ' Fig. 4 
 
 97-100 MOTOR DYNAMO DEMONSTRATION APPARATUS. • 
 
 From an educational point of view, teachers will appreciate the open construction and the ease with 
 which the student may see at a glance the various poles of either type of dynamo or motor, and in 
 consequence be free from the perplexing problem of determining the exact position of the pole. 
 
 Some of the points that may be easily studied by the student are briefly outlined as follows: — 
 
 1. The two-pole Magneto. 
 
 2. The two, three, or four-pole Armature in a two-pole field. 
 
 3. The effect of varying the strength of the field. 
 
 4. Shunt-wound Motors having like or unlike number of armatures and field poles. 
 
 5. Series-wound Motors having like or unlike number of armatures and field poles. (This point 
 is rendered especially easy since all the armatures are interchangeable with all the field systems 
 so that they are easily combined in any desired manner.) 
 
 6. A study of the neutral point. 
 
 7. A study of the effect of changing the direction of the current in either armature or field. Many 
 other experiments applicable to the Dynamo and Motor may be readily performed. Price com¬ 
 plete with 3 Armatures, 
 
 6 Field Coils, 
 
 2 Bar Magnets.-.$3.86 
 
 97-106 METAL MOUNTED IMPROVED ST. LOUIS MOTOR, with Im¬ 
 proved Brush Carrier and Armature. 
 
 This apparatus is an improved form of the apparatus known as 
 the St. Louis Motor. It may be used as a dynamo or motor. Al¬ 
 though similar to No. 97-100 in its application to principles 
 of dynamo and motor construction, it is limited in range of 
 experiments possible. It serves effectively, however, to teach 
 with permanent field magnets, — 
 
 1. Strength of magnet field at different distances from arma¬ 
 ture. 
 
 2. Effect of two like and effect of two unlike poles; with elec¬ 
 tromagnet field, series and shunt dynamo. 
 
 It is a simple and effective means in individual laboratory work 
 of making simple and clear, — No. 97-106 
 
 1. Polarity of armature at different points in its revolution. 
 
 2. Direction of current in armature and field. 
 
 3. Commutation, position of armature, commutator and brushes. 
 
 Complete as illustrated, with permanent and electromagnet attachments. $2.80 
 
392 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 
 No. 97-115 
 
 GILLEY GRAMME MACHINE 
 
 No. 97-115 Fig. 1 
 
 of force are thus permitted to arrange themselves under 
 in the armature and field. 
 
 The Gramme Machine represents a type of generator 
 now generally used in large units for power and lighting 
 stations. The Gilley Gramme Machine is a modification 
 so worked out that the lines of force may be easily plotted 
 by the compass and filings method. 
 
 No other apparatus has yet been designed with which 
 it is possible to show the lines of force in a working model 
 of the dynamo and motor with the armature in position 
 and in actual operation. Both the field and armature 
 are designed and made in flat form, so that the upper sur¬ 
 faces of both are level, permitting the paper or glass upon 
 which the lines of force by the filings method are to be 
 mapped to take a smooth horizontal position. The lines 
 no other influence than that of the magnetic force existing 
 
 Dissectible Features. Fig. 2 shows the three basic parts of the apparatus, — the armature with the commu¬ 
 tator, the field magnet with base, and the brush-holder. The instrument is readily dissected, as the illustration 
 shows. Each part may be studied separately, as will be noted from the following list of experiments. 
 
 We desire to call attention also to the fact that the field coil is easily removed from its base and the base so 
 designed that 6-inch permanent magnets may be substituted for the field coil, thus teaching the fundamental prin¬ 
 ciple of the magneto. 
 
 WHAT THE INSTRUMENT IS DESIGNED TO TEACH 
 
 Experiment 1. Study of the field 
 magnet in an electromagnet, the lines 
 of force being mapped out either by 
 compass or filings method. 
 
 Experiment 2. To show what ef¬ 
 fect the soft iron ring of the armature 
 has upon field magnets. The value of 
 this exercise is greatly increased by 
 using the filings method of mapping 
 the field and comparing the field with 
 results obtained above. 
 
 Experiment 3. A detailed study 
 of the armature, showing that it is 
 wound in sections and where the ends 
 of each section are. 
 
 Experiment 4. A detailed study 
 of the commutator by passing the 
 current into the armature magnet 
 through the brushes, showing by this 
 method the exact position of each 
 section when polarity is reversed. 
 Experiment 5. The method of answering definitely why the armature of a motor rotates. The action 
 of the lines of force as indicated by the filings method will make this clear. 
 
 Experiment 6. A study of the magneto generator, its relation to the regular commercial dynamo, showing 
 definitely why the current is generated when the armature is rotated between the poles of a magnet. 
 
 Experiment 7. A study of the magneto and its relation to the dynamo, also why the armature in a 
 magneto machine rotates. 
 
 Experiment 8. A study of the dynamo using electromagnetic field and armature. Determining the 
 relation of the armature to the field coils and the speed of the armature to the strength of the magnetic field. 
 
 Experiment 9. The study of different types of dynamos and motors depending upon whether the arma¬ 
 ture and field are connected in series or in multiple, and what are the conditions regulating the method of 
 connecting in any given machine. 
 
 Experiment 10. To show what the result will be if the armature is removed and a permanent bar magnet 
 be mounted on the same bearing. This experiment teaches clearly the reason why the armature must be an 
 electromagnet and not a permanent magnet. 
 
 Gilley Gramme Machine. 
 
 No. 97-116 (Dissected) Fig. 2 
 
 $7.76 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 393 
 
 No. 97-125 
 
 / 
 
 I 
 
 MILLER-COWEN ATTACHMENT TO GILLEY 
 
 GRAMME MACHINE 
 
 This attachment, designed by 
 G. A. Cowen and F. R. Miller of the 
 Boston High Schools, further in¬ 
 creases the educational value of the 
 Gilley Gramme Machine by apply¬ 
 ing the method of clear, open con¬ 
 struction as used in that machine 
 to the parts that are too often 
 neglected but the operation of which 
 is of the utmost importance. This 
 attachment allows of the removal of 
 the armature iron so that experi¬ 
 ments may be conducted either 
 with a simple revolving armature 
 coil or with the enclosed iron core 
 as desired. 
 
 In addition to a large commu¬ 
 tator, collecting rings are provided 
 for the proper investigation of the 
 alternating type of motor and gen¬ 
 erator. A handle furnishes a ready 
 means of revolving the armature. 
 
 No. 97-125 (Dismounted Field Magnet) 
 
 The use of this device in connection with our 
 Universal Galvanometer No. 93-130 is recom¬ 
 mended, as it is built to work in connection with 
 an instrument of its range. This attachment is 
 carefully constructed and most rigidly tested in 
 our laboratory before shipment. Each instrument 
 is guaranteed satisfactory, and its design will com¬ 
 mend it as a valuable educational instrument. 
 
 Special Features. The large commutator for 
 both A. C. and D- C., the ready means of chang¬ 
 ing brushes to make contacts with either A. C. or 
 D. C. commutator without changing the galvanom¬ 
 eter connections, the ease with which the field mag¬ 
 nets may be removed and bar magnets substituted, 
 the ready removal of the laminated core, are fea¬ 
 tures which make it an educational instrument of 
 the utmost value. 
 
 As a dynamo analysis machine of simplest form 
 it has met with much favor in vocational schools. 
 
 No. 97-126 (Mounted Field Magnet) 
 
 97-125 MILLER-COWEN ATTACHMENT, including the Field Magnet.$10.60 
 
 97-127 MILLER-COWEN ATTACHMENT, without the Field Magnet for those who already have No. 
 
 97-116 Gilley-Gramme Machine. 
 
 8.00 
 
394 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 97-148 
 
 DIRECT CONNECTED HAND POWER 
 DYNAMO AND MOTOR 
 
 No. 97-148 
 
 This instrument is provided with coils, collecting rings and commutator so that it will work to highest efficiency 
 in the production of either alternating or direct current. As ordinarily used on the lecture table the output may be 
 roughly stated as 15 volts and 7 amperes, but a greater output can be obtained if desired. 
 
 Field and armature may be connected in series or shunt, making it possible to teach definitely, — Direct Current 
 
 Shunt Wound Dynamo, Self-Exciting Alternating Current Dynamo, Series Dynamo Motor, Rotary Converter or 
 Motor Generator. 
 
 SPECIAL FEATURES: 
 
 Dissectibility. Pole pieces separated and armature removed without the use of wrench or screw 
 driver. Can be taken apart and reassembled on the lecture table while the lecture is in process. 
 
 Efficiency. Will easily generate 100 watts of electrical energy and is guaranteed to give 200 watts, 
 
 — a new accomplishment in instruments for educational work. 
 
 Design. Careful study has been made of commercial types which we have modified only to the 
 extent of obtaining the dissectible and educational features which we consider of prime importance. 
 
 Driving Mechanism. In eliminating the belt and substituting the enclosed oil-immersed, direct con¬ 
 nected gear drive, a long step in advance has been made in the construction of Hand Power Dy¬ 
 namos. This feature had in part been worked out in our Hand Power Dynamo No. 97-160, the 
 success of which led us to take the next step and eliminate entirely the losses due to the belt drive. 
 
 By careful estimate, this method of drive gives an increased efficiency' of about 60 per cent. 
 
 Field Magnet. Two-pole type which allows the use of a large amount of iron and permits of a 
 construction which makes the shortest magnetic circuit, at the same time allowing a clear view 
 of the pole pieces and their relation to the armature. 
 
 Field Coils. Wound on thin-spun metal bobbins, each core being designed for a definite purpose, 
 depending upon whether the instrument is to be connected series or shunt wound, giving the 
 greatest efficiency for each type. 
 
 Armature. Drum type, which has proven best suited for withstanding hard usage. The coil sec¬ 
 tions are wound in slots in the laminated iron core. The anchoring of the coil has been done in the 
 most perfect workmanlike manner. 
 
 Commutator. Larger size proportionately than would be used on a regular commercial machine, 
 for the reason that it is a part of the design of this instrument that all of the essential features 
 be large enough so that the students can readily study' their functions. 
 
 Collecting Rings. Placed on the same end of the shaft as the commutator, a design which sim¬ 
 plifies the instrument. The attachment holding the brushes serves both for alternating and di¬ 
 rect circuit, thus offering a ready method of comparison. Price.$40.00 
 

 CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 395 
 
 MAGNETO. This instrument is a regular commercial dynamo o: the permanent magnet type, em¬ 
 ploying magnets of unusual strength. A very ernciect armature is provided with crank and gears 
 so that it may be readily operated by hand. This instrument is frequently used in telephone ex¬ 
 changes and often as a testing instrument in locating broken circuits in cofls. Its operation b 
 similar to that which takes place in the Page Motor Apparatus below. Its educational value b 
 in the practical and powerful effects that can be obtained by rsqng permanent magnets. The 
 earlier forms of power machines were built on thb principle. 
 
 97-160 PAGE MOTOR APPARATUS. Thb apparatus will be found of great value in teaching the basic 
 principles of the electric motor and dynamo. By utilizing the horseshoe magnet, the student 
 b not confounded with the unusual shape of pole pieces as met with in most motor or dynamo ap¬ 
 pliances. It wiH also be seen that the use of a permanent horseshoe magnet allows the armature 
 and its commutator together with the brushes to be laid out on a fat surface so that each part can 
 be seen whether as a unit or working together. If desired, the lines of force can be readily plotted 
 in the usual method by bon tilings. Thb instrument can be used either as a generator or a motor, 
 as desired. By slowly moving the armature by hand, a clear understanding can be had of its 
 operation. 
 
 The instrument b well made, employing a powerful magnet, so that it can be depended upon to give 
 satisfactory results in the hands of students .. 
 
 97-166 
 
 
 
 97-165 PAGE MOTOR APPARATUS, ELECTROMAGNETIC FIELD. Thb apparatus b particularly 
 designed to show in a clear and comprehensive manner the action of an electromagnet as used in 
 the modern motors and dynamos. The held coils are mounted on a soft U-shaped frame corre¬ 
 sponding in general appearance to the permanent magnet of the Xe. 97-160 Page Motor Appara¬ 
 tus above, thus permitting direct and dear comparisons of the magnetic fields. The armature 
 provided with thb outfit still farther illustrates the actios of the electric current, for the iron used 
 in the motor apparatus above b entirely dbpensed with, the rotation bring brought about by the 
 direct action of the electromagnet add on a solenoid. Commutators, binding posts and brushes 
 for connecting in various series and shunt combinations, are placed so that they can be dearly 
 inspected. The apparatus wDI operate as a motor on two ceils of battery. 
 
 Thb apparatus b constructed accurately of the bet obtainable material, and ah parts are nicely acted. 
 It wiH be found a valuable instrument in the tearhirg of electro-dynamics. As a companion 
 instrument with the Page Motor Apparatus Xo. 97-160, a direct comparison of permanent and 
 electromagnetic types of instruments makes an interesting study. 
 
 96.65 
 
 3.50 
 
 9.75 
 
396 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • » 
 
 MOTORS 
 
 ALTERNATING AND DIRECT CURRENT 
 
 1/30 TO 1/4 H. P. 
 
 The well-known line of “Standard” Motors listed on this page is guaranteed to be mechanically and electri¬ 
 cally perfect. The solidity of construction, the correctness of design coupled with the unsurpassed enameled finish, 
 place them at once at the head of all motors. The material used is the best that can be obtained. They are of un¬ 
 usually high efficiency and are fully as durable as the larger size machines. They may be absolutely relied upon 
 for years of satisfactory service. 
 
 Nos. 97-176 to 97-179 Nos. 97-181 to 97-183 
 
 DIRECT CURRENT COMPOUND WOUND MOTORS 
 
 Prices of series or shunt wound motors on application. 
 
 Prices 
 
 Number 
 
 H. P. 
 
 Speed 
 
 115 
 
 Volts 230 
 
 97-176 
 
 Vso 
 
 1150 
 
 $14.16 
 
 $16.60 
 
 97-177 
 
 V 20 
 
 1750 
 
 16.86 
 
 17.26 
 
 97-179 
 
 y 8 
 
 2000 
 
 18.00 
 
 19.80 
 
 97-181 
 
 H 
 
 1150 
 
 20.26 
 
 22.00 
 
 97-183 
 
 Vs 
 
 1750 
 
 21.76 
 
 23.26 
 
 97-186 
 
 Vs 
 
 1150 
 
 28.60 
 
 30.00 
 
 97-187 
 
 % 
 
 1750 
 
 31.00 
 
 34.60 
 
 97-189 
 
 V\ 
 
 2000 
 
 34.60 
 
 38.00 
 
 SINGLE PHASE INDUCTION MOTORS 
 
 Full Load Start 
 
 60 Cycles 
 
 
 Continuous Duty 
 
 Number 
 
 H. P. 
 
 Speed 
 
 115 
 
 Prices 
 
 Volts 
 
 230 
 
 97-200 
 
 Vso 
 
 1150 
 
 $17.60 
 
 
 $19.60 
 
 97-202 
 
 Vso 
 
 1750 
 
 16.00 
 
 
 18.00 
 
 97-204 
 
 V 20 
 
 1150 
 
 24.26 
 
 
 26.26 
 
 97-206 
 
 V 20 
 
 1750 
 
 21.00 
 
 
 23.00 
 
 97-208 
 
 /1o 
 
 1150 
 
 27.60 
 
 
 29.60 
 
 97-210 
 
 X 
 
 1750 
 
 23.76 
 
 
 26.76 
 
 97-212 
 
 Vs 
 
 1150 
 
 29.26 
 
 
 31.26 
 
 97-214 
 
 Vs 
 
 1750 
 
 28.76 
 
 
 30.76 
 
 97-216 
 
 Ve 
 
 1150 
 
 44.00 
 
 
 46.00 
 
 97-218 
 
 Vo 
 
 1750 
 
 40.00 
 
 
 42.00 
 
 97-220 
 
 X 
 
 1150 
 
 64.00 
 
 
 66.00 
 
 97-222 
 
 X 
 
 1750 
 
 61.00 
 
 
 63.00 
 
 97-260 CANVAS FRICTION BRAKE, after Fuller and Brown¬ 
 lee (Experiment 86).$0.76 
 
 Nos. 97-200 to 97-222 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 397 
 
 Nos. 97-270 to 97-272 Nos. 97-274 to 97-278 
 
 The generators listed below are guaranteed to be of the very best material and workmanship, free from either 
 electrical or mechanical defects, and will carry their rated load continuously without attaining a temperature greater 
 than 40° Centigrade in excess of that of the surrounding air. 
 
 Prices are for compound wound generators and include standard pulley, sliding base with belt-tightening attach¬ 
 ment and wall type field regulating rheostat. 
 
 The speed stamped on the name plate of each dynamo is that at which it should be driven when it is desired 
 to operate it at the voltage marked. 
 
 Number 
 
 K. W. 
 
 Number of 
 
 25 Watt 
 
 16 C. P. Lamps 
 
 Speed 115 and 
 230 Volts 
 
 97-270 
 
 Vi 
 
 20 
 
 1850 
 
 97-272 
 
 % 
 
 30 
 
 1750 
 
 97-274 
 
 1 
 
 40 
 
 1650 
 
 97-276 
 
 
 60 
 
 1550 
 
 97-278 
 
 2 
 
 80 
 
 1400 
 
 Sire Pulley Price 
 
 Diam. 
 
 Face 
 
 115 V. 
 
 230 V. 
 
 4 
 
 2 
 
 $48.00 
 
 $61.00 
 
 4 
 
 2'A 
 
 62.60 
 
 66.00 
 
 5 
 
 iy 2 
 
 80.00 
 
 84.00 
 
 5 
 
 3 
 
 88.60 
 
 93.00 
 
 5V 2 
 
 YA 
 
 110.00 
 
 116.00 
 
 No. 97-286 
 
 97-286 CONTROLLER MODEL. The above illustrated device is designed to illustrate in a practical 
 manner the method of controlling the speed and operation of the modern electric railroad motor. 
 
 The commutator, resistances, etc., are well worked out in open construction so that the various 
 changes that occur and their effects upon the included model motor may be noted with ease and 
 accuracy. 
 
 The construction is substantial, parts clearly shown, and the whole design well suited for its didactic 
 purpose. 
 
 Complete as illustrated with motor.$31.00 
 
398 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ELECTRO-DYNAMIC CHARTS 
 
 No. 97-300 
 
 97-300 ELECTRO-DYNAMIC CHARTS for demonstrating the principles of dynamos and motors. These 
 charts, which are finely lithographed in colors and mounted on heavy cardboard, are of ample 
 size, 28 X 30 inches. They may be seen across the largest lecture hall; the complex mechanism 
 of the dynamo and motor, both alternating and direct current, may be clearly shown. The dif¬ 
 ferent windings, connections, armatures, poles, etc., are greatly magnified that they may be readily 
 seen. Each chart is mounted in a frame and the armature is rotated by means of a crank operated 
 from the rear. That the change of polarity may be demonstrated, change of poles in the armature 
 is automatically shown by different colors, one color for the North pole and another for the South 
 pole. 
 
 The set consists of charts as follows:.— 
 
 Group I. Double Chart consisting of; — 
 
 a. 1 Attachable hinged disc for the dynamo. 
 
 b. 1 Attachable hinged disc for the motor. 
 
 c. 2 Discs for Gramme’s Ring. 
 
 d. 1 Colored disc for the magnetic field. 
 
 e. 1 Double Collector, one side with two collecting rings, the other with an eight-segment 
 
 commutator. 
 
 f. 2 Brushes. 
 
 g. 4 Connecting Cords. 
 
 With the above Group the following demonstrations can be readily performed: — 
 
 1. Magneto Electric Machine, 2-pole armature, alternating current. 
 
 2. Magneto Electric Machine, 2-pole armature, direct current. 
 
 3. Two-pole Dynamo. 
 
 4. Dynamo with Gramme’s Ring Armature. 
 
 5. Alternating Current Motor, 2-pole. 
 
 6. Motor with Gramme’s Ring Armature. 
 
 Accessory Chart II for use in demonstrating alternating current machines. 
 
 Accessory Chart III for demonstrating alternating current motor. 
 
 Complete as above listed.Duty Free 
 
 No. 97-305 
 
 97-306 PROJECTION FREQUENCY INDICATOR for 110 
 A. C. Volt Current. This instrument is designed 
 primarily to show on the screen the effect pro¬ 
 duced by an alternating current on an electro¬ 
 magnet. The length of the vibrating reed is such as 
 to show clearly on the screen, the one-quarter wave 
 length, the one-half wave length, and the three- 
 quarter wave length. In use the instrument is con- 
 . nected directly to 110 volt alternating current with¬ 
 out additional resistance. 
 
 $7.60 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 399 
 
 Fig. 4 Fig. 3 Fig. 6 
 
 No. 97-310 
 
 WEINHOLD’S ROTARY FIELD APPARATUS for the study of the essential principles of an in¬ 
 duction or alternating current motor for either two-phase or three-phase currents, demonstrating 
 clearly the rotating magnetic fields. 
 
 The complete apparatus consists of a substantial base on which are mounted the current distributing 
 apparatus, Figure 1, connecting wires, and necessary devices for the interchangeable parts, the 
 one illustrated on the base board being a double coil. In addition there are furnished accessory 
 coils as follows: Ferraris’ Double Coil, Figure 2; Ferraris’ Triple Coil, Figure 3; 4-coil Iron Ring, 
 
 Figure 4; Ring of 6 Coils, Figure 5; Magnetized Needle and Iron-plate Disc with agate socket, 
 closed circuit armature; and perforated glass plate with alcoholized iron filings. 
 
 This apparatus permits of experiments demonstrating in a practical manner the effect of the rotary 
 field. In use from 4 to 6 cells of battery are required. This current can be changed into an alter¬ 
 nating current or rotary current by the distributing apparatus. This current is made to pass 
 through the twofold or three-fold crossed coils of wire of various colors. In the middle of either 
 of these coils may be placed a magnetic needle or an iron disc. By the rotation of the distributing 
 apparatus there is produced a current of either two or three phases, according as the twofold or 
 threefold ring is used, and the bodies placed within the coils rotate under the influence of the rotary 
 field. Instead of these wire armatures, however, an iron ring of 4 or 6 coils may also be used. 
 
 Such rings, Figures 1 and 3, are wound with wire wrapped with a covering of different colors. By 
 means of such rings synchronous rotation may be produced by the insertion of a magnetic needle or 
 an iron disc; and by an iron ring wound with copper wire (closed circuit armature) non-synchronous 
 
 The lines marking the direction of the influence of the rotary field 
 can also be more strikingly shown by means of a glass disc covered 
 with the iron filings furnished with the apparatus. 
 
 This instrument is of substantial structure, all parts neatly and hand¬ 
 somely finished, especially designed for teaching the principles in¬ 
 volved. The rotating parts are mounted with agate caps and steel¬ 
 bearing points. All wiring is indicated by different colors. All 
 connections are open to view on top of the base. The base is of 
 highly polished hardwood. 
 
 Complete with full directions for use.$40.00 
 
 THREE-PHASE CURRENT MOTOR MODEL (Tesla Motor) for 
 use with above Weinhold’s Rotary Demonstration Apparatus, 
 for the study of a rotary current motor. 
 
 This model is furnished with six fields, closed circuit armature., 
 with three leads. The winding is made in three colors and the 
 connections are open and in colors. The apparatus is practical, 
 clearly arranged, and shows the experiments in all their bearings. 
 
 It is highly recommended as an additional accessory to the above 
 outfit.19.60 
 
 rotation can be produced. 
 
 97-316 
 
 No. 97-316 
 
 ALTERNATING CURRENT DEMON¬ 
 STRATION APPARATUS 
 
 97-310 
 
400 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 TELEGRAPHY AND TELEPHONY 
 
 TELEGRAPH INSTRUMENTS 
 
 No. 98-20 No. 98-56 
 
 98-10 TELEGRAPH KEY, nickel-plated lever, brass frame, gutta-percha knobs, improved adjustment 
 
 spring holders, all parts finely finished, without legs.$1.90 
 
 98-12 TELEGRAPH KEY PARTS, after Turner and Hersey (Experiment E100).Set 1.00 
 
 98-16 IMPROVED SOUNDER, unequaled for quick action, loudness, and clear tone, proportioned scientifi¬ 
 cally correct, brass lever, resistance 5 ohms. 2.60 
 
 98-17 TELEGRAPH SOUNDER PARTS, after Turner and Hersey (Experiment E100).Set 1.00 
 
 98-20 TELEGRAPH RELAY, excellent quality, finely finished and mounted on polished mahogany base 
 
 with ornamented metallic sub-base. Standard resistance of 5 ohms. 3.40 
 
 98-26 COMBINATION KEY AND SOUNDER. This instrument is designed to fulfil the requirements of 
 a short-line apparatus. The sounder magnets, lever, anvil, and key lever are the same as used on 
 the preceding instruments. The frames for holding the sounder lever and key lever are stamped 
 from wrought iron and heavily japanned. The base is constructed of polished mahogany. 
 
 This instrument will give entire satisfaction on lines up to five miles in length. Resistance 5 ohms . . 2.60 
 
 TELEPHONE INSTRUMENTS 
 
 00 
 
 No. 98-100 No. 98-106 
 
 No. 98-110 
 
 98-100 DEMONSTRATION POSTLESS BI-POLAR RECEIVER. As may be noted from the illustration, 
 this instrument is entirely dissectible, and in consequence has a value as a demonstration instru¬ 
 ment, as well as that of a working receiver. All parts are carefully fitted and finished and the 
 
 receiver is high grade in every respect.$1.46 
 
 98-106 SOLID BACK WATCH CASE RECEIVER, 2J4 inches diameter, weight 6 ounces, resistance 75 
 ohms, rigid adjustment. 
 
 This is a simple receiver sufficiently sensitive for practically all laboratory work. 1.00 
 
 98-110 SOLID BACK LONG-DISTANCE TRANSMITTER. This transmitter is the standard commercial 
 type furnished on long-distance telephones. They articulate distinctly and plainly with no up 
 and down variations or sizzling. 2.00 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 401 
 
 No. 98-125 No. 98-135 
 
 98-125 TELEPHONIC MICROPHONE. This instrument illustrates in a clear and comprehensive manner 
 not only the microphone but the adaptation of same in the articulating telephone. It is in reality 
 two instruments in one, requiring only the simple adjustment of a thumb screw to change it from 
 a simple contact telephone to a practical working telephone. The small induction coil on the base 
 shows the manner of raising the potential of the telephonic circuit, which is inductively connected. 
 The results attending the connecting of the instrument with an ordinary telephone receiver and 
 battery cell are surprising. The ticking of a watch or the fall of a feather is heard with remark¬ 
 able distinctness. 
 
 98-135 
 
 KNOTT BATTERY CALL TELEPHONE. This is a handsome, well-constructed instrument with 
 solid back transmitter, double pole receiver, vibrating bell and call button. Guaranteed to give full 
 satisfaction on all short lines. Readily set up from full directions which accompany the instru¬ 
 ment .Each 
 
 Per pair 
 
 SELENIUM CELLS 
 
 98-140 SELENIUM CELL. The scientific 
 importance of the Selenium Cell 
 has been recognized since the 
 work of Bell and Ruhmer. It was 
 not, however, until recently that 
 its possibilities in the commercial 
 field were fully realized. Many 
 experimenters now agree that it is 
 through the medium of the Seleni¬ 
 um Cell that the “seeing” telephone 
 may eventually become a reality. 
 In our work with Selenium we have 
 discovered a most satisfactory 
 method of attaching the material 
 to the metal backing and im¬ 
 proved methods of annealing are 
 employed. The object has been to 
 obtain a permanent surface and 
 large area for the light to act upon 
 and an area which will give as low 
 initial electrical resistance as possi¬ 
 ble. 
 
 This Selenium Cell is extremely sensitive to light, dropping in resistance many thousands of ohms 
 when illuminated by a light of average intensity. Connected in series with a relay and battery, it 
 will cause the relay circuit to be closed when the cell is illuminated. If a screen be interposed be¬ 
 tween the light and the cell, the relay circuit will be immediately opened. A telephone receiver 
 connected in series with the Selenium Cell and a suitable battery will cause fluctuations in light 
 to be detected. For example, the alternating current arc gives a tone depending upon the fre¬ 
 quency of the current. Changes in the intensity of*a direct current arc produced by superimposing 
 on it a telephone current are audible. 
 
 Selenium Cell unmounted, surface 7 mm. square. 
 
 98-141 SELENIUM CELL, same as above, but with rectangular selenium surface. 44 X 19 mm. 
 
 98-142 MOUNTED SELENIUM CELL. Consists of Selenium Cell No. 98-141 above with Adjustable 
 Support No. 98-146 . 
 
 98-146 WNIVERSALLY ADJUSTABLE SUPPORT, especially designed for holding the mounted Selenium 
 Cell. 
 
 $5.75 
 
 4.25 
 
 8.50 
 
 $5.00 
 
 11.50 
 
 14.00 
 
 2.50 
 
402 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 MISCELLANEOUS APPLICATIONS OF 
 
 ELECTRICITY 
 
 ELECTROLYSIS AND ELECTRO-CHEMISTRY 
 
 No. 99-6 
 
 No. 99-10 
 
 99-6 PACKARD’S ELECTROLYSIS APPARATUS. We 
 
 are indebted to Mr. John C. Packard of Brookline 
 High School for this design. In simplicity of opera¬ 
 tion and cleanliness, it excels other apparatus de¬ 
 signed for the same purpose. There are no parts 
 which, when broken, cannot readily 
 be replaced. Consists of two special 
 moulded porcelain bottle rests 
 which are designed as electrode supports. 
 
 These bottle and electrode supports can be 
 used close together or apart to the limit of 
 the glass tray. In use, the bottles and tray 
 are filled to a point covering the mouths, 
 with the electrolyte. When current is con¬ 
 nected, action immediately begins. 
 
 Complete as illustrated with glass tray . . . $2.60 
 
 No. 99-30 
 
 30- 
 
 m 
 
 60= 
 
 1=30 
 
 =40 
 
 =50 
 
 99-20 
 
 1 99-10 SIMPLE ELECTROLYSIS APPARATUS. This is the standard form with sliding 
 graduated tubes and platinum electrodes. 
 
 99-16 THE H-ELECTROLYSIS OF WATER APPARATUS. This is an improved type 
 of electrolysis apparatus so designed that the platinum electrodes may easily be 
 replaced by those of carbon or copper. In addition the reservoir tube is directly 
 connected without bend to the junction tube of the gas tubes. 
 
 This type is ungraduated, and is for use with rubber tubing and pinch-cocks. 
 
 Complete with platinum electrodes. 
 
 99-20 THE HOFFMAN’S H-FORM ELECTROLYSIS OF WATER APPARATUS. This 
 design has the same improvements as the one above. It, however, has grad¬ 
 uated gas tubes provided with glass stop-cocks and the reservoir is globular 
 shaped. 
 
 Complete with platinum electrodes... 
 
 99-30^1,OSBORNE’S IMPROVED ELECTROLYSIS APPARATUS. This design has the 
 merit of efficient use in study of principles involved in electrolytic dissociations. 
 It consists of an H-tube with graduated slide tubes, each with shot valve. By 
 the improved construction of detachable electrodes the platinum electrodes may 
 be readily replaced by those of carbon or copper as illustrated. With a glass stop¬ 
 per plug the apparatus is set up as a conductivity cell. In use for study of elec¬ 
 trolysis of water the stopper plug is replaced by the bent end of the thistle tube. 
 
 Complete as illustrated. 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 
 
 403 
 
 99-50 CARBON ELECTRODES, as used in Nos. 99-15 and 99-30 .$0.66 
 
 99-62 -, for No. 99-20 . 75 
 
 99-65 COPPER ELECTRODES, as used in Nos. 99-16 and 99-30 .55 
 
 99-67 -, for No. 99-20 . . 
 
 99-60 PLATINUM ELECTRODES, as used in Nos. 99-16 and 99-30 . 1.60 
 
 99-62 -, for No. 99-20 .• 3 qq 
 
 99-76 TUBE SUPPORT. It is always advisable and oftentimes necessary to support an Electrolysis of 
 Water Apparatus during experimentation. Our support consists of a neat stand with clamp and 
 binding posts. 155 
 
 99-80 -, same as above, but smaller in size.. 1.40 
 
 No. 99-100 
 
 No. 99-105 
 
 No. 99-195 
 
 99-100 LANTERN ELECTR9LYSIS DEMONSTRATION APPARATUS. This design consists of a U- 
 shaped trough provided with a hard rubber cover with binding posts to which are connected the 
 platinum electrodes. This form will not leak and is not constructed with cumbersome com¬ 
 pressor clamps. 
 
 It is a neatly and handsomely finished scientific piece of apparatus.$4.76 
 
 99-106 HYDROGEN ABSORPTION APPARATUS, after Hall’s “Elements of Physics,” Paragraph 50, 
 for showing the power of palladium to absorb hydrogen. Consists of a palladium and a platinum 
 wire mounted parallel in a solid vulcanite frame. Binding posts supplied for connecting to a source 
 of electric current. 
 
 The frame is placed upright in a two per cent, solution of sulphuric acid and then an electric current, 
 strong enough to decompose the solution, is connected to the binding posts. It will be noted that 
 there is a visible flow of oxygen bubbles from the platinum wire, but no hydrogen bubbles from 
 the palladium wire. Palladium, when cold, absorbs several hundred times its own bulk of hy¬ 
 
 drogen. Without beaker. 4.25 
 
 MATERIAL FOR ELECTROPLATING 
 
 99-110 SILVER ANODE, sheet form. 1.25 
 
 99-116 NICKEL ANODE, sheet form. 75 
 
 99-120 COPPER ANODE, sheet form.60 
 
 COPPER SULPHATE, 1 pound bottle.20 
 
 AMMONIA HYDROXIDE, 1 pound bottle.30 
 
 AMMONIA HYDROXIDE, 4 pound bottle. 1.00 
 
 POTASSIUM CYANIDE, 1 pound bottle.60 
 
 NICKEL AND AMMONIUM SULPHATE, 1 pound bottle.60 
 
 SILVER CHLORIDE, 1 ounce bottle. .90 
 
 POWDERED PUMICE, 1 pound package.16 
 
 ROUGE, 1 pound package.40 
 
 TRIPOLI, 1 pound package.15 
 
 POWDERED EMERY, 1 pound package.16 
 
 99-126 ROUGE CLOTH, especially prepared. .20 
 
 99-130 CHAMOIS SKIN.66 
 
 We shall be very glad to supply the formulae on request for making solutions for silver, nickel, or copper electro¬ 
 plating. 
 
 99-170 ELECTROTYPING LETTERS, after Turner and Hersey (Experiment E163); also used in Fuller 
 and Brownlee (Experiment 71 ). 
 
 Set of three letters. .$0.15 
 
 99-195 ELECTROPLATING OUTFIT FOR COPPER PLATING, consisting of jar, special clamp cast¬ 
 ings, insulating support for same, two copper electrodes, chemicals and complete directions for 
 copper plating. 1-65 
 
404 
 
 L. J£. KNOTT APPARATUS CO., BOSTON 
 
 f 
 
 No. 99-200 
 
 99-200 SIMPLE ELECTRIC FURNACE. A simple practical form of electric furnace that will be found of 
 great utility in the teaching of the electric arc, electric furnace, as well as the melting and com¬ 
 bining properties of many elements. The construction enables a clear understanding of the many 
 principles involved. Its open construction has great pedagogic value. 
 
 A great variety of experiments may be conveniently performed, — the melting of platinum or like 
 refractory metals, the reduction or production of aluminum or carbides. The manufacture of 
 calcium carbide from lime and sawdust or carbon makes a striking and interesting experiment. 
 
 Complete ready for use.$ . . . . 
 
 No. 99-360 
 
 99-360 DEMONSTRATION ARC LAMP WITH REFLECTOR for use with any strong source of battery 
 current, but excellent for use with our No. 97-148 Gear Drive Hand Power Dynamo in demon¬ 
 strating the principle of arc lamps. It is a near approach to the automatic form, adjustment by 
 counterpoise gravity feed. Quite simple in form and of open construction throughout. A simple 
 reflector attached adds greatly to the effectiveness of the design. Complete as illustrated . . . 
 
 $26.00 
 
 $3.30 
 
CATALOGUE OF PHYSICAL INSTRUMENTS 405 
 
 TOOLS 
 
 We list below various tools which will be found of service in the laboratory. 
 
 200-10 AUGUR BITS, set of thirteen, from 34 to 1 inch.$4.75 
 
 200-15 BIT BRACE. . 
 
 200-20 BLOCK PLANE of iron, 534 inches long. .45 
 
 200-22 BREAST DRILL. Chuck has three drawers which hold round shanked bits from 0 to 34 inch. Drive 
 wheel 5 inches diameter. Gearing changeable three to one. Crank adjustable permitting varia¬ 
 tion in length of 334 inches. A first-grade tool throughout. 3.80 
 
 200—25 CHISEL, best Sheffield steel, one inch wide.60 
 
 200-30 CLAW HAMMER, first quality of cast steel, weight one pound.60 
 
 200-35 CLAW HAMMER, nickel-plated, ordinary grade. .48 
 
 200-40 COLD CHISEL, 34 inch.. .20 
 
 200-45 CORK SCREW, large size. 16 
 
 200-50 FILE, flat, 8 inches long. .20 
 
 200-55 FILE, half round, 8 inches long. .20 
 
 200-60 FILE, round, 8 inches long. .18 
 
 200-62 FILE, triangular, 8 inches long.•.. .18 
 
 200-66 GIMLET, large size, 5 inches long. .16 
 
 200-70 HACK SAW, consisting of malleable steel frame and saw blade . . . r. .55 
 
 200-76 HACK SAW BLADES, 8 inch, to fit the above frame.Per Dozen .60 
 
 200-77 HATCHET, STEEL CLAW, best forged steel, highly polished blade, bronze finish. .76 
 
 200-78 NIPPER, end cutting, length 6 inches.50 
 
 200-80 OIL STONE, in wooden box, 7 inches long. .36 
 
 200-82 PITCH GAUGE, “V” threads, 22 pitches, — 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 
 
 62, 64, 66, 68, 70, 72 and 74 threads per inch. 1.25 
 
 200-85 PLIERS, with side cutting blade, 5 inches. 50 
 
 200-86 PLIERS, COMBINATION SLIP JOINT, best forged steel, natural finish, polished jaws, length 
 
 634 inches. .. Each .40 
 
 200-88 PUNCH, SPRING, cast steel, first quality, full polished.35 
 
 200-90 SAW, CROSS-CUT, 26 inches long. 1.60 
 
 200-95 SAW, RIP, 26 inches long. 1.66 
 
 200-100 SAW, KEY-HOLE.25 
 
 200-105 SCREW DRIVER, instrument size, with small sharp blade. .20 
 
 200-110 SCREW DRIVER, heavy, 8 inch. .25 
 
 200-115 SHEARS, metal cutting, 234 inch blade.76 
 
 200-116 TAP AND DIE SET. Complete with stock round tap wrench, seven adjustable dies and seven taps 
 cutting the standard threads used in the manufacture of our apparatus: — %e, Vsa, % 2 , %2, 10 /s2, x %4 
 and 1 %4. In polished hardwood case. 7.60 
 
 200-117 TOOL CABINET for wall. Contains 18-inch panel saw, smoothing plane, half hatchet, nail hammer, 
 bit brace, 34 an d 34-inch bits, 5-inch butt chisel, scraper, awl and tool set, 6-inch flat-nose plier, 
 
 %2-inch nail set, 6-inch try square, folding boxwood rule, marking gauge, %0-inch gimlet bit, 8-inch 
 mill file with handle, oil stone, carpenter’s pencil, oil can, can of glue, 2 sheets of sandpaper, spool of 
 wire, assorted screws, nails, brads and tacks. All tools of the highest grade of steel. Solid oak 
 cabinet 24 X 16 X 6 inches deep, doors panelled, antique finish, varnished and hand rubbed, with 
 brass padlock with two keys.21.00 
 
 200-118 TOOL HOLDER, hollow polished cocobolo handle, containing the following tools warranted the 
 highest grade of steel:— two sizes firmer chisels, gouge, three sizes of screw drivers, gimlet, key¬ 
 hole saw, scriber, reamer, finely finished throughout. 1.10 
 
 200-119 -, similar to above but smaller and containing ten tools, as commonly supplied. .40 
 
 200-120 WRENCH (MONKEY WRENCH), 8 inches long.60 
 
 FIRST AID CABINET 
 
 No. 200-150 
 
 Every science laboratory should be equipped to render first aid in treating cuts and burns. That we may ad¬ 
 equately meet this need, we have made up a first aid cabinet containing both gauze and cotton bandages, 
 styptic and surgical gauze, court plaster, pins and the ordinary condiments required to stop bleeding 
 and for the proper treatment of burns, as well as for first aid treatment in case of poisoning. Cabinet 
 filled complete.$2.60 
 
406 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 
 3600 AIR TESTER, DEWING’S, for testing the amount of CO 2 in the air, according to National Biology 
 Note-book Sheet P61. Complete with Lime Water, Phenolphthalein, Pipette, Graduated Flask, 
 
 Graduated Cylinder, Graduated Tube and Plunger, with full directions. 
 
 3602 AIR TESTER, after Dr. G. W T . Fitz, for the accurate determination of CO 2 . 
 
 Consists of a carefully graduated instrument, set of Storage Vials, Graduated Flask, Graduated 
 Pipette and full set of directions. A most satisfactory piece of apparatus for an accurate determina¬ 
 tion of the amount of CO 2 in a room. With reagents in neat board case. 
 
 3604A PHENOLPHTHALEIN SOLUTION. Quantity sufficient for 100 tests. 
 
 3604B LIME WATER. Quantity sufficient for 100 tests. 
 
 3604C GRADUATED FLASK, 100 cc., for above apparatus. 
 
 3604D GRADUATED PIPETTE, 1 cc., for above apparatus. 
 
 3604E GRADUATED PIPETTE, 10 cc., for above apparatus. 
 
 ALCOHOLOMETERS. See Nos. 6673A and 6673B, page 448. 
 
 3606 SOLID ALCOHOL for use in the can as an alcohol stove. This alcohol is a patented product moulded 
 in solid form in a slip cover can. Always ready for instant use by removing cover and lighting con¬ 
 tents of can. An intense heat is at once generated and can and contents can be used to as good 
 advantage as an alcohol lamp. Flame readily extinguished by replacing cover upside down on top 
 of can. Capacity of can 3J£ ounces. Will burn continuously from one to one and one-half hours 
 3610 ALUNDUM, 60 mesh, for protecting the bottoms of Alundum Combustion Boats from the slagging 
 
 effect of the iron oxide during the combustion of the sample .Per A-\b. Bottle 
 
 3612 ALUNDUM CEMENT, superior to other mixtures for covering wire resistors in many kinds of high 
 
 temperature electrical apparatus and appliances .Per 2-lb. Bag 
 
 3616 APRON, chemical and water-proof, 48 inches long, 36 inches wide, readily adjusted to both sexes . . 
 
 OVERSLEEVES. See page 471. 
 
 3620 AQUARIA JARS, ROUND, heavy colorless glass. 
 
 a b c 
 
 Capacity, quarts 2 4 8 
 
 Size, inches 6X6 7X7 9X9 
 
 Each $0.80 1.10 1.66 
 
 3622 AQUARIUM JAR, RECTANGULAR, heavy colorless glass, capacity 2J4 gallons, 10J6 inches long, 
 
 6J£ inches wide, 10J£ inches high. 
 
 3626 AQUARIA, enameled metal frames, glass bottoms, finished in dark olive green with gilt decorations. 
 
 abed 
 
 3627 
 
 3628 
 
 Length, inches 
 
 12 
 
 15 
 
 18 
 
 21 
 
 Width, inches 
 
 8 
 
 10 
 
 12 
 
 14 
 
 Height, inches 
 
 7 
 
 9 
 
 11 
 
 13 
 
 Capacity, gallons 
 
 2'A 
 
 5 
 
 7 
 
 12 
 
 Each 
 
 $4.00 
 
 6.00 
 
 7.00 
 
 8.00 
 
 AQUARIUM TANK, with iron frame work and stone base. This aquarium must not be confused with 
 those where the light is blocked from the ends by stone slabs. Our tank has heavy plate glass in all four 
 sides, these glass plates being held by substantial iron frames locked at the corners by iron castings/! 
 
 The base is of alberene stone 1 inches thick. In sealing the plates water-tight, we use a cement which 
 we compound in our laboratories and which we guarantee will not leak nor soften by action of water. 
 
 Alberene stone base measures 32 X 21 ins. Dimensions of tank, outside, 30X 19 X 16 ins. deep. 
 
 Complete with standing ove rflow and brass gauze separating partition. 
 
 SUPPORTING AQUARIUM TABLE. We have frequently supplied a table support for the above 
 aquarium. This table is built of solid oak with acid proofed built-up maple top. It is equipped 
 with one drawer and further provided with a special long goose-neck water supply faucet. 
 
 F. O. B. Factory. 
 
 $3.60 
 
 3.00 
 
 .40 
 
 .30 
 
 .40 
 
 .10 
 
 .20 
 
 .10 
 
 .60 
 
 .70 
 
 .80 
 
 $4.00 
 
 $48.00 
 
 26.00 
 
CHEMISTRY AND BIOLOGY 
 
 407 
 
 1 
 
 6875 ARSENIC TUBES, hard glass. 
 
 a b 
 
 Each $0.06 .06 
 
 Set of four.• 
 
 c d 
 
 .06 .06 
 .$ 0.22 
 
 3540 
 
 3541 
 
 3543 
 
 3545 
 
 42-150 
 
 42-162 
 
 42-163 
 
 42-160 
 
 42-162 
 
 42-163 
 
 42-190 
 
 42-175 
 
 42-177 
 
 42-178 
 
 3550 
 
 ASBESTOS 
 
 Asbestos is fire and acid-proof and is, therefore, particularly adapted for use in science laboratories. 
 
 ASBESTOS BOARD, 40 X 40 inches. 
 
 a b 
 
 Thickness, inch %2 V ie 
 
 Per Sheet $0.42 .81 
 
 ASBESTOS BOARDS, inch thick. 
 
 a b 
 
 Size, inches 4X4 6X6 
 
 Each $0.03 .04 
 
 ASBESTOS BOARDS, Ys 2 inch thick. 
 
 a b 
 
 Size, inches 4X4 6X6 
 
 Each $0.02 .03 
 
 ASBESTOS WOOL, long selected fibre. Per 4-ounce package 
 
 1.20 
 
 c 
 
 12 X 12 
 
 .16 
 
 d 
 
 %0 
 
 2.20 
 
 $ 1.10 
 
 ASPIRATOR, CHAPMAN’S, of brass, 334 inches long, 34 inch I. P. size thread, capacity 5 cubic 
 feet per hour. 1.45 
 
 HYDRANT COUPLING for attaching above aspirator to a % inch hose bib or faucet. .30 
 
 HYDRANT COUPLING for attaching above aspirator to a smooth faucet. This coupling cannot 
 
 leak or be forced off.60 
 
 ASPIRATOR, CHAPMAN’S, of brass, 4% inches long, 34-inch I. P. size thread, capacity 18 cubic 
 
 feet per hour. 1.95 
 
 HYDRANT COUPLING for attaching above aspirator to a 34-inch hose bib or faucet. .30 
 
 HYDRANT COUPLING for attaching above aspirator to a smooth faucet. This coupling cannot 
 
 leak or be forced off.60 
 
 ASPIRATOR, MUENCKE’S, of glass, 834 inches long. This is a convenient demonstration in¬ 
 strument as all parts are of glass. 1.00 
 
 ASPIRATOR, RICHARDS’, of brass, very powerful, 7 inches long, %-incb I. P. size thread .... 1.80 
 
 HYDRANT COUPLING for attaching above aspirator to a 34-inch hose bib or faucet.30 
 
 HYDRANT COUPLING for attaching above aspirator to a smooth faucet. This coupling will not 
 
 leak and cannot be forced off. .60 
 
 ASPIRATOR, HIGH VACUUM, more powerful than preceding and uses less water, 34-inch I. P. size 
 thread. Length, 434 inches. 1.66 
 
408 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • ) 
 
 ^^pr^CS^BOSTON.MASS. 
 
 No. 3560 
 
 No. 3563 
 
 3560 HARCOURT STUDENTS’ AUXANOMETER. This instrument is not intended for precision work, 
 but will be found most satisfactory in measuring the growth of plants with a reasonable degree of 
 accuracy and sensibility. The apparatus as shown in the illustration is used on the regulation sup¬ 
 port stand and plant growth is indicated by movement of a pointer over a graduated arc. Without 
 Support Stand.$3.25 
 
 3563 BOVEE PRECISION AUXANOMETER, an invention by Dr. W. T. Bo vie of Harvard University, 
 for recording the growth of plants. For classroom or out-of-door use. Will indicate growth by as 
 small as 0.1 millimeter. 
 
 The Bovie Precision Auxanometer consists essentially of a device which is carried upward as the plant 
 grows. 
 
 When the device has moved a certain distance, it closes an electric circuit which operates the record¬ 
 ing pen of the chronograph. This arrangement makes it possible to have the recording mechanism at 
 any desired distance from the plant and to make simultaneous records of a number of plants or of 
 various parts of the same plant. 
 
 The instrument is light, compact and quickly set up for use and, as the force of gravity is not utilized for 
 moving any of its parts, it may be set at any angle with the vertical so that growth in any direction 
 may be measured and recorded. Records of each 0.1 mm. of growth can be made and the instru¬ 
 ment will be found reliable in or out-of-doors. The experimental model was run by Prof. Bovie 
 the entire summer in the garden exposed to the weather, the brass case being open part of the time 
 so that the internal mechanism was exposed. 
 
 Complete specifications furnished upon request. 
 
 Furnished in plush-lined polished hardwood box with hinged cover 
 
 BALANCES AND WEIGHTS. See pages 46 to 63. 
 
 25.00 
 
CHEMISTRY AND BIOLOGY 
 
 409 
 
 No. 3675 No. 3677 
 
 3570 BATHS, SAND, DEEP HEMISPHERICAL, of sheet iron. 
 
 a b c 
 
 Diameter, inches 3 4 6 
 
 Each $0.10 .14 .27 
 
 3572 BATHS, SAND, SHALLOW, of sheet iron. 
 
 a b c 
 
 Diameter, inches 3 4 6 
 
 Each $0.08 .10 .18 
 
 d 
 
 8 
 
 .45 
 
 d 
 
 8 
 
 .35 
 
 3576 BATH, SAND or HOT PLATE. Measures 6X8 inches. 
 
 On legs.$1.70 
 
 3577 BATH, SAND or HOT PLATE, RUEDORFF’S with ATTACHED BURNER. Of cast iron. Meas¬ 
 
 ures 11 X 7 inches, with three rows of burners that are adjustable in height.14.25 
 
 3579 PARAFFINE BATH, POLISHED COPPER, with tubulations for thermometer, gas regulator and 
 three test tubes. Dimensions, 7 inches long, Z % /i inches wide and 334 inches deep. With extra sheet 
 iron bottom and iron base which is 5 inches high. Provided with a space for heating slides and two 
 nickel-plated cups. The shallow cup is 234 inches diameter, 24-inch deep, watch glass shape, and 
 the deep one is 2% inches diameter and 134 inches deep. 9.75 
 
 3580 PARAFFINE BATH, LEWIS’, POLISHED COPPER. Temperature of this bath is maintained by a 
 constant convectional current. The heated water enters the bath through the heating tube, lead¬ 
 ing from the heating cylinder into the side of the bath and the return pipe from the bottom of the 
 bath conveys the cooler water back to the heating cylinder. The stopcock serves, also, to regulate 
 the amount of hot water, thus regulating the temperature. Three deep cups, 1% inches diameter 
 by 134 inches deep, tw'o shallow cups, 1J4 inches diameter by %• inch deep, four test tube or vial 
 receptacles and one opening for the thermometer are provided.19.76 
 
4io 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 WATER BATHS 
 
 The water baths listed below are of polished copper, tin-lined, most carefully made throughout. 
 
 No. 3682 
 
 No. 3686 
 
 No. 3687 
 
 No. 3683 
 
 No. 3690 
 
 No. 3693 
 
 3682 WATER BATHS, POLISHED COPPER, tin-lined, with concentric rings and steam cover. 
 
 abed 
 Diameter, inches 5 6 8 10 
 
 No. of Rings 4 5 7 8 
 
 Each $1.30 1.70 2.70 6.30 
 
 3683 WATER BATHS WITH STEAM VALVE, POLISHED COPPER, tin-lined, most excellent and eco¬ 
 
 nomical. 
 
 a b c 
 
 Diameter, inches 6 8 10 
 
 No. of Rings 5 7 8 
 
 Each $4.90 6.86 8.26 
 
 3686 WATER BATH, POLISHED COPPER, ON TRIPOD, tin-lined. Seamless body with concentric 
 
 rings and cover, steam escape and extra plate perforated for test tubes. 
 
 a b c 
 
 Diameter, inches 5 6 8 
 
 No. of Rings 4 5 7 
 
 Each $3.26 3.86 6.90 
 
 3687 WATER BATH, POLISHED COPPER, tin-lined, seamless body, with concentric rings and cover, 
 
 steam escape and extra plate perforated for test tubes. 
 
 a b c 
 
 Diameter, inches 5 6 8 
 
 No. of Rings 4 5 7 
 
 Each $2.90 3.26 6.26 
 
 3690 WATER BATH, FUNNEL SHAPE, POLISHED COPPER, tin-lined. With concentric rings and con¬ 
 stant water level. Height including tripod, 8 inches. 
 
 a b 
 
 Diameter, inches 6 8 
 
 No. of Rings 5 7 
 
 Each $3.90 4.86 
 
 3693 WATER BATH, HOFFMAN’S, of heavy polished copper, with a set of concentric rings and plate with 
 
 five holes of different sizes, each with cover. With constant water level. Diameter at top, 8 inches $13.76 
 

 
 CHEMISTRY AND BIOLOGY 
 
 3695 WATER BATH, GRIFFIN’S, POLISHED COPPER, tin-lined for hot filiations and evaporations. 
 
 Provided with a constant water level, an extra sheet iron bottom and rests on four detachable legs. 
 Size 13 X 7 X 5 inches deep. One 5-inch hole with four concentric rings and steam cover and one 
 
 open with copper funnel.$11.60 
 
 3600 WATER BATH, ELECTRICALLY HEATED, POLISHED COPPER, tin-lined. With two remova¬ 
 ble covers, one cover with two 5-inch openings and concentric rings, the other with thirty-six 
 inch holes for test tubes. Size 14J4 X 6J4 X 3 inches deep. Height over all 734 inches. Provided 
 with automatic cut-out that shuts off current if bath is allowed to run dry.32.50 
 
 3606 WATER BATH, POLISHED COPPER, tin-lined, with concentric rings and steam cover. Provided 
 
 with stopcock and Kekule’s Water Level Regulator. With extra sheet iron bottom, and supported 
 by four detachable legs. Size 14 X 14 X 5 inches deep. Four openings, 5 inches in diameter, 
 
 with rings and steam cover.17.00 
 
 3606A WATER BATH, STEAM, POLISHED COPPER, tin-lined, same as above, but arranged with coil 
 
 to be heated by steam.20.75 
 
 3606B WATER BATH, ELECTRIC, POLISHED COPPER, tin-lined, same as above, but arranged for elec¬ 
 trical heating.39.26 
 
 3607 WATER BATH, POLISHED COPPER, tin-lined, with concentric rings and cover, provided with stop¬ 
 
 cock and Kekule’s Water Level Regulator. With extra sheet iron bottom supported by four de¬ 
 tachable legs. Size 23 X 13J4 X 5 inches deep. Seven openings, three of 6 inches diameter and 
 
 four of 4 inches diameter with concentric rings and steam cover.23.50 
 
 3607A WATER BATH, STEAM, POLISHED COPPER, tin-lined, same as above, but arranged with coil to 
 
 be heated by steam.28.26 
 
 3607B WATER BATH, ELECTRIC, POLISHED COPPER, tin-lined, same as above, but arranged for elec¬ 
 trical heating.54.00 
 
 3610 WATER BATH, POLISHED COPPER, tin-lined, with concentric rings and steam cover. Provided 
 with stopcock and Kekule’s Water Level Regulator. With extra sheet iron bottom and supported 
 by four detachable legs. Size 28 X 14 X 5 inches deep, eight openings 5 inches in diameter with 
 
 rings and steam cover.29.60 
 
 3610A WATER BATH, STEAM, POLISHED COPPER, tin-lined, same as above, but arranged with coil to 
 
 be heated by steam....34.25 
 
 3610B WATER BATH, ELECTRIC, POLISHED COPPER, tin-lined, same as above, but arranged for elec¬ 
 trical heating.'.58.50 
 
 BATTERIES. See pages 320 to 325. 
 
 BATTERY JARS. See pages 326 and 461. 
 
 3616 BEADS, GLASS, hollow, for filtering and drying gases by means of acid.Per pound .96 
 
412 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 BEAKERS 
 
 Our line of Beakers has been selected with unusual care. We are confident that our customers will find not only 
 the kind but also the quality desired. 
 
 We have given special attention to our Glass Beakers. We offer an exceptionally high grade glass in our Har- 
 court Line and, quality considered, we feel that this line cannot be excelled at even a much higher cost. 
 
 L-r'KMOfiT APkftVAfUS CO 
 
 ROiT-jw .MAOS 
 
 
 3625 BEAKERS, HARCOURT GLASS, low, wide Griffin form, with lip. 
 
 
 a 
 
 b 
 
 c d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 No. 
 
 1 
 
 2 
 
 3 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 Capacity, cc. 
 
 75 
 
 100 
 
 200 300 
 
 400 
 
 600 
 
 800 
 
 1000 
 
 Each 
 
 $0.10 
 
 .13 
 
 .16 .19 
 
 .24 
 
 .30 
 
 .35 
 
 .45 
 
 BEAKERS, HARCOURT GLASS, 
 
 same as above, but nested as follows: 
 
 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 
 f 
 
 No. in Nest 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 
 8 
 
 Size No. 
 
 1-3 
 
 2-5 
 
 1-5 
 
 1-6 
 
 1-7 
 
 
 1-8 
 
 Capacity, cc. 
 
 75-200 
 
 100-400 
 
 75-400 
 
 75-600 
 
 75-800 
 
 
 75-1000 
 
 Per Nest 
 
 $0.39 
 
 .72 
 
 .82 
 
 1.12 
 
 1.47 
 
 
 1.92 
 
 3628 BEAKERS, “PYREX” GLASS. (See index, “Pyrex Glassware” for characteristics.) Griffin low 
 
 form, with lip. 
 
 a bcdefgh i jk 1 
 Capacity, cc. 50 100 150 250 400 600 800 1000 1300 1500 2000 2500 
 
 Each $0.13 .15 .17 .19 .27 .33 .38 .64 .65 .73 .98 1.13 
 
 3629 BEAKERS, “PYREX” GLASS, same as above, but nested as follows: 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 No. in Nest 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 Capacity, cc. 
 
 50-150 
 
 50-250 
 
 50-400 
 
 50-600 
 
 50-800 
 
 50-1000 
 
 Per Nest 
 
 $0.45 
 
 .64 
 
 .91 
 
 1.24 
 
 1.62 
 
 2.16 
 
 3631 
 
 BEAKERS, HARCOURT GLASS, 
 
 wide, usual form, without lip. 
 
 
 
 
 
 
 a b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 
 Size No. 
 
 1 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 
 Capacity, cc. 
 
 75 100 200 
 
 300 
 
 400 
 
 600 
 
 800 
 
 1000 
 
 
 Each 
 
 $0.10 .13 .16 
 
 .19 
 
 .24 
 
 .30 
 
 .35 
 
 .46 
 
 3632 
 
 BEAKERS, HARCOURT GLASS, 
 
 same as above, but nested as follows: 
 
 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 
 f 
 
 
 No. in Nest 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 
 8 
 
 
 Size No. 
 
 1-3 
 
 2-5 
 
 1-5 
 
 1-6 
 
 1-7 
 
 
 1-8 
 
 
 Capacity, cc. 
 
 75-200 
 
 100-400 
 
 75-400 
 
 75-600 
 
 75-800 
 
 75-1000 
 
 
 Per Nest 
 
 $0.39 
 
 .72 
 
 .82 
 
 1.12 
 
 1.47 
 
 
 1.92 
 
 3635 
 
 BEAKER, VASE SHAPE, ON ROOT, for use 
 
 on lecture desk for a large class of 
 
 
 chemical experiments. 
 
 
 
 
 
 
 
 
 Capacity 350 cc 
 
 
 
 
 
 
 
 . . $0.60 
 
 No. 3635 
 
CHEMISTRY AND BIOLOGY 
 
 413 
 
 3638 
 
 3640 
 
 3646 
 
 3660 
 
 3660 
 
 3661 
 
 3663 
 
 3664 
 
 3666 
 
 3667 
 3676 
 
 3676, 
 
 BEAKERS, ALUMINUM, Griffin form, with lip. 
 
 a b c 
 
 Capacity, cc. 250 500 1000 
 
 Each $0.66 1.00 1.60 
 
 BEAKERS, SPUN COPPER, polished, Griffin form, with lip. 
 
 a b c 
 
 Capacity, cc. 250 500 1000 
 
 Each $0.66 .90 1.60 
 
 BEAKERS, PORCELAIN, without lip, glazed inside and outside, extensively used in testing 
 
 stuffs, etc. 
 
 a 
 
 b 
 
 c 
 
 Capacity, cc. 
 
 340 
 
 580 
 
 970 
 
 Height, inches 
 
 4 H 
 
 5 Vi 
 
 6 Vs 
 
 Diameter, inches 
 
 3 
 
 3% 
 
 4 
 
 Each 
 
 $1.00 
 
 1.26 
 
 1.76 
 
 of dye 
 
 BEAKERS, FUSED SILICA. (See index, “Fused Silica Ware” for characteristics.) With lip. 
 
 Capacity, cc. 
 Each 
 
 a b 
 
 50 100 
 
 $0.90 1.00 
 
 c d 
 
 150 200 
 
 1.10 1.20 
 
 e f 
 
 250 400 
 
 1.46 1.70 
 
 g 
 
 500 
 
 1.96 
 
 h 
 
 600 
 
 2.20 
 
 800 
 
 2.66 
 
 BELL GLASSES. See page 164. 
 
 BIRDS 
 
 BIOLOGY AND NATURE STUDY 
 
 We have made arrangements with a leading taxidermist so that we carry the following: 
 
 COLLECTION OF MOUNTED BIRDS FOR SCHOOL USE. Contains thirty 
 of our common species representing the common orders. It includes *Grebe, 
 
 Tern, Teal, ’Heron, Rail, ’Sandpiper, *Hawk, Owl, Kingfisher, ’Woodpecker, 
 ’Kingbird, Phoebe, ’Bluejay, ’Crow, Cowbird, ’Blackbird, Meadow Lark, 
 Goldfinch, Native and English ’Sparrow, Towhee, Scarlet Tanager, ’Barn- 
 Swallow, Red-Eyed Vireo, ’Common Warbler, Catbird, House Wren, Chicka¬ 
 dee, ’American Robin, ’Bluebird.$74.00 
 
 SKINS of the above, unmounted.36.00 
 
 FIFTEEN COMMON SPECIES representing those starred in above list . . . 38.00 
 
 SKINS, unmounted.18.00 
 
 COLLECTION OF EGGS, corresponding to above collection (in a few cases 
 
 not identical with it in species). 6.40 
 
 COLLECTION OF EGGS, representing those starred in above list. 2.76 
 
 BLAST APPARATUS, RICHARDS’, for use where water pressure is available, 
 in obtaining either blast or vacuum. Desirable for quick filtering and oper¬ 
 ating blast lamp. Complete with one Aspirator. 9.76 
 
 -, with two Aspirators.12.00 
 
 No. 3676 
 
414 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 3686 BLAST LAMP, GASOLINE, pint capacity, giving a small hot flame, generating its own gas. With 
 
 holder with cork-lined cap on side of the body for holding cleaner wire and nozzle when not in use. 
 
 Will burn constantly for about three hours with one filling.$1.60 
 
 3687 BLAST LAMP, GASOLINE, one pint capacity, giving an intensely hot blue flame which can be regu¬ 
 
 lated to a small pointed flame or brush flame as desired. Of seamless drawn brass and fitted with an 
 
 automatic brass pump. 4.60 
 
 For other BLAST LAMPS and BURNERS, see pages 200-202. 
 
 BLOWERS, FOOT, for supplying a blast of air for lamps, blowpipes, etc. A rubber disc forms the 
 air reservoir and equalizes the pressure by its elasticity. By increasing the number of discs a greater 
 air pressure is obtained. 
 
 We list two styles, one with air reservoir above, the other with legs and air reservoir below. 
 
 3696 BLOWER, FOOT, air reservoir above, diameter of reservoir 7J4 inches, pressure of blast per inch 
 one pound, cubic feet of air per hour 190. 
 
 With single disc. 6.00 
 
 3696 -, diameter of reservoir 9 inches, pressure of blast per inch pounds, cubic feet of air per hour 
 
 330 . With double disc. 8.16 
 
 3697 -, diameter of reservoir 11 inches, pressure of blast per inch 1% pounds, cubic feet of air per 
 
 hour 625. With three discs.12.90 
 
 3699 BLOWER, FOOT, with legs, air reservoir below. Diameter of reservoir 7}^ inches, pressure of blast 
 
 per inch one pound, cubic feet of air per hour 190. With single disc. 6.86 
 
 3700 -, diameter of reservoir 9 inches, pressure of blast per inch 1J^ pounds, cubic feet of air per hour 
 
 330 . With double disc... . 9.36 
 
 3701 -, diameter of reservoir 11 inches, pressure of blast per inch pounds, cubic feet of air per hour 
 
 625. With three discs.13.80 
 
 3702 RUBBER DISC, made of the best quality para rubber, steam cured. 9J4 inches diameter, for use with 
 
 Blowers Nos. 3696 and 3699 .Each .96 
 
 3702A , same as above, but 11J4 inches diameter, for use on Blowers Nos. 3696 and 3700 .Each 1.36 
 
 3702B , same as above, but 14^ inches diameter, for use on Blowers Nos. 3697 and 3701 .Each 1.96 
 
 3702C BLOWER NETS, as used on above Blowers.Each .46 
 
 3710 
 
 BLOWPIPES, of brass, plain. 
 
 a 
 
 b 
 
 
 Length, inches 
 
 8 
 
 10 
 
 
 Each 
 
 $0.22 
 
 .28 
 
 3711 
 
 BLOWPIPES, of brass, with bulb. 
 
 a 
 
 b 
 
 
 Length, inches 
 
 8 
 
 10 
 
 
 Each 
 
 $0.36 
 
 .42 
 
 3716 BLOWPIPE MOUTH PIECE, trumpet shape, hard rubber, \% inches diameter.$0.40 
 
 3716A BLOWPIPE MOUTH PIECE, ordinary form, of close grained hard wood, 1 inches long.12 
 
 3720 BLOWPIPE, AUTOMATIC BRAZING, nickel-plated, for light soldering. Length 10 inches . . . 2.46 
 
 3722 BLOWPIPE, AUTOMATIC BRAZING, with pilot light. Small size, of brass, with two stopcocks, 
 
 % 5 -inch air tube and %-inch gas tube. Length 11 inches. 1.96 
 
 3724 BLOWPIPE, AUTOMATIC BRAZING, for general work. Of brass, with two stopcocks, %-inch air pf« 
 
 tube and 5^-inch gas tube. Length 16 inches. 4.40 
 
CHEMISTRY AND BIOLOGY 
 
 415 
 
 3726 BLOWPIPES, GLASS BLOWERS’ FIRES OR BURNERS. Two required, one mounted opposite to 
 other. For use with foot blowers or other forms of blast. Each with three burners. Mounted 
 
 as illustrated on stand. Per set of two .. $14.76 
 
 BONE CUTTING FORCEPS, see page 433. 
 
 BONE SAW. See page 433. 
 
 BOTANICAL MOUNTS. See SPECIMEN MOUNTS, page 480. 
 
 BOTANICAL PRESS. See PLANT PRESS, page 472. 
 
 3736 
 
 3736 
 
 3737 
 
 3738 
 
 3740 
 
 3742 
 
 3746 
 
 3747 
 3749 
 
 3761 
 
 3763 
 
 b 
 
 2 
 
 .04 
 
 b 
 
 2 
 
 .04 
 
 No. 3737 
 
 BOTTLES, prescription, narrow mouth. a 
 
 Capacity, ounces 1 
 
 Each $0.03 
 
 BOTTLES, prescription, wide mouth. a 
 
 Capacity, ounces 1 
 
 Each $0.03 
 
 BOTTLES, tincture, narrow mouth, with ground glass stopper. 
 
 a b c 
 
 Capacity, ounces 12 4 
 
 Each $0.09 .10 .12 
 
 BOTTLES, salt mouth, wide mouth with ground glass stopper. 
 
 a b c 
 
 Capacity, ounces 12 4 
 
 Each $0.09 .10 .12 
 
 BOTTLES, ACID or STORAGE, with ground glass stoppers. 
 Capacity, pints 
 Each 
 
 No. 3738 
 
 c 
 
 4 
 
 .06 
 
 c 
 
 4 
 
 .06 
 
 d 
 
 8 
 
 .09 
 
 d 
 
 8 
 
 .09 
 
 e 
 
 16 
 
 .14 
 
 e 
 
 16 
 
 .14 
 
 d 
 
 8 
 
 .16 
 
 d 
 
 8 
 
 .16 
 
 a 
 
 1 
 
 $0.16 
 
 e 
 
 16 
 
 .22 
 
 e 
 
 16 
 
 .22 
 
 b 
 
 5 
 
 .30 
 
 f 
 
 32 
 
 .20 
 
 f 
 
 32 
 
 .20 
 
 f 
 
 32 
 
 .36 
 
 f 
 
 32 
 
 .36 
 
 3746 
 
 No. 3747 
 
 3749 
 
 No. 3761 
 
 No. 3763 
 
 BOTTLE, ASPIRATOR, with tubulature for rubber tubing, capacity 32 ounces.$1.26 
 
 BOTTLE, BALSAM or DROPPING, triangular shaped ground glass stopper, drawn to a point, 
 
 ground glass cap. Capacity 1J4 ounces. 
 
 BOTTLE, BALSAM or DROPPING, with ground glass cap and glass rod. Capacity 2 ounces . . . 
 BOTTLE, DROPPING, bulb pipette, ground into the neck, forms an air-tight container. Capacity one 
 
 ounce . 
 
 BOTTLE, DROPPING (COBALT BOTTLE), with ball top, pipette ground in. Capacity one ounce 
 BOTTLES, DROPPING, with grooves in neck and in stopper. When the grooves coincide, the con¬ 
 tents may be poured out drop by drop. A quarter turn of the stopper closes the bottle air-tight. 
 
 a b 
 
 Capacity, ounces 1 2 
 
 Each $0.26 .30 
 
 .35 
 
 .48 
 
 .36 
 
 .48 
 
4i6 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 Vitrified Labels 
 Transparent Letters 
 
 Capacity 
 Height, inches 
 Per dozen 
 
 REAGENT BOTTLES 
 
 With Indestructible Vitrified Labels—With Raised Ground Glass Labels— 
 
 Transparent Letters. 
 
 Both types of Reagent Bottles listed are free from lead, zinc or other me¬ 
 tallic flux. They are uniform in shape and the different capacities are uniform 
 in height. The Reagent Bottles with Raised Ground Glass Labels have long 
 been in use and can, therefore, be called the Standard Type. The variety of 
 stock labels, however, is limited and many science laboratories have required 
 us to furnish bottles which will have labels covering chemicals and reagents 
 complete as used in science laboratories. Our Reagent Bottles with Indestructi¬ 
 ble Vitrified Labels meet this demand. 
 
 REAGENT BOTTLES WITH RAISED GROUND GLASS LABELS. ORDER 
 BY CATALOGUE NUMBERS in the following listings. When no number is listed 
 the raised ground glass label cannot be obtained, but to order, and at an extra 
 price, the same shape and size may be obtained with label engraved on the bottle. 
 
 Ounce 
 
 Ounce‘(W 7 ide Mouth) 
 
 Pint 
 
 J4 Pint (Wide Mouth) 
 
 Vi Pint 
 
 3^4 
 
 
 5^4 
 
 4 Vs 
 
 6V 2 
 
 $1.35 
 
 1.48 
 
 1.96 
 
 2.15 
 
 2.66 
 
 
 Raised Ground 
 Glass Labels 
 
 Pint Quart 
 
 7 H 9'A 
 
 3.65 4.86 
 
 REAGENT BOTTLES WITH INDESTRUCTIBLE VITRIFIED LABELS 
 
 These bottles have a smooth white background against which the transparent letters and symbols are clearly 
 defined. Although higher in cost than Reagent Bottles above described, these bottles greatly enhance the appear¬ 
 ance of the equipment and have the advantage that stock labels for practically all the chemicals and reagents used 
 in science laboratories may be obtained. ORDER BY CATALOGUE NUMBERS, in the following listings. Where 
 no number is listed, bottles with labels not on the list can be obtained but at an extra price and on order only. 
 Capacity M Pint 34 Pint (Wide Mouth) 34 Pint Pint Quart 
 
 Height, inches 534 534 634 734 934 
 
 Per Dozen $5.76 6.76 6.80 7.26 8.90 
 
 Suggestive Equipments for Students’ Desks, General Laboratory Use and Stock May Be Obtained on Application. 
 
 SS^ 
 
 3 w 
 
 ° c 
 
 ’"O, 
 
 V* 
 
 CO 0 ) 
 
 S3 
 
 Oti 
 
 csj 2 
 
 w <5 
 
 j 
 
 o 
 
 m 
 
 2 
 
 >< 
 
 C/3 
 
 WITH INDESTRUCTIBLE VITRIFIED LABELS 
 J 
 
 a^ss 
 
 0-5 Cd^ 0-5 
 
 n g ooa. 
 
 * 
 
 401 402 801 1601 3201 
 
 403 404 803 1603 3203 
 
 405 406 805 1605 3205 
 
 409 410 809 1609 3209 
 
 413 414 813 1613 3213 
 
 417 418 817 1617 3217 
 
 — - 819 1619 - 
 
 - 821 1621 3221 
 
 423 424 823 1623 3223 
 
 427 428 827 1627 3227 
 
 - — 829 1629 3229 
 
 WITH RAISED GROUND GLASS LABELS 
 
 NAME 
 
 J 
 
 O 
 
 ffl 
 
 S 
 
 >- 
 
 co 
 
 e 
 
 3 
 
 O 
 
 as 
 
 H 
 
 a 
 
 o »> 
 
 n 
 
 ao 
 
 a 
 
 437 
 
 438 
 
 837 
 
 1637 
 
 3237 
 
 (NHi)sS. 
 
 441 
 
 442 
 
 841 
 
 1641 
 
 3241 
 
 NH«CNS. 
 
 — 
 
 — 
 
 845 
 
 1645 
 
 3245 
 
 SbCl 6 . 
 
 449 
 
 450 
 
 849 
 
 1649 
 
 3249 
 
 BaCl 2 . 
 
 451 
 
 452 
 
 851 
 
 1651 
 
 3251 
 
 Ba(OHl 2 . 
 
 453 
 
 454 
 
 853 
 
 1653 
 
 3253 
 
 Ba(N0 3 ) 2 . 
 
 — 
 
 — 
 
 855 
 
 1655 
 
 3255 
 
 C 6 H 6 . 
 
 457 
 
 458 
 
 857 
 
 1657 
 
 3257 
 
 
 461 
 
 462 
 
 861 
 
 1661 
 
 3261 
 
 Br. 
 
 463 
 
 464 
 
 863 
 
 1663 
 
 3263 
 
 CaCh. 
 
 — 
 
 — 
 
 865 
 
 1665 
 
 3265 
 
 CaCl 2 . 
 
 467 
 
 468 
 
 867 
 
 1667 
 
 3267 
 
 Ca(OH) s . 
 
 
 
 R71 
 
 lfi7l 
 
 3971 
 
 
 473 
 
 474 
 
 873 
 
 1673 
 
 3273 
 
 CS 2 . 
 
 
 
 875 
 
 1675 
 
 3275 
 
 
 477 
 
 478 
 
 877 
 
 1677 
 
 3277 
 
 Cl. 
 
 — 
 
 — 
 
 879 
 
 1679 
 
 3279 
 
 CHCI 3 . 
 
 481 
 
 482 
 
 — 
 
 — 
 
 — 
 
 H3C6H5O7 . 
 
 483 
 
 484 
 
 883 
 
 1683 
 
 3283 
 
 Co(NOs ) 2 . 
 
 485 
 
 486 
 
 885 
 
 1685 
 
 3285 
 
 
 — 
 
 488 
 
 — 
 
 — 
 
 — 
 
 Cu. 
 
 489 
 
 490 
 
 889 
 
 1689 
 
 3289 
 
 CuS 04 . 
 
 491 
 
 492 
 
 891 
 
 1691 
 
 3291 
 
 
 493 
 
 494 
 
 893 
 
 1693 
 
 3293 
 
 
 — 
 
 — 
 
 895 
 
 1695 
 
 — 
 
 
 HC 2 H 3 O 2 .Acetic Acid. 
 
 C 2 H s OH.Alcohol. 
 
 NHj.Ammonia. 
 
 (NH 4 ) 2 C0 3 .Ammonium Carbonate. 
 
 NH 4 CI.Ammonium Chloride. 
 
 NH 4 OH.Ammonium Hydroxide. 
 
 ..Ammonium Hydroxide. Cone.. 
 
 ..Ammonium Hydroxide, Dil.... 
 
 (NH 4 )eMo 7024 .Ammonium Molybdate. 
 
 (NH 4 ) 2 C 2 0 «.Ammonium Oxalate. 
 
 (NH 4 ) 2 HP 04 .Ammonium Phosphate. 
 
 ..Ammonium Sodium Phosphate 
 
 Ammonium Sulphate . 
 
 Ammonium Sulphydrate . 
 
 Barium Carbonate. 
 
 Blank. 
 Borax. 
 
 Calcium Sulphate .. 
 Carbon Bisulphide. 
 
 Carbon Tetrachloride. 
 
 Cochineal. 
 
 Esbach's Solution. 
 
 Ether. 
 
 Ethyl Alcohol.... 
 
 HC 2 H 3 O 2 . 
 
 C 2 H 5 OH. 
 
 NH 3 . 
 
 (NH4) S C03.... 
 
 NH 4 CI. 
 
 NH 4 OH. 
 
 .NiLOH+Aq;; 
 
 (NH4)6Mo7024.- - 
 
 (NH4) 2 C 2 04 . . .- 
 
 (NH4) 2 HP04 ..-R130 
 
 NaNH 4 HP 04 . .-R132 
 
 (NH 4 )2S04 .... -- 
 
 (NH 4 ) 2 S. 
 
 NH 4 CNS. 
 
 •NH 4 HS. 
 
 BaCOs. 
 
 BaCl 2 . 
 
 Ba(OH )2 . 
 
 Ba(N 0 3 )2 . 
 
 -R157 R158 
 
 Na 3 B407 .. R160 
 
 CaCl 2 . 
 
 CaCb. 
 
 Ca(OH) 2 . . . . 
 
 CaS 04 ...... 
 
 CS 2 . 
 
 CHCI 3 . . . . - 
 
 Co(NOj) 2 '. ’.’.'. R183- 
 
 Cu.." !.’-R188 
 
 CUSO 4 .. . 
 
 (C 2 H5) 2 0.. . 
 
 -3 
 
 O.S 
 
 3 . a. 
 
 R401 
 
 R403 
 
 R405 
 
 R409 
 
 R413 
 
 R417 
 
 R423 
 
 R427 
 
 ►J 
 
 SJ 
 
 tfl 
 
 o a> 
 
 S c 
 
 *5 
 
 eS 
 
 3*. 
 
 o.s 
 
 00 0 . 
 
 R801 
 
 R803 
 
 R805 
 
 R809 
 
 R813 
 
 o*. 
 
 to 0) 
 
 si 
 
 (N « 
 W 3 
 O 
 
 R817 R1617 
 
 R823 
 
 R827 
 
 R1621 
 
 R437 
 
 R441 
 
 R443 
 
 R447 
 
 R449 
 
 R451 
 
 R453 
 
 R457 
 
 R461 
 
 R463 
 
 R465 
 
 R467 
 
 R469 
 
 R434 
 
 R837 R1637 
 
 R849 R1649 
 
 R458 
 
 R460 
 
 R857 R1657 
 
 R867 R1667 
 - R1669 
 
 R473 
 
 R479 
 
 R485 
 
 R489 
 
 R493 
 
 R1693 
 
CHEMISTRY AND BIOLOGY 
 
 417 
 
 WITH INDESTRUCTIBLE VITRIFIED LABELS 
 
 WITH RAISED GROUND GLASS LABELS 
 
 g^o-s 
 S ied. a'-' 
 3 " 3 -w 
 
 0.3 o.S 
 
 w ^ 
 
 wj 
 o'-* 
 c> 
 
 W 
 
 Q i> 00 
 
 o 
 
 
 °r 
 
 CO C 
 
 IB 
 
 w, 
 
 <N g 
 m 3 
 O 
 
 W 
 
 O 
 
 ra 
 
 5 
 
 >< 
 
 CO 
 
 511 
 
 512 
 
 517 
 
 518 
 
 521 
 
 522 
 
 525 
 
 526 
 
 529 
 
 530 
 
 533 
 
 534 
 
 535 
 
 536 
 
 537 
 
 538 
 
 541 
 
 542 
 
 — 
 
 546 
 
 549 
 
 550 
 
 551 
 
 552 
 
 553 
 
 554 
 
 555 
 
 556 
 
 561 
 
 562 
 
 563 
 
 564 
 
 565 
 
 566 
 
 569 
 
 570 
 
 575 
 
 576 
 
 581 
 
 582 
 
 583 
 
 584 
 
 585 
 
 586 
 
 587 
 
 588 
 
 591 
 
 592 
 
 593 
 
 594 
 
 597 
 
 598 
 
 599 
 
 600 
 
 601 
 
 602 
 
 603 
 
 604 
 
 605 
 
 606 
 
 607 
 
 608 
 
 609 
 
 610 
 
 611 
 
 612 
 
 613 
 
 614 
 
 615 
 
 616 
 
 617 
 
 618 
 
 619 
 
 620 
 
 621 
 
 622 
 
 623 
 
 624 
 
 627 
 
 628 
 
 631 
 
 632 
 
 633 
 
 634 
 
 635 
 
 636 
 
 641 
 
 642 
 
 643 
 
 644 
 
 647 
 
 648 
 
 651 
 
 652 
 
 — 
 
 654 
 
 655 
 
 656 
 
 — 
 
 662 
 
 663 
 
 664 
 
 zz 
 
 666 
 
 897 
 
 1697 
 
 3297 
 
 899 
 
 1699 
 
 3299 
 
 901 
 
 1701 
 
 3301 
 
 903 
 
 1703 
 
 3303 
 
 905 
 
 1705 
 
 3305 
 
 907 
 
 1707 
 
 3307 
 
 909 
 
 1709 
 
 3309 
 
 911 
 
 1711 
 
 3311 
 
 915 
 
 1715 
 
 3315 
 
 917 
 
 1717 
 
 3317 
 
 921 
 
 1721 
 
 3321 
 
 923 
 
 1723 
 
 3323 
 
 925 
 
 1725 
 
 3325 
 
 929 
 
 931 
 
 1729 
 
 3329 
 
 
 
 933 
 
 1733 
 
 3333 
 
 935 
 
 1735 
 
 3335 
 
 937 
 
 1737 
 
 3337 
 
 939 
 
 1739 
 
 3339 
 
 941 
 
 1741 
 
 3341 
 
 • 943 
 
 1743 
 
 3343 
 
 ■ 947 
 
 1747 
 
 3347 
 
 1 949 
 
 1749 
 
 3349 
 
 : 951 
 
 1751 
 
 3351 
 
 : 953 
 
 1753 
 
 3353 
 
 i 955 
 
 1755 
 
 3355 
 
 • 957 
 
 1757 
 
 3357 
 
 959 
 
 1759 
 
 3359 
 
 ! 961 
 
 1761 
 
 3361 
 
 : 963 
 
 1763 
 
 3363 
 
 i 965 
 
 1765 
 
 3365 
 
 967 
 
 1767 
 
 3367 
 
 1 969 
 971 
 
 1769 
 
 1771 
 
 3369 
 
 
 ■ 973 
 
 1773 
 
 3373 
 
 975 
 
 1775 
 
 3375 
 
 • 977 
 
 1777 
 
 3377 
 
 979 
 
 1779 
 
 3379 
 
 : 983 
 
 1783 
 
 3383 
 
 985 
 
 1785 
 
 3385 
 
 987 
 
 1787 
 
 3387 
 
 989 
 
 1789 
 
 3389 
 
 991 
 
 1791 
 
 3391 
 
 993 
 
 1793 
 
 3393 
 
 995 
 
 1795 
 
 3395 
 
 999 
 
 1799 
 
 3399 
 
 1001 
 
 1801 
 
 3401 
 
 1003 
 
 1803 
 
 3403 
 
 1005 
 
 1805 
 
 3405 
 
 1007 
 
 1807 
 
 3407 
 
 1009 
 
 1809 
 
 3409 
 
 1011 
 
 1811 
 
 3411 
 
 1013 
 
 1813 
 
 3413 
 
 1017 
 
 1817 
 
 3417 
 
 1021 
 
 1821 
 
 3421 
 
 1023 
 
 1823 
 
 3423 
 
 1027 
 
 1827 
 
 3427 
 
 1031 
 
 1831 
 
 3431 
 
 1033 
 
 1833 
 
 3433 
 
 
 1039 
 
 1839 
 
 3439 
 
 1041 
 
 1841 
 
 3441 
 
 1045 
 
 1845 
 
 3445 
 
 1047 
 
 1847 
 
 3447 
 
 1051 
 
 1851 
 
 3451 
 
 1055 
 
 1855 
 
 3455 
 
 1057 
 
 1857 
 
 3457 
 
 
 1063 
 
 1863 
 
 3463 
 
 NAME 
 
 . Fehling’s Alkaline Solution. 
 . Fehling’s Copper Solution. . 
 . Fehling’s Solution. 
 
 W 
 
 O 
 
 m 
 
 S 
 
 ;* 
 
 to 
 
 c 
 
 3 
 
 o 
 
 a 
 
 H 
 
 p 
 
 O <u 
 
 WO 
 
 Q 
 
 W vao 
 4JX 
 o r_> 
 
 a 
 
 O.S 
 
 i-3 
 
 wx 
 
 Si 
 
 §s 
 
 Qg 
 
 *1 
 
 (DV* 
 
 C —* 
 3 4-» 
 
 O.S 
 00 a. 
 
 §$ 
 co G 
 
 co o 
 
 O 4-» 
 
 «d 
 
 3 
 
 a 
 
 ■ Fe 2 Cl 6 . 
 .FeS0 4 . 
 .FeS... 
 
 . Formalin. 
 
 . Glycerine.. 
 
 . Gold Chloride.AuCl 3 . 
 
 R501 
 
 -R503 - 
 
 R206 R505 R506 R905 
 R208 
 
 R1705 
 
 . R213 
 
 . Hydrochloric Acid.HC1 . 
 
 .Hydrochloric Acid, Cone.HC1 . 
 
 . Hydrochloric Acid, Dil.HC1 . 
 
 . Hypophosphoric Acid, Dil.. . . 
 . Indigo Solution. 
 
 .Pb(C 2 H 3 0 2 ) 2 . 
 
 .Litmus Paper. 
 
 .Litmus Solution... . 
 
 .Magnesia Mixture . 
 
 • MgS0 4 . 
 
 • HgClj. . 
 ■ HgNOs- 
 
 . Methyl Orange... 
 . Millon's Reagent. 
 
 . Nessler’s Solution. 
 
 . Nitric Acid.HNO 3 . 
 
 . Nitric Acid, Cone.HNO 3 . 
 
 . Nitric Acid, Dil.HNO 3 . 
 
 . Nitro Hydrochloric Acid.. 
 
 . Nitro Hydrochloric Acid, Dil...- 
 
 .Nitro Sulphuric Acid.. 
 
 . Oil Turpentine. 
 
 . h 2 c 2 o 4 . 
 
 . Phenolphthalein. 
 
 . Phosphoric Acid, Dil. 
 
 PtCU. 
 
 . R291 
 
 KBr.Potassium Bromide . 
 
 k 2 co 3 . 
 
 KNO 3 .Potassium Nitrate. . 
 
 KNaC 4 H 4 06+4H 2 0 ..Potassium Sodium T 
 K 2 S0 4 .Potassium Sulphate. 
 
 .KI.... 
 
 .KNO3. 
 
 .k 2 so 4 . 
 
 R302 
 
 R306 
 
 R316 
 
 . Silver Sulphate.Ag 2 S0 4 . 
 
 . R323 
 
 .Sodium Bitartrate.NaHC 4 H 4 06 . 
 
 • R330 
 
 633 634 1033 1833 3433 Na 2 C0 3 .Sodium Carbonate.Na 2 CO s . 
 
 NaC10 3 .Sodium Chlorate.. 
 
 ..Sodium Cobaltic Nitrite.. 
 
 641 642 1041 1841 3441 NaOH.Sodium Hydroxide.NaOH. 
 
 NaPH 2 0 2 .Sodium Hypophosphite. 
 
 . Sodium Nitrate.NaN 03 . 
 
 . Sodium Thiosulphate.Na 2 S 2 0 3 . 
 
 . Stannous Chloride.SnCl 2 .. . 
 
 . Starch... 
 
 . .. ..Sulphuric Acid......H 2 S0 4 .. 
 
 1057 1857 3457 H^S0 4 .Sulphuric Acid, Dil.H 2 S0 4 .. 
 
 . Sulphuric Acid, Cone.H 2 S0 4 . . 
 
 Test Paper... 
 
 Turmeric.. 
 
 Zn.Zinc....Zn. 
 
 R346 
 
 R354 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 R517 
 
 R519 
 
 
 
 R1717 
 
 R1719 
 
 
 — 
 
 R919 
 
 R921 
 
 R3319 
 
 R3312 
 
 
 
 
 R525 
 
 R529 
 
 
 
 
 
 
 R929 
 
 
 
 
 
 
 R533 
 
 
 
 
 
 
 
 
 
 R537 
 
 
 
 
 
 
 
 
 
 R541 
 
 
 R941 
 
 
 
 
 
 
 
 
 
 
 
 R547 
 
 R549 
 
 R551 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 R555 
 
 R557 
 
 R559 
 
 R561 
 
 
 R955 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 R565 
 
 
 
 
 
 
 
 
 
 R569 
 
 R571 
 
 
 
 R1769 
 
 R1771 
 
 
 — 
 
 R971 
 
 R973 
 
 R3371 
 
 R3373 
 
 
 
 
 
 
 
 R583 
 
 R585 
 
 R587 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 R591 
 
 R593 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 R599 
 
 
 
 
 
 
 
 
 
 R603 
 
 
 
 
 
 R606 
 
 
 
 
 R607 
 R609 
 R611 
 R613 
 
 
 
 
 
 
 
 
 
 RlOll 
 
 R1811 
 
 
 
 
 R616 
 
 
 
 
 
 
 
 
 R619 
 
 R621 
 
 R623 
 
 R625 
 
 R627 
 
 
 
 
 
 
 
 
 
 
 R1023 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 R633 
 
 R634 
 
 R1033 
 
 
 
 
 
 R637 
 
 
 
 
 
 
 
 
 
 R641 
 
 
 R1041 
 
 
 
 
 
 
 
 R647 
 
 R649 
 
 R651 
 
 
 R1047 
 
 
 
 
 
 
 
 R1051 
 
 
 
 
 
 
 R655 
 
 
 
 R1855 
 
 
 
 R1057 
 
 R1059 
 
 R3457 
 
 R3459 
 
 R659 
 
 
 R1859 
 
 - 1067 1867 3467 ZnS0 4 .Zinc Sulphate . 
 
 R366 
 
 R663 
 
 R662 
 
 SUGGESTIVE EQUIPMENTS FOR STUDENTS’ DESKS, GENERAL LABORATORY USE AND 
 
 MAY BE OBTAINED ON APPLICATION 
 
 STOCK 
 
418 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 3760 
 
 No. 31-140 
 
 No. 31-126 
 
 No. 3770 
 
 No. 3777 
 
 31-132 
 
 3760 
 
 31-140 
 
 31-126 
 
 3770 
 
 3776 
 
 3777 
 
 3782 
 
 3784 
 
 3790 
 
 3792 
 
 BOTTLE, SPECIFIC GRAVITY (PYKNOMETER), not adjusted, with perforated stopper ground 
 
 into neck. Capacity 25 cc. 
 
 BOTTLES, SPECIFIC GRAVITY (PYKNOMETERS), accurately adjusted, with perforated stop¬ 
 pers ground into necks. < a b c d 
 
 Capacity, cc. 10 25 50 100 
 
 Each $0.60 0.67 0.92 1.10 
 
 BOTTLE, SPECIFIC GRAVITY (PYKNOMETER), double wall with vacuum, accurately adjusted. 
 
 Capacity 25 cc. 
 
 BOTTLE, SPECIFIC GRAVITY (PYKNOMETER) with GROUND-IN CENTIGRADE THER¬ 
 MOMETER, accurately adjusted. With stoppered capillary tube. Capacity 50 cc. 
 
 BOTTLES, SPECIMEN, Bent neck, square, — will lie flat. 
 
 a b c 
 
 Small Medium Large 
 
 Size, ounces )4 1 2 
 
 Per Dozen $0.94 1.10 1.22 
 
 BOTTLES, WASHING, DRECHSEL’S, with tubes ground into the neck. 
 
 a b c 
 
 Capacity, cc. 125 250 500 
 
 Each $1.00 1.26 1.60 
 
 BOTTLES, WASHING, with antimony rubber stoppers and two bent tubes as illustrated. 
 
 a b c 
 
 Capacity, cc. 250 500 1000 
 
 Each $0.32 .42 .68 
 
 BOTTLES, WEIGHING, cylindrical, light blown glass, with shoulder and ground-in glass stopper. 
 
 a b 
 
 Capacity, cc. 
 
 20 
 
 50 
 
 Each 
 
 $0.40 
 
 .60 
 
 :tles, weighing, 
 
 flat bottom, ground glass 
 a 
 
 stopper 
 
 Diameter, mm. 
 
 25 
 
 40 
 
 Length, mm. 
 
 50 
 
 50 
 
 Each 
 
 $0.46 
 
 .66 
 
 No. 3792 No. 3790 
 
 BREEDING CAGE, HARCOURT, FOR INSECTS. Wooden frame, solid bottom, gauze front, 
 back, top and sides. One end hinged and provided with clasp. Outside dimensions 24 X 18 X 12 
 
 inches.. 
 
 BREEDING CAGE, KNOTT’S, FOR AQUATIC INSECTS. Can also be used for wood boring 
 larvae, etc. This outfit is in reality a combination aquarium and breeding cage. The lower part 
 is a substantially constructed aquarium 13)4 X 8)4 X 8 inches deep, inside dimensions. With 
 glass front, back and ends, and provided with stopcock. The upper part measures 14 X 11 X 9 
 inches over all and is provided with glass front and gauze back and ends. One end is hinged 
 and provided with clasp. Substantially framed in metal and painted throughout. Top remova¬ 
 ble. Dimensions over all 14 % inches long, 10 inches wide, 20)4 inches high. 
 
 $0.30 
 
 2.16 
 
 2.76 
 
 $4.70 
 
 13.76 
 
 
 
 
 
 
 
 
No. 3820 No. 3845 
 
 No. 3860 No. 3861 No. 3865 
 
 No. 3824 
 
 No. 3825 
 
 3800 
 
 3802 
 
 3803 
 3806 
 16-260 
 3808 
 
 3810 
 
 3811 
 3813 
 3820 
 3822 
 
 3824 
 
 3825 
 3830 
 3840 
 
 3842 
 
 3843 
 3845 
 3850 
 
 3852 
 
 3853 
 
 3855 
 
 3856 
 
 3860 
 
 3861 
 3865 
 
 3870 
 
 3871 
 
 BRUSH, ACID, of spun glass.$0.45 
 
 BRUSH, BEAKER or FUNNEL, with long wooden handle. .22 
 
 BRUSH, BOTTLE, with wood handle... .20 
 
 BRUSH, BURETTE, or TUBE, with 3-foot wire handle. .10 
 
 BRUSH, CAMEL’S-HAIR, J^ inch wide, best quality. .16 
 
 BRUSH, “COUNTER,” best quality. Should be in every laboratory. .60 
 
 BRUSH, TEST TUBE, bristle end, wire handle.,. .07 
 
 BRUSH, TEST TUBE, sponge end, wire handle. .07 
 
 BRUSH, TUBE, for narrow tubes, wire handle.•..03 
 
 BULB, CONNECTING, Hopkins’ New Form .., . . . .36 
 
 BULB, POTASH, Liebig’s, with five bulbs..... .44 
 
 BULB, POTASH, Mohr’s, improved by Geissler. 1.25 
 
 BULB, POTASH, Mohr’s, improved by Geissler, with drying tube attached . 1.60 
 
 BULB EXPANDER, for stretching necks of rubber bulbs . .50 
 
 BURETTES, MOHR’S, for pinchcock. Without fittings. Subdivided into tenths. 
 
 abed 
 Capacity, cc. 10 25 50 100 
 
 Each $0.46 .66 1.00 1.80 
 
 BURETTE, SCHELLBACH’S, Mohr’s, white back with color line, without fittings. 25 cc. X M cc. $1.26 
 
 -, 50 cc. X H cc.. 1.48 
 
 ATTACHMENT, Glass Tips, Rubber Tubing and Pinchcock for use with Nos. 3840,3842 and 3843 above .25 
 BURETTES, GEISSLER’S, with straight glass stopcocks. Subdivided into tenths. 
 
 abed 
 Capacity, cc. 10 25 50 100 
 
 Each $1.40 1.65 1.90 2.70 
 
 BURETTE, FRESENIUS’, 25 cc. X % cc.,.$1.60 
 
 -, 50 cc. X % cc. 2.20 
 
 BURETTE, SCHELLBACH’S, Geissler’s, white back with color line. 25 cc. X ;h6 cc. 1.60 
 
 -, 50 cc. X % cc. 2.20 
 
 BURETTE CAPS.. Per Dozen .60 
 
 BURETTE FLOAT, Erdmann’s. When ordering, state the accurate inside diameter of the burette .33 
 
 BURETTE FUNNELS.Each .16 
 
 BURETTE, AUTOMATIC ZERO, three-way stopcock for filling, discharging reservoir. 25 cc. X % cc. 6.26 
 -, 50 cc. X H cc. 6.00 
 
 

 420 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 3875 
 
 No. 3880 
 
 No. 3881 
 
 No. 3882 No. 3900 No. 3902 
 
 No. 3883 No. 3886 
 
 No. 3903 No. 3904 No. 3905 
 
 No. 3906 No. 3907 
 
 No. 3890 
 
 3876 BURNER, HIGH TEMPERATURE for either coal, natural or gasoline gas. Both air and gas can be 
 
 regulated separately. The special feature of this burner is that the whole flame is practically uniform 
 in temperature, eliminating entirely the cold air zone. Height 6% inches with 1-inch grid .... $1.85 
 
 3880 BURNER, TWO TUBE, with air regulators. Height 6 inches, diameter of tubes % inch. 1.30 
 
 3881 BURNER, THREE TUBE CLUSTER, with air regulators. Height 6 inches, diameter of tubes % 
 
 inch. 1.60 
 
 3882 BURNER, FOUR TUBE CLUSTER, with air regulators. Height 6 inches, diameter of tubes J4 inch 1.95 
 
 3883 BURNER, FOUR TUBE GANG, with air regulators and stopcocks. Diameter of tubes J4, inch, 
 
 height 8 inches. 4.46 
 
 3885 BURNER, BUNSEN’S, FOUR TUBE GANG with support and trough for heating tubes. With air 
 
 regulators, stopcocks and wing tops. Complete as illustrated.>. 9.25 
 
 3890 BURNERS, RING, for heating funnels, etc. May be attached to any support. 
 
 a b c 
 
 Diameter, inches 3 4 6 
 
 Each $1.30 1.50 1.90 
 
 BURNERS, GLASS BLOWERS’. See BLOWPIPES, Page 416. 
 
 BURNERS FOR SOLDERING IRONS. See SOLDERING IRON HEATERS, Page 479. 
 
 For other BURNERS, see Pages 200-202. 
 
 BURNER ATTACHMENTS 
 
 for 
 
 Burners with Tubes Jje-Inch Diameter 
 
 3900 BURNER TUBE for blowpiping with yellow flame. Fits inside the burner 
 
 3901 BURNER TIP with rest for blowpipe. 
 
 3902 BURNER CROWN for heating small dishes. Gives a round flame .... 
 
 3903 BURNER GAUZE TOP giving a large round flame. 
 
 3904 BURNER WING TOP for bending glass tubing, etc. 
 
 3905 BURNER STAR. 
 
 3906 BURNER TRIPOD.'. 
 
 3907 BURNER CHIMNEY of sheet iron, 2 inches diameter at the bottom . . . 
 
 $0.13 
 
 .12 
 
 .38 
 
 .24 
 
 .09 
 
 .21 
 
 .17 
 
 .14 
 
3915 
 
 70-50A 
 
 70- 50B 
 
 71- 272 
 
 3925 
 
 3927 
 
 3929 
 
 3931 
 
 3934 
 
 3938 
 
 CHEMISTRY AND BIOLOGY 
 
 421 
 
 CAGES, BREEDING. See Page 418. 
 
 CALCIUM CHLORIDE TUBES. See TUBES, Page 490. 
 
 CALCIUM CHLORIDE HOLDER for balance cases.$0.33 
 
 CANDLES, PARAFFINE, Sixes (six to the pound). Per Dozen .33 
 
 CANDLES, PARAFFINE, Twelves (twelve to the pound). Per Dozen .20 
 
 CANDLE, STANDARD, made of sperm, six to the pound. Will burn 120 grains 
 
 (7.776 grams) per hour.Each .25 
 
 No. 3915 
 
 CAPSULES, CIRCULAR, FUSED SILICA. (See index, “Fused Silica Ware,” for 
 characteristics.) Plain, glazed. 
 
 a b c d e f 
 
 Diameter, mm. 
 
 35 
 
 44 
 
 51 
 
 57 60 
 
 70 
 
 Depth in Center, mm. 
 
 13 
 
 13 
 
 13 
 
 13 13 
 
 16 
 
 Price, each 
 
 $0.60 
 
 .60 
 
 .90 
 
 .90 1.00 
 
 1.26 
 
 CAPSULES, IGNITION, ALUNDUM. 
 
 (See index, 
 
 “Alundum Ware,” for characteristics.) 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 
 Diameter, inches 
 
 1VS2 
 
 1 % 
 
 1 5 A 
 
 
 
 Height, inches 
 
 K 
 
 5 A 
 
 5 A 
 
 7 A 
 
 
 Capacity, cc. 
 
 7 
 
 10 
 
 18 
 
 25 
 
 
 Each 
 
 $0.28 
 
 .33 
 
 .38 
 
 .44 
 
 
 CAPSULES, RECTANGULAR, 
 
 FUSED 
 
 SILICA. 
 
 (See index, 
 
 “Fused Silica Ware,”„for 
 
 charac- 
 
 teristics.) Glazed. 
 
 a 
 
 
 b 
 
 c 
 
 
 Length, mm. 
 
 56 
 
 
 48 
 
 63 
 
 
 Width, mm. 
 
 24 
 
 
 38 
 
 35 
 
 
 Depth, mm. 
 
 10 
 
 
 16 
 
 10 
 
 
 Each 
 
 $1.00 
 
 
 1.00 
 
 1.25 
 
 
 CARDS, LOGARITHM. See LOGARITHM CARDS, Page 462. 
 
 CASSEROLES, AGATE WARE, with attached handle. 
 
 ~-7 
 
 --—- . --f - 
 
 a 
 
 b 
 
 
 c 
 
 d 
 
 Capacity, cc. 
 
 250 
 
 500 
 
 
 750 
 
 1000 
 
 Each 
 
 $0.20 
 
 .22 
 
 
 .28 
 
 .30 
 
 CASSEROLES, 
 
 PORCELAIN, with porcelain handle. 
 
 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 Capacity, cc. 
 
 125 
 
 190 
 
 375 
 
 625 
 
 1000 
 
 Each 
 
 $0.60 
 
 .60 
 
 1.00 
 
 1.76 
 
 2.00 
 
 CASSEROLES, 
 
 FUSED SILICA. (See index, 
 
 “Fused Silica Ware, 
 
 ” for characteristics.) 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 Diameter, mm. 51 
 
 70 
 
 82 
 
 95 
 
 108 
 
 Depth, mm. 
 
 25 
 
 35 
 
 44 
 
 51 
 
 63 
 
 Each 
 
 $1.76 
 
 2.15 
 
 2.65 
 
 3.40 
 
 4.40 
 
422 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 CENTRIFUGES 
 
 No. 3945 
 
 No. 3950 
 
 No. 3955 
 
 3946 CENTRIFUGE, DOUBLE ARM, HAND DRIVE, accurately cut phosphor-bronze gears with Babbitt 
 metal bearing and ball-bearing rest. Entirely dust-proof. Relief clutch in handle makes it impos¬ 
 sible to stop suddenly and disturb sediment in the glass tubes. New style holder eliminates danger 
 of breaking the tubes. Speed, 2000 to 2500 R. P. M., obtained with ease and entire safety. 
 
 Complete with two plain and two graduated 15-cc. glass tubes.$13.60 
 
 CENTRIFUGE, ELECTRIC, for use on 110 or 220 volts D. C. and A. C. Circuits, on direct current 
 approximately 1500 R. P. M., on alternating current, approximately 1300 R. P. M. Prices include 
 attachment cord and plug, with rotating head with metal tubes. Glass parts are extra as listed. 
 
 3948 -, for 110 volts, D. C. With Rheostat.24.76 
 
 3950 -——, for 110 volts, A. C. Without Rheostat (not required)..22.26 
 
 3952A PLAIN GLASS TUBES, 15 cc. for above centrifuges.Each .12 
 
 3952B GRADUATED GLASS TUBES, 15 cc. for above centrifuges.Each .45 
 
 3952C RUBBER CAPS for above tubes.Each .08 
 
 3955 CENTRIFUGE, ELECTRIC, DOUBLE ARM, for blood, sputum, and milk analysis. Enclosed rheostat 
 
 for control of speed. Can be used on both direct and alternating current at 110 volts, but not ad¬ 
 vised or guaranteed on direct current for a longer period than three to five minutes. Improved tube 
 holder eliminates danger of breaking the tubes. 
 
 Complete with two plain and two graduated 15-cc. tubes and six feet of electric cord with plug . . . 34.00 
 
 Note: —When either direct or alternating current is available, it is advisable to order this Cen¬ 
 trifuge for the particular current on which the motor is to be run. 
 
 CENTRIFUGE ACCESSORIES 
 
 3957 PLAIN GLASS TUBE, 15 cc.$0.12 
 
 3958 GRADUATED GLASS TUBE, 15 cc..45 
 
 3969 HAEMATOKRIT, with tubes for examination of blood and sputum. 4.90 
 
 3970 CHARCOAL BLOCKS for blowpipe work..Per Dozen .46 
 
 3975 CHART, ATOMIC WEIGHT, compiled by Dr. F. W. Clarke and reported to the American Chemical 
 
 Society. Corrected to 1911. Length 62 inches; mounted on common rollers. 1.35 
 
 3976 CHART, PERIODIC LAW, according to MendelejeS, on basis of 0 = 16. Revised and corrected by 
 
 Dr. F. W. Clarke, up to 1911. American nomenclature. Length 62 inches; mounted on common 
 
 rollers. 1.50 
 
 77-80 CHART, SPECTRUM, after Kirchhoff and Bunsen, showing beautifully the spectrum of the sun, K, 
 
 Rb, Cs, Tl, Na, Li, Ca, Sr and Ba. Mounted on linen back with common rollers. 4.25 
 
 77-82 CHART, SPECTRUM, after Kirchhoff and Bunsen, showing the following spectra, — In, C, Bo, Mn, 
 
 Pb, Cu, Co, Ni and Fe. Mounted on linen back with common rollers. 4.26 
 
 6895 CHLORINE TUBE, after Newell’s “Descriptive Chemistry,” Experiment 23, and “General Chemis¬ 
 try,” Experiment 29. .77 
 
CHEMISTRY AND BIOLOGY 
 
 423 
 
 No. 4000 
 
 No. 4002 
 
 No. 4004 
 
 No. 4006 
 
 No. 4008 
 
 No. 4026 No. 4030 
 
 No. 4040 
 
 4000 
 
 4002 
 
 4004 
 
 4006 
 
 4008 
 
 4011 
 
 4013 
 
 4015 
 
 4017 
 
 4020 
 
 4022 
 
 4026 
 
 4026 
 
 4030 
 
 4032 
 
 4034 
 
 4036 
 
 4040 
 
 4042 
 
 6305 
 
 CLAMP, BURETTE, with attached Clamp Holder. Check nut to adjust to any position, cork-lined 
 
 jaws open to 1J4 inches. 
 
 CLAMP, DOUBLE BURETTE, closes automatically by means of coiled springs; cork-lined jaws . . 
 
 CLAMP, DOUBLE BURETTE, HOFFMAN’S, opening 134 inches, length 7 inches. 
 
 CLAMP, BUNSEN’S, for attaching to support rods of ring stands by means of Clamp Holder. Cork- 
 
 lined round jaws open to 134 inches. Without Clamp Holder. 
 
 CLAMP, BUNSEN’S, for attaching to support rods of ring stands by means of Clamp Holder. One 
 
 flat and one V-shaped cork-lined jaw. Opens to 2 inches. W’ithout Clamp Holder. 
 
 CLAMP HOLDER for use with either of above clamps. 
 
 CLAMP, BUNSEN’S QUICK ACTING, compound lever adjustment. Jaws open to 134 inches. 
 
 Adjustment to full opening of the jaws by one-half turn of the turn buckle. 
 
 CLAMP, BUNSEN’S CONDENSER, for attaching to support rod of ring stands by means of Clamp 
 Holder. With swivel cork-lined jaws which adapt themselves to regular or irregular shapes. Jaws 
 
 open to 234 inches. Without Clamp Holder. 
 
 CLAMP HOLDER for use with either of above clamps. 
 
 CLAMPS, CABINET MAKERS’, of malleable iron, japanned, with ball and socket, swivel cap and 
 screw.. a b c 
 
 Open, inches 3 4 6 
 
 Each $0.28 * .38 .60 
 
 CLAMPS, HAND SCREW, of wood, superior quality. 
 
 a b c 
 
 Length of Jaws, inches 7 8 10 
 
 Open, inches 3 434 534 
 
 Each $0.40 .48 .60 
 
 CLAMP, “CUT-OFF,” of brass, nickel-plated, for tubes up to 34-inch diameter. 
 
 CLAMP, “CUT-OFF,” nickel-plated, with 34-inch opening. 
 
 CLAMPS or SCREW COMPRESSORS, of brass, nickel-plated. Can be placed upon tube without 
 disconnecting the apparatus. a b 
 
 Size, inches 34 X ^ 34 X 134 
 
 Each $0.26 .30 
 
 CLAMPS, HOFFMAN’S SCREW COMPRESSORS, nickel-plated. 
 
 a b 
 
 Size, inches 34 X 34 34 X 1 
 
 Each $0.25 .30 
 
 CLAMP, LEVER SCREW COMPRESSOR, for heavy walled tubing, of brass, nickel-plated, nicely 
 
 finished with rounded edges. Size, 34 inch. 
 
 CLAMPS, MOHR’S PINCHCOCKS, of brass, nickel-plated. 
 
 a b c 
 
 Small Medium Large 
 
 Length, inches 234 234 3J4 
 
 Each $0.10 .12 .16 
 
 CLAMP, TEST TUBE, of spring wire. Will hold test tubes from 34 to 134 inches diameter. Will 
 
 not burn. 
 
 CLAMP, TEST TUBE, of wood, with wire spring. 
 
 CLAY PIPES.Per Dozen 
 
 $0.33 
 
 .80 
 
 .95 
 
 .30 
 
 .38 
 
 .16 
 
 1.25 
 
 .80 
 
 .16 
 
 .03 
 
 .05 
 
 .30 
 
 .08 
 
 .08 
 
 .16 
 
424 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • J 
 
 HARCOURT CLINOSTATS 
 
 STUDENTS’ — ADVANCED 
 
 No. 4050 
 
 Showing Pot mounted vertically 
 
 No. 4050 
 
 Showing Pot mounted horizontally 
 
 4060 HARCOURT STUDENTS’ CLINOSTAT for small pots or especially for seeds growing in moss. Con¬ 
 sists of a 24-hour clock enclosed in a practically dust and moisture-proof case of cast metal. De¬ 
 signed so that shaft may be used horizontally or vertically. $ 7.60 
 
 No. 4052 
 
 Showing Pot mounted horizontally 
 
 No. 4052 
 
 Showing Pot mounted vertically 
 
 4062 HARCOURT ADVANCED CLINOSTAT for pots up to 3 inches horizontally or larger vertically or for 
 seeds growing in moss. This clinostat consists essentially of an eight-day clock enclosed in a prac¬ 
 tically dust and moisture-proof casing of cast metal. A 3-inch pot is recommended, as the instrument 
 works best with.this size. A 4-inch pot may be used, however, especially in the vertical position. 
 
 Complete with set of clamps for holding pot as illustrated.. $ 16.00 
 

 CHEMISTRY AND BIOLOGY 
 
 425 
 
 
 4066 
 
 COMBUSTION BOATS, ALUNDUM. (See index, “Alundum Ware,” for characteristics.) 
 
 Valuable for all kinds of determinations involving combustions at high temperatures, particularly well 
 suited for conditions met in the determination of carbon in iron and steel. Wall, V, inch. 
 
 a b c d e 
 
 4067 
 
 4069 
 
 4071 
 
 Length, inches 
 
 3H 
 
 3% 
 
 4H 
 
 5 
 
 5V 
 
 Width, inches 
 
 k 
 
 Vs 
 
 Vs 
 
 V 
 
 y 2 
 
 Height, inches 
 
 % 
 
 Vs 
 
 K 
 
 Ji 
 
 
 Each 
 
 $ 0.33 
 
 .38 
 
 .46 
 
 .45 
 
 .46 
 
 COMBUSTION BOAT SHIELDS, ALUNDUM. (See index, “Alundum Ware,” for characteristics.) 
 For protecting combustion boats from the spattering of overheated metal. Wall, %2 inch. 
 
 a b 
 
 Length, inches 
 
 4>i 
 
 5V 2 
 
 Bore, inches 
 
 
 13 /i6 
 
 Each 
 
 $0.83 
 
 1.10 
 
 COMBUSTION BOATS, PLATINUM. See PLATINUM WARE, page 473. 
 
 COMBUSTION BOATS, ROYAL WORCESTER 
 Porcelain Ware,” for characteristics.) a 
 
 Length, mm. 60 
 
 Width, mm. 10 
 
 Each $0.22 
 
 COMBUSTION BOATS, FUSED SILICA. (See index, 
 
 a b 
 
 PORCELAIN, 
 b 
 75 
 11 
 .30 
 
 (See 
 
 c 
 
 75 
 
 15 
 
 .35 
 
 index, “Royal 
 d 
 
 100 
 18 
 
 .66 
 
 Worcester 
 
 “Fused Silica Ware,” for characteristics.) 
 
 Length, mm. 
 
 44 
 
 76 
 
 76 
 
 102 
 
 152 
 
 Width, mm. 
 
 13 
 
 13 
 
 16 
 
 16 
 
 12 
 
 Depth, mm. 
 
 8 
 
 8 
 
 10 
 
 10 
 
 12 
 
 Each 
 
 $0.60 
 
 .76 
 
 .90 
 
 1.15 
 
 1.60 
 
 
 4076 
 
 COMBUSTION FURNACES. See FURNACES, pages 440 to 
 443. 
 
 CONDENSERS, LIEBIG’S, GLASS, with rubber connections 
 and adapters. a b c 
 
 Length, inches 12 15 18 
 
 Each $0.96 1.26 1.40 
 
 No. 4079 
 
 'S' 
 
 No. 4081 
 
 4077 CONDENSER, LIEBIG’S, METAL, for. the distillation of liquids, made entirely of brass, highly 
 
 polished. Length 30 inches; diameter 1J4 inches. This form prevents breakage.$2.76 
 
 4079 CONDENSER, SOXHLET’S BALL, copper, tinned inside, for use with extraction apparatus. Pol¬ 
 ished and nickel-plated. Diameter 4 inches. 3.00 
 
 4081 CONDENSER, SOXHLET’S DOUBLE, same as above, but with two bulbs, 4 inches in diameter. 
 
 Connected as illustrated... 8.26 
 
 4085 CONDENSERS, ZINC, with pure block tin worm. 
 
 a b c d e 
 
 Capacity, gallons 1 2 3 5 
 
 Each $6.60 6.60 8.00 11.00 16.00 
 
 90-310 CONNECTORS, DOUBLE.Each .11 
 
 90-316 CONNECTORS, TRIPLE.Each .18 
 
I 
 
 426 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6005 
 
 CORKS, REGULAR LENGTH, 
 
 Nos. 
 
 TAPERED, 
 
 0 
 
 excellent quality. 
 
 1 2 
 
 3 
 
 4 
 
 
 5 
 
 Length, inches 
 
 % 
 
 34 
 
 34 
 
 34 
 
 34 
 
 
 34 
 
 Diameter large end, inches 
 
 34 
 
 % 
 
 34 
 
 %0 
 
 34 
 
 
 1 34e 
 
 Per Dozen 
 
 $0.03 
 
 .03 
 
 .03 
 
 .03 
 
 .04 
 
 
 .04 
 
 Per Gross 
 
 $0.15 
 
 .16 
 
 .17 
 
 .20 
 
 .23 
 
 
 .30 
 
 Nos. 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 
 11 
 
 Length, inches 
 
 34 
 
 X 
 
 % 
 
 X 
 
 1 
 
 
 1 
 
 Diameter large end, inches 
 
 % 
 
 x %8 
 
 34 
 
 15 /l6 
 
 1 
 
 
 134 
 
 Per Dozen 
 
 $0.06 
 
 .06 
 
 .07 
 
 .08 
 
 .09 
 
 
 .10 
 
 Per Gross 
 
 $0.33 
 
 .44 
 
 .55 
 
 .65 
 
 .80 
 
 
 .90 
 
 Nos. 
 
 12 
 
 13 
 
 14 
 
 15 
 
 16 
 
 
 17 
 
 Length, inches 
 
 1 
 
 1 
 
 1 
 
 1 
 
 1 
 
 
 1 
 
 Diameter large end, inches 
 
 134 
 
 1% 
 
 134 
 
 1*6 
 
 134 
 
 
 1*6 
 
 Per Dozen 
 
 $0.12 
 
 .12 
 
 .14 
 
 .16 
 
 .18 
 
 
 .20 
 
 Per Gross 
 
 $1.00 
 
 1.05 
 
 1.20 
 
 1.35 
 
 1.70 
 
 
 1.85 
 
 Nos. 
 
 18 
 
 19 
 
 20 
 
 22 
 
 24 
 
 
 26 
 
 Length, inches 
 
 1 
 
 1 
 
 1 
 
 1 
 
 1 
 
 
 1 
 
 Diameter, large end, inches 
 
 134 
 
 1%6 
 
 134 
 
 IX 
 
 134 
 
 
 2 
 
 Per Dozen 
 
 $ 0.22 
 
 .26 
 
 .30 
 
 .35 
 
 .42 
 
 
 .54 
 
 Per Gross 
 
 $ 1.95 
 
 2.10 
 
 2.20 
 
 2.90 
 
 3.40 
 
 
 3.90 
 
 CORKS, SPECIE, FLAT or JAR, excellent quality, 34 inch thick. 
 
 abed 
 
 e 
 
 f 
 
 g 
 
 h 
 
 Diameter, large end, inches 
 
 1 
 
 13 i 
 
 134 m 
 
 2 
 
 234 
 
 234 
 
 2 H 
 
 Per Dozen 
 
 $0.08 
 
 .11 
 
 .16 .20 
 
 .25 
 
 .32 
 
 .42 
 
 .55 
 
 4099 CORKS, ASSORTED, Nos. 0 to 11.Per Gross $0.40 
 
 CORKS, RUBBER. See Rubber Stoppers, Page 478. 
 
 6001 CORK BORERS, of hard metal with sharp cutting edge; polished, in sets with punch. 
 
 abed 
 No. in Set 3 6 9 12 
 
 Per Set $0.56 .90 1.50 2.00 
 
 6003 CORK BORERS, of hard drawn metal with sharp cutting edge, each borer with handle. 
 
 abed 
 No. in Set 3 6 9 12 
 
 Per Set $0.98 2.16 2.65 3.76 
 
 5005 CORK BORER SHARPENER, a steel blade, and cone of brass, wood handle. 1.25 
 
 5007 CORK KNIFE, good steel blade, wood handle. .18 
 
 5010 CORK MATS for supporting beakers, flasks, etc. 
 
 a b 
 
 Diameter, inches 4 6 
 
 Each $0.09 .14 
 
 5013 CORK PRESS, Lever Form, japanned.25 
 
 5014 CORK PRESS, ROTARY, wheel form, taking corks up to %-inch diameter, japanned. .60 
 
 5015 CORK PRESS, ROTARY, wheel form, taking corks up to 134 inches diameter, japanned. .86 
 
 5017 CORK SCREW, excellent quality, wood handle .. .18 
 
 5020 CORK SHEET for lining insect boxes and cabinets, 10 X 30 mm. X 5 mm. thick. .14 
 
 COVER GLASSES. See page 461. 
 
CHEMISTRY AND BIOLOGY 
 
 427 
 
 5030 
 
 6031 
 
 5031A 
 
 5033 
 
 CRUCIBLES, ALUNDUM. (See index, “Alundum Ware,” for characteristics.) For general labo¬ 
 ratory use where an ignition of carbonaceous material is involved. Without covers. 
 
 abcdefghi 
 
 Diameter at Top, inches 
 
 1* 
 
 1 TS 
 
 IK 
 
 IK 
 
 m 
 
 IK 
 
 IK 
 
 2K 
 
 2K 
 
 Height, inches 
 
 1 Tf 
 
 IK 
 
 1 TS 
 
 IK 
 
 IK 
 
 IK 
 
 IK 
 
 IK 
 
 3 
 
 Capacity, cc. 
 
 10 
 
 15 
 
 20 
 
 25 
 
 30 
 
 40 
 
 70 
 
 80 
 
 95 
 
 Each 
 
 $0.28 
 
 .33 
 
 .34 
 
 .40 
 
 .41 
 
 .42 
 
 .43 
 
 .44 
 
 .85 
 
 CRUCIBLE COVER, ALUNDUM, diameter 1 K inches. 
 
 -, diameter 1% inches... 
 
 CRUCIBLES, GRAPHITE, Dixon’s genuine. Capacities given are actual total, not working capaci- 
 
 ties, which are variable. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 Capacity, ounces 
 
 2 
 
 4 
 
 8 
 
 12 
 
 16 
 
 Height, inches 
 
 2K 
 
 2ii 
 
 3K 
 
 4 K 
 
 5K 
 
 Diameter, inches 
 
 ltt 
 
 2K 
 
 3K 
 
 3K 
 
 4K 
 
 Each 
 
 $0.52 
 
 .52 
 
 .92 
 
 1.05 
 
 1.12 
 
 Nos. 6035 and 5039 
 
 No. 6037 
 
 $0.33 
 
 .38 
 
 5035 
 
 6037 
 
 5039 
 
 5042 
 
 6043 
 
 CRUCIBLES, SHEET IRON, with Covers. 
 Capacity, cc. 
 
 Each 
 
 a b c d 
 
 20 ^IPW50 100 200 
 
 $0.24 Iff* .28 .33 .40 
 
 CRUCIBLE, SKIDMORE’S IRON, for making oxygen from MnO‘ 2 , calcination of chalk with recovery 
 of the expelled CO 2 , manufacture of soda from cryolite, preparation of ammonia, destructive dis¬ 
 tillation of coal, wood or other organic substance, or for any use in which the materials employed 
 or evolved do not act destructively on hot iron. Can be used equally well as an open crucible, 
 
 closed crucible or retort. Capacity IK ounces.$0.98 
 
 CRUCIBLES, SHEET NICKEL, with covers. 
 
 abed 
 
 Capacity, cc. 20 
 
 
 30 
 
 50 
 
 
 100 
 
 
 Each $0.94 
 
 
 1.10 
 
 1.20 
 
 
 1.95 
 
 
 CRUCIBLES, PLATINUM. See PLATINUM WARE. 
 
 
 
 
 
 CRUCIBLES, PORCELAIN, excellent quality, well adapted to general chemical work in the laboratory. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 Capacity, cc. 13 
 
 14 
 
 25 
 
 45 
 
 80 
 
 140 
 
 280 
 
 Diameter at Top, mm. 33 
 
 41 
 
 46 
 
 55 
 
 69 
 
 82 
 
 86 
 
 Diameter at Bottom, mm. 15 
 
 17 
 
 20 
 
 21 
 
 27 
 
 32 
 
 40 
 
 Height, mm. 25 
 
 25 
 
 30 
 
 39 
 
 45 
 
 54 
 
 72 
 
 Each $0.20 
 
 .27 
 
 .35 
 
 .42 
 
 .55 
 
 .60 
 
 .74 
 
 CRUCIBLES, PORCELAIN, ROYAL WORCESTER. (See index, “Royal Worcester Porcelain Ware,” 
 
 for characteristics.) Glazed inside and outside, 
 
 with covers and rings 
 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g h 
 
 Diameter at Top, mm. 32 
 
 37 
 
 41 
 
 46 
 
 56 
 
 67 
 
 81 96 
 
 Diameter at Bottom, mm. 13 
 
 15 
 
 15 
 
 18 
 
 18 
 
 23 
 
 29 35 
 
 Height, mm. 19 
 
 21 
 
 25 
 
 29 
 
 36 
 
 44 
 
 52 65 
 
 Capacity, cc. 8 
 
 12 
 
 17 
 
 30 
 
 50 
 
 90 
 
 145 265 
 
 Each $0.20 
 
 .22 
 
 .30 
 
 .38 
 
 .62 
 
 .57 
 
 .66 .85 
 
428 
 
 BOSTON 
 
 6045 
 
 6048 
 
 6049 
 
 6060 
 
 6061 
 
 6052 
 
 5055 
 
 6066A 
 
 6055B 
 
 6056 
 
 5066A 
 
 5066B 
 
 L. E. KNOTT APPARATUS 
 
 C O 
 
 CRUCIBLES, GOOCH, PORCELAIN, ROYAL WORCESTER. (See Index, “Royal Worcester 
 Porcelain Ware,” for characteristics.) Thin wall, bottom unglazed, outside and inside glazed. 
 
 a be 
 
 Diameter at Top, mm. 
 
 27 
 
 35 
 
 40 
 
 Diameter at Bottom, mm. 
 
 18 
 
 22 
 
 25 
 
 Height, mm. 
 
 30 
 
 40 
 
 43 
 
 Capacity, cc. 
 
 10 
 
 25 
 
 35 
 
 Each 
 
 $0.34 
 
 .48 
 
 .58 
 
 CRUCIBLES, FUSED SILICA. (See index, “Fused Silica Ware,” for characteristics.) Glazed. Berlin 
 
 porcelain shape. Measurements given are outside measurements. 
 
 
 a 
 
 b 
 
 c 
 
 
 d 
 
 e 
 
 f 
 
 Height, mm. 
 
 19 
 
 25 
 
 28 
 
 
 37 
 
 44 
 
 51 
 
 Diameter at Top, mm. 
 
 41 
 
 41 
 
 48 
 
 
 57 
 
 67 
 
 81 
 
 Crucibles, each 
 
 $0.60 
 
 .60 
 
 .76 
 
 
 .90 
 
 1.25 
 
 1.60 
 
 Lids to Fit, each 
 
 $0.50 
 
 .60 
 
 .60 
 
 
 .75 
 
 .90 
 
 1.10 
 
 CRUCIBLES, FUSED SILICA. 
 
 . (See index, ‘ 
 
 ‘Fused Silica Ware” for characteristics.) Unglazed. 
 
 Measurements are outside 
 
 measurements. 
 
 
 
 
 
 
 
 
 a b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h i 
 
 Height, mm. 
 
 111 102 
 
 156 
 
 190 
 
 196 
 
 213 
 
 260 
 
 324 508 
 
 Diameter at Top, mm. 
 
 95 108 
 
 114 
 
 127 
 
 149 
 
 158 
 
 196 
 
 257 305 
 
 Each 
 
 $2.16 2.15 
 
 3.16 
 
 3.75 
 
 4.00 
 
 5.00 
 
 8.00 
 
 12.60 18.00 
 
 CRUCIBLES, FUSED SILICA. (See index, “Fused Silica Ware,” for characteristics.) Glazed. 
 
 Platinum shape. 
 Height, mm. 
 
 Diameter at Top, mm. 
 Crucibles, each 
 Lids to Fit, each 
 
 a 
 
 51 
 
 51 
 
 $1.25 
 
 $0.60 
 
 b 
 
 35 
 
 35 
 
 1.26 
 
 .60 
 
 c 
 
 38 
 
 43 
 
 1.25 
 
 .50 
 
 CRUCIBLE, FUSED SILICA, GOOCH, %-inch hole in bottom, with¬ 
 out disc. (See index, “Fused Silica Ware,” for characteristics.) 
 Outside measurements, — height inches (41 mm.), diameter at 
 
 top 1 % inches (41 mm.) Glazed. 
 
 CRUCIBLE, FUSED SILICA, SPECIAL. (See index, “Fused Silica 
 Ware,” for characteristics.) Glazed. Outside measurements, — 
 height 3^ inches (81 mm.), diameter at top 2% inches (73 mm.) 
 CRUCIBLE, FILTER, ALUNDUM, for the separation of liquids from 
 solids in laboratory practice. For rapid filtration, it is necessary 
 to maintain a reduced pressure as secured by an aspirator, etc. 
 Special glass funnels and rubber gaskets are necessary to give the 
 proper fit between the container and filtering medium. Three de¬ 
 grees of porosity may be obtained, — 36.9 per cent., 40.7 per cent, 
 and 47.4 per cent. We carry in stock, however, 40.7 per cent. only. 
 Diameter 1% inches, height inches, capacity 25 cc. 
 
 Proper method of supporting 
 Alundum Crucible 
 
 GLASS SUPPORTING FUNNEL for use with above Crucible and Rubber Gasket following, in mak¬ 
 ing close connection with the filtering medium. 
 
 RUBBER GASKET for use with above Filter Crucible and Supporting Funnel in making close con¬ 
 nection with the filtering medium . 
 
 CRUCIBLE, FILTER, ALUNDUM, same as No. 6056, but 1% inches diameter, 1^ inches high and 
 
 35 cc. capacity. 
 
 GLASS SUPPORTING FUNNEL for use with above Crucible and Rubber Gasket following, in mak¬ 
 ing close connection with the filtering medium. 
 
 RUBBER GASKET for use with the above Filter Crucible and Supporting Funnel in making a close 
 connection with the filtering medium. 
 
 $0.36 
 
 .42 
 
 .08 
 
 .42 
 
 .48 
 
 .08 
 
 
 
 
CHEMISTRY AND BIOLOGY 
 
 429 
 
 
 
 
 No. 5060 
 
 6060 
 
 5063 
 
 * 
 
 No. 5063 No. 5067 Nos. 5075 and 5076 
 
 CRUCIBLE, ROSE’S, with perforated cover and delivery tube, unglazed, vitreous. 
 
 Capacity 30 cubic centimeters ... 1 .. $0.60 
 
 CRUCIBLES, SAND, round form with lip. 
 
 a b c d e 
 
 Height, inches 
 
 2 % 
 
 3 
 
 3V 2 
 
 4 
 
 4J^ 
 
 Diameter, inches 
 
 1 Vz 
 
 1% 
 
 2H 
 
 2Vs 
 
 2Vs 
 
 Per Dozen 
 
 $0.42 
 
 .78 
 
 .84 
 
 .96 
 
 1.44 
 
 5066 CRUCIBLE BLOCKS for No. 0 Porcelain Crucibles, according to specifications by Dr. Lyman C. 
 
 Newell.Per Dozen .80 
 
 6067 CRUCIBLE FUNNEL, of glass, according to Dr. Lyman C. Newell. .20 
 
 6069 CRUCIBLE RUBBER TUBING for connecting Gooch Crucible and Funnel.Per Foot .30 
 
 5076 CRUCIBLE TONGS, steel, double bend, 9-inch.22 
 
 6076 CRUCIBLE TONGS, steel, nickel-plated, double bend, 9-inch.33 
 
 CULTURE TUBES. See TUBES, CULTURE, Page 490. 
 
 No. 31-260 
 
 No. 6095 
 
 No. 6098 
 
 5080 
 
 31-260 
 
 6096 
 
 6096 
 
 6098 
 
 CUPS, POROUS. 
 
 Diameter, inches 
 Height, inches 
 Each 
 
 c 
 
 2M 
 
 5 
 
 .26 
 
 d 
 
 3 
 
 7 
 
 .30 
 
 Of 
 
 a b 
 
 1H 2 
 
 3 4 
 
 $0.16 .20 
 
 CYLINDERS or HYDROMETER JARS for use where a tall jar of small diameter is desired, 
 clear white glass with foot and rim. 
 
 a b c d e 
 
 Size, inches 12 Xl 12 X 2 15 X 2 15 X 3 18 X 3 
 
 Each $0.60 .56 .80 1.00 1.36 
 
 CYLINDERS, GRADUATED, of glass, broad base, with lip, graduated in cubic centimeters. 
 
 a b c d e f g 
 
 Capacity, cc. 10 25 50 100 250 500 1000 
 
 Each $0.30 .36 .40 .62 .90 1.10 1.85 
 
 CYLINDERS, GRADUATED, double graduations, reading up and down, of glass, broad base, with 
 lip. Graduated in cubic centimeters. 
 
 a b c d e f 
 
 Capacity, cc. 25 50 100 250 500 1000 
 
 Each $0.38 .46 .66 .96 1.20 2.00 
 
 CYLINDERS, MIXING, GRADUATED AND STOPPERED, serviceable when making standard solu¬ 
 tions. Of glass, broad base, round glass stoppers, graduated in cubic centimeters. 
 
 a b c d e f g 
 
 Capacity, cc. 
 Each 
 
 25 
 
 $0.76 
 
 50 
 
 .85 
 
 100 
 
 .96 
 
 200 
 
 1.20 
 
 250 
 
 1.30 
 
 500 
 
 1.85 
 
 1000 
 
 2.25 
 
430 
 
 L, E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 No. 5116 No. 6116 No. 6118 
 
 DEFLAGRATING SPOONS. See SPOONS, DEFLAGRATING, Page 479. 
 
 5115 DESSICATOR or ACID DISH, PORCELAIN, for use with acid in dessicators.$0.85 
 
 5116 DESSICATOR, HARCOURT. Consists of ground glass plate, bell glass and acid dish as illustrated. 
 
 Set. 2.46 
 
 5118 DESSICATORS, SCHEIBLER’S, of glass, with covers ground air-tight. 
 
 a b 
 
 Diameter, inches 4 6 
 
 Each $0.75 1.15 
 
 5120 DESSICATOR PLATES, glazed, on three small feet, for use in Scheibler’s Dessicators. 
 
 a b 
 
 Diameter, mm. 
 
 95 
 
 140 
 
 No. of Holes 
 
 3 
 
 5 
 
 Each 
 
 $0.80 
 
 1.10 
 
 5122 DIAMOND for writing on glass. Excellent quality. 6.40 
 
 No. 6126 
 
 5125 DIGESTING SHELF, KJELDAHL’S, oblong form of sheet iron, with rod to support the flasks. The 
 shelf is supported on adjustable legs. Size 24 inches long, 5J6 inches wide, 9J£ inches high. Com¬ 
 plete with six burners, each with stopcock.$17.00 
 
 6127 DIGESTING SHELF, ELECTRICALLY HEATED, KJELDAHL’S, oblong form of sheet iron, with 
 
 rod to support the flasks. Each heater, 3J£ inches in diameter, is a unit, and either one or all may 
 be used at one time, as desired. Size 24 inches long, inches wide, 9 inches high. With six heaters 44.00 
 
 5134 DISHES, AGATE WARE. a 
 
 Dimensions, inches X 1J6 
 
 Capacity, quarts 
 
 Each $0.16 
 
 b 
 
 x i y 8 
 
 i 
 
 .18 
 
 8MX 
 
 2 
 
 .22 
 
 5136 DISHES, CRYSTALLIZING. 
 
 Of clear white glass, flat bottoms, straight sides. 
 
 a b c 
 
 3 4 
 
 .24 .32 
 
 Diameter, inches 
 Each 
 
 a 
 
 2 
 
 $0.18 
 
 No. 5136 
 
I 
 
 CHEMISTRY AND BIOLOGY 
 
 EVAPORATING DISHES 
 
 5139 
 
 5141 
 
 6142 
 
 DISHES, EVAPORATING, PURE SHEET NICKEL, with lip, polished. 
 
 „ k 
 
 
 
 
 
 Diameter, inches 
 
 
 a 
 
 2 
 
 
 2 % 
 
 
 8 l A 
 
 
 
 
 Capacity, cc. 
 
 
 40 
 
 
 100 
 
 
 200 
 
 
 
 
 Each 
 
 
 $0.90 
 
 
 1.30 
 
 
 1.90 
 
 
 
 
 DISHES, EVAPORATING, PORCELAIN, excellent quality, well adapted to general chemical work 
 
 
 in the laboratory. Thin, uniform, glazed inside and outside. 
 
 
 
 
 
 
 a b 
 
 c 
 
 d 
 
 e 
 
 f g 
 
 h 
 
 i 
 
 j 
 
 k 
 
 1 
 
 Size, No. 00 0 
 
 1 
 
 2 
 
 3 
 
 4 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 Diameter, cm. 7 8 
 
 8A 
 
 9 
 
 10 
 
 11 12 
 
 14 H 
 
 18 
 
 21H 
 
 26^ 
 
 31 
 
 Capacity, cc. 65 85 
 
 110 
 
 140 
 
 165 
 
 250 290 
 
 475 
 
 810 
 
 1320 
 
 2585 
 
 4000 
 
 Each $0.16 .20 
 
 .26 
 
 .35 
 
 .40 
 
 .45 .55 
 
 .70 
 
 .90 
 
 1.20 
 
 1.76 
 
 2.75 
 
 DISHES, EVAPORATING, ROYAL WORCESTER PORCELAIN. 
 
 (See index, “RoyalfrWorcester 
 
 
 Porcelain Ware,” for characteristics.) Glazed inside and outside, 
 
 with spout. 
 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 1 
 
 j 
 
 Size No. 00 
 
 0 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 Diameter, outside, mm. 70 
 
 80 
 
 85 
 
 90 
 
 100 
 
 110 
 
 120 
 
 145 
 
 185 
 
 215 
 
 Height, mm. 27 
 
 30 
 
 33 
 
 37 
 
 42 
 
 43 
 
 50 
 
 48 
 
 54 
 
 63 
 
 Capacity, cc. 60 
 
 80 
 
 100 
 
 140 
 
 175 
 
 210 
 
 300 
 
 385 
 
 765 
 
 1285 
 
 Each $0.33 
 
 .39 
 
 .48 
 
 .60 
 
 .76 
 
 .84 
 
 .96 
 
 1.35 
 
 1.80 
 
 2.16 
 
 5145 
 
 5146 
 
 DISHES, EVAPORATING, FUSED SILICA. (See index, “Fused Silica Ware,” for characteristics.) 
 Glazed. Measurements given are inside measurements. 
 
 a b c 
 
 Diameter, inches 
 
 2 
 
 
 2 H 
 
 
 
 Depth, inches 
 
 13 /ie 
 
 
 1 
 
 
 i % 
 
 Diameter, mm. 
 
 51 
 
 
 . 70 
 
 
 82 
 
 Depth, mm. 
 
 21 
 
 
 25 
 
 
 30 
 
 Each 
 
 $1.00 
 
 
 1.16 
 
 
 1.25 
 
 ISHES, EVAPORATING, FUSED SILICA. 
 
 (See 
 
 index, 
 
 Unglazed. 
 
 a b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 Diameter, inches 
 
 5 H SH 
 
 6 
 
 6 
 
 7 
 
 7 
 
 Depth, inches 
 
 2M 2A 
 
 2'A 
 
 3 
 
 2% 
 
 3% 
 
 Diameter, mm. 
 
 137 130 
 
 152 
 
 152 
 
 178 
 
 178 
 
 Depth, mm. 
 
 57 63 
 
 63 
 
 76 
 
 70 
 
 95 
 
 Each 
 
 $2.86 3.00 
 
 3.15 
 
 3.60 
 
 3.76 
 
 3.90 
 
 e 
 
 
 3^ 
 
 
 8 7 A 
 
 4J4 
 
 
 
 Vs 
 
 
 1 3 A 
 
 m 
 
 
 
 89 
 
 
 98 
 
 108 
 
 
 
 22 
 
 
 30 
 
 44 
 
 
 
 1.35 
 
 
 1.60 
 
 1.85 
 
 • 
 
 ‘Fused Silica Ware 
 
 for characteristics.) 
 
 
 g 
 
 h 
 
 i 
 
 j k 
 
 1 m 
 
 n 
 
 8 
 
 8 
 
 9 
 
 9 12K 
 
 15 H 18 
 
 18 
 
 3H 
 
 4 H 
 
 3V 2 
 
 4H 5K 
 
 4 7 
 
 8A 
 
 20 3 
 
 203 
 
 229 
 
 229 311 
 
 394 458 
 
 458 
 
 82 
 
 108 
 
 89 
 
 120 133 
 
 102 178 
 
 216 
 
 4.35 
 
 5.00 
 
 6.00 
 
 6.76 10.00 
 
 12.00 14.00 
 
 15.00 
 
432 
 
 BOSTON 
 
 « 
 
 L. E. KNOTT APPARATUS CO., 
 
 5148 
 
 6150 
 
 5151 
 
 5154 
 
 5155 
 
 6157 
 
 5159 
 
 6161 
 
 No. 5148 
 DISHES, FILTER, ALUNDUM 
 
 per cent, carried in stock, 
 prices. 
 
 Dimensions, inches 
 Capacity, cc. 
 
 Each 
 
 No. 6160 
 
 (See index, “Alundum Ware,” for characteristics.) Porosity 40.7 
 Porosities of 36.9 per cent, and 47.4 per cent, can be obtained at same 
 a b c 
 
 2^X1 4X2 5% X 2 
 
 50 300 400 
 
 $0.44 1.10 1.66 
 
 DISH, INCINERATING, ALUNDUM. (See index “Alundum Ware,” for characteristics.) Rectangu¬ 
 lar form. a b c , 
 
 Dimensions, inches 4% X 4% X 1 9% X 4 X % 12% X 6% X 2% 
 
 Each $1.65 2.60 6.50 
 
 -, round form. 2% inches diameter, % inch deep. 
 
 $0.55 
 
 No. 6169d 
 
 No. 5165 No. 5167 No. 5159 
 
 DISHES, LEAD, of heavy sheet lead, a b c 
 
 Diameter, inches 2 3 4 
 
 Each $0.12 .20 .32 
 
 DISH, LEAD, rectangular, for etching.$0.20 
 
 DISHES, MILK, ALUMINUM, flat bottom, straight sides. a b c 
 
 Diameter, inches 2 3 4 
 
 Each $0.21 .33 .60 
 
 DISHES, PETRI or DOUBLE, glass cover, diameter 10 centimeters. .28 
 
 DISHES, PETRI or DOUBLE, porous porcelain cover, according to Boston Board of Health. Diam¬ 
 eter 10 centimeters... .30 
 
 No. 6165 
 
 5165 DISHES, FUSED SILICA. (See index, “Fused Silica Ware,” for characteristics.) Flat, with lip, 
 
 glazed. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 Diameter, mm. 
 
 63 
 
 73 
 
 95 
 
 124 
 
 Depth, mm. 
 
 13 
 
 13 
 
 18 
 
 21 
 
 Each 
 
 $1.16 
 
 1.25 
 
 1.35 
 
 1.85 
 
 6167 DISH, STAINING, with cover, for staining slide sections.$0.75 
 
 6169 DISHES, STENDER or PREPARATION, of clear white glass, covers grooved and ground on. 
 
 abed 
 m 2 2% 3% 
 
 H 1 1 Vs 3% 
 
 $0.12 .15 .22 .25 
 
 Diameter, inches 
 Height, inches 
 Each 
 
CHEMISTRY AND BIOLOGY 
 
 433 
 
 DISSECTING INSTRUMENTS 
 
 No. 5196 No. 5190 No. 5182 No. 5184 No. 5186 No. 5188 No. 5192 No. 5194 No. 5201 No. 5208 No. 5210 No. 5214 
 
 No. 5216 
 
 No. 6230 No. 6232 No. 6234 No. 6224 No. 5226 No. 6227 
 
 6180 BLOWPIPE, 2y inches, for inflating arteries, etc.$0.16 
 
 6181 DISSECTING PAN, BUSSEY’S, iy 2 X 11 inches, with black wax.48 
 
 6182 FORCEPS, steel, 6-inch, nickel-plated, straight, heavy corrugated points, corrugated handles . . . .46 
 
 6184 FORCEPS, FINE, STRAIGHT, steel, 4-inch, nickel-plated, corrugated points, corrugated handle, 
 
 with guide pin. .46 
 
 6186 FORCEPS, FINE, CURVED, steel, 4-inch, nickel-plated, corrugated points, corrugated handle, with 
 
 guide pins. .60 
 
 6188 FORCEPS, FINE POINTS, plain, 4J^ _ inch, smooth handles. .16 
 
 6190 FORCEPS, BONE-CUTTING, 6J^-inch, strong, accurately made, knife shaped blades. With lock . . 1.16 
 
 6192 FORCEPS, COVER-GLASS, STEWART’S, 4^-inch, nickel-plated steel wire.16 
 
 6194 FORCEPS, COVER-GLASS, NOVY’S, WITH LOCK, 4^-inch. The thin edge of the lower blade 
 
 enables one to pick up a cover glass readily. The curving pointed blade prevents capillary drainage 1.26 
 
 6196 HOOKS AND CHAINS, triple hooks and connecting chains, nickel-plated. .18 
 
 5198 NEEDLES, STRAIGHT, wood handle .Per Dozen .30 
 
 6199 NEEDLES, BENT, wood handle . Per Dozen .30 
 
 6201 NEEDLE HOLDER, bone handle with clamping holder for straight or bent needles, 3 J^-inch.10 
 
 6203 NEEDLES, STRAIGHT, for use with above holder .Per Dozen .10 
 
 6204 NEEDLES, BENT, for use with above holder .Per Dozen .10 
 
 6208 RAZOR, SECTION, folding handle, superior quality, 3-inch blade, one side flat, straight edge . . . 1.10 
 
 6210 RAZOR, SECTION, straight handle, finest steel, 3-inch blade, one side flat, straight edge. 1.86 
 
 5214 SAW, BONE, superior grade, 4 inches long. 1.76 
 
 6216 SCALPEL, 1%-inch blade, excellent quality steel, ebony handles riveted to the blade. .40 
 
 6217 --, 1 y inch blade.40 
 
 6218 -, 1-inch blade. .40 
 
 6220 SCALPEL, CARTILAGE (Cartilage Knife), 63^-inch, all steel; blade 2 inches long; corrugated handle . .66 
 
 6224 SCISSORS, 4 y 2 inch, medium heavy, straight, fine cutting points.48 
 
 5226 SCISSORS, 4H inch, fine sharp straight points; heavy pattern.66 
 
 5227 SCISSORS, 4H-»nch, fine sharp curved points; heavy pattern.66 
 
 6230 SECTION LIFTER, thin flexible blade, \% X % inches, ebony handle riveted to blade.30 
 
 6232 -, blade 1 % X % inches. .35 
 
 6234 -, blade 2 X 1H inches. .40 
 
 6238 TENACULUM, steel shank with sharp hook, ebony handle riveted to blade. .36 
 
 6240 TENACULUM AND NEEDLE, solid steel, sharp hook, sharp point.40 
 
434 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • » 
 
 DISSECTING SETS 
 
 Our sets of dissecting instruments have been made up with great care. The instruments are of finely tempered 
 steel and the shapes and sizes chosen for the various sets have met with complete approval of teachers of the natural 
 sciences. 
 
 The cases are of the folding pocket form with separate loops for each instrument. The leatherette cases are 
 strong and durable. They are lined with cloth, with cloth flaps. The leather cases are made of black morocco and 
 are lined with leather with chamois flaps to protect the instruments. 
 
 No. 5256 
 
 No. 6257 
 
 No. 5269 
 
 n 
 
 
 
 nji 
 
 II gH 
 
 
 
 
 
 
 
 
 PI 
 
 
 * 
 
 i i 
 
 
 
 
 
 
 
 
 1 |J 
 
 No. 6261 
 
 6265 HARCOURT FIRST YEAR STUDENTS’ DISSECTING SET, one fold leatherette case containing 
 
 Ruler and six high-grade instruments as follows: — 2 Dissecting Needles, Forceps, Scissors, Scalpel 
 and Pipette.Set $1.20 
 
 6257 HARCOURT ADVANCED STUDENTS’ DISSECTING SET, one fold leatherette case containing 
 
 five high grade instruments, — 2 Bone-handle Clamping Needle Holders with needle for each, For¬ 
 ceps, Scissors and Scalpel.Set 1.25 
 
 6259 HARCOURT SUPERIOR DISSECTING SET, two fold leatherette case containing, — Cartilage 
 
 Knife, Scalpel, Tenaculum, Forceps, Blowpipe, Scissors and Hooks and Chains.Set 2.66 
 
 6261 THE UNIVERSITY DISSECTING SET, — morocco leather case, leather lined, chamois flaps, con¬ 
 taining the following extra fine grade instruments, — two Bone-handle Clamping Needle Holders, 
 each with needle, Fine-pointed Curved Forceps, Fine-pointed Scissors, Medium Scissors, Blowpipe, 
 
 Hooks and Chains, Tenaculum, Heavy Forceps and three sizes of Scalpels. Twelve instruments 
 in case.Set 3.00 
 
 6263 HARCOURT RESEARCH DISSECTING SET, leatherette covered case with clasp, containing 
 the following extra fine grade instruments, — Cartilage Knife, four sizes of Scalpels, Tenaculum, 
 Forceps, Hooks and Chains, Blowpipe, Scissors and Bone Saw. Eleven instruments in case. Set 6.76 
 

 CHEMISTRY AND BIOLOGY 
 
 435 
 
 No. 5276 No. 5277 No. 5286 No. 5285A No. 5285B 
 
 6275 DISTILLING APPARATUS, HEAVY POLISHED COPPER, for destructive distillation of heavy oils 
 and other liquids or solids requiring a high heat. The distillation may be made by live steam or 
 by direct heat with or without agitation by hot air blown through, as desired. Capacity gallon $18.50 
 5277 DISTILLING APPARATUS, SALLERTON’S, POLISHED COPPER, for determining percentage of 
 
 alcohol in wine, beer, cider, etc. Capacity pint. 9.76 
 
 5415 DISTILLATION FLASKS, FRACTIONAL, with side tubes. (For illustration, see page 438) 
 
 a bed —e f 
 
 Capacity, cc. 15 30 100 250 500 1000 
 
 Each $0.20 .26 .45 .60 .75 .95 
 
 5285 DISTILLATION TUBE, FRACTIONAL. Plain, with side tube.$0.26 
 
 5285A -, with one bulb. .44 
 
 5285B -, with two bulbs. .56 
 
 DRYING OVENS 
 
 These ovens are of polished copper, with tubulations for thermometer and gas regulator. Extra sheet iron bot¬ 
 tom, single and double wall, as listed below. 
 
 No. 6295 
 
 No. 5299 
 
 5295 DRYING OVEN, single wall, on iron stand 8 inches high, with set screw by which oven is held firmly. 
 
 Inside dimensions, 6X8X6 inches deep. With one removable shelf.$5.50 
 
 5297 DRYING OVEN, double wall, otherwise same as above. With one removable shelf. 7.75 
 
 6299 DRYING OVEN, double wall, same as No. 6297, but with the addition of water bath top. With one 
 
 removable shell. 9.76 
 
 6301 DRYING OVEN, double wall, same as No. 5297, but inside dimensions 8 X 10 X 8 inches high. With 
 
 one removable shelf.11.76 
 
 DRYING PAPER. See page 472. 
 

 436 L. E. KNOTT APPARATUS CO., BOSTON 
 
 5310 
 
 5312 
 
 5314 
 
 5316 
 
 5325 
 
 3830 
 
 5330 
 
 5332 
 
 5335 
 
 5342 
 
 6344 
 
 ELECTRIC IRON with “Inverted Rack,” enabling the iron to be used as a stove when so desired. Size, 
 334 X 7 inches, weight 5 pounds. Consumption 475 watts on 120 volts either D. C. or A. C. With 
 
 6 feet cord and lamp socket plug. 
 
 ELECTRIC STOVE, PORTABLE, 4J4 inches diameter, for use on either D. C. or A. C. circuits of 120 
 volts. Consumption 250 watts; mounted on enamel slate base. With 6 feet cord and plug for at¬ 
 taching lamp socket. 
 
 ELECTRIC SOLDERING IRON, 14 ounce, 34 X 11 inches, for use on either D. C. or A. C. circuits 
 
 of 120 volts. Consumption 75 watts. With cord and plug. 
 
 ELECTRIC PORTABLE WATER HEATER, of copper, nickel-plated. Capacity one pint. For use 
 on either D. C. or A. C. circuits of 110 volts. Consumption 400 watts. With 6 feet of cord . . . 
 ELECTROLYSIS APPARATUS. See Index. 
 
 EUDIOMETERS, BUNSEN’S, with platinum electrodes, graduated to 34 cc. 
 
 a b 
 
 Capacity, cc. 50 100 
 
 Each $2.70 3.40 
 
 EVAPORATING DISHES. See DISHES, EVAPORATING. 
 
 EXPANDER, TUBE AND BULB, for stretching necks of rubber bulbs and tubes.. For illustration 
 
 see Page 419. 
 
 EXTRACTION APPARATUS, SOXHLET’S. Complete with flask, extractor and condenser. 
 
 a b c 
 
 Small Medium Large 
 
 Each $2.76 3.00 3.76 
 
 EXTRACTION APPARATUS, SOXHLET’S. The Water Bath is made of heavy polished copper, tinned 
 inside. 23 inches long, 4 inches deep and 434 inches wide, with six holes 234 inches in diameter, 
 
 on legs 7 inches high. Extreme height, including rods, is 31 inches. Rack adjustable. 
 
 EXTRACTION CARTRIDGES. Seamless, of fat-free paper. May be used repeatedly. Per package 
 EXTRACTION FLASKS. See FLASKS, Page 438. 
 
 EXTRACTION THIMBLES, ALUNDUM. fSee index, “Alundum Ware,” for characteristics.) Alun- 
 dum thimbles, are preferable to paper thimbles in that they remain constant in weight and may be 
 used an indefinite number of times and permit the ignition of the extracted residue without remov¬ 
 ing the residue from the thimble. Thickness of wall, about one mm. 
 
 Three degrees of porosity may be obtained, — 36.9 per cent. — 40.7 per cent, and 47.4 per cent. We 
 carry in stock, however, only 40.7 per cent. 
 
 a b c d e f g 
 
 Outside diameter, mm. 6 
 
 19 
 
 25 
 
 30 
 
 34 
 
 35 
 
 45 
 
 Height, mm. 
 
 31 
 
 90 
 
 70 
 
 80 
 
 100 
 
 55 
 
 127 
 
 Round Bottom, each 
 
 $0.30 
 
 
 
 
 .70 
 
 
 1.16 
 
 Flat Bottom, each 
 
 
 .60 
 
 00 
 
 .60 
 
 
 .60 
 
 
 EXTRACTION TUBES, 
 
 SOXHLET’S. 
 
 
 
 
 
 
 
 
 a 
 
 
 b 
 
 c 
 
 
 
 
 
 Small 
 
 
 Medium 
 
 Large 
 
 
 
 
 Each 
 
 $1.76 
 
 
 2.10 
 
 2.40 
 
 
 
 
 FAUCETS, WATER. See Page 9. 
 
 $3.90 
 
 4.75 
 6.80 
 
 6.75 
 
 .60 
 
 24.25 
 
 3.50 
 
 
 
 
 }- 
 
 
 
 
 
 
 
 
CHEMISTRY AND BIOLOGY 
 
 437 
 
 5360 
 
 6351 
 
 6365 
 
 FILE, ROUND, rat-tail, good quality, 5 inches long. $0.16 
 
 .15 
 
 m 
 
 234 
 
 • 3 ' 
 
 434 
 
 i X 
 
 i v% 
 
 2 
 
 334 
 
 20 
 
 / 50 
 
 60 
 
 100 
 
 $0.33 
 
 .39 
 
 .45 
 
 .56 
 
 .08 
 
 .12 
 
 .16 
 
 FILE, TRIANGULAR, glass cutting, good quality, 5 inches long. 
 
 FILTER CONES, ALUNDUM, for use with the ordinary 60 degree funnel to which it is held firmly 
 by stretching a rubber gasket over the top of the funnel before introducing the cone. Light alumi¬ 
 num stands are supplied, without extra charge, with the cones for supporting them on the balance pan. 
 
 Three degrees of porosity may be obtained, — 36.9 per cent., 40.7 per cent, and 47.4 per cent. Our 
 stock, however, contains Filter Cones 40.7 per cent. only. 
 
 abed 
 
 Diameter, inches 
 Height, inches 
 Capacity, cc. 
 
 Each 
 
 5356A RUBBER GASKETS for use with above Filter Cones in making the proper connections with the fun¬ 
 nels. For use with Nos. 6355 a and b.*. . .. 
 
 5356B -, for use with No. 5355c. 
 
 6366C -, for use with No. 5355d. ...... 
 
 FILTER DISCS. See PLATES, FILTER, Page 472. 
 
 We carry in stock two lines of FILTER PAPER,—’the HARCOURT FILTER PAPER for general laboratory 
 use in qualitative work and the WHATMAN FILTER PAPER selected with extreme care for different kinds of 
 quantitative work. 
 
 5365 FILTER PAPER, HARCOURT, round, a pure white paper of exceptional quality, of tough texture and 
 very rapid. This grade of paper is suggested for general use in the laboratory and for all qualitative 
 work. a b c d e f 
 
 Diameter, inches 3 4 5 6 - 8 10 
 
 Per Box of 100 Papers $0.09 - .15 .18 .20 .30 .45 
 
 6366 -, in sheets, same quality as above. Sheets 19 X 19 inches .... Per Quire $0.38; Per Ream $6.60 
 
 Few, if any, manufacturers have devoted so much attention during the past twenty years to the chemical prob¬ 
 lems pertaining to the manufacture of high grade papers as the Whatman Paper Company. We are now able to 
 offer their high grade line of filter papers which we are able to guarantee to be of the very highest quality. 
 
 Please note the low percentage of ash in the various sizes given below. 
 
 6370 WHATMAN NO. 1 FILTER PAPER for general quantitative and qualitative work. The paper is 
 
 6371 
 
 6372 
 
 6373 
 
 5374 
 
 6376 
 
 tasteless and free from chlorine and starch. 
 
 a 
 
 Diameter, cm. 9 
 
 Ash per Circle, gram .00076 
 
 Price per 100 $0.19 
 
 -, in sheets, same quality as above. 
 
 6385 
 
 5386 
 
 Retains barium sulphate when properly precipitated, 
 bed 
 11 1234 15 
 
 .0017 .0016 .0021 
 
 .22 .24 .34 
 
 Sheets 18J4 X 22inches ..Per C $3.24 
 
 WHATMAN NO. 4 FILTER PAPER for filtering fruit juices, syrups, oils, varnishes, etc. 
 
 a b c d e 
 
 Diameter, cm. 11 1234 15 1834 32 
 
 Price per 100 $0.34 .36 .46 .58 1.44 
 
 - , in sheets, same quality as above. Sheets 1834 X 2234 inches.Per C 6.04 
 
 WHATMAN NO. 30 FILTER PAPER for quantitative work. This paper has low ash and close texture. 
 Treated by hydrochloric acid to remove such chemical salts as are normally contained in the fibre. 
 
 abed 
 Diameter, cm. 9 11 1234 15 
 
 Ash per Circle, gram .00056 .00089 .00108 .00159 
 
 Price per 100 $0.60 .75 .96 1.25 
 
 WHATMAN NO. 40 “ASHLESS” FILTER PAPER for quantitative work in which a high degree of 
 accuracy is desirable. This paper being pure, gives a very low ash and being close in texture, will 
 retain even the finest precipitates. Subjected to a combined treatment of hydrochloric and hy¬ 
 drofluoric acid, it is lower in ash than No. 30 above, the hydrochloric acid having the effect of remov¬ 
 ing traces of silicious matter. a b c d 
 
 Diameter, cm. 9 11 1234 15 
 
 Ash per Circle, gram .00016 .00024 .00030 .00043 
 
 Price per 100 $1.08 1.32 1.44 1.68 
 
 FILTER PLATES, WITTE’S, PORCELAIN. Diameter 134 inches . . . . '. 36 
 
 -, diameter 234 inches. -40 
 
43 « 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 1 
 
 5405 
 
 6407 
 
 5408 
 
 5409 
 
 5411 
 
 5413 
 
 5415 
 
 6423 
 
 5425 
 
 6427 
 
 6429 
 
 5430 
 
 5431 
 
 6433 
 
 FLASKS, FLAT BOTTOM. 
 
 a 
 
 Capacity, cc. 25 
 
 Each $0.07 
 
 FLASKS, FLAT BOTTOM, 
 a 
 
 Capacity, cc. 50 
 
 Takes Stopper No. Kll 
 Each $0.12 
 
 b 
 
 50 
 
 .08 
 
 “PYREX.” 
 b c 
 
 100 150 
 
 Kll K13 
 
 .13 .16 
 
 c d 
 
 100 250 
 
 .10 .14 
 
 (See index, “I 
 
 d 
 
 200 
 
 K15 
 
 .18 
 
 e 
 
 300 
 
 K21 
 
 .21 
 
 e 
 
 500 
 
 .20 
 ex Gli 
 f 
 
 400 
 K21 
 .26 
 
 FLASKS, RING NECK, FLAT BOTTOM, “PYSIEX GLASS.” 
 
 Capacity, cc. 
 
 Takes Stopper No. 
 
 Each 
 
 FLASKS, FLAT BOTTOM, “FUSED SILICA.” (See index, 
 Spherical shape. a b c 
 
 Capacity, cc. 50 100 150 
 
 Each $2.75 4.00 4.25 
 
 FLASKS, ROUND BOTTOM, spherical. a 
 
 Capacity, cc. 100 
 
 Each $0.10 
 
 FLASKS, ROUND BOTTOM, “FUSED SILICA.” (See index, 
 a b c d e f 
 Capacity, cc. 50 100 150 200 250 500 
 
 Each $2.75 4.00 4.25 6.00 6.26 7.50 
 
 f 
 
 1000 
 
 .30 
 
 g 
 
 2000 
 
 .60 
 
 h 
 
 4000 
 
 1.10 
 
 g 
 
 h 
 
 i j 
 
 k 1 
 
 500 
 
 700 
 
 1000 1500 
 
 2000 3000 
 
 K25 
 
 K28 • 
 
 K30 K30 
 
 K33 K37 
 
 .29 
 
 .36 
 
 .43 .61 
 
 .60 .76 
 
 a 
 
 b 
 
 c 
 
 d 
 
 500 
 
 700 
 
 1000 
 
 2000 
 
 K28 
 
 K28 
 
 K30 
 
 K37 
 
 $0.38 
 
 .47 
 
 .56 
 
 .78 
 
 “Fused 
 
 Silica Ware,” for characteristics.) 
 
 d 
 
 „ e 
 
 f 
 
 g 
 
 200 
 
 250 
 
 500 
 
 1000 
 
 5.00 
 
 6.25 
 
 7.60 
 
 16.00 
 
 b 
 
 c 
 
 d 
 
 
 250 
 
 500 
 
 1000 
 
 
 .14 
 
 .20 
 
 .30 
 
 
 “Fused Silica Ware,” for characteristics.) 
 g 
 
 1000 
 
 16.00 
 
 b c d e f 
 
 
 Capacity, cc. 
 
 
 
 
 15 30 
 
 100 
 
 250 500 
 
 1000 
 
 
 Each 
 
 
 
 
 $0.20 .26 
 
 .46 
 
 .60 .75 
 
 .95 
 
 6417 
 
 FLASKS, DISTILLATION, 
 
 “FUSED SILICA.” 
 
 (See index, “Fused Silica Ware, 
 
 for characteristics.) 
 
 
 Spherical, with side arm. 
 
 a 
 
 b 
 
 c d 
 
 e 
 
 f g 
 
 
 
 Capacity, cc. 
 
 
 50 
 
 100 
 
 150 200 
 
 250 
 
 500 1000 
 
 
 
 Each 
 
 
 $3.25 
 
 4.76 
 
 5.00 6.00 
 
 7.60 
 
 9.00 18.50 
 
 
 5419 
 
 FLASKS, ERLENMEYER. 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 
 
 Capacity, cc. 
 
 
 60 
 
 125 
 
 250 
 
 500 
 
 1000 
 
 
 
 Each 
 
 
 $0.10 
 
 .12 
 
 .14 
 
 .18 
 
 .30 
 
 
 6421 
 
 FLASKS, ERLENMEYER, “PYREX GLASS.” (See index 
 
 :, “Pyrex Glassware, 
 
 for characteristics.) 
 
 
 
 a 
 
 b 
 
 c d 
 
 e 
 
 f g h 
 
 i 
 
 j k 
 
 1 
 
 
 Capacity, cc. 50 
 
 100 
 
 150 200 
 
 250 
 
 300 500 600 
 
 750 
 
 1000 1500 
 
 2000 
 
 
 Takes Stopper No. Kll 
 
 K17 
 
 K19 K23 
 
 K23 
 
 K25 K25 K25 
 
 K30 
 
 K33 K37 
 
 K43 
 
 
 Each $0.11 
 
 .12 
 
 .13 .16 
 
 .17 
 
 .19 .27 .29 
 
 .33 
 
 .42 .51 
 
 .60 
 
 FLASK, ERLENMEYER, WIDE MOUTH, “PYREX GLASS.” 
 
 6% inches, diameter of mouth 2 inches; takes rubber stopper K47. 
 FLASKS, EXTRACTION, SOXHLET’S, large mouth. a 
 
 Capacity, cc. 60 
 
 Each $0.15 
 
 Greatest diameter 2% inches, height 
 
 Capacity 500 cc. $0.27 
 
 b c d e 
 
 100 250 500 1000 
 
 .20 .30 .40 .60 
 
 Height 3>y% inches, diameter 
 Height 9 1J Ae inches, diam- 
 
 FLASK, EXTRACTION, “PYREX.” Round bottom, capacity 100 cc. 
 
 2 % inches, diameter of neck 1%2 inches. 
 
 FLASK, EXTRACTION, “PYREX.” Round bottom, capacity 2000 cc. 
 
 eter 6jj6 inches, diameter of neck 2 2 %2 inches . 
 
 FLASKS, FILTERING, conical form with side neck, heavy glass, uniform. a b 
 
 Capacity, cc. 250 500 
 
 Each $0.30 .45 
 
 FLASK, KJELDAHL or DIGESTION, for nitrogen determinations. Capacity 200 cubic centimeters 
 FLASKS, KJELDAHL or DIGESTION, “PYREX.” (See index, “Pyrex Glassware,” for charac¬ 
 teristics.) Round bottom, long neck. a b c 
 
 Capacity, cc. 300 500 800 
 
 Each $0.28 .37 .45 
 
 $0.15 
 
 .69 
 
 $0.22 
 

 439 
 
 No. 5466 
 
 No. 6468 
 
 No. 5464 
 
 6435 FLASKS, VOLUMETRIC, without glass stopper, graduated with one and two marks as follows: 
 
 6437 
 
 6-270 
 
 6-272 
 
 6446 
 
 6460 
 
 3865 
 
 6467 
 
 6459 
 
 6460 
 
 6462 
 
 6464 
 
 6466 
 
 6468 
 
 6470 
 
 5470A 
 
 6472 
 
 6472A 
 
 J 
 
 200 & 220 
 
 .65 
 
 g 
 
 1000 
 1.35 
 
 -, tapped % X 
 
 SUPPORT RODS. 
 
 abode f g h i 
 
 Capacity, cc. 5 10 20 25 50 50 & 55 100 100 & 110 200 
 
 Each $0.15 .20 .26 .30 .36 .40 .46 .48 .60 
 
 FLASKS, VOLUMETRIC, with glass stopper, graduated as follows. 
 
 a b c d e f 
 
 Capacity, cc. 25 50 100 200 250 500 
 
 Each $0.60 .60 .70 .75 .80 .96 
 
 FLUSH PLATE, nickel-plated, for inserting in any table flush with the top surface. When fitted 
 to a table and screwed into place, it offers an excellent socket for a support rod for funnel and filter 
 
 rings, clamps, etc. Tapped )4 X 20 for 10 mm. rods. $0.35 
 
 16 for 13 mm. rods. .. .46 
 
 See page 10. 
 
 FORCEPS, STEEL, 5-inch, for handling phosphorous, potassium, etc. 10 
 
 FUNNELS, BUNSEN’S, stem cut at an angle of 60°. 
 
 a b 
 
 Diameter, inches 2 2)4 
 
 Each $0.16 .18 
 
 FUNNELS, BURETTE (For illustration see Page 419). Each .16 
 
 FUNNELS, SEPARATORY, cylindrical. 
 
 Capacity, cc. 
 
 Each 
 
 FUNNELS, SEPARATORY, globe shape. 
 
 Capacity, cc. 
 
 Each 
 
 FUNNELS, SEPARATORY, SQUIBB’S, pear shape, with glass stopper. 
 
 a b c 
 
 Capacity, cc. 125 250 500 
 
 Each $2.35 3.40 4.30 
 
 FUNNEL, GRADUATED, SEPARATORY, CYLINDRICAL. Long stem, capacity 250 cc. $4.26 
 
 FUNNEL, POLISHED COPPER, DOUBLE WALL, for hot filtrations. 4.86 
 
 FUNNEL, KOCH’S, POLISHED COPPER, single wall for hot filtrations. With legs. 3.70 
 
 - , double wall for hot filtrations. With legs. 6.76 
 
 FUNNEL, PORCELAIN, small perforations, for use in rapid filtrations, diameter 4)4 inches. 70 
 
 -, diameter 5)4 inches.90 
 
 FUNNEL, BUCHNER, PORCELAIN, with fixed perforated porcelain plate, diameter 80 millimeters .90 
 -, diameter 100 millimeters.■. 1.30 
 
 c d 
 
 
 e 
 
 
 f 
 
 g 
 
 h 
 
 3 4 
 
 
 5 
 
 
 6 
 
 8 
 
 10 
 
 .20 .25 
 
 
 .35 
 
 
 .45 
 
 .76 
 
 1.60 
 
 Page 419) . . 
 
 
 
 
 
 
 
 a 
 
 
 
 b 
 
 
 c 
 
 
 30 
 
 
 
 60 
 
 
 125 
 
 
 $1.20 
 
 
 
 1.46 
 
 
 1.90 
 
 
 a 
 
 b 
 
 
 c 
 
 
 d 
 
 e 
 
 60 
 
 125 
 
 
 250 
 
 
 500 
 
 1000 
 
 $1.46 
 
 1.96 
 
 
 2.36 
 
 
 2.80 
 
 3.90 
 
 No. 5435 
 
 No. 5437 
 
 No. 6460 
 
 No. 6457 No. 6469 No. 5460 No. 6462 
 
 No. 6446 
 
 Nos. 6472 and 6472A 
 
440 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 3886 
 
 6477 
 
 6478 
 
 6479 
 
 6479A 
 
 6480 
 
 5482 
 
 6484 
 
 • > 
 
 Furnace Open Ready 
 for the Introduc¬ 
 tion of a Tube 
 
 No. 6480 
 
 No. 6479 
 
 Nos. 6482 and 6484 
 
 FURNACE, COMBUSTION, four burners with air regulators, stopcocks, and wing tops. With sup¬ 
 port and trough for heating tubes. Complete as illustrated, Page 420 .$9.25 
 
 FURNACE, CRUCIBLE, for illuminating gas. Consists of a simple pot for holding the crucible, wdth 
 a lid and a blowpipe all mounted on a suitable cast iron base. Takes No. 00 Clay or Lead 
 Crucibles. Clay parts, outside, measure \]/ 2 X 5% inches high. Pot, inside, measures 2% 
 inches X 2 x / 2 inches deep. Furnace on stand is 6 x / 2 inches high over all. 
 
 Without Foot Blower, but complete with No. 00 Clay Crucible.. 3.60 
 
 FURNACE, CRUCIBLE, similar to above but with Injector Gas Burner. Operates with illuminating 
 gas, natural gas or gasoline gas. Takes No. 00 Clay or Lead Crucibles. Clay parts, outside, 
 measure 4 }/% inches X 5% inches high. Pot inside, measures 2% inches X 2 Y inches deep. 
 Furnace on stand is 6Y inches high over all. 
 
 Without Foot Blower, but complete with one No. 00 Clay Crucible. 4.60 
 
 FURNACE, CRUCIBLE AND MUFFLE. Operates with illuminating gas, natural gas or gasoline 
 gas. Takes muffle 3 x / 2 X 2 Y% X 6J4 inches and No. 3 Clay or Lead Crucible (3% inches diameter 
 X 4 inches high). Pot and cover, outside, measures 9% inches X 11 inches high; inside, 6% 
 inches deep X 6 inches diameter. 
 
 Without Blower, but complete with Muffle and Clay Crucible. 12.50 
 
 PLUMBAGO MUFFLE, 3}/ 2 X 2% X 6J4 inches. 1.90 
 
 FURNACES, TUBE for combustions. Using the ordinary foot blower, this furnace will heat an iron 
 tube % to 1 inch in diameter, to its softening point in ten minutes. Without the blast it will heat 
 the same tube to redness. Can be used with natural gas, coal gas or gasoline gas. 
 
 a b c 
 
 For tubes of length, inches 12 18 24 
 
 Each $12.76 16.25 19.50 
 
 FURNACES, ELECTRIC, CRUCIBLE, for work up to 1000° C. (1832° F.). Operates on 110 or 220 
 Volt A. C. or D. C. The heating element of “Chromel” wire is wound on an alundum core, sur¬ 
 rounded by a packing of special heat insulating material, enclosed in a sheet iron case. The maximum 
 working capacity is 1000° C. (1832° F.) and by means of a controlling rheostat should be kept within 
 this limit. 
 
 With wire stand for using in a horizontal position, but without Controlling Rheostat. 
 
 a b c 
 
 2 4 5 
 
 2Y 2 4 5 
 
 300 900 1100 
 
 $20.00 44.50 66.76 
 
 FURNACES, ELECTRIC CRUCIBLE, same as above, complete with wire stand for using in a hori 
 zontal position and with Controlling Rheostat. 
 
 a b c i 
 
 2 4 5 
 
 2 x / 2 4 5 
 
 300 900 1100 
 
 $26.60 64.00 76.00 
 
 Chamber, Diameter, inches 
 Chamber, Depth, inches 
 Current Consumption, watts 
 Each 
 
 Chamber, Diameter, inches 
 Chamber, Depth, inches 
 Current Consumption, watts 
 Each 
 
 REPAIR PARTS. PRICES ON APPLICATION. 
 
Nos. 5510 to 6513 
 
 C. (1832° F.). Operates on 110 or 220 Volts 
 
 Nos. 5494 and 5496 
 
 5494 FURNACES, ELECTRIC MUFFLE, for work up to 1000 
 A. C. or D. C. 
 
 The heating unit of “Chromel” wire is wound on an alundum muffle surrounded by a packing of special 
 heat insulating material, enclosed in a sheet iron case. The maximum working capacity is 1000° C. 
 (1832° F.) and by means of a controlling rheostat, should be kept within this limit. 
 
 Without Controlling Rheostat abed 
 
 Chamber, Length, inches 5 8 9 11 
 
 Chamber, Width, inches 3^g 4^ 5% 7 ]/ 2 
 
 Chamber, Height, inches 2 1 /2 3 3 z /± 
 
 Current Consumption, watts 650 1100 1800 3300 
 
 Price, 110 or 220 Volts, A. C. or D. C. $44.60 56.00 72.50 100.00 
 
 Note: —When ordering, specify Line Voltage and whether A. C. or D. C. 
 
 5496 FURNACES, ELECTRIC MUFFLE, same as above, with Controlling Rheostat. 
 
 abed 
 
 Chamber, Length, inches 
 Chamber, Width, inches 
 Chamber, Height, inches 
 Current Consumption, watts 
 Price, 110 or 220 Volts, A. C. (60 Cycle) or D. C. 
 
 Note: —When ordering, specify Line Voltage, and whether A. C. or D. C. 
 
 REPAIR PARTS AND CHARGES 
 
 Immediate renewals can be made easily with the repair parts listed below. 
 
 6600 ALUNDUM MUFFLE for Furnace Nos. 5494a and 5496a. 
 
 5500A -, wound, ready for use. 
 
 5501 ALUNDUM MUFFLE for Furnace Nos. 6494b and 6496b. 
 
 6501A -, wound, ready for use. 
 
 5502 ALUNDUM MUFFLE for Furnace Nos. 6494c and 6496c. 
 
 5502A -, wound ready for use. 
 
 6503 ALUNDUM MUFFLE for Furnace Nos. 5494d and 5496d. 
 
 5503A -, wound ready for use. 
 
 6504 CHROMEL WIRE for Furnace Nos. 5494a and 5496a.Lot 
 
 6606 , for Furnace Nos. 5494b and 5496b . .. Lot 
 
 6606 , for Furnace Nos. 6494c and 5496c.Lot 
 
 6607 , for Furnace Nos. 5494d and 5496d.Lot 
 
 6510 FURNACE, ELECTRIC TUBE, for work up to 1000° C. (1832° F. ). Operates on 110 or 220 Volts 
 
 A. C. or D. C. 
 
 5 
 
 8 
 
 9 
 
 11 
 
 3V 8 
 
 4^ 
 
 5H 
 
 7 Vt 
 
 iy 2 
 
 3 
 
 3M 
 
 5 H 
 
 650 
 
 1100 
 
 1800 
 
 3300 
 
 $52.25 
 
 66.00 
 
 85.75 
 
 122.60 
 
 The heating unit of “Chromel” wire is wound on an alundum tube, surrounded by a packing of special 
 heat insulating material, enclosed in a sheet iron case. The maximum working capacity is 1000° C. 
 (1832° F.) and, by means of a controlling rheostat, should be kept within this limit. Chamber iy 
 inches diameter by 12 inches long. Current consumption 500 watts. Without Controlling Rheo¬ 
 stat . 
 
 6611 -, chamber 1J4 inches diameter by 12 inches long. Current consumption 500 watts. 
 
 6512 FURNACE, ELECTRIC TUBE, same as No. 6510 but with Controlling Rheostat. 
 
 6513 - —, same as No. 6611, but with Controlling Rheostat.. 
 
 REPAIR PARTS AND CHARGES 
 
 Immediate renewals can be made easily with the repair parts listed below. 
 
 5516 ALUNDUM TUBE for Furnace Nos. 6510 and 5512. 
 
 6515A -, wound ready for use. 
 
 6516 ALUNDUM TUBE for Furnace Nos. 6511 and 5613. 
 
 5516A -, wound ready for use. 
 
 6517 CHROMEL WIRE for Furnace Nos. 6510 and 5612 .Lot 
 
 6618 -, for Furnace Nos. 5511 and 6613 .Lot 
 
 $2.75 
 
 10.00 
 
 4.60 
 
 16.00 
 
 5.75 
 
 20.00 
 
 7.75 
 31.60 
 
 2.75 
 4.50 
 
 6.75 
 11.25 
 
 27.75 
 
 27.75 
 
 36.00 
 
 36.00 
 
 2.35 
 
 7.75 
 
 2.50 
 
 7.75 
 
 2.25 
 
 2.25 
 
442 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 5620 
 
 5522 
 
 6525 
 
 5526 
 
 5527 
 
 5630 
 
 5530A 
 
 5533 
 
 6533A 
 
 5535 
 
 6535A 
 5537 
 
 6637A 
 
 5540 
 
 5541 
 
 5542 
 6543 
 
 Nos. 6520 and 5622 
 
 Nos. 6630 to 6637 
 
 FURNACES, ELECTRIC CRUCIBLE, for work requiring temperatures up to 1100° C. (2000° F.) for 
 use on alternating current only. 
 
 The heating unit is of “Chromel” wire wound in the form of a core which radiates heat directly on 
 the contents of the furnace. Surrounding the heating unit is a layer of special fire brick heat insu¬ 
 lation, and outside of this, a sheet iron case. 
 
 These furnaces operate on low voltages (10 to 57 volts) and as regularly supplied for 110, 220 or 440 
 volts (60 cycles) circuit, require a transformer and controlling rheostat. 
 
 a b c 
 
 Diameter, Chamber, inches 1)4 2 4 
 
 Depth, Chamber, inches 1)4 2)4 
 
 Current Consumption, watts 650 1000 2000 
 
 Price, 110, 220 or 440 volts (60 cycles) A. C. $44.60 49.00 122.00 
 
 Note: —When ordering specify Line Voltage. 
 
 FURNACES, ELECTRIC CRUCIBLE, same as above, but Furnace only, without Transformer and 
 Controlling Rheostat. a b c 
 
 Diameter, Chamber, inches 1)4 2 4 
 
 Depth, Chamber, inches 1 % 2)4 6 
 
 Current Consumption, watts 650 1000 2000 
 
 Price, 110, 220 or 440 volts (60 cycles) A. C. $20.00 22.25 67.60 
 
 Note: —When ordering specify Line Voltage. 
 
 EXTRA HEATING UNITS 
 
 When not heated above 1100° C. (2000° F.), the life of a heating unit should be at least 1000 hours. 
 By having at hand extra heating units, immediate repairs can be made by the operator. 
 
 EXTRA HEATING UNIT for Furnace Nos. 6620a and 6622a . >. 
 
 -, for Furnace Nos. 5520b and 5522b... 
 
 -, for Furnace Nos. 5520c and 6522c.,. 
 
 
 $3.35 
 
 4.50 
 
 9.00 
 
 FURNACE, ELECTRIC MUFFLE, for work up to 1100° C. (2000° F.) for use on alternating current 
 only. 
 
 The heating unit is in the shape of heavy hair pins which are distributed around the top, bottom and 
 sides of a refractory muffle. Surrounding the heating units is a layer of special fire brick heat in¬ 
 sulation and outside of this, a sheet iron case. 
 
 This furnace operates on low voltage and as regularly supplied, for 110, 220 or 440 volts (60 cycles) 
 circuits, requires a transformer and a controlling rheostat. 
 
 Chamber 4)4 inches wide, 3 inches high, 9 inches long. Current consumption 2750 watts. 
 
 Complete with Transformer and Controlling Rheostat. 130.00 
 
 -, same as above, but Furnace only, without Transformer and Controlling Rheostat. 67.50 
 
 FURNACE, ELECTRIC MUFFLE, same as No. 5530, but designed so that temperature regulation is 
 secured by regulating transformer. 
 
 This furnace is also mounted on an angle iron stand that brings the shelf 40 inches above the floor. 
 
 Chamber 7)4 inches wide, 5 inches high, 12)4 inches long. Current consumption, 6000 watts . . . 212.00 
 
 -, same as above, but Furnace only, without Regulating Transformer. 106.00 
 
 FURNACE, ELECTRIC MUFFLE, same as No. 5530, but chamber 12 inches wide, 8 inches high, 19 
 
 inches long. Current consumption 12,500 watts. With Regulating Transformer. 476.00 
 
 -, same as above, but Furnace only, without Regulating Transformer. 280.00 
 
 FURNACE, ELECTRIC MUFFLE, same as No. 6630, but chamber 12 inches wide, 8 inches high, 26 
 
 inches long. Current consumption 15,000 watts. With Regulating Transformer. 640.00 
 
 -, same as above, but Furnace only, without Regulating Transformer. 335.00 
 
 Note: —When ordering any of the above Muffle Furnaces, specify Line Voltage. 
 
 EXTRA HEATING ELEMENTS 
 
 When not heated above 1100° C. (2000° F.) the life of a heating unit should be at least 1000 hours. 
 
 By having at hand extra heating units, immediate repairs can be made by the operator. 
 
 EXTRA HEATING UNITS for Furnace No. 6630 (10 per set).Each Unit 
 
 -, for Furnace No. 5533 (10 per set).Each Unit 
 
 -, for Furnace No. 5535 (14 per set).Each Unit 
 
 -, for Furnace No. 6537 (14 per set).Each Unit 
 
 1.16 
 
 2.25 
 
 3.35 
 
 4.50 
 

 CHEMISTRY AND BIOLOGY 
 
 443 
 
 Nos. 5545 to 5548 
 
 5545 FURNACE, ELECTRIC TUBE for work up to 1100° C. 
 
 (2000° F.) for use on alternating circuits only, 110, 220 
 or 440 volts (60 cycles). 
 
 The heating unit is of “Chromel” wire, in the form of 
 a coil which radiates heat directly on the contents of 
 the furnace. 
 
 Surrounding the heat unit is a layer of special fire brick 
 heat insulation, and outside of this, a sheet iron case. 
 
 The temperature regulation is by means of a control¬ 
 ling rheostat. 
 
 Diameter of chamber, 1 inch, length, 11 inches. Current 
 
 consumption 1000 watts. With Controlling Rheostat $60.00 
 
 6646 - —, same as above, but Furnace only, without Con¬ 
 
 trolling Rheostat. 33.50 
 
 6647 FURNACE, ELECTRIC TUBE, same as No. 6645, but 
 
 diameter of chamber 1)4 inches, length 11 inches. 
 Current consumption 1000 watts. With Controlling 
 Rheostat. 60.00 
 
 6648 -, same as above, but Furnace only, without Con¬ 
 
 trolling Rheostat. 33.60 
 
 REPAIR PARTS 
 
 When not heated above 1100° C. (2000° F.) the life of the heating unit should be at least 1000 hours. 
 By having at hand extra heating units, immediate repairs can be made by the operator. 
 
 5660 EXTRA HEATING COIL for Furnace No. 6645 
 
 4.60 
 
 6661 -, for Furnace No. 6647 
 
 4.60 
 
 ELECTRIC FURNACE CORES 
 
 6566 FURNACE CORES, ELECTRIC, ALUNDUM. Alundum Refractory Cores have -high heat conduc¬ 
 tivity and do not become electrical conductors when at the highest temperature obtained in the fur¬ 
 nace. The wires should be protected by embedding them in Alundum Cement. Thus fully pro¬ 
 tected, they do not corrode under the most severe conditions, since the alundum mixtures are chemi¬ 
 cally inert. 
 
 Bore, inches 
 Length, inches 
 Pitch, inch 
 Both Ends Open 
 One End Closed 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 i 
 
 1 
 
 l H 
 
 2 
 
 2 % 
 
 2H 
 
 2X 
 
 3 
 
 3 
 
 3 Vi 
 
 10 
 
 12 
 
 10 
 
 2 % 
 
 2 % 
 
 5 
 
 7 
 
 24 
 
 5 
 
 Vi* 
 
 % 
 
 V» 
 
 A 
 
 % 
 
 X 
 
 % 
 
 Vi 
 
 % 
 
 $4.26 
 
 4.60 
 
 4.60 
 
 $1.76 
 
 1.15 
 
 2.25 
 
 4.60 
 
 13.60 
 
 4.60 
 
 ] 
 
 5 
 
 9 
 
 % 
 
 k 
 
 5 
 
 12 
 
 X 
 
 7.26 
 
 6.76 
 
444 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 FURNITURE 
 
 No. 6575 
 
 5575 STUDENTS’ COMBINATION BIOLOGY TABLE. The table illustrated is made up from four dif¬ 
 ferent units, — the table proper, two bottle racks and the case of drawers. 
 
 Table Proper. Body constructed of selected solid oak with top of selected narrow strips of kiln-dried 
 maple, machined, matched and glued in a manner to prevent warping. A dividing strip runs length¬ 
 wise on the top through the center. Length, 6 feet, width, 3 feet, height, 30 inches. 
 
 Bottle Racks. One at each end is of unit construction and may, if desired, be added to the table proper 
 at any time. It provides three shelves, the two lower being 4 inches apart. These racks will be 
 found most convenient. 
 
 Case of Drawers. The case is designed to slide under the aprons and to extend front to back flush with 
 the aprons. The sides are panelled and ends provided with four drawers. Width over all, 15 inches; 
 height over all, about 24 inches. 
 
 Complete with Case of Drawers and two Bottle Racks.$48.00 
 
 5575A STUDENTS’ BIOLOGY TABLE, plain, same as above, but without Case of Drawers and without 
 
 Bottle Racks.21.00 
 
 5575B CASE OF DRAWERS for use with above table and as described under No. 5675 . 22.00 
 
 5575C BOTTLE RACKS for use on above or any table, and as described under No. 6575 .Each 4.50 
 
 n 
 
 No. 5680 
 
 5580 BIOLOGY LECTURE TABLE, length over all, feet, width, 3 feet, height, 34 inches. 
 
 The body of table is constructed of selected kiln-dried solid oak, the top of narrow strips of straight 
 grained maple, machined, matched and glued in a manner to prevent warping. 
 
 The front and ends are panelled, the back provided with a cupboard at each end and two large and 
 two small drawers and a drop front compartment over the drawers between. The compartment over 
 the drawers is intended for dissecting boards, large drawings, charts, etc. 
 
 The sink is of heavy construction, lined with sheet lead. It measures, inside, 22 X 20 X 12 inches 
 deep and is fitted with a standing overflow 10}^ inches high and with flush cover. 
 
 We supply our Triple Interchangeable Nozzle Goose-neck Faucet for water supply and our Four¬ 
 way Gas Turret with Lever Handle Serrated End Gas Cocks for gas supply. 
 
 The top is treated and carbonized to make acid and alkali-proof. The body is finished in standard 
 light antique color. 
 
 Without cocks.F. O. B. Factory $140.00 
 
 For AQUARIUM for this table, if desired, see No. 3527, Page 406. 
 
CHEMISTRY AND BIOLOGY 
 
 445 
 
 No. 1-726 No. 1-700 
 
 No. 1-760 
 
 No. 6606 
 
 No. 6590A 
 
 No. 6690B 
 
 6690 GAS APPARATUS for sulphur determinations, according to Mr. C. D. Jenkins, Massachusetts State 
 
 Inspector of Gas and Meters.$12.60 
 
 5590A GAS SAMPLE TUBES, according to Mr. C. D. Jenkins. 1.00 
 
 6690B GAS AMMONIA BULBS, according to Mr. C. D. Jenkins. 1.00 
 
 6693 GAS BAGS, pure gum rubber, without stopcock. a b 
 
 Capacity, quarts 4 8 
 
 Each $2.18 2.66 
 
 6694 GAS STOPCOCK for use on above GAS BAGS.70 
 
 6697 GAS BOTTLE GENERATOR, capacity 32 ounces, complete with fittings. .90 
 
 KNOTT’S GAS COCKS 
 
 The Knott Gas Cocks are of brass. The nipples are long, and with five sharp serrations which make it easy 
 to slip on rubber tubing, but impossible to pull it off accidentally. Adjustment is secured by means of a lever 
 handle. 
 
 1-700 KNOTT’S LEVER HANDLE GAS COCK, J^-inch I. P. $0.66 
 
 1-710 KNOTT’S SINGLE GAS TURRET, one gas cock. 1.46 
 
 1-716 KNOTT’S TWO-WAY GAS TURRET, two gas cocks. 1.86 
 
 1-720 KNOTT’S THREE-WAY GAS TURRET, three gas cocks. 2.26 
 
 1-726 KNOTT’S FOUR-WAY GAS TURRET, four gas cocks. 2.66 
 
 1-760 THE KNOTT MOUNTED FOUR-WAY GAS TURRET. The use of this design obviates all necessity 
 of cutting a table top. It is connected by rubber tubing to a supply cock left at the floor line or 
 above the table. 4.60 
 
 6606 GAS COLLECTOR (Beehive Shelf) of unglazed porcelain, 2% inches high, for use in a sink or dish as 
 
 the bottle rest for collecting gases over water. .30 
 
 6607 GAS COLLECTOR (Packard’s Glazed Porcelain Beehive Shelf). This collector is provided with a 
 
 recessed top for holding the neck of the bottle, and since it is but one inch high, requires very little 
 
 water, thus permitting the use of a shallow dish. Excellent for lecture desk. 18 
 
 6610 GAS GENERATOR, GASOLINE, constructed wholly of brass, polished and nickeled. Height 7 
 inches, diameter 4 Yi inches. Interior contains 14 lineal feet of evaporating surface. Turret valve 
 at top controls both gas and air outlets, also controls the size of the blowpipe flame. Built absolutely 
 proof against any danger of flashing back of the flame. An air check is attached at the end of the filler 
 tube to prevent over filling. Complete as illustrated. 9.76 
 
 6612 GAS GENERATOR, OXYGEN, of polished metal, inches high, weighing but lYi pounds. Ca¬ 
 
 pacity at one charge 27 liters, — nearly one cubic foot. The charge consists of an “Oxone Cart¬ 
 ridge,” a hermetically sealed tin which is to be punctured on top and bottom. 
 
 Produces pure oxygen instantaneously. This oxygen is at low pressure and as it leaves the generator 
 is 99.3 per cent. pure. As it leaves the wash bottle it is considered 100 per cent, pure oxygen. 
 
 Simple and easy to handle, quickly recharged and always a source for obtaining pure oxygen instantly. 
 Complete outfit is packed in a finished portable case and comprises the generator with wash bottle, 
 
 awl for perforating the tin, four oxone cartridges and rubber tubing lead.20.00 
 
 Note: — The above outfit, using “Hydrone” in place of “Oxone,” may be used to generate pure 
 hydrogen. 
 
 6613 “OXONE” CARTRIDGES, sold only in two pound tins . Per Tin 1.60 
 
 6614 “HYDRONE” CARTRIDGES, sold only in two pound tins.Per Tin 1.60 
 

 446 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6620 
 
 L!ikl4iliniBnMT 
 
 No. 6616 No. 12-296 
 
 6616 GAS HOLDER, Gasometer, Berzelius’ and Pepy’s, improved form, of heavy copper. Capacity, 
 
 5 gallons. $19.60 
 
 6617 -, capacity 10 gallons. 24.60 
 
 5620 GAS MEASURING TUBES for collecting gases over mercury. Subdivided by cc. 
 
 a b 
 
 Capacity, cc. 50 100 
 
 Each ' $1.46 1.80 
 
 6626 GAS PRESSURE REGULATOR, Murrill’s Improved, for use with a thermostat. A constant tem¬ 
 perature can be maintained regardless of the pressure variations in the gas supply. With two out¬ 
 lets as illustrated. $9.76 
 
 6626 GAS REGULATOR, Reichert’s, adapted for water baths, drying ovens, incubators, sterilizers, etc. 
 
 Secures constant temperature at any desired point from 1° C. up to the boiling point of mercury 3.25 
 6628 GAS REGULATOR, Roux Bi-metallic, an accurate gas regulator, simple in construction, easily oper¬ 
 ated and adjusted to regulate an even temperature more constantly than any other thermo-regu¬ 
 lator. Not liable to leak as it is made entirely of metal. Particularly well adapted for ovens and 
 
 sterilizers. Length 10 inches. Complete with directions. 8.60 
 
 5629 GAS REGULATOR, Roux Bi-metallic. Same as above, but for high temperatures. 9.76 
 
 GAS STOVES. See STOVES, Pages 483 and 484. 
 
 12-295 GAUGE, POLISHED STEEL, INSIDE TAPER, for inside measure of tubes, holes, etc. Made of 
 
 hardened polished steel and about 18 centimeters long. Will measure from to 15 millimeters .80 
 6632 GAUZE, ASBESTOS CENTER, tinned iron wire, 5X5 inches with asbestos compressed in the 
 
 mesh. Excellent for slow evaporations.Each .10 
 
 6634 GAUZE, COPPER, thick wire, mesh selected for use in heating chemical ware. 
 
 a b c 
 
 Size, inches 4X4 6X6 12X12 
 
 Each $0.10 .20 .70 
 
 6636 GAUZE, COPPER, 80 mesh, 4X4 inches. 18 
 
 6637 GAUZE, IRON, thick wire, mesh selected for use in heating chemical ware. 
 
 a b c 
 
 Size, inches 4X4 6X6 12X12 
 
 Each $0.04 .07 .27 
 
 GENUS COVERS. See Page 472. 
 
 3636 GLASS, LECTURE, for use on lecture desk for a large class of chemical experiments. Capacity 350 
 
 cc. (For illustration see Page 412). 60 
 
 6642 GLASSES, TEST, on foot, clear colorless glass. 
 
 a b 
 
 Capacity, ounces 2 4 
 
 Each $0.40 .46 
 
 3616 GLASS BEADS, hollow, for filtering or drying gases by means of acid.Per Pound .95 
 
CHEMISTRY AND BIOLOGY 
 
 447 
 
 6645 
 
 5646 
 
 6649 
 
 5650 
 
 5651 
 5653 
 
 6330 
 
 6482 
 
 No. 5653 No. 6095 No. 5098 
 
 GLASS BLOWERS’ FIRES. See BLOWPIPES, Page 416. 
 
 GLASS CUTTER, single steel wheel, with metal handle. $0.07 
 
 GLASS CUTTER, TURRET HEAD. Turret contains six high grade steel wheels, hardened and tem¬ 
 pered and carefully tested. Ebony finished handle, nickeled ferrule, highly polished. .30 
 
 GLASS CUTTING DIAMOND, excellent quality. 6.40 
 
 GLASS TUBE CUTTER, BUNSEN’S, a practical tool with steel wheel, hardened and tempered . . . 
 GLASS TUBE CUTTER for tubes up to j^-inch diameter, inexpensive but efficient, rapid and practical 
 GLASS CUTTER FOR CIRCLES. Cuts circles from 2J4 to 22^4 inches in diameter. Cutter head 
 is interchangeable, allowing for renewing of cutters, and is secured firmly to the graduated rod 
 
 Hardwood handles and base with felt covered bottom 
 
 b c 
 
 5X5 6X6 
 
 .04 .05 
 
 marked to ]/% inches. All parts nickel-plated. 
 GLASS PLATES for covers. a 
 
 Size, inches 4X4 
 
 Each $0.03 
 
 GLASS RODS. See RODS, GLASS, Page 477. 
 GLASS RODS, stirring rods, finished ends. 
 
 Size, mm. 
 
 Per Dozen 
 
 GLASS TUBING. See TUBING, GLASS, Page 491 
 
 a 
 
 X 150 
 
 $0.16 
 
 b 
 
 X 150 
 
 .20 
 
 6660 
 
 GLASS WOOL for filtering acids, etc. . . . 
 
 
 
 
 
 
 Per 
 
 ounce 
 
 5662 
 
 GOLD BEATERS’ SKIN . . 
 
 
 
 
 
 
 
 
 5664 
 
 GRADUATES, conical, graduated in ounces. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 
 Capacity, ounces 
 
 Vi 
 
 1 
 
 2 
 
 4 
 
 8 
 
 16 
 
 32 
 
 
 Each 
 
 $0.20 
 
 .22 
 
 .25 
 
 .30 
 
 .50 
 
 .70 
 
 1.10 
 
 5666 
 
 GRADUATES, conical, graduated in cubic centimeters. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 
 Capacity, cc. 
 
 
 30 
 
 60 
 
 100 
 
 250 
 
 500 
 
 1000 
 
 
 Each 
 
 
 $0.25 
 
 .28 
 
 .32 
 
 .55 
 
 .81 
 
 1.25 
 
 6667 
 
 GRADUATES, conical, graduated in both ounces and cubic centimeters. 
 
 
 
 
 
 
 a b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 
 
 
 
 Capacity, ounces 1 2 
 
 4 
 
 8 
 
 16 
 
 32 
 
 
 
 
 
 Capacity, cc. 30 60 
 
 125 
 
 250 
 
 500 
 
 1000 
 
 
 
 
 
 Each $0.30 .36 
 
 .46 
 
 .66 
 
 1.00 
 
 1.66 
 
 
 
 
 6095 GRADUATES, CYLINDRICAL, of glass, broad base, with lip, graduated in cubic centimeters. 
 
 a b c d e f g 
 
 Capacity, cc. 10 25 50 100 250 500 1000 
 
 Each $0.30 .36 .40 .62 .90 1.10 1.86 
 
 6096 GRADUATES, CYLINDRICAL, double graduations, reading up and down, of glass, broad base, with 
 
 lip, graduated in cubic centimeters. a b c d e f 
 
 Capacity, cc. 25 50 100 250 500 1000 
 
 Each $0.38 .45 .56 .96 1.20 2.00 
 
 6098 GRADUATES, MIXING, STOPPERED, serviceable when making standard solutions. Of glass, broad 
 base, round glass stoppers, graduated in cubic centimeters. 
 
 a b c d e f g 
 
 Capacity, cc. 25 50 100 200 250 500 1000 
 
 Each $0.75 .85 .96 1.20 1.30 1.85 2.25 
 
 .60 
 
 .30 
 
 1.35 
 
 .60 
 
 .10 
 

 448 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6671 
 
 HEATER, ELECTRIC, WATER. See ELECTRIC APPLIANCES, Page 436. 
 
 HEATERS, SOLDERING IRON. See SOLDERING IRON HEATERS, Page 479. 
 
 HOT PLATES. See STOVES, Pages 483 and 484, and BATHS, SAND, Page 409. 
 
 HYDROMETERS 
 
 Our line of hydrometers has been selected with unusual care to cover the requirements not only 
 of commercial, but also of educational laboratories as well. We believe tve have covered general 
 requirements. We most respectfully solicit correspondence relative to special individual requirements 
 which are not met in the following listings. 
 
 31-170 HYDROMETER for light liquids, double scale, Beaume, 70 to 10, Specific Gravity, 
 
 0.7000 to 1.000 .$0.60 
 
 31-171 HYDROMETER for heavy liquids, double scale, Beaume, 0-70, Specific Gravity, 1.000 
 
 to 2.000 .60 
 
 31-176 HYDROMETER, Specific Gravity Scale onlv, for both light and heavy liquids. Range 
 
 0.7000 to 2.000 . 1.26 
 
 6668A HYDROMETER, Twaddle Scale, 0° to 24°, x / 2 ° graduation. .86 
 
 6668B , 24° to 48°, x / 2 ° graduation. .86 
 
 6668C , 48° to 72°, j^° graduation. .86 
 
 6668D , 72° to 100°, y 2 ° graduation.86 
 
 6668E , 100° to 134°, x / 2 ° graduation. .86 
 
 6668F -, 134° to 180°, y 2 ° graduation.86 
 
 6669A HYDROMETER, Specific Gravity scale, 0.600 to 0.700, .02° graduation. 1.00 
 
 6669B -, 0.700 to 0.800, .02° graduation.. . 1.00 
 
 6669C , 0.800 to 0.900, .02° graduation. 1.00 
 
 6669D , 0.900 to 1.000, .02° graduation. 1.00 
 
 6669E , 1.000 to 1.200, .05° graduation. 1.00 
 
 6669F , 1.200 to 1.400, .05° graduation. 1.00 
 
 6669G , 1.400 to 1.600, .05° graduation. 1.00 
 
 6669H , 1.600 to 1.800, .05° graduation. 1.00 
 
 56691 , 1.800 to 2.000, .05° graduation. 1.00 
 
 6670A HYDROMETER, Beaume Scale, coal oil hydrometer, 10° to 50°, 1° graduation ... .76 
 
 6670B , 40° to 70°, 1° graduation ..75 
 
 5670C , 60° to 100°, 1° graduation.76 
 
 6671 HYDROMETER for storage batteries, consisting of the hydrometer proper inside a 
 
 glass tube with a rubber bulb at the top and a rubber tube at the bottom. The 
 rubber tube may be inserted in the storage battery, a quantity of acid withdrawn 
 into the glass tube, the reading taken and the liquid replaced within a few seconds, 
 and with great convenience. Outfit complete. 1.66 
 
 6672 HYDROMETER, similar to the one used in the above set, scale 1.150° to 1.300°, 
 
 .005° graduation. Length about 5 inches. With test jar in wooden case .... .76 
 
 6136 LACTOMETER, Spence’s, New York Board of Health pattern, 0° to 120°, 2° graduation 1.00 
 
 6137 LACTODENSIMETER, Quevenne’s Pattern, scale 15° to 40° (1.015 to 1.040 Specific 
 
 Gravity), 1° graduation. 1.00 
 
 5673A ALCOHOLOMETER, Proof Scale, 50° below proof to 0° (proof), 1° graduation. 1.00 
 
 5673B ALCOHOLOMETER, Proof and Tralle Scale, 100° below to 100° above proof; 0° to 100° Tralle; 
 
 1° graduation. 1.00 
 
 5674A HYDROMETER, for Sugar, Brix scale, 0 to 30°, x / 2 ° graduation. 1.00 
 
 5674B -, 30° to 60°, y 2 ° graduation.. 1.00 
 
 5674C -, 60° to 90°, y 2 graduation. 1.00 
 
 31-250 HYDROMETER JARS or CYLINDERS, of clear white glass, with foot and rim. 
 
 a b c d e 
 
 Size, inches 12 X 1H 12 X 2 15 X 2 15 X 3 18 X 3 
 
 Each $0.60 .66 .80 1.00 1.35 
 
 HYPERDERMIC SYRINGE. See SYRINGE, HYPERDERMIC, Page 486. 
 
 .. 
 
 V 
 
 
 
 •••*#*»■>' -^v? i nr-v ■ ■*. 
 
CHEMISTRY AND BIOLOGY 
 
 449 
 
 
 INCUBATORS 
 
 Nos. 6680 and 6682 No. 6683 
 
 6680 INCUBATOR, POLISHED COPPER, double wall, sheet iron base 9 inches high, — otherwise the same 
 as the Triple Wall Incubators Nos. 6686 to 6688. Inside dimensions 10 inches high, 8 inches wide, 
 8 inches deep; outside, 13 inches high, 113-6 inches wide, 113-6 inches deep. With one shelf .... 
 
 6682 INCUBATOR, POLISHED COPPER, double wall, same as above, but inside dimensions, 12 inches 
 
 high, 10 inches wide, 10 inches deep; outside, 15 inches high, 133-6 inches wide, 133-6 inches deep . 
 
 6683 INCUBATOR, POLISHED COPPER, double wall, the outer one covered with insulating material. 
 Two-inch water space, water gauge and stopcock. Base is of sheet iron and is 9 inches high. A glass 
 
 plate in the top permits of examination of contents without opening the top. Inside measurements, 8 
 X 9 inches; outside, 12 X 12 inches. With one perforated tray. 
 
 6685 
 
 INCUBATOR, POLISHED 
 COPPER, three wall, hav¬ 
 ing both air and water 
 space, the outer surface 
 being covered with insulat¬ 
 ing material to insure an 
 even temperature. Double 
 doors, the inner one of 
 beveled glass to permit ob¬ 
 servation of cultures with¬ 
 out disturbing the tem¬ 
 perature. Tubulations for 
 gas regulator, thermometer 
 and for filling water space. 
 
 Supported on a sheet iron 
 base, 10 inches high, fin¬ 
 ished in durable black, hav¬ 
 ing a door with an open¬ 
 ing covered with mica for 
 observation of the flame. 
 Inside dimensions, 9 inches 
 high, 7 inches wide, 7 inches . 
 deep. Outside dimensions, 
 
 13 inches high, 11 inches 
 wide and 103-6 inches deep. 
 
 With one shelf .... $43.76 
 
 Nos. 6686 and 6686 
 
 6686 
 
 INCUBATOR, POLISHED COPPER, three wall, having both air and water space. Same as above, 
 but inside dimensions 12 inches high, 9 inches wide, 9 inches deep. Outside dimensions, 17 inches 
 high, 14 inches wide, 13 inches deep. With one shelf. 
 
 $42.60 
 
 52.60 
 
 19.50 
 
 $64.00 
 
450 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 6687 INCUBATOR, POLISHED 
 COPPER, three wall.' 
 
 Same as No. 6685, but height 
 of base 11 inches and inside 
 dimensions, 14 inches high, 
 
 12 inches wide, 10 inches 
 deep. Outside dimensions, 
 
 19 inches high, 17 inches 
 wide, 14 inches deep. With 
 two shelves.$72.00 
 
 6688 INCUBATOR, POLISHED 
 COPPER, three wall. ' 
 
 Same as above, but inside 
 dimensions, 20 inches high, 
 
 18 inches wide, 10 inches 
 deep. Outside dimensions, 
 
 25% inches high, 23% inch¬ 
 es wide, 14% inches deep. 
 
 With two shelves .... 98.00 
 
 Nos. 5687 and 5688 
 
 INCUBATORS, ELECTRICALLY HEATED WITH ELECTRICAL CONTROL 
 
 Can be used on Direct or Alternating Current 
 
 The following incubators are the same sizes 
 and have the same points of excellence as Nos. 
 5685 to 5688. They are, however, built with proper 
 insulation for electrical heating. If at any time it 
 should be desired to use these incubators on gas, 
 the electric attachment may readily be removed. 
 
 The electric regulator is a device, simple and 
 practical in construction, and one quite easily 
 operated. When once set, it requires absolutely 
 no attention and there will hardly be a noticeable 
 variation in temperature. Operation by expanded 
 mercury, positively insures the finest adjustment. 
 
 6690 ELECTRIC INCUBATOR, 9X7x7 
 
 inches, inside measurements. With 
 one shelf. $96.00 
 
 6691 -, 12 X 9 X 9 inches, inside 
 
 measurements. With one shelf . . 110.00 
 
 5692 -, 14 X 12 X 10 inches, inside 
 
 measurements. With two shelves 136.00 
 
 5693 -, 20 X 18 X 10 inches, inside 
 
 measurements. With two shelves 165.00 
 
 6700 INK, DIAMOND, for writing on glass, 
 labeling bottles, beakers, etc. Per 
 ounce.. .76 
 
 IRON, ELECTRIC. See ELECTRIC 
 APPLIANCES, Page 436. 
 
 Nos. 5690 to 5693 
 

 CHEMISTRY AND BIOLOGY 
 
 451 
 
 No. 5717 
 
 a b c 
 No. 6945 
 
 5705 
 
 5096 
 
 6096 
 
 g 
 
 1000 
 
 1.85 
 
 Of glass, broad 
 
 No. 6730 No. 5727 No. 6705 
 
 JARS, AQUARIA. See AQUARIA, Page 406. 
 
 31-265 JARS, BATTERY, of excellent quality. 
 
 a bed 
 
 Size, inches 2 }•i X 3J4 4X5 6X8 8 X 12 
 
 Each $0.12 .26 .40 1.50 
 
 91-380 . JARS, RECTANGULAR BATTERY, of excellent quality. 
 
 a b 
 
 Size, inches 2 l A X 4 % X 7 4X4X8 
 
 Each $0.35 .45 
 
 JAR, CALCIUM CHLORIDE (Drying Tower). Clear white glass, 10 inches high. $1.00 
 
 JARS, GRADUATED, CYLINDRICAL. Of glass, broad base, with lip, graduated in cubic centimeters, 
 a b c d e f 
 
 Capacity, cc. 10 25 50 100 250 500 
 
 Each $0.30 .36 .40 .52 .90 1.10 
 
 JARS, GRADUATED, CYLINDRICAL, double graduations, reading up and down, 
 base, with lip, graduated in cubic centimeters. 
 
 a b c d e f 
 
 Capacity, cc. 25 50 100 250 500 1000 
 
 Each $0.38 .45 .56 .95 1.20 2.00 
 
 JARS, GRADUATED, MIXING, STOPPERED. Of glass, broad base, round glass stoppers, gradu¬ 
 ated in cubic centimeters. 
 
 a b c d e f g 
 
 Capacity, cc. 25 50 100 200 250 500 1000 
 
 Each $0.75 .85 .95 1.20 1.30 1.85 2.25 
 
 JARS, HYDROMETER, of clear white glass, with foot and rim. 
 
 a b c d e 
 
 Size, inches 12 X 1H 12 X 2 15 X 2 15 X 3 18 X 3 
 
 Each $0.50 .55 .80 1.00 1.35 
 
 JARS, MUSEUM, for preserving and displaying specimens in laboratories and museums. Of clear 
 colorless glass. Mouth same width as inside diameter. Contents securely sealed by a metal clamp 
 which binds the glass cover to jar with thin rubber gasket between. On the under side of the cover 
 are two glass rings from which specimens may be suspended. 
 
 abed e 
 
 Height, without Lid, inches 
 Width of Mouth, inches 
 Approximate Capacity, pints 
 Each 
 
 JAR, STAINING, COPLIN’S, for use in staining sections for microscopic work. With glass lid 
 
 ground on shoulder. For ten slides.. 
 
 JARS, NESSLER, for ammonia tests in water analysis; of colorless glass.. 
 
 5098 
 
 31-260 
 
 5715 
 
 6717 
 
 6945 
 
 5720 
 
 6727 
 
 4 
 
 8 
 
 8 
 
 8 
 
 12 
 
 2H 
 
 2K 
 
 3'A 
 
 5 
 
 5 
 
 h 
 
 1 
 
 2V 2 
 
 sy 2 
 
 8 
 
 $0.65 
 
 .70 
 
 1.00 
 
 1.90 
 
 2.10 
 
 .36 
 
 5730 
 
 a b c 
 
 Graduated, cc. 50 100 50 and 100 
 
 Each $0.66 .80 .95 
 
 JARS, SHOW, INVERTED, clear, colorless glass. 
 
 a bed 
 
 H 12 4 
 
 $0.20 .26 .36 .60 
 
 “Lightning Sealing,” for chemical, biological and botanical specimens, 
 a bed 
 
 X 12 4 
 
 $0.10 .12 .14 .20 
 
 Capacity 3 gallons, with cover and handles. 
 
 Capacity, pints 
 Each 
 
 JARS, STORAGE, 
 
 Capacity, pints 
 Each 
 
 JAR, WASTE, stoneware. 
 
 .85 
 
452 
 
 L . E. KNOTT APPARATUS CO., BOSTON 
 
 6750 
 
 6763 
 
 6758 
 
 6760 
 
 6761 
 
 6766 
 
 6770 
 
 6770A 
 
 6773 
 
 6773A 
 
 6780 
 
 6781 
 5782 
 6783 
 6789 
 5796 
 
 No. 6766 
 
 LABELS, GUMMED, red border, in boxes. 
 
 No. 5770 
 
 No. 5773 
 
 Trade No. 
 
 217 
 
 213 
 
 209 
 
 205 
 
 201 
 
 2004 
 
 2007 
 
 2002 
 
 2001 
 
 2006 
 
 2005 
 
 2003 
 
 Length, inches 
 
 i 1 
 
 134 
 
 134 
 
 134 
 
 234 
 
 234 
 
 3 
 
 334 
 
 3 34 
 
 434 
 
 4 34 
 
 434 
 
 Width, inches 
 
 34 
 
 1 
 
 134 
 
 m 
 
 134 
 
 l 
 
 134 
 
 134 
 
 134 
 
 134 
 
 2 
 
 2 
 
 Per Box 
 
 $0.07 
 
 .07 
 
 .07 
 
 .07 
 
 .07 
 
 .17 
 
 .20 
 
 .20 
 
 .25 
 
 .30 
 
 .33 
 
 .42 
 
 LABELS, GUMMED, perforated, in rolls, 1000 labels in a roll. Numbers given are same sizes as above. 
 Each roll contained in a special box with slot opening so that labels can be drawn out as needed 
 without opening the box. abed 
 
 Trade No. , 205 209 217 221 
 
 Per Roll $0.80 .75 .65 .60 
 
 LABELS, CHEMICAL, in book, names and symbols for all chemicals and reagents in general use in 
 laboratories. Gummed and perforated so that any label may be removed without destroying the 
 
 book.Per Book 
 
 LABELS, MICROSCOPIC SLIDE, 34 X 34 inch, gummed . Per Box 
 
 LABELS, MICROSCOPIC SLIDE, 34 X 34 inch, gummed, black border. Per Box 
 
 LACTOMETERS. See MILK TESTING APPARATUS, Page 468. 
 
 LADLE, COPPER with wood handle. Diameter of bowl 134 inches, depth 134 inches, extreme length 
 
 8 inches.. 
 
 LAMPS, ALCOHOL, of colorless glass, with ground glass cap, wick and wick holder. 
 
 a b 
 
 Capacity, ounces 4 8 
 
 Each $0.25 .40 
 
 LAMP WICKS for above glass Alcohol Lamps.Per Dozen 
 
 LAMP, POLISHED BRASS, ALCOHOL, nickel-plated. Capacity 2 ounces. 
 
 LAMP WICKS, special for above.Per Dozen 
 
 LAMPS, BLAST. See pages 201 and 202. 
 
 LEAD DISHES. See DISHES, LEAD, Page 432. 
 
 LITMUS PAPER, red, in sheets.Per Sheet .04. Per Quire 
 
 LITMUS PAPER, red, in books of strips.Per Book 
 
 LITMUS PAPER, blue, in sheets.Per Sheet .04. Per Quire 
 
 LITMUS PAPER, blue, in books of strips .. Per Book 
 
 LITMUS PENCIL. 
 
 LOGARITHM TABLES, a heavy board card, 1434 X 934 inches, with four place tables of logariths 
 and anti-logariths, with table of atomic weights, also Factors for Analysis. Computed by Dr. 
 Hubert G. Shaw. This card is of convenient size for students’ use in the laboratory. Used ex¬ 
 tensively and for years at the Massachusetts Institute of Technology.Each 
 
 $0.45 
 
 .10 
 
 .10 
 
 .50 
 
 .18 
 
 .65 
 
 .18 
 
 .66 
 
 .06 
 
 .66 
 
 .06 
 
 .26 
 
 .35 
 
 MAGNIFIERS 
 
 Our line of magnifiers has been selected with the greatest care. We list below types that have succeeded best 
 in meeting the diversified requirements of science laboratories and feel, therefore, that our customers will be able 
 to select the type or types best suited to their particular needs. 
 
 No. 6816 
 
 No. 6820 
 
 No. 6823 
 
 No. 6825 
 
 No. 74-236 
 
 6815 MAGNIFIER, TRIPOD, giving a large clear field and a magnification sufficient for elementary work. 
 
 The lens may be focussed by screwing it up and down in its frame.$0.66 
 
 6817 MAGNIFIER, POCKET, single, 34 inch lens, mounted and encased in vulcanite. -40 
 
 6819 , single, same as above, but lens 1 inch in diameter. -60 
 
 6820 , double, 34 an d 34 inch lenses mounted and encased in vulcanite. *68 
 
 6821 , double, J4 and 1 inch lenses, mounted and encased in vulcanite. -80 
 
 6823 ——, triple, 34 > 34 and 34 inch lenses, mounted and encased in vulcanite._. *95 
 
 6826 MAGNIFIER, CODDINGTON, sharp definition, large, clear, flat field. Mounted in nickel-plated 
 
 74-236 MAGNIFIER, FOLDING (LINEN TESTER), brass mounted, short focus, 34 inch aperture . . . . .44 
 
 74-230 MAGNIFIER, READING (Reading Lens), diameter 3 inches, in nickel-plated brass mount, polished 
 
 wood handle . 1*30 
 
CHEMISTRY AND BIOLOGY 
 
 453 
 
 Nos. 5835 to 5839 
 
 Nos. 5841 to 5845 
 
 Nos. 5847 to 5851 
 
 DOUBLET MAGNIFIERS. These magnifiers are composed of two separate plano-convex lenses, very carefully 
 and accurately ground and polished and substantially set in their mounts. Nos. 5835 to 6839 are black lacquered 
 and Nos. 5841 to 5851 are nickel-plated. Excellent definition and an exceptionally flat field with greatest focal length 
 are characteristics of these lenses. 
 
 For use on Dissecting Stands. 
 
 5835 6X DOUBLET MAGNIFIER, 41.6 mm. (1.6 inches) focal distance, working distance 22 mm., field 22 
 
 mm... 
 
 5836 9X DOUBLET MAGNIFIER, 27.8 mm. (1.1 inch) focal distance, working distance 15 mm., field 16 
 
 mm. 
 
 5837 12X DOUBLET MAGNIFIER, 20.8 mm. (0.8 inch) focal distance, working distance 12 mm., field 11 
 
 mm. 
 
 5838 18X DOUBLET MAGNIFIER, 13.9 mm. (0.5 inch) focal distance, working distance 8 mm., field 8 
 
 mm.'. 
 
 6839 24X DOUBLET MAGNIFIER, 10.4 mm. (0.4 inch) focal distance, working distance 6 mm., field 5.5 
 
 mm. 
 
 With Hexagonal Handles for use on the Desk. 
 
 6841 6X DOUBLET MAGNIFIER, 41.6 mm. (1.6 inches) focal distance, working distance 22 mm., field 22 
 mm.—. 
 
 5842 9X DOUBLET MAGNIFIER, 27.8 mm. (1.1 inches) focal distance, working distance 15 mm., field 16 
 
 mm. 
 
 5843 12X DOUBLET MAGNIFIER, 20.8 mm. (0.8 inch) focal distance, working distance 12 mm., field 11 
 
 mm. 
 
 6844 18X DOUBLET MAGNIFIER, 13.9 mm. (0.5 inch) focal distance, working distance 8 mm., field 8 
 
 mm. 
 
 6845 24X DOUBLET MAGNIFIER, 10.4 mm. (0.4 inch) focal distance, working distance 6 mm., field 5.5 
 
 mm.. 
 
 In Folding Pocket Cases. 
 
 6847 6X DOUBLET MAGNIFIER, 41.6 mm. (1.6 inches) focal distance, working distance 22 mm., field 22 
 mm. 
 
 5848 9X DOUBLET MAGNIFIER, 27.8 mm. (1.1 inches) focal distance, working distance 15 mm., field 16 
 
 mm.. 
 
 5849 12X DOUBLET MAGNIFIER, 20.8 mm. (0.8 inch) focal distance, working distance 12 mm., field 11 
 
 mm. 
 
 5850 18X DOUBLET MAGNIFIER, 13.9 mm. (0.5 inch) focal distance, working distance 8 mm., field 8 
 
 mm. 
 
 6851 24X DOUBLET MAGNIFIER, 10.4 mm. (0.4 inch) focal distance, working distance 6 mm., field 5.5 
 mm. 
 
 $1.00 
 
 1.00 
 
 1.00 
 
 1.25 
 
 1.50 
 
 1.00 
 
 1.00 
 
 1.00 
 
 1.25 
 
 1.60 
 
 1.25 
 
 1.25 
 
 1.25 
 
 1.50 
 
 1.50 
 
 MANIKINS 
 
 The manikin is a reproduction of the Complete Anatomy of the human body in all its details, and is an invalua¬ 
 ble aid in teaching Physiology. 
 
 It can be hung upon the wall closed, occupying the space of a picture. Open it and you will see fold after fold 
 that can be turned just as you would turn the pages of a book. Each fold is a picture of some part of the Complex 
 Anatomy. 
 
 Every muscle, ligament, bone, nerve, vein, artery and organ is seen in its natural position. 
 
 Every such part is numbered and its name and purpose is learned by reference to the index that accompanies 
 the Manikin. 
 
 The Pilz Manikin, life size, shows every detail of the human body full size, thirty folds being necessary to ac¬ 
 complish this. 
 
 It is of indestructible linen-centered cardboard and will last a lifetime. 
 
 Size: 5 feet, 5 inches high. 
 
 Number of Parts. There are 455 parts covering all the Anterior and Posterior Muscles, Circulation of the Blood, 
 Nervous System, Skeleton and Viscera. 
 
 6856 Male full size, each. $13.60 
 
 6866 Female full size, each. 17.50 
 
 6867 Sexless full size, each. 13.50 
 
 Dr. Minder’s Manikins are of smaller size, but contain all of the essential features of the above. They are of 
 
 special interest to schools not able to purchase the large size editions. 
 
 Size: Twenty (20) inches tall. 
 
 Number of Parts. Minder’s Manikins contain 384 distinct parts, covering the Muscles, Circulation of the 
 Blood, Nervous System, Skeleton and Viscera. 
 
 6869 Female, each. $3.60 
 
 6860 Sexless, each. 2.76 
 
 A key and descriptive text with all parts named and numbered is furnished. 
 
 In ordering be particular to state which manikin is wanted, male, female or sexless. 
 
454 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 COMPOUND MICROSCOPES 
 
 The microscopes listed as follows with the exception of Nos. 6868 and 6870 
 are the product of the Spencer Lens Company. The best of material is used and is 
 worked by the best modern machinery in the hands of men of skilled mechanics, 
 carefully trained, each to his particular work. 
 
 The stands are for the most part in a neat black finish which is baked in at 
 a high temperature and which is resistant to wear, to acid, to alcohol, and all the 
 common reagents. This effect is heightened by the yellow finish of the smaller 
 parts. This yellow finish is also alcohol and reagent proof. 
 
 We call particular attention to features which are peculiar to these microscopes. 
 
 Unexcelled Optics. 
 
 Fine adjustments are automatically lubricated and protected from dust. 
 
 All fine adjustments are so protected that no harm can come to them from 
 handling the microscope by the arm. 
 
 All fine adjustments cease to work when the objective rests on the cover glass. 
 
 No lost motion or lateral displacement in either type of fine adjustment. 
 
 Unusually large stages on which the vulcanite stages are vulcanized directly 
 to the metal stage. 
 
 Unexcelled optical and mechanical workmanship throughout. 
 
 6868 COMPOUND MICROSCOPE, SMALL. This microscope, though 
 but 7 inches high, is an efficient compound microscope for the general 
 work of a school laboratory. Constructed of brass throughout and 
 handsomely finished. Stage is large and provided with nickel-plated 
 spring clips. Furnished with ocular and three objectives giving 
 magnifications of 30, 50, and 80 diameters. In box with receptacle 
 for slides and forceps . $9.80 
 
 No. 6870 5870 COMPOUND MICROSCOPE, a low priced instrument of exception¬ 
 
 ally fine quality well adapted for school laboratories. It is a full 
 size instrument conforming to standards by Royal Microscopical Society, and objectives and ocu¬ 
 lars of any other make conforming to the same standards, may be added to its equipment. 
 
 Stage, 2 % X 2% inches, has attached to it a supplementary micrometer stage affording a very deli¬ 
 cate fine adjustment with nickel-plated spring stage clips. 
 
 Stand is made entirely of brass, handsomely finished in lacquer and black enamel. The draw tube 
 is 160 mm. long and is nickel-plated and polished where it slides in the main tube. 
 
 Mirror is plane, 1% inches diameter, so mouthed that it can be adjusted to any angle. With a 7X 
 
 ocular and a % and 1 inch divisible objective, in case . .. 13.60 
 
 COMPOUND MICROSCOPES, suggested for commercial, house¬ 
 hold or elementary school purposes where the magnification re¬ 
 quired is not great. 
 
 Focussing adjustment, coarse adjustment only, by rack and 
 pinion. 
 
 Stage of brass, black lacquered. Measures 112 X 108 mm. and 
 distance of optical axis to base of arm is 75 mm. 
 
 Mirror, plano-concave, 50 mm. diameter, on swing bar. 
 
 6873 -, with divisible objective 32-14 mm. and 10X ocular giving 
 
 magnifications of 35 and 130 diameters. $17.60 
 
 6873A -, with divisible objective 32-14 mm. and 6 mm . special ob¬ 
 
 jective and 6X and 10X oculars giving magnifications of 17, 
 
 35, 65,130 and 360 diameters. 23.00 
 
 6873B -, same as above, but with revolving dust-proof double nose- 
 
 piece .27.00 
 
 6873C -, with 16 and 4 mm. objectives and 10X ocular giving mag¬ 
 nifications of 100 and 440 diameters. 26.60 
 
 6873D -, same as above, but with revolving dust-proof double nose- 
 
 piece . 29.60 
 
 No. 6873 
 
CHEMISTRY AND BIOLOGY 
 
 455 
 
 Nos. 5876 to 5876E 
 
 Nos. 5878 to 6878E 
 
 Nos. 6880 to 5880F 
 
 5876 
 5876A 
 5876B 
 
 5876C 
 
 6876D 
 
 5876E 
 
 MICROSCOPES, side fine adjustment. Stage 108 mm. deep X 112 mm. wide, with iris diaphragm in 
 the stage. 
 
 Plano-concave mirror 50 mm. diameter. Coarse and fine adjustments. The fine adjustment located 
 on the side is of simplest possible construction and cannot get out of order. One complete revolution 
 of shaft raises or lowers the body tube .2 millimeter. 
 
 -, with 16 and 4 mm. objectives and 10X ocular giving magnifications of 100 and 440 diameters . $30.00 
 
 -, same as above, but w r ith revolving dust-proof double nosepiece.34.00 
 
 -, with 16 and 4 mm. objectives and 6X and 10X oculars giving magnifications of 60, 100, 264 and 
 
 440 diameters.. 31.50 
 
 —, same as above, but with revolving dust-proof double nosepiece.35.60 
 
 —, with Abbe Condenser (N. A. 1.20) 16 and 4 mm. objectives and 10X ocular giving magnifica¬ 
 tions of 100 and 440 diameters. 39.50 
 
 —, with Abbe Condenser (N. A. 1.20) 16 and 4 mm. objectives, with revolving dust-proof double 
 nosepiece, and 6X and 10X oculars giving magnifications of 60, 100, 264 and 440 diameters 
 
 5878 
 
 6878A 
 
 5878B 
 
 5878C 
 
 5878D 
 
 5878E 
 
 MICROSCOPES, top lever type, fine adjustment, stage 108 mm. deep by 112 mm. wide, with iris dia¬ 
 phragm in the stage, plano-concave mirror 50 mm. diameter. Both coarse and fine adjustments. 
 One complete revolution of shaft raises or lowers the body tube .5 millimeter. 
 
 -, with 16 and 4 mm. objectives and 10X ocular giving magnifications of 100 and 440 diameters . . 
 
 -, same as above, but with revolving dust-proof double nosepiece. 
 
 -, with 16 and 4 mm. objectives and 6X and 10X oculars giving magnifications of 60, 100, 264 and 
 
 41.00 
 
 27.50 
 
 31.50 
 
 440 diameters.. . 29.00 
 
 —, same as above, but with revolving dust-proof double nosepiece.33.00 
 
 —, with Abbe Condenser (N. A. 1.20) 16 and 4 mm. objectives, with revolving dust-proof double 
 
 nosepiece, and 10X ocular giving magnifications of 100 and 440 diameters. 37.00 
 
 with Abbe Condenser (N. A. 1.20), 16 and 4 mm. objectives, with revolving dust-proof double 
 
 nosepiece, and 6X and 10X oculars giving magnifications of 60, 100, 264 and 440 diameters .... 38.60 
 
 COMPOUND MICROSCOPES suggested to micro-biologists who desire an efficient, yet comparatively inex¬ 
 pensive instrument. 
 
 Side fine adjustment of very simple yet practical construction. Cannot get out of order. One complete revo¬ 
 lution of shaft moves body tube 2 Ao mm. 
 
 Stage, vulcanized top and sides, is 112 mm. wide by 108 mm. deep. Working space 80 mm. from arm to optical axis. 
 
 Substage. A sextuple screw, protected from dust, carries the substage arm up and down on a perpendicular 
 axis, around which the arm is free to revolve when at the lower limit of the screw. When at the lower limit the arm 
 may be swung out of the optical axis, carrying with it the small iris diaphragm fastened to its upper surface, and also 
 the condenser with its larger iris. The small upper iris is automatically locked open when the condenser is in place. 
 
 6880 - . .- 
 
 5880A - 
 6880B - 
 
 6880C 
 
 5880D 
 
 5880E 
 
 6880F 
 
 with 16 and 4 mm. objectives and 10X ocular giving magnifications of 100 and 440 diameters . $31.60 
 
 —, same as above but with revolving dust-proof double nosepiece.36.60 
 
 —, with 16 and 4 mm. objectives and 6X and 10X oculars giving magnifications of 60, 100, 264 and 
 
 440 diameters. 33.00 
 
 —, same as above, with revolving dust-proof double nosepiece.37.00 
 
 with Abbe Condenser (N. A. 1.20), 16 and 4 mm. objectives with revolving dust-proof double 
 
 nosepiece, and 10X ocular giving magnifications of 100 and 440 diameters. 41.00 
 
 —, with Abbe Condenser (N. A. 1.20), 16 and 4 mm. objectives, with revolving dust-proof double 
 
 nosepiece and 6X and 10X oculars giving magnifications of 60, 100, 264 and 440 diameters. 42.50 
 
 with Abbe Condenser (N. A. 1.20), 16, 4 and 1.8 mm. (oil immersion) objectives with revolving 
 
 dust-proof triple nosepiece and 6X and 10X oculars giving magnifications of 60, 100, 264, 440, 570 
 and 950 diameters.. 67.50 
 
456 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 5882 No. 5886 
 
 COMPOUND MICROSCOPE suggested for advanced laboratory research work and clinical work of the most 
 exacting character. 
 
 Side fine adjustment having no lost motion and no side thrust, automatically taking up for any wear as it may 
 occur. Each of the one hundred divisions of the graduated button represents a movement of 1 micron. 
 
 Stage, 110 X 95 mm., is of brass, covered top and edges with rubber vulcanized directly to the stage plate. 
 
 Substage. A sextuple screw, protected from dust, carries the substage arm up and down on a perpendicular 
 axis, around which the arm is free to revolve when at the lower limit of the screw. When at the lower limit, the arm 
 may be swung out of the optical axis, carrying with it the small iris diaphragm fastened to its upper surface, and 
 also the condenser with its larger iris. The small upper iris is automatically locked open when the condenser is in 
 
 place. 
 
 5882 - , with Abbe Condenser (N. A. 1.20), 16 and 4 mm. objectives and 10X ocular giving magnifica¬ 
 tions of 100 and 440 diameters. . $54.00 
 
 5882A - , same as above, but with revolving dust-proof double nosepiece.68.00 
 
 6882B -, with Abbe Condenser (N. A. 1.20), 16 and 4 mm. objectives and 6X and 10X oculars giving 
 
 magnifications of 60, 100, 264 and 440 diameters... 55.50 
 
 5882C — —, same as above, but with revolving dust-proof double nosepiece.69.50 
 
 ing dust-proof triple nosepiece, and 6X and 10X oculars, giving magnifications of 60, 100, 264, 440, 
 
 570 and 950 diameters.'. . .. 85.00 
 
 COMPOUND MICROSCOPE suggested to micro-biologists’ who demand a large and very efficient instrument 
 where critical work is a necessity. 
 
 Side fine adjustment having no lost motion and no side thrust; automatically taking up for any wear as it may 
 occur. Each of the one hundred divisions of the graduated button represents a movement of 1 micron. 
 
 Revolving Stage, 120 mm. in diameter, is covered with vulcanite; axis of revolution is 90 mm. from the arm. 
 Provided with Mechanical Stage, buttons of which are on concentric axes; lateral movement 60 mm., to-and-fro 
 movement 38 mm. 
 
 Sub-stage. May be moved up and down on its bearing by rack and pinion. The iris diaphragm beneath the 
 condenser is located on one arm, which swings to the right and on which provision is made for oblique light, the de¬ 
 centering secured by rack and pinion. The condenser is of the drop swing type. The upper iris diaphragm is located 
 on one arm which swings to the left. The mirror is mounted on a swing arm mounted independent of the stage. 
 
 5885 -, with Abbe Condenser (N. A. 1.40), 16 and 4 mm. objectives, and 10X ocular giving magnifications 
 
 of 100 and 440 diameters. .$110.00 
 
 5885A -, same as above, but with revolving dust-proof double nosepiece.114.00 
 
 6886B -, with Abbe Condenser (N. A. 1.40), 16 and 4 mm. objectives and 6X and 10X oculars giving mag¬ 
 nifications of 60, 100, 264 and 440 diameters. 111.50 
 
 5885C -, same as above, but with revolving dust-proof double nosepiece.. 115.50 
 
 6886D -, with Abbe Condenser (N. A. 1.40), 16,4 and 1.8 mm. (oil immersion) objectives, with revolving 
 
 dust-proof triple nosepiece, and 6X and 10X oculars giving magnifications of 60, 100, 264, 440, 570 
 
 and 950 diameters. 140.00 
 
CHEMISTRY AND BIOLOGY 
 
 457 
 
 BINOCULAR MICROSCOPES, offered to meet the demands for a binocular instrument with wide range of 
 adaptability. 
 
 Special Features:—Inclination Joint. Long Range. The inclination part carries a long slide which, when the 
 microscope is erect, projects downward through the pillar and base until it nearly touches the table. Removable 
 Stage. Universal Mirror Adjustment. Swings backward, forward and sidewise. Can be used horizontally to ex¬ 
 amine vertical objects. Accommodation for any pupillary distance. The light to either eye can be shut off by 
 a shutter which automatically returns to central position. Accurately paired objectives and oculars. 
 
 6890 , with 40 mm. paired objectives and 10X paired oculars.$62.00 
 
 6890A - , with 48 and 32 mm. paired objectives and 6X and 10X oculars.77.00 
 
 5890B - , with 66, 40 and 26 mm. paired objectives and 4X, 6X and 10X oculars.92.00 
 
 6890C - , with 66, 48,32 and 26 mm. paired objectives and 4X, 6X and 10X oculars.104.00 
 
 6890D - , with 66, 48,40, 32 and 26 mm. paired objectives and 4X, 6X and 10X oculars.116.00 
 
 METALLURGICAL MICROSCOPES, suggested as inexpensive microscopes for metallurgical purposes. 
 May also be used to advantage in Biological work. 
 
 Arm and pillar are of a shape to give a working radius of 85 mm. from optical axis to the arm. With inclina¬ 
 tion joint. 
 
 Top Fine Adjustment of lever type, very sensitive and accurate. One complete revolution of the shaft moves 
 body tube millimeter. 
 
 Stage, 120 mm. in diameter. The center is covered by a removable disc that may be racked up and down through 
 a distance of 45 mm., or may be removed entirely to allow placing under the objective an object larger than could 
 be accommodated otherwise. 
 
 Accessories. Included at prices below are the Vertical Illuminator No. 6971 described on page 460 and the small 
 frame by which metals may be held with the polished side upwards. 
 
 6896 , with 16 and 4 mm. objectives and 10X ocular.$88.00 
 
 6896A - , same as above, but with revolving dust-proof double nosepiece.92.00 
 
 6896B -, with 16 and 4 mm. objectives and 6X and 10X oculars.89.60 
 
 6895C - , same as above, but with revolving dust-proof double nosepiece.93.60 
 
 6896D -, with 32, 16 and 4 mm . objectives, with revolving dust-proof triple nosepiece, and 6X and 10X 
 
 oculars....98.00 
 
 6906 DISSECTING MICROSCOPE, Regent’s Type, complete with lens 
 
 1.96 
 
 DISSECTING MICROSCOPE, BLOCK, with hollow 
 center designed as a receptacle for dissecting tools and 
 magnifiers. This is closed by a door hinged at the lower 
 end. Heavy glass stage with a black and a white back¬ 
 ground for use beneath the stage. 
 
 6907 -, .with 9X Doublet Magnifier giving a 
 
 magnification of 9 diameters, equivalent 
 focus 27.8 mm., working distance 15 mm. $2.60 
 
 6908 -, with 6X and 12X Doublet Magnifiers 
 
 giving magnifications of 6 and 12 diam¬ 
 eters, equivalent foci 41.6 and 20.8 mm. 
 and working distances of 22 and 12 mm. 
 respectively.. . 3.26 
 
 No. 6907 Back View 
 
458 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 Nos. 5910 to 5910E 
 
 
 
 
 
 DISSECTING MICROSCOPE, rack and pinion focussing adjustment, stage 75 X 100 mm. Covered by a heavy 
 polished glass plate with a black and a white background to fit beneath the plate. Metal hand rests; jointed lens 
 carrier permits of use of lens on any part of the stage; plano-concave mirror 50 mm. in diameter. In handsome cabi¬ 
 net. 
 
 5910 -, with 9X doublet magnifier, magnification 9 diameters. Equivalent focus of 27.8 mm. and a 
 
 working distance of 15 mm.. $9.00 
 
 5910A -, with 6X and 12X doublet magnifiers, magnifications of 6 and 12 diameters. Equivalent foci of 
 
 41.6 and 20.8 mm. respectively, and working distance of 22 and 12 mm. respectively. 9.75 
 
 5910B -, with 9X Triple Aplanat Magnifier, magnification 9 diameters. Large flat field and great working 
 
 distance, equivalent focus 27.8 mm., working distance 24.5 mm.11.75 
 
 5910C -, with 6X and 12X Triple Aplanat Magnifiers having magnifications of 6 and 12 diameters. Large 
 
 flat fields and great working distances. Equivalent foci 41.6 and 20.8 mm. and working distances of 
 
 36.8 and 18.4 mm. respectively.15.25 
 
 5910D -, with 9X Veraplanat Magnifier, giving magnification of 9 diameters. Most critical definition, 
 
 large, clear and flat field and long working distance.14.25 
 
 5910E -, with 6X and 12X Veraplanat Magnifiers, giving magnifications of 6 and 12 diameters. Most 
 
 critical definitions, large, clear and flat fields and long working distances.20.25 
 
 Note. —Following outfits do not include the metal hand rests illustrated. 
 
 METAL HAND RESTS, extra . . . . ‘.Per Pair .75 
 
 DISSECTING MICROSCOPES, similar to above, but focussing is accomplished by means of the button at the 
 side of the pillar. 
 
 5912 
 5912A 
 . 5912B 
 
 5912C 
 
 ACHROMATIC OBJECTIVES. These objectives are all corrected for a tube length of 160 mm. and for a cover 
 glass thickness of 0.18 mm. They give a sharp critical definition to the edge of the field and at the same time give 
 exceptional long working distance and unusual flatness of field. All objectives are made with the Society Screw 
 furnished by the Royal Microscopical Society and are interchangeable with those of European manufacture. All 
 objectives are mounted directly into the model and are thus unharmed when cleaned with a solvent. 
 
 -, with 9X doublet magnifier giving a magnification of 9 diameters, equivalent focus 27.8 mm., 
 
 working distance 15 mm... $6.75 
 
 -, with 6X and 12X Doublet Magnifiers, giving magnifications of 6 and 12 diameters, equivalent 
 
 foci 41.6 and 20.8 and working distances 22 and 12 mm. respectively. 7.60 
 
 -, with 9X Triple Aplanat Magnifier, giving magnification of 9 diameters. Large flat field and long 
 
 working distance, equivalent focus 27.8 mm., working distance 24.5 mm. 9.60 
 
 -, with 6X and 12X Triple Aplanat Magnifiers, giving magnifications of 6 and 12 diameters; ex¬ 
 ceptionally sharp definitions, large, clear and flat fields and long working distances. Equivalent foci 
 
 41.6 and 20.8 mm., working distances 36.8 and 18.4 mm. respectively. 13.00 
 
 Note. —The prices above do not include the Metal Hand Rests illustrated. 
 
 METAL HAND RESTS, extra.Pel- Pair .75 
 
 iITT V iiirnr' itfliMatf '-'~HT ~ •*<•*•*«■ 
 
CHEMISTRY AND BIOLOGY 
 
 459 
 
 ACHROMATIC OBJECTIVES 
 
 Catalogue 
 
 No. 
 
 Equivalent 
 
 Focus 
 
 Num. 
 
 Working 
 
 Distance* 
 
 Diam. of 
 the t real 
 --field 
 
 Price 
 
 mm. 
 
 inches 
 approx. 
 
 Aperture 
 
 With 160 mm. tube length 
 and lOx eye piece 
 mm. mm. 
 
 Fixed 
 
 Mount. 
 
 Adjust. 
 
 Mount. 
 
 5920 
 
 48 
 
 2 
 
 0.10 # 
 
 28.0 
 
 6.5 
 
 $ 4.00 
 
 
 5921 
 
 40 
 
 W 
 
 0.10 
 
 28.0 
 
 6.3 
 
 4.00 
 
 
 5922 
 
 32 
 
 1 Vs 
 
 0.10 
 
 15.0 
 
 4.7 
 
 4.00 
 
 
 6924 
 
 6926 
 
 30-22 
 
 variable 
 
 25 
 
 m 
 
 to 
 
 %0 
 
 1 
 
 0.25 
 
 25.0 
 
 2.0 
 
 9.5 
 
 15.0 
 
 8.0 
 
 3.3 
 
 5.00 
 
 $20.00 
 
 6926 
 
 16 
 
 % 
 
 0.25 
 
 5.0 
 
 2.1 
 
 5.00 
 
 
 5927 
 
 12 
 
 y 2 
 
 0.40 
 
 1.8 
 
 1.4 
 
 8.00 
 
 
 5928 
 
 8 
 
 % 
 
 0.50 
 
 1.5 
 
 1.0 
 
 8.00 
 
 
 5929 
 
 5 
 
 % 
 
 0.70 
 
 0.4 
 
 0.55 
 
 8.00 
 
 
 6930 
 
 4 
 
 Ye 
 
 0.85 
 
 0.46 
 
 0.40 
 
 8.00 
 
 18.00 
 
 5931 
 
 3 
 
 y 8 
 
 0.85 
 
 0.26 
 
 0.30 
 
 8.00 
 
 18.00 
 
 6932 
 
 Water 
 
 Im. 
 
 Ya 
 
 1.15 
 
 0.22 
 
 0.30 
 
 20.00 
 
 24.00 
 
 6933 
 
 Oil-Im. 
 
 1.8 
 
 Yu 
 
 1.30 
 
 0.13 
 
 0.20 
 
 27.00 
 
 
 6934 
 
 Oil-Im. 
 
 1.5 
 
 Me 
 
 1.30 
 
 0.10 
 
 0.14 
 
 40.00 
 
 
 ♦Working distance is the distance between the front lens and cover glass. 
 
 fReal field is the distance of the circular area seen through the microscope and measured in the plane of the object. 
 HUYGHENIAN OCULARS. These oculars all fit the standard tube adopted by Royal Microscope Society and 
 are interchangeable with those of European manufacture. The terms 4X, 6X, 8X, 10X, etc., designate the mag¬ 
 nification based on the size of the image projected the distance of distinct vision, i. e., 250 mm. (10 inches). 
 
 5940 
 
 6941 
 
 5942 
 
 5943 
 6944 
 5946 
 
 — , 4X OCULAR, equivalent focus, 62.5 mm. — 2 inches. $1.50 
 
 — , 6X OCULAR, equivalent focus, 50 mm. — 2 inches. 1-50 
 
 — , 6X OCULAR, equivalent focus, 40 mm. — 1% inches. 1-50 
 
 — , 8X OCULAR, equivalent focus, 30 mm.— 1% inches. 1-50 
 
 — , 10X OCULAR, equivalent focus, 25 mm. — 1 inch. 1-60 
 
 — , 12X OCULAR, equivalent focus, 20 mm. — % inch. 1-50 
 
 REVOLVING DUST-PROOF NOSEPIECE, most carefully made and greatest care exercised to see that they 
 are perfectly centered and are strong enough to remain so. Neatly finished in alcohol-proof enamel, with the focal 
 lengths of the objectives used neatly engraved on the edge of the revolving portion. 
 
 6962 REVOLVING DUST-PROOF NOSEPIECE, double.$4.00 
 
 6963 -, triple .'.. 5.50 
 
 6964 -, quadruple.... 
 
 SUBSTAGE ABBE CONDENSERS. These are non-achromatic lenses mounted with an iris diaphragm beneath 
 
 to modify the amount of light and with a ring beneath the iris to hold a blue glass for cutting out the yellow rays 
 of artificial light. 
 
 5960 ABBE CONDENSER, N. A. 1.20. $™0 
 
 6961 ABBE CONDENSER, N. A. 1.40 . 9 00 
 
460 
 
 L. E. KNOTT APPARATUS CO., 
 
 BOSTON 
 
 MICROSCOPE ACCESSORIES 
 
 6965 BULL’S EYE CONDENSER, for illuminating opaque objects, etc. 
 
 A plano-convex lens mounted on an adjustable stand. 
 
 Diameter of lens inches..$4.76 
 
 6966 -, diameter of lens, 3 inches. 6.00 
 
 6968 ABBE CAMERA LUCIDA, showing the whole of the field, the object and the pencil point clearly. 
 
 Prism so mounted that the opening in the silvering case can be lowered in the case of the higher 
 power oculars or raised with the lower powers until it comes in the exact focus of the ocular. It can 
 be so centered with one hand by two concentric screws, that the field is free from color to the ex¬ 
 treme edge. The smoked glasses are so mounted around and below the prism that the light from 
 the pencil and the object can be easily modified to make them equally distinct. The mirror (70 mm. 
 
 X 105 mm.) is supported on an adjustable graduated bar. In mahogany case.20.00 
 
 5969 ABBE CAMERA LUCIDA, similar to above, but the prism is permanently centered and there is no 
 
 means of modifying the light from the ocular.10.00 
 
 VERTICAL ILLUMINATORS. These instruments are constructed to screw into the nosepiece, be¬ 
 tween it and the objective. The light is directed into the opening in the side until it strikes the sil¬ 
 vered surface from which it is reflected down through the objective to the object to be examined. It 
 is then reflected back through the objective to the eye. The opening in the side is so arranged that 
 it can be turned in any direction. 
 
 6971 -, with silvered prism for reflecting the light. Prism is so mounted that it can be turned to reflect 
 
 the light down through the objective as desired . . 6.60 
 
 6972 -, with silvered cover glass for reflecting the light. Provided with three openings of different sizes . 6.60 
 
 5976 MECHANICAL STAGE, new construction, so made that the vernier reading designating the locations 
 of objects taken on one microscope will register with the readings for the same objects taken on any 
 other microscope. This feature is made possible from the fact that the vernier for the vertical move¬ 
 ment and the arms holding the slide are adjustable. The stage will handle a slide 3X2 inches. 
 
 Range 85 mm. lateral motion and 65 mm. vertical. In mahogany case. 18.00 
 
 6980 MICROSCOPE LAMP designed primarily for use with the dark field illuminator and vertical illumina¬ 
 tor. This lamp serves most admirably as a lamp for general microscopic illumination. It works 
 on any incandescent circuit, but must always be provided with a rheostat suitable for the voltage. 
 Adjustments provided for moving the carbons and focussing the condenser, also for raising or lower¬ 
 ing the height and angle of the lamp on its upright support. Provided with one blue*and one ground 
 glass plate, both of which fit into a groove in front of the condenser. Complete with five feet of Con¬ 
 necting Cord.. 14.00 
 
 6980A FIXED RHEOSTAT for 110 volts—5 amperes.. 6.60 
 
 6980B -, for 220 volts—5 amperes... 9.00 
 
 6980C CARBONS for use in above lamp .... .Each .06 
 
CHEMISTRY AND BIOLOGY 
 
 461 
 
 MICROSCOPIC SLIDES AND ACCESSORIES 
 
 Ko - 6000 COVER GLASSES 
 
 We have long been headquarters for the greatest variety of cover glasses, round, square or rectangular. Our 
 stock, despite the shortage due to unusual conditions, is quite complete. We carry two thicknesses in stock, — No. 1 
 that varies from 0.11 to 0.17 millimeter thick, and No. 2, from 0.17 to 0.25 millimeter. Specify not only by catalogue 
 number, but give also shape, thickness number, size and quantity. 
 
 CIRCULAR COVER GLASSES 
 
 Thickness No. Diameter Per Fifty 
 
 5985A 
 
 1 
 
 15 mm. (^-inch) 
 
 $0.30 
 
 6986B 
 
 2 
 
 15 mm. (5^-inch) 
 
 .30 
 
 5985C 
 
 1 
 
 12 mm. (J^-inch) 
 
 .20 
 
 5985D 
 
 2 
 
 12 mm. (J^-inch) 
 
 .20 
 
 5986 COVER 
 
 GLASSES, 
 
 CIRCULAR, 18 mm. (%-inch) 
 
 diameter . . 
 
 Per V 2 ounce $1.00 
 
 RECTANGULAR COVER GLASSES 
 
 5988A 
 
 Thickness No. 
 
 1 
 
 Dimensions 
 
 15 X 15 mm. 
 
 Per Fifty 
 
 $0.30 
 
 5988B 
 
 1 
 
 12 X 12 mm. 
 
 .20 
 
 5988C 
 
 2 
 
 12 X 12 mm. 
 
 .20 
 
 5988D 
 
 2 
 
 10 X 10 mm. 
 
 .18 
 
 5988E 
 
 1 
 
 32 X 32 mm. 
 
 1.00 
 
 6988F 
 
 1 
 
 35 X 35 mm. 
 
 1.35 
 
 5988G 
 
 1 
 
 22 X 40 mm. 
 
 1.30 
 
 6988H 
 
 2 
 
 22 X 40 mm. 
 
 1.30 
 
 69881 
 
 1 
 
 15 X 45 mm. 
 
 1.10 
 
 6988J 
 
 2 
 
 15 X 45 mm. 
 
 1.10 
 
 5988K 
 
 1 
 
 36 X 50 mm. 
 
 2.50 
 
 5989 COVER GLASSES, SQUARE, 18 X 18 mm. {% X %-inch) .Per 14 Ounce 
 
 5990 SLIDES, MICROSCOPIC, GLASS, 3X1 inch, ground edges.Per Gross 
 
 5992 SLIDES, GLASS, concave centers .Per Dozen 
 
 6995 LIFE SLIDE, HOLMAN’S, a deep cylindrical cavity connected by a small channel with a more shallow 
 
 beveled cavity. Complete with cover. 
 
 6000 SLIDE BOX AND COVER, GLASS, for use in staining sections. Width 2% inches, length 3% inches 
 
 STAINING JAR. See JARS, Page 461. 
 
 6006 TURN TABLE, finely centered, all adjustments for preparing microscope slides. 
 
 6010 SLIDE BOX, of white wood, with closely fitting cover, grooved, to hold 25 slides, numbered and indexed 
 
 6012 SLIDE BOX for 100 slides. Covered with a heavy cloth. Hinged cover with two catches. 
 
 6013 SLIDE BOX, similar to above, but for 30 slides. 
 
 6014 SLIDE CABINET, MINOT’S METAL, a most compact fire-proof receptacle for storing slides. Con¬ 
 
 structed of metal throughout, neatly finished, inside and outside, w'ith japan. Contains 30 japanned 
 metal trays, each having a capacity for 24 slides. Each tray with knob and card holder. The cabinet 
 is provided with brass lock. Size 36.5 cm. high, 32.5 cm. deep and 17.5 cm. wide, outside measure¬ 
 ments. 
 
 Complete with 30 trays .. 
 
 $1.00 
 
 1.68 
 
 1.20 
 
 1.35 
 
 .20 
 
 2.50 
 
 .10 
 
 .40 
 
 .35 
 
 20.03 
 
462 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 SLIDES, PREPARED MICROSCOPE MOUNTS 
 
 ZOOLOGY 
 
 6020 Knott’s Prepared Microscope Mounts for Zoology: 
 
 a Skeleton of Commercial Sponge. $0.50 
 
 b Transverse section of Sponge Grantia show¬ 
 ing flesh and spicules. .50 
 
 c Fresh Water Hydra, entire. .60 
 
 d Transverse section of Fresh Water Hydra 
 Ectodern 
 Mesodem 
 
 Endodem.75 
 
 e Campanularian Hydroid (Obelia). .50 
 
 f Tubularian Hydroid (Pennaria). .50 
 
 g Transverse section of Sea Anemone (Metrid- 
 ium marginatum) showing plan of body 
 
 structure of coral polyp....,. .50 
 
 h Pedicellaria of Echinoderm (Starfish or Sea 
 
 Urchin). .50 
 
 i Amoeba. 1.00 
 
 j Transverse section of Earthworm. .50 
 
 k Circumcesophageal nerve ring and part of 
 
 ventral nerve-cord of Earthworm. 1.00 
 
 1 Transverse section through heart of Clam... .50 
 
 m Transverse section through gill of Clam.... .60 
 
 n Mouth parts of biting Insect: Labrum, Man¬ 
 dibles, Maxillae. Maxillary palpi. Labium, 
 
 and Labial palpi. .70 
 
 o Proboscis of House Fly.50 
 
 p Wing of Fly. .50 
 
 q Spiracle of Cricket. .50 
 
 r Tracheae of Insect. .50 
 
 s Scales on Wing of Moth. .50 
 
 t Section through Compound Eye. £5 
 
 u Gizzard of Cricket. .50 
 
 v Mouth Parts of Honey Bee. .65 
 
 w Blood of Fish.55 
 
 x Blood of Frog. .55 
 
 6021 Price, complete set, as listed above. 12.00 
 
 PHYSIOLOGY 
 
 6023 Knott’s Prepared Microscope Mounts for Physiology: 
 
 a Blood, Human. $0.70 
 
 b Blood, Frog, double stained. .55 
 
 c Bone, longitudinal section, showing Haver¬ 
 sian canals, canaliculi and lacunae. ,80 
 
 d Bone, transverse section, showing Haversian 
 
 systems, etc. .80 
 
 e Cerebrum, section showing white and gray 
 
 matter, etc. .50 
 
 f Cerebellum, showing 
 
 1 Cortical layer of gray matter. 
 
 2 White matter of medulla, white me¬ 
 dullary substance, the granule layer, 
 the molecular stratum, and the layer 
 
 of the cells of Purkinji. .50 
 
 g Stomach, transverse section, showing the 
 
 general arrangement of its coats 
 
 1 Mucosa containing tubular peptic 
 glands and acid cells. 
 
 2 Sub-mucous coat. 
 
 3 Blood vessels. 
 
 4 Circular and longitudinal muscular 
 layers. 
 
 5 Fibrous tunic covered with peri¬ 
 
 toneum. .50 
 
 h Small intestine, transverse section, showing 
 
 villi, unicellular glands, mucosa, etc. ,80 
 
 i Section of Spleen. .60 
 
 j Adipose tissue. .50 
 
 k Connective tissue.50 
 
 1 Heart muscle, double stained, showing cross 
 striations, nuclei, and characteristic branch¬ 
 ing of cardiac muscle cells. .50 
 
 m Voluntary muscles, double stained, showing 
 
 cross striations, nuclei saicolemma, etc. .50 
 
 n Involuntary muscle, teased preparation, show¬ 
 ing isolated muscle cells with nuclei. .60 
 
 o Nerve Cells, from Cerebrum, showing pro¬ 
 toplasmic processes and nuclei. .50 
 
 p Cartilage, hyaline. $0.50 
 
 q Spinal Cord, transverse section. .50 
 
 r Large Intestine, double stained. .55 
 
 s Sciatic Nerve, transverse section showing 
 axis-cylinder, medullary substance, sup¬ 
 porting connective tissue, etc. .50 
 
 t Scalp, section of. showing hair, follicles, and 
 
 sebaceous glands. .70 
 
 u Skin, section of, showing sweat glands. .70 
 
 v Lung, section of...50 
 
 w Liver, section of, with blood vessels injected 
 
 with red gelatin.55 
 
 x Kidney, section of, injected. .55 
 
 y Retina of Eye, showing coats.80 
 
 6024 Price, complete set, as listed above. 12.00 
 
 BOTANY 
 
 6026 Knott’s Prepared Microscope Mounts for Botany: 
 
 a Longitudinal section of root tip of onion, show¬ 
 ing 
 
 1 Root Cap. 
 
 2 Cell division and various icaryokinetic 
 
 nuclear stages. $0.65 
 
 b Longitudinal section through apical cell of 
 
 Nitella. .80 
 
 c Cell formation by budding. .50 
 
 d Spirogyra showing 
 
 1 Protoplasm and nucleus. 
 
 2 Chlorophyll bands. .65 
 
 e Spirogyra in conjunction.... .55 
 
 f Spores of Corn Smut. .50 
 
 g Mucor (black mould of bread).50 
 
 h Section through archegonium of moss. .75 
 
 i Section through antheridium of moss. .75 
 
 j Peristome of moss (Polytricum). .50 
 
 k Prothallium of fern (Polypodium) showing 
 
 1 Reproductive organs. 
 
 2 Chlorophyll bodies.60 
 
 1 Section through archegonium of fern pro¬ 
 thallium. .95 
 
 m Prothallium with young fern attached. .80 
 
 n Transverse section of rhizome of fern (Pteris) 
 showing 
 
 1 Close 1 concentric fibro-vascular bun¬ 
 dles. 
 
 2 Scalariform vessels. 
 
 3 Parenchyma. 
 
 4 Parenchymatous sclerenchyma. 
 
 5 Prosenchymatous sclerenchyma. .55 
 
 o Longitudinal section of n, showing 1,2,3, 4, 
 
 5, in longitudinal view. .55 
 
 p Sporangin and Spores of Fern.50 
 
 q Longitudinal tangential section of wood of 
 
 Pine showing cut ends of Medullary Rays .50 
 r Longitudinal Radial section of wood of Pine 
 showing 
 
 1 Pitted tracheids. 
 
 2 Medullary rays... .50 
 
 s Transverse section of vine stem showing first 
 
 year's growth and arrangement of fibro- 
 
 vascular bundles. .50 
 
 t Tran verse section of wood of Pine. .50 
 
 u Epidermis of leaf showing stomata. .50 
 
 v Transverse section of leaf of Trillium. .50 
 
 w Transverse section of ovary of Trillium..,. .50 
 
 x Transverse section of stem of Indian Com 
 showing 
 
 1 Conjoint, collateral, closed vascular 
 bundles. 
 
 2 Parenchyma. 
 
 3 Sclerenchyma. .75 
 
 y Transverse section of exogenous stem show¬ 
 ing 
 
 1 Cortex. 
 
 2 Camnium. 
 
 3 Rings of growth. 
 
 4 Pith. 
 
 5 Medullary rays. .50 
 
 6027 Price, complete set, as listed above. 12.00 
 
CHEMISTRY AND BIOLOGY 
 
 463 
 
 SPECIAL MICROSCOPIC SLIDES 
 
 These slides are very valuable as indicating a wider range of structures than the previous sets. They will be 
 found especially valuable to all teachers who are using or intend to use THE NATIONAL BIOLOGY NOTE-BOOK. 
 To assist such teachers the numbers of the sheets in the note-book, in which slides are particularly useful, are in¬ 
 dicated at the right. 
 
 6030 BOTANY. 
 
 a Spirogyra in Conjugation (B30).$0.75 
 
 b Conceptacles of Fucus (F10).75 
 
 c Section of Cotyledon showing starch grains (F20) .50 
 
 d Section of Wheat (F21).75 
 
 e Section of Oats (F21).75 
 
 f Section of Nut (F21).75 
 
 g Section of Pine (F21).75 
 
 h Root-tip of Barley (F30).65 
 
 i Root-tip of Dandelion (F30).65 
 
 j Leaf-bud of Sycamore (F40).65 
 
 k Flower-bud of Wallflower (F40).65 
 
 1 Flower-bud of Lily (F40).65 
 
 m Section through Anther showing pollen chambers 
 
 (low power) (F60).65 
 
 n Varieties of Stamens showing methods of dehis¬ 
 cence (low power) (F60). 1.00 
 
 o Different types of Pollen Grains (low power) 
 
 (F60).65 
 
 p Cross-section of Simple Ovary showing ovules 
 
 (low power) (F60). 65 
 
 q Sections of Compound Ovary showing types of 
 
 placentae (low power) (F60). 1.00 
 
 A Set of Bacteria Slides Showing: 
 r 1 Diplococcus (Y20) 
 s 2 Staphylococcus (Y20) 
 t 3 Streptococcus (Y20) 
 
 u 4 Bacillus (Tetanus with spores, an excellent 
 type form) (Y20) 
 v 5 Comma Bacillus (Y20) 
 w 6 Streptobacillus (Y20) 
 
 x 7 Streptothrix (Y20).Complete set $7.00 
 
 6033 ZOOLOGY. 
 
 a Paramoecium (Rll). 1.00 
 
 b Paramoecium in Conjugation (Rll). 2.50 
 
 c Carchesium, double stained (Rll). 2.00 
 
 d Mitosis in Protozoa (Opalina), beautiful slide 
 with two large nuclei in Mitosis, triple stained. 
 
 One of the most admirable specimens for show¬ 
 ing the metotic cell division (Rll). 2.50 
 
 e Hydra showing both reproductive organs (Rll) 2.00 
 
 f Hydra showing ovary and bud (R11). 2.50 
 
 g Hydra showing bud (Rll). 2.00 
 
 h Slides showing mitosis in Spermary (Rll).2.50 
 
 We frequently have been requested to supply a series of slides particularly adapted to the requirements of schools 
 which do not differentiate between the biological sciences. We offer, therefore, for those schools the following lists 
 of slides selected as best adapted to a general biology course of Botany, Physiology and Zoology. 
 
 6035 
 
 6036 
 
 6038 
 
 GENERAL BIOLOGY COLLECTION, 40 Microscopic Slides selected to accompany a general course in 
 Botany, Physiology and Zoology. 
 
 I ALGAE: 
 
 Chlorophyceae (Green Algse) 
 
 Conjugates 
 
 a Spirogyra; (Conjunction and zygo¬ 
 spores), V. T. of glyc.$0.60 
 
 II FUNGI 
 
 Phycomycetes 
 
 b Mucor (or Rhizopus), zygospores.60 
 
 III MUSCI (MOSSES) 
 
 c Funaria, small plants with rhizoids, 
 
 whole.50 
 
 IV FILICALES 
 
 Leptosporanglatse 
 
 d Pteris, T. S. and L. S. of the rhizone.. .60 
 
 V GYMNOSPERM/E (Gymnosperms, cyads, 
 
 conifers, etc.) 
 
 Coniferales 
 
 Ptnaceae 
 
 Abietlneae 
 
 e Pinus, L. S. of the staminate cone.60 
 
 f Pinus, cross section of the leaf.50 
 
 g Pinus, Ra., Ta., and Tr. sections of the 
 
 wood.60 
 
 VI ANGIOSPERMS 
 
 Stems 
 
 Monocotyledones 
 
 h Sea Mays, L. S. and T. S. general stem 
 structure with collat. bundles. 
 
 Leaves 
 
 Sections showing structure 
 
 i Lilium pardalinum, T. S. (general 
 structure). 
 
 The Flower 
 
 Stamens, anthers, pollen, male 
 gametophytes 
 
 j Lilium, T. S. of anther. 
 
 VII PROTOZOA 
 
 Rhizopoda 
 
 Lobosa 
 
 k Amoeba, 1st class. 
 
 VIII PORIFERA 
 
 1 Skeleton of Commercial Sponge. 
 
 IX CCELENTER AT A 
 
 Hydrozoa 
 
 Leptolinte 
 
 m Hydra, E. 
 
 n Hj'dra, T. S. 
 
 .50 
 
 .50 
 
 .60 
 
 1.00 
 
 .50 
 
 .75 
 
 .60 
 
 , complete set as listed above 
 
 X PLATYHELMINTHES 
 Cestoda 
 
 o Taenia solium, proglottis, E.$0.60 
 
 XI NEMATHELMINTHES 
 
 Nematoda 
 
 p Trichinella spiralis, in flesh. 
 
 XII ECHINODERMATA 
 
 Echinoidea 
 
 q Echinus, pedicellaria. 
 
 XIII ANNULATA 
 
 Chaetopoda 
 
 Oligochaeta 
 
 r Lumbricus, earthworm, T. S. 
 
 XIV ARTHROPODA 
 
 Insecta 
 
 Musca domestlca (House Fly) 
 
 s Insect, proboscis. 
 
 Lepldoptera 
 
 Bombyx (Silk Moth) 
 
 t Imago, scales. 
 
 Coleoptera 
 
 Dytiscus marginalis (Water Beetle) 
 
 u Insect; trachea. 
 
 v Insect; maxilla and palpus. 
 
 XV CHORDATA 
 
 Mammalia 
 
 Cat Tissue, D. S. 
 
 w Cerebrum.,. 
 
 x Duodenum, T. S. 
 
 y Eye, retina. 
 
 z Heart; cardiac muscle, striations, etc. 
 
 aa Liver. 
 
 bb Lung; Alveolar structure, bronchi, etc 
 cc Muscle, voluntary, T. S. and L. S. 
 
 dd Nerve Cells, multipolar. 
 
 ee Nerve fibers, medullated (Sciatic Nerve) 
 
 ff Pad of Toe... 
 
 gg Stomach, T. S., Cardiac. 
 
 hh Trachea, T. S. 
 
 Rabbit Tissues, D. S. 
 
 ii Kidney, T. S. 
 
 Ox Tissues 
 
 jj Ear; yellow elastic cartilage. 
 
 kk Ligamentum nuchae. 
 
 HUMAN HISTOLOGY 
 
 11 Blood; leukaemia, D. S. 
 
 mm Scalp: white. 
 
 an Skin: white, sweat glands, etc. 
 
 .60 
 
 .50 
 
 .50 
 
 .50 
 
 .45 
 
 .60 
 
 .60 
 
 .60 
 
 .60 
 
 .60 
 
 .50 
 
 .60 
 
 .50 
 
 .60 
 
 .60 
 
 .60 
 
 .60 
 
 .60 
 
 .50 
 
 .60 
 
 .60 
 
 .60 
 
 .50 
 
 .50 
 
 .50 
 
 $ 20.00 
 
 SLIDE MAKING MATERIAL. Teachers of Biology oftentimes have considerable difficulty in as¬ 
 sembling material for mounting on slides. We have arranged for a careful selection of 50 packages 
 of materials, diatoms, pollens, seed spores, parts of plants, insects, hairs, etc., etc., prepared es¬ 
 pecially for mounting. Per set of 50 packages . .. 
 
464 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6040 
 
 6040 MICROTOME, HAND. The object is placed in a clamp in the upper end of the tube and is raised 
 through the hole in the glass plate by an accurately cut screw which is entirely enclosed from dust 
 and injury. The feed is accurate and finely graduated, each division representing 10 microns. The 
 plate at the top is 3 inches in diameter and makes a firm support for the knife.$6.00 
 
 6042 MICROTOME, TABLE. Can be readily attached by a screw clamp to the laboratory table or other 
 support. Object clamp sets in a vertically moving socket held as illustrated. Feed regulated by 
 micrometer screw with graduated disc and index plate. Glass surface plates provide traveling 
 
 ways which are extra long, so that the knife will not be drawn off from the ends.12.60 
 
 6043 -, same as above, fitted with CO 2 Freezing Attachment No. 6069 . 22.60 
 
 6044 -——, same as No. 6042, fitted with Ether Freezing Attachment No. 6067 . 18.50 
 
 MICROTOME, AUTOMATIC LABORATORY, for attaching to the edge of the table. The upper part of the 
 casting of which the table clamp is a part is designed as a frame which forms a support for the laterally swinging 
 arms which carry the knife holder. By an ingenious method of mounting this holder, the knife is given a move¬ 
 ment which utilizes the entire length of the cutting edge, thus insuring uniform wear and permitting the cutting of 
 large sections. Absolute uniformity of thickness in all sections is insured. 
 
 Feed secured by a vertical feed screw with fine micrometer thread. This feed screw is keyed to an accurately 
 cut ratchet wheel in the teeth of which a hardened steel pawl engages. This pawl may be thrown out or may be set 
 to cut sections of any desired thickness. Each division of the graduated scale marks 5 microns. 
 
 The drop pan beneath the object clamp may be removed if desired and it will be found desirable to remove it 
 when the freezing chamber is attached. 
 
 6046 MICROTOME, AUTOMATIC LABORATORY. Complete with one knife and object clamp for par¬ 
 
 affine or celloidin. In case. .$45.00 
 
 6047 -, same as above, but fitted with COa Freezing Attachment. (See No. 6069).. 55.00 
 
 6048 -, same as No. 6046, but fitted with Ether Freezing Attachment. (See No. 6067). 51.00 
 
 No. 6050 
 
 ROTARY MICROTOME 
 
 New Construction 
 
 This microtome is the result of a most careful investigation of the requirements for a rotary microtome and a 
 thorough study of the inaccuracies inherent in the earlier types. There are, in this new instrument, a number of 
 points of advantage which will readily recommend themselves to the most exacting operator. 
 
 An accurate and reliable feed mechanism acting entirely independent of any inaccuracies due to the up and 
 down movement of the object. 
 
 A modified escapement in connection with the ratchet wheel insures against momentum, — a cause for inaccuracy 
 in the older models. 
 
 The feeding is done when the object is above the knife. 
 
 Feed adjustment is convenient and definite and may be set for any thickness from 1 micron to 60 microns. 
 
 No. 6042 
 
 No. 6046 
 
CHEMISTRY AND BIOLOGY 
 
 465 
 
 No. 6050 
 
 Total excursion of the feed is 37 mm., — double that of most microtomes. 
 
 The feed pawl is automatically raised above the teeth on the return stroke and feeding is automatically stopped 
 when the feed nut has reached its limit. 
 
 The adjusting of the object to the knife can be done more delicately than on any other microtome. 
 
 The object clamp is absolutely rigid, of great capacity and is most easily and carefully oriented. 
 
 An up and down stroke of 50 mm. is possible, — sufficient for cutting very large sections, also for cutting celloidin 
 sections. 
 
 The knife may be attached at each end at the edge as well as at the back. These clamps may be moved towards 
 one another to provide additional rigidity when desired and to permit using practically the whole of the cutting edge 
 
 of the knife before resharpening. 
 
 The whole mechanism is covered dust-proof. 
 
 The microtome may be run by a motor. 
 
 With three object discs, one knife and handle and back for sharpening, all in case.$100.00 
 
 6060A KNIFE HOLDER for celloidin sections.Extra 16.00 
 
 6050B KNIFE fox paraffine sections.Extra 5.00 
 
 6060C KNIFE for celloidin sections Extra $6.00 
 
 6051 MOTOR with enclosed speed regula¬ 
 tor, mounted on neat microtome 
 table 38 X 26 inches. For 110 
 volts.Extra 60.00 
 
 6062 - —, same as above, for 220 volts 
 
 Extra 60.00 
 
 6053 RIBBON CARRIER, an aluminum 
 cylinder, inches long by 25-6 
 
 inches diameter. It is mounted in 
 an aluminum frame work under the 
 base of which are little rollers roll¬ 
 ing in the direction of the long di¬ 
 mension of the frame. The end of 
 the ribbon adheres to the cylinder, 
 which in use is slowly turned by 
 the buttons as the ribbon lengthens. 
 
 At the same time the cylinder and 
 frame are gently pushed forward 
 on the rollers to place the ribbon on 
 the cylinder in the long spiral . . $8.00 
 
466 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 MICROTOME ACCESSORIES 
 
 No. 6067 
 
 6067 MICROTOME FREEZING ATTACHMENT FOR ETHER. Consists of a freezing chamber of hard 
 rubber which so prevents the radiation of the cold that the tissue is quickly frozen. The ether is 
 held in a metal tank which for filling may be unscrewed from the support from which it is suspended. 
 
 This attachment will freeze tissue 15 millimeters in diameter and 3 mm. thick in one minute, using only 
 
 5 cubic centimeters of ether.$6.00 
 
 6069 MICROTOME FREEZING ATTACHMENT FOR CARBON DIOXIDE, for use on Microtomes Nos. 
 
 6042 and 6046. The freezing chamber is provided with a pin like that on the object clamp which 
 fits into the same socket on the microtome. The chamber is connected with the CO 2 chamber by a 
 flexible copper tube. With this freezing attachment it is possible to cut, stain and mount a section 
 ready for examination in one and one-half minutes from the time the tissue is put in the chamber. 
 Complete with copper tube connections.10.00 
 
 Nos. 6073 to 6081 
 
 No. 6084 
 
 6073 
 
 6074 
 6076 
 
 6076 
 
 6077 
 
 6078 
 
 6079 
 6081 
 6082 
 6084 
 
 6086 
 
 6088 
 
 6090 
 
 6092 
 
 MICROTOME KNIVES. These knives are broad and heavy, steel most carefully selected, evenly 
 tempered throughout their lengths. They are ground perfectly true so that when one is placed on an 
 absolutely plane surface, the edge touches along its whole length, while the back does the same. 
 
 -, 50 mm. cutting edge. 
 
 -, 110 mm. cutting edge. 
 
 -, 120 mm. cutting edge. 
 
 -, 185 mm. cutting edge.. , . 
 
 -, 240 mm. cutting edge, Wald make.,*; 
 
 -, 250 mm. cutting edge.. , 
 
 -, 110 mm. cutting edge, ground especially for celloidin. 
 
 -, 150 mm. cutting edge, with handle. 
 
 -, special Wald make, 240 mm. cutting edge, curved metal shank. 
 
 MICROTOME KNIFE HANDLE for holding the knives while sharpening. Handles ebonized, metal 
 
 parts finely nickel-plated. 
 
 MICROTOME KNIFE BACKS. In order that the knife 
 
 $2 
 4 
 6 
 
 7 
 
 8 
 12 
 
 6 
 4.76 
 10.26 
 
 1.00 
 
 may rest upon the honing stone at the proper angle 
 when being sharpened, a special steel honing back has 
 been designed. This slips ever the back of the knife $0.60 
 MICROTOME KNIFE STROP, a flat piece of wood 
 with a handle at one end. At one side of this strop 
 is cemented a piece of leather 1 % inches wide and 11 
 inches long, into which a very fine carborundum pow¬ 
 der has been rubbed. The other side is covered by a 
 
 very fine grade of leather for finishing. .90 
 
 PITH for cutting sections.Per Package .10 
 
 WARMING TABLE for use in embedding objects in 
 paraffine. Copper plate, 14 X 4 inches on stand 
 
 inches high. 1.60 
 
 PARAFFINE BATHS. See BATHS, PARAFFINE, Page 409 
 
 oooo§8§ 
 
CHEMISTRY AND BIOLOGY 
 
 467 
 
 MILK TESTING APPARATUS 
 
 No. 6100 
 
 No. 6102 
 
 6100 HAND DRIVE TWO-BOTTLE BABCOCK MILK TESTER. Consists oi but two castings forming 
 
 the gear case united at a ground joint, forming an air-tight gear case. Drive secured by one large 
 steel gear and the steel vertical spindle which has spiral teeth directly milled into it. 
 
 Bottle carriers of heavily tinned malleable iron are removably attached to the top of the spindle. Ro¬ 
 tating pockets are seamless brass. 
 
 Complete for milk testing, including test bottles, pipette, acid measure, test bottle brush, pint bottle 
 of acid and full directions for making tests.$4.00 
 
 6101 -, with addition of cream test bottles, for making both milk and cream tests. 4.60 
 
 6102 HAND DRIVE FOUR-BOTTLE BABCOCK MILK TESTER, same as No. 6100, but with bottle 
 carrier for four bottles and four seamless brass pockets. 
 
 Complete with test bottles, pipette, acid measure, test bottle brush, pint bottle of acid, and full di¬ 
 rections . 6.00 
 
 6103 
 
 -, with addition of cream test bottles, for making tests for both milk and cream. 6.60 
 
 6106 BABCOCK TEST TRAVELING OUTFIT. Comprises No. 6102 Four-Bottle Babcock Milk Tester, 
 
 3 Babcock Full Milk Test Bottles, 2 Cream Test Bottles, 2 Double-neck Skim Milk Bottles, 
 
 1 Pipette, graduated for both milk and cream, 1 Test Bottle Brush, 1 Acid Measure, 1 small 
 Quevenne Lactometer, 1 glass Thermometer, 1 bottle Testing Acid, all with full directions for 
 making milk, cream and butter tests. 
 
 In hardwood Carrying Case with separate compartments for glassware and acid. Weight complete, 
 
 15J4 pounds...10.00 
 
 6107 HAND DRIVE ENCLOSED BABCOCK MILK TESTERS for 6-inch long test bottles. Bottle carriers 
 
 are solid malleable iron castings heavily tinned, swinging pockets of seamless brass with tinned 
 malleable hangers. Solid cast iron case is 16 inches in diameter; cover split 
 and hinged. Rotation is secured through a pair of steel worm or spiral gears 
 and a pair of steel spur gears which are mounted on a separate frame detach¬ 
 ably secured to the under side of the body. 
 
 These machines turn with remarkable ease and run with that smoothness and 
 freedom from jar that are required to make an accurate test. 
 
 Prices include milk test bottles, pipette, acid measure, test bottle brush, pint 
 of acid and full directions, all securely packed. 
 
 No. of Bottles 
 , Complete 
 
 a 
 
 6 
 
 $9.00 
 
 b 
 
 8 
 
 10.00 
 
 c 
 
 10 
 
 12.00 
 
 d 
 
 12 
 
 14.00 
 
 No. 6107d 
 
468 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 Direct Connected 
 
 Motor-Belt-Driven 
 
 Nos. 6112a-d 
 
 6109 
 
 6110 
 
 6112 
 
 MOTOR DRIVEN TWO-BOTTLE BABCOCK MILK TESTER, for 6-inch long test bottles. This 
 
 machine consists of a Yao H. P. vertical spindle electric motor which carries directly on the extended 
 spindle, the bottle carriers with swinging pockets. 
 
 Complete with regular equipment of glassware and sundries as ordinarily supplied. (When ordering 
 
 state whether for D. C. or A. C. and voltage. If A. C., state also the number of cycles and phases) . $36.00 
 MOTOR DRIVEN FOUR-BOTTLE BABCOCK MILK TESTER, same as above, but with four bot¬ 
 tle carriers and necessary extra glassware and sundries.-.36.00 
 
 MOTOR DRIVEN ENCLOSED BABCOCK MILK TESTERS, direct connected, for 6-inch long test 
 bottles. In these machines the motor has a vertical shaft on which the bottle carrier is directly 
 mounted. This brings the motor underneath the machine. In this construction the weight of the 
 bottle carrier and its load of bottles is, of course, directly on the motor. The motor belt driven style, 
 while not so compact, will be found the most desirable, all things considered. 
 
 When ordering, specify style desired, also whether for A. C. or D. C. circuits and voltage. 
 
 state number of cycles. a b 
 
 No. of Bottles 6 8 
 
 Complete, Direct Connected Type or Motor-Belt Driven $49.00 60.00 
 
 If A. C., 
 c 
 
 10 
 
 62.00 
 
 d 
 
 12 
 
 64.00 
 
 No. 6116 No. 6123 No. 6126 No. 6130 No. 6132 No. 6136 No. 6139 No. 6141*No. 6146 No. 6147 No. 6160 
 
 6116 
 
 6118 
 
 6119 
 
 6120 
 6123 
 6126 
 
 3803 
 
 6130 
 
 6132 
 
 6134 
 
 6136 
 
 6137 
 6139 
 
 6141 
 
 6142 
 
 6143 
 
 6146 
 
 6147 
 
 6150 
 
 6161 
 
 6152 
 
 6155 
 
 6160 
 
 CREAM TEST BOTTLES, 6-inch, 9-gram, 30 per cent. X Y per cent.Per Dozen 
 
 CREAM TEST BOTTLES, 6-inch, 18-gram, 30 per cent. X Yi per cent.Per Dozen 
 
 -, 40 per cent. X Y per cent...Per Dozen 
 
 -, 50 per cent. X Yi per cent.Per Dozen 
 
 MILK TEST BOTTLES, 6-inch, 18-gram, 10 per cent. X Ye> per cent.. Per Dozen 
 
 SKIM MILK TEST BOTTLE. Gives readings down to one hundredth, each space representing five 
 
 TEST BOTTLE BRUSH for cleaning Babcock bottles. 
 
 ACID BURETTES in 17.5 cc. divisions. abed 
 
 No. of Charges 3 6 12 25 
 
 Each $2.00 2.00 2.50 3.00 
 
 CREAMOMETER JAR, 12 X 2 inches, graduated 0-30 and M or PM. 
 
 FUNNEL, ACID, for filling milk and cream test bottles with acid. 
 
 LACTOMETER, SPENCE’S, New York Board of Health pattern; 0° to 120° by 2° divisions .... 
 LACTOMETER, QUEVENNE’S. Scale 15° to 40° by single degrees. Sp. gr. Scale 1.015 to 1.040 
 
 ACID MEASURE, 17.5 cc.1.. 
 
 ACID PIPETTE, accurately graduated, 17.6 cc. 
 
 -, accurately graduated, 18 cc. 
 
 -, combined graduated, with two marks, 17.6 and 18 cc. 
 
 AUTOMATIC PIPETTE. To operate, squeeze rubber bulb, then insert point of pipette in milk, release 
 
 bulb and the pipette fills, the overflow going into the large glass bulb. 
 
 IMPROVED PIPETTE. By suction milk is drawn up until it is above the glass top, the stopcock is 
 
 then closed and the measured milk is put in the test bottle. 
 
 BICHROMATE POTASSIUM TABLETS for preserving composite test samples.Per 50 
 
 CORROSIVE SUBLIMATE TABLETS for preserving and coloring samples.Per 50 
 
 FARRINGTON’S ALKALINE TABLETS for determining the degree of acidity of milk, cream or 
 
 whey.Per 50 
 
 RICHMOND’S SLIDE RULE for determining total solids in milk. With full directions for use . . 
 FLOATING DAIRY THERMOMETER, 8 inches long. 
 
 $2.60 
 
 2.20 
 
 2.40 
 
 2.60 
 
 1.70 
 
 .60 
 
 .20 
 
 .50 
 
 .12 
 
 1.00 
 
 1.00 
 
 .15 
 
 .16 
 
 .15 
 
 .26 
 
 2.00 
 
 2.40 
 
 .25 
 
 .26 
 
 .25 
 
 3.60 
 
 .50 
 
CHEMISTRY AND BIOLOGY 
 
 469 
 
 6170 
 
 6171 
 
 6172 
 
 6173 
 
 6174 
 
 6176 
 
 6176 
 
 6177 
 
 6178 
 
 6179 
 
 6180 
 6181 
 
 6182 
 
 6183 
 
 6184 
 
 6186 
 
 6186 
 
 6187 
 
 6188 
 
 6189 
 
 6190 
 
 6191 
 
 6200 
 
 6201 
 
 6202 
 
 6203 
 
 6204 
 
 6205 
 
 6206 
 
 6207 
 
 6208 
 
 MINERAL COLLECTIONS 
 
 WASHINGTON SCHOOL COLLECTION, 20 Minerals, 20 Rocks, in clothboard case, printed label 
 
 list on lid.p er Set 
 
 HARDNESS COLLECTION, 9 specimens, each in tray, all in oak box. With smail diamond Per Set 
 SPECIFIC GRAVITY COLLECTION, 25 specimens, large size, in improved trays .... Per Set 
 
 LUSTER COLLECTION, 16 specimens, large size, in improved trays.Per Set 
 
 MISCELLANEOUS COLLECTION, 16 specimens, selected especially to show Play of Colors, Change 
 of Colors, Opalescence, Iridescence, Tarnish, Asterism, Schillerization, Fluorescence, Phosphores¬ 
 cence. Large size specimens, in improved trays.. Per Set 
 
 FUSIBILITY COLLECTION, 6 specimens, large size, in improved trays.Per Set 
 
 COLLECTION ILLUSTRATING TASTE, ODOR AND FEEL, 20 specimens, large size, in improved 
 
 trays.Per Set 
 
 BLOWPIPE COLLECTION, 50 most important species, each in tray, all in oak box . . . Per Set 
 
 NEW YORK STATE PHYSICAL GEOGRAPHY COLLECTION, 64 specimens, each in tray, all in 
 
 pine box.Per Set 
 
 COLLECTION OF SOILS, 20 specimens, each in quarter-pint glass show bottle, then in improved 
 
 trays.Per Set 
 
 COLLECTION OF FUELS AND USEFUL HYDRO-CARBONS (with Associated Rocks and Fossils), 
 
 40 specimens, extra large size, in improved trays.Per Set 
 
 ORES OF GOLD, SILVER, PLATINUM AND IRIDIUM, 60 specimens, each in tray, all in oak 
 
 C 3 _g 0 . . . "... Per Set 
 
 COPPER ORES AND MINERALS, 50 specimens, each in tray, all in oak case.Per Set 
 
 IRON ORES AND MINERALS, 60 specimens, each in tray, all in oak case.Per Set 
 
 ORES AND MINERALS OF THE LEAD AND ZINC GROUPS (Lead, Tin, Zinc, Cadmium and Mer¬ 
 cury), 60 specimens, each in tray, all in oak case.Per Set 
 
 ORES AND MINERALS OF METALS USED FOR ALLOYING STEEL (Chromium, Cobalt, Man¬ 
 ganese, Molybdenum, Nickel, Titanium, Tungsten and Vanadium), 60 specimens, each in tray, all in 
 
 oak case..Per Set 
 
 ORES AND MINERALS OF THE ALUMINUM AND MAGNESIUM GROUPS. (Aluminum, Barium, 
 
 Calcium, Magnesium and Strontium), 50 specimens, each in tray, all in oak case.Per Set 
 
 ORES AND MINERALS OF THE ALKALI METALS (Caesium, Lithium, Sodium, and Potassium), 26 
 
 specimens, each in tray, all in oak case.Per Set 
 
 ORES AND MINERALS OF THE NON-METALLIC AND SEMI-METALLIC ELEMENTS (Arsenic, 
 Antimony, Bismuth, Boron, Carbon, Selenium, Silicon, Sulphur and Tellurium), 50 specimens, 
 
 each in tray, all in oak case.Per Set 
 
 ORES AND MINERALS CONTAINING THE RARE EARTH ELEMENTS (Beryllium, Cerium, Didy- 
 mium, Erbium, Lanthanum, Niobium, Scandium, Tantalum, Thorium, Uranium, Yttrium, and 
 
 Zirconium), 72 specimens, each in tray, all in oak case.Per Set 
 
 ROUGH PRECIOUS AND SEMI-PRECIOUS STONES, 26 specimens, each in tray, all in oak 
 
 case.Per Set 
 
 MISCELLANEOUS NON-METALLIC ECONOMIC MINERALS, 60 specimens, each in tray, all in 
 oak case.Per Set 
 
 MODELS — PHYSIOLOGICAL 
 
 ENLARGED SIZES—NATURAL COLORS 
 
 HUMAN HEART: The anterior wall may be removed, exposing the four cavities of the heart, and their 
 
 openings and valves. 
 
 HUMAN EYE: The upper portion, containing a microscopical representation of the layers of the 
 retina, can be removed, when the cornea and the iris, the lens and the vitreous body may be taken 
 
 out. 
 
 HUMAN EAR: Separates into parts, showing the membrana tympani, the ossicles of the tympanum, 
 
 the labyrinth and the half-opened cochlea. 
 
 HUMAN SKIN: Transverse section, showing the organs of perspiration, a hair and its follicles, the 
 
 pulp, sebaceous glands and tactile corpuscles. 
 
 HUMAN TEETH: The anterior portion of the left maxillary bone is removed to show the develop¬ 
 ment and structure of the teeth. 
 
 HUMAN BRAIN: Four views: 
 
 a View of upper portion. 
 
 b View of the lower portion (basis of cerebral nerves). 
 
 c View of perpendicular section along the median line. 
 
 d View of transverse section of the head, showing the cavities. 
 
 HUMAN HEAD: Three Views: 
 
 a Head with muscles, nerves and blood vessels of one side. 
 
 b Cavities of skull and eye, upper and lower jaw.. 
 
 c View of perpendicular section of the head, showing the brain, cavities of the mouth and nose, 
 
 and the larynx and pharynx divided along the median line. 
 
 HUMAN LUNGS, with the heart in normal position: 
 
 a Anterior view of the lungs and heart. The pericardium opens and the anterior portion of the left 
 
 lung may be removed, showing the bronchial ramifications, aveoli, etc. 
 
 b Posterior view of the lungs and heart, with a representation of the bronchial ramifications, air 
 
 cells, blood vessels and Iobuli. 
 
 ORGANS OF RESPIRATION, AIR PASSAGES, LUNGS AND HEART: The anterior part of both 
 lungs and heart removes, laying open the lungs and showing the ramifications of the windpipe, and 
 
 the connection of the pulmonary blood vessels with the heart. 
 
 Continued on Next Page. 
 
 $2.50 
 
 2.76 
 
 22.50 
 
 9.75 
 
 18.25 
 2.76 
 
 9.50 
 
 4.50 
 
 2.50 
 9.00 
 
 22.50 
 
 19.75 
 
 9.50 
 
 6.75 
 
 10.00 
 
 12.50 
 
 3.76 
 
 2.76 
 
 9.75 
 
 22.76 
 
 9.25 
 
 4.75 
 
 $8.00 
 
 6.50 
 
 7.00 
 
 3.60 
 
 3.50 
 
 3.25 
 
 3.25 
 
 3.25 
 
 3.25 
 
 6.50 
 
 6.60 
 
 5.50 
 
 4.50 
 
 4.60 
 
 11.00 
 
470 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 PHYSIOLOGICAL MODELS — Continued 
 
 6209 HUMAN LARYNX: Anterior and posterior views: 
 
 a Is an anterior aspect, showing base of tongue, hyoid bone, thyroid gland, etc. $2.76 
 
 b Posterior aspect, showing the glottis and vocal cords. 2.76 
 
 c Larynx in connection with the tongue and pharynx, the latter is opened from behind, and parts 
 
 showing mucous membrane. 3.26 
 
 6210 HUMAN JOINTS: Partially opened, showing their bones and ligaments: 
 
 a Arm-joint of the shoulder, opened. 2.60 
 
 b Elbow-joint, a, anterior view.✓. 2.00 
 
 c Elbow-joint, b, lateral view. 2.00 
 
 d Wrist-joint and hand. 2.76 
 
 e Hip-joint. 2.60 
 
 f Knee-joint . 2.60 
 
 g Ankle-joints and foot. 3.60 
 
 6211 HUMAN TRUNK (Torso), with viscera of the chest and abdomen laid open. 32.60 
 
 6212 HUMAN SKULL AND BRAINS, the various parts of which can be taken out.11.00 
 
 6213 LARYNX PHANTOM, mask of the face with mouth open. 9.50 
 
 6216 PHYSIOLOGICAL MODELS. Set Complete, 28 models as above listed.126.00 
 
 No. 6222 
 
 No. 6224 
 
 No. 6226 
 
 6220 MORTARS, PRESSED GLASS, with pestles. 
 
 a 
 
 Capacity, ounces 2 
 
 Diameter, inches 2 % 
 
 Each $0.22 
 
 6222 MORTARS AND PESTLES, IRON, urn sha 
 
 a 
 
 Capacity, pints 1 
 
 Each $0.60 
 
 6224 MORTARS AND PESTLES, PORCELAIN, 
 
 a 
 
 Diameter, inches 2)4, 
 
 Each $0.33 
 
 b 
 
 c 
 
 d 
 
 4 
 
 8 
 
 16 
 
 4 
 
 4J'2 
 
 5 
 
 .28 
 
 .36 
 
 .60 
 
 b 
 
 c 
 
 
 2 
 
 4 
 
 
 .80 
 
 1.10 
 
 
 porcelain pestles. 
 
 b 
 
 c 
 
 d • 
 
 4 
 
 5 M 
 
 7 
 
 .48 
 
 1.00 
 
 1.26 
 
 6226 MORTAR, of chilled steel, pestle 15 mm. diameter. 
 
 MOUNTING PAPER. See PAPER, MOUNTING, Page 472. 
 
 6236 MUFFLES, FUSED SILICA. (See index, “Fused Silica Ware,” for characteristics.) Highly refrac¬ 
 tory, will not crack with sudden and extreme changes of temperature, absolutely gas tight. 
 
 For assaying, ash determinations, ignition of precipitates, and general analytical and chemical work, 
 they are unequalled. Especially valuable for enamelling small work, hardening and annealing small 
 parts and for general testing and experimental use. 
 
 a b c d e f 
 
 Length, outside, inches 
 
 ^A 
 
 6H 
 
 9'A 
 
 7H 
 
 9'A 
 
 18 M 
 
 Width, outside, inches 
 
 2 % 
 
 
 3% 
 
 4 K 
 
 6 H 
 
 
 Height, inches 
 
 2% 
 
 3 y 2 
 
 5 
 
 2% 
 
 4 34 
 
 5 
 
 Each 
 
 $1.86 
 
 2.60 
 
 4.26 
 
 2.60 
 
 3.76 
 
 6.76 
 
 MUSEUM JARS. See JARS, MUSEUM, Page 461. 
 
 6246 NEEDLE, INOCULATING, platinum point sealed in glass handle. 
 
 NEEDLES, DISSECTING. See Page 433. 
 
 6946 NESSLER’S JARS OR TUBES for ammonia tests in water analyses; of colorless glass. 
 
 a be 
 
 50 100 50 & 100 
 
 $0.66 .80 .96 
 
 $ 2.00 
 
 $0.60 
 
 Graduated, cc. 
 Each 
 
CHEMISTRY AND BIOLOGY 
 
 47i 
 
 
 No. 6255 
 
 No. 20-215 
 
 No. 6296 
 
 6248 OIL STONE, high grade, an excellent stone for scalpels. 
 
 6256 OIL TESTER, Cleveland Open Fire Tester, for high grade lubricating oils. Made of very heavy 
 
 copper and brass casting, nickel-plated. 
 
 6266 OIL TESTER, ELLIOT’S, POLISHED COPPER for flash point determinations, adopted as stand¬ 
 ard by the states of New York, New Jersey, Iowa, Michigan, and in genpral use everywhere 
 20-215 OSMOSIS APPARATUS, STUDENTS’, for qualitative as well as quantitative work in osmosis. 
 
 The apparatus consists of an osmosis tube of design as illustrated, held adjustably in a nickel-plated 
 clamp which may be clamped to the side of a jar. One end of the osmosis tube is closed by a thin 
 porous membrane which may be removed and replaced from time to time as needed. 
 
 Apparatus complete as illustrated. 
 
 6268 OVERSLEEVES, Chemical and Water-proof, ample in size, readily adjusted to both sexes. Per Pair 
 
 6134 PANS, AGATE WARE. a b c 
 
 Dimensions, inches 6}4 X 1J3 7 X 1/4 8}4 X 2 
 
 Capacity, quarts Vi 1 2 
 
 Each $0.16 .18 .22 
 
 6280 PAPER, SAND. a b c 
 
 Fine Medium Medium Coarse 
 
 Per Dozen Sheets $0.18 .18 .18 
 
 PAPER, FILTER. See FILTER PAPER, Page 437. 
 
 6285 PAPER, GLAZED, for use in laboratory, in color reactions. 
 
 a be 
 
 Color White Black Blue 
 
 Per Quire $0.30 .30 .30 
 
 6780 PAPER, LITMUS, red, in sheets. Per Sheet $0.04 Per Quire 
 
 6781 PAPER, LITMUS, red, in books of strips.Per Book 
 
 6782 PAPER, LITMUS, blue, in sheets. Per Sheet $0.04 Per Quire 
 
 6783 PAPER, LITMUS, blue, in books of strips.Per Book 
 
 6290 PAPER, PARCHMENT, best grade of vegetable parchment.Per Sheet 
 
 6990 PAPER, TUMERIC. Per Sheet $0.04 Per Quire 
 
 6292 PENCIL, INDELIBLE, for marking glass utensils. 
 
 6789 PENCIL, LITMUS . 
 
 PETRI DISHES. See DISHES, Page 432. 
 
 6295 PETRI DISH HOLDER, POLISHED COPPER, with Inside Tray to lift out. Size 9 inches high by 
 
 inches diameter. 
 
 PINCHCOCKS. See CLAMPS, Page 423. 
 
 6300 PINS, INSECT, special, double japanned black, finely tempered steel, needle points, absolutely fast 
 
 heads. a bcdefgh 
 
 Size No. 00 0 1 2 3 4 5 6 
 
 Per 100 $0.20 .20 .18 .18 .18 .18 .18 .18 
 
 6301 PINS, INSECT, special, double plated white steel pins, finely tempered steel, needle points, absolutely 
 
 fast heads. a bcdefgh 
 
 Size No. 00 0 1 2 3 4 5 6 
 
 Per 100 $0.26 .25 .20 .20 .20 .20 .20 .20 
 
 6302 PINS, INSECT, wth yellow heads, japanned steel pins, needle points, absolutely fast heads. 
 
 a bcdefgh 
 
 Size No. 00 0 1 2 3 4 5 6 
 
 Per 100 $0.18 .18 .15 .15 .16 .16 .16 .15 
 
 6303 PINS, INSECT, INDESTRUCTIBLE, non-corrosive metal, needle points, absolutely fast heads. 
 
 Guaranteed not to corrode under the most trying conditions. 
 
 a bcdefgh 
 
 Size No. 00 0, 1 2 3 4 5 6 
 
 p er 100 $0.30 .30 .26 .25 .26 .25 .36 .35 
 
 6306 PIPES, CLAY.Per Dozen 
 
 $0.36 
 
 14.00 
 
 9.00 
 
 1.25 
 
 .40 
 
 $ 0.66 
 
 .06 
 
 .66 
 
 .06 
 
 .06 
 
 .66 
 
 .22 
 
 .26 
 
 3.50 
 
 i 
 
 7 
 
 .18 
 
 i 
 
 7 
 
 .20 
 
 i 
 
 7 
 
 .15 
 
 7 
 
 .35 
 
 $0.16 
 
472 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 No. 6308 
 
 No. 6309 
 
 No. 6322 
 
 No. 6317 
 
 No. 6312 No. 6313 
 
 6313 
 
 6314 
 
 6317 
 
 6318 
 6090 
 6322 
 
 6322A 
 
 6323 
 
 6324 
 
 6325 
 6327 
 
 6308 
 
 6309 
 6312 
 
 PIPETTES, Medicine Droppers, straight tubes with pure rubber bulbs. Per Dozen $0.35 
 -, bent tubes with pure rubber bulbs.Per Dozen .36 
 
 6330 
 
 6332 
 
 6332a 
 
 6334 
 
 6336 
 
 6337 
 
 6339 
 
 6340 
 6342 
 
 6345 
 
 PIPETTES, MOHR’S, accurately graduated 
 
 a b c d e 
 
 Capacity, cc. 1 X Vioo 2 X ^ 10 X % 20 X 34 25 X 34 
 
 Each $0.36 .30 .44 .55 .62 
 
 PIPETTES, VOLUMETRIC, accurately graduated with one mark. 
 
 a bcdefghi j 
 
 Capacity, cc. 1 2 3 5 10 15 20 25 50 75 
 
 Each $0.09 .10 .12 .13 .17 .21 .22 .27 .33 .40 
 
 PIPETTES, VOLUMETRIC WITH STAND, a set of above pipettes, 1, 2, 5, 10, 25, 50 and 100 cc., 
 
 with improved stand.Set 
 
 PIPETTES, OVERFLOW, AUTOMATIC, with patent three way stopcock and reservoir for collecting 
 
 the excess liquid. Capacity 25 cubic centimeters. 
 
 -, capacity 100 cubic centimeters. 
 
 PITH for cutting sections.Per Package 
 
 PLANT PRESS. This press is a simple contrivance by which a plant is dried in a few hours without the 
 troublesome changing of blotters and shifting of specimens. Consists of a series of layers of tubular 
 paper inserted between sheets of blotting paper and absorbent cotton so that all the moisture is 
 
 carried off by a current of hot air passing through the tubes. Size 9 X 12 inches. 
 
 - ci7p 19 V 10 lnrliPQ 
 
 MOUNTING PAPER, 11 X ^'inches' .’ .' .’ .' .' .' .' .' .' .' .’ .' .' .' .' .' .' .’ .' Per Quire 
 
 DRYING PAPER, 11 X 17 inches.Per Quire 
 
 GENUS COVERS for mounting specimens? 1134 X 1734 inches when folded.Per Quire 
 
 PLATES, FILTER, ALUNDUM, for filtering where a small amount of solid matter is present in a 
 large amount of liquid. May also be used for filtering dust from air or flue gases. Porosity 43.9 
 per cent, carried in stock. Porosity 47.4 per cent, may also be obtained on application. 60° bev¬ 
 elled edge. a bed 
 
 Inches % X 34 1 X 34 
 
 Each $0.28 .30 
 
 PLATES, GLASS for covers of bottles, beakers, etc. 
 
 f 
 
 50 X % 
 
 1.00 
 
 k 
 
 100 
 
 .45 
 
 $3.60 
 
 3.26 
 
 3.85 
 
 .10 
 
 1.66 
 
 2.95 
 
 .50 
 
 .30 
 
 1.00 
 
 a 
 
 Size, inches 4X4 
 
 Each $0.03 
 
 PLATES, GLASS, blue cobalt glass. 
 
 -, 4X4 inches. 
 
 b 
 
 X 
 
 .04 
 
 .40 
 
 c 
 
 X 
 
 .05 
 
 „:OOOj 
 /oOOOi 
 <£-5 
 
 X 4 inches.$0.07 
 
 .12 
 
 No. 6334 
 
 PLATE, PORCELAIN, glazed, 11X9 centimeters, with twelve cavities for color reactions.$0.76 
 
 PLATE, PORCELAIN, unglazed and porous for drying crystals. 2234 cm. diameter. .16 
 
 PLATE, STREAK, unglazed porcelain, 634 X 5 centimeters, for arsenic test, etc. .30 
 
 PLATES, PORCELAIN, porous, square, for drying crystals and precipitates. 10 mm. thick, size 
 
 6X6 inches. .26 
 
 -, same as above, but 8X8 inches. .66 
 
 PLATES, PERFORATED GLAZED PORCELAIN, for use in funnels. 
 
 a be 
 
 Diameter, mm. 25 38 50 
 
 Each $0.16 .20 .26 
 
 PLATES, FUSED SILICA, UNGLAZED. (See index, “Fused Silica Ware,” for characteristics.) 
 
 a b c d e 
 
 Thickness, inch 34-34 % 34 24 34 
 
 Per Square Inch $0.03 .06 .06 .07 .08 
 
 PLATES, FUSED SILICA, GL.AZED, 34“J4 inch thick, in plates up to 6 inches square. Per Square Inch .08 
 
 6346 
 
473 
 
 CHEMISTRY AND BIOLOGY 
 
 PLATINUM WARE 
 
 All of the following ware is hammered to shape, tested and finished in the best manner. It is guaranteed free 
 from flaws and blisters and to give entire satisfaction in competent hands. Approximate weights are given without 
 
 price. Prices will be governed by the market price of platinum. 
 
 Nos. 6364a-e 
 
 n. 6355 No. 6357 
 
 Nos. 6363a-k 
 
 No. 6371 
 
 No. 6373 
 
 No. 6370 
 
 No. 6375 
 
 6350 
 
 PLATINUM FOIL. 
 
 Light Medium 
 
 Thickness, inch .001 .002 
 
 Thickness, mm. .03 .05 
 
 Approximate Weight per Square Inch 0.353 0.705 
 
 PLATINUM WIRE. Platinum loops for chemical laboratory work are usually made of No. 28 Wire, platinum triangles of Nos. 
 24 or 26, platinum inoculating needles of No. 24 and sometimes of No. 20. 
 
 B. & S. Gauge No. 18 20 22 24 25 
 
 Diameter, inch .0403 .0319 .0253 .0201 .0179 
 
 Diameter, mm. .81 .64 .51 .45 
 
 Weight per Foot, grams 5.365 3.404 2.081 1.330 1.077 
 
 PLATINUM ANODE, spiral % inch in diameter, made of .040 inch wire, 6J-6 turns, weight approximately 7 grams. 
 
 the standard form and designed particularly for use with Cathode No. 6357 following. 
 
 PLATINUM CATHODE, diameter of cylinder 1 inch, height 2 inches, height of stem 2 inches, height over all 4 inches. Diam¬ 
 eter of stem .040 inch. Approximate weight 11 grams. 
 
 PLATINUM FILTER CONES, seamless, 60°, perforations .016 to .025 inch. 
 
 a b c d e f g 
 
 Diameter, inches % % 1 1 Vi 1 % 2 
 
 Approximate Weight, grams 1 1.5 2.1 3.1 5.3 7.5 9.2 
 
 PLATINUM CRUCIBLES WITH COVERS. A crucible with cover weighs approximately as many grams as it holds cubic 
 centimeters. 
 
 a b c d e f 
 
 6355 
 
 6357 
 
 6361 
 
 6363 
 
 6364 PLATINUM CRUCIBLES, GOOCH, WITH COVERS. 
 
 Heavy 
 
 .0035 
 
 .09 
 
 1.058 
 
 26 
 
 .0159 
 
 .40 
 
 0.851 
 
 28 
 
 .0126 
 
 .32 
 
 0.480 
 
 30 
 
 .01 
 
 .26 
 
 0.332 
 
 32 
 
 .0079 
 .20 
 0.213 
 This is 
 
 g 
 
 j 
 
 Diameter, cm. 
 
 2.2 
 
 2.5 
 
 3.0 
 
 3.3 
 
 3.5 
 
 4.0 
 
 4.2 
 
 4.4 
 
 4.7 
 
 5.0 
 
 5.3 
 
 Depth, cm. 
 
 2.2 
 
 2.5 
 
 3.0 
 
 3.3 
 
 3.5 
 
 4.0 
 
 4.2 
 
 4.4 
 
 4.7 
 
 5.0 
 
 5.3 
 
 Capacity, cc. 
 
 8 
 
 10 
 
 15 
 
 20 
 
 25 
 
 30 
 
 40 
 
 50 
 
 60 
 
 70 
 
 80 
 
 Approximate Weight, grams 
 
 8 
 
 10 
 
 15 
 
 20 
 
 25 
 
 30 
 
 40 
 
 50 
 
 62 
 
 65 
 
 68 
 
 Diameter, cm. 
 
 Depth, cm. 
 
 Capacity, cc. 
 
 Approximate Weight, grams 
 
 a 
 
 2.7 
 
 2.7 
 
 10 
 
 13 
 
 6366 PLATINUM DISHES, round bottom 
 
 b 
 
 3.2 
 
 3.2 
 
 15 
 
 18 
 
 c 
 
 3.3 
 
 3.3 
 
 20 
 
 22 
 
 d 
 
 3.6 
 
 3.6 
 
 25 
 
 29 
 
 e 
 
 3.9 
 
 3.9 
 
 30 
 
 34 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 i 
 
 ] 
 
 k 
 
 1 
 
 3.8 
 
 4.2 
 
 4.4 
 
 4.8 
 
 5.6 
 
 6.5 
 
 6.5 
 
 7.2 
 
 7.8 
 
 8.4 
 
 8.9 
 
 9.4 
 
 1.0 
 
 2.0 
 
 2.2 
 
 2.4 
 
 2.7 
 
 3.0 
 
 3.3 
 
 3.5 
 
 3.7 
 
 3.7 
 
 4.1 
 
 4.3 
 
 15 
 
 20 
 
 25 
 
 35 
 
 50 
 
 65 
 
 75 
 
 100* 
 
 125 
 
 150 
 
 175 
 
 200 
 
 5 
 
 6 
 
 8 
 
 12 
 
 17 
 
 22 
 
 25 
 
 33 
 
 42 
 
 50 
 
 55 
 
 67 
 
 6367 
 
 6368 
 
 6369 
 
 6370 
 
 6371 
 6373 
 6375 
 
 6377 
 
 6379 
 
 6380 
 
 6381 
 
 Diameter, cm. 
 
 Depth, cm. 
 
 Capacity, cc. 
 
 Approximate Weight, grams 
 
 PLATINUM DISHES, without lip, a to 1, same sizes and weights as above. 
 
 PLATINUM DISH for iron, steel or water analysis, capacity 45 cc., approximate weight 15 grams. 
 PLATINUM DISH for milk analysis, capacity 45 cc., approximate weight 17 grams. 
 PLATINUM DISH for sugar analysis. Capacity 35 cc., approximate weight 16 grams. 
 PLATINUM DISH for water analysis. Capacity 100 cc.. approximate weight 20 grams. 
 PLATINUM TIPPED FORCEPS for blowpipe work and general laboratory use. 
 
 PLATINUM INCINERATING DISHES. 
 
 Capacity, cc. 
 
 Approximate Weight, grams 
 
 PLATINUM SPATULAS. 
 
 Length, cm. 
 
 Approximate Weight, grams 
 PLATINUM TRIANGLES, solid ends 
 For Crucible, Capacity cc. 
 
 Size of Wire, inch 
 Weight in Grams 
 
 PLATINUM TRIANGLES, twisted ends 
 
 For Crucible, Capacity cc. 
 
 Size of Wire, inch 
 Weight in Grams 
 
 PLATINUM TRIANGLES WITH HOLDE 
 
 crucible up to 100 cc. a 
 
 For Crucible, Capacity cc. 10 
 
 Size of Wire, inch .047 
 
 Weight in Grams 2 
 
 a 
 
 
 b 
 
 
 
 
 15 
 
 
 20 
 
 
 
 
 10 
 
 
 14 
 
 
 
 
 a 
 
 
 b 
 
 
 
 
 7 
 
 
 10 
 
 
 
 
 5 
 
 
 8 
 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 10 
 
 15 
 
 20 
 
 30 
 
 40 
 
 60 
 
 .045 
 
 .045 
 
 .055 
 
 .055 
 
 .064 
 
 .064 
 
 5 
 
 8 
 
 11 
 
 12 
 
 15 
 
 18 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 10 
 
 15 
 
 20 
 
 30 
 
 40 
 
 60 
 
 .045 
 
 .045 
 
 .055 
 
 .055 
 
 .064 
 
 .064 
 
 5 
 
 6 
 
 11 
 
 12 
 
 18 
 
 20 
 
 rolders nickel-plated and 
 
 will accommodate any 
 
 size triangle for he 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 15 
 
 20 
 
 30 
 
 40 
 
 60 
 
 80 
 
 .047 
 
 .050 
 
 .050 
 
 .062 
 
 .062 
 
 .064 
 
 2.5 
 
 4.5 
 
 5 
 
 7 5 
 
 8 
 
 9 
 
 h 
 
 100 
 
 .064 
 
 10 
 
474 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 6386 PLIERS, SIDE CUTTING, good quality. 
 
 PNEUMATIC TROUGHS. See TROUGHS, PNEUMATIC, Page 489. 
 
 6390 POROUS CUPS. 
 
 Diameter, inches 
 Height, inches 
 Each 
 
 a 
 
 1H 
 
 3 
 
 $0.16 
 
 b 
 
 2 
 
 4 
 
 .20 
 
 No. 6386 
 
 POTASH APPARATUS. See BULBS, POTASH, Page 419. 
 PRESSES FOR CORKS. See Page 426. 
 
 PRESSES FOR PLANTS. See Page 472. 
 
 c 
 
 5 
 
 .26 
 
 Each $0.40 
 
 d 
 
 3 
 
 7 
 
 .30 
 
 6396 PUMP, CARBOY, for pumping acid from a carboy through a siphon. A carboy inclinator is not always 
 safe and requires considerable care when used. This carboy obviates all danger and will be found a 
 most satisfactory method of readily transferring acid from carboy to bottles. 
 
 Complete.$6.00 
 
 PYROMETERS 
 
 INDICATING METERS—THERMO-COUPLES 
 
 A Pyrometer of two essential parts, — the Meter which indicates or records the temperature and the Thermo- 
 Couple which, on being placed in the heat to be measured, generates the electromotive force that actuates the meter. 
 
 We have listed below two different types of meters each of which can be obtained with different ranges and 
 graduated in Fahrenheit or Centigrade divisions. We have also listed various types of thermo-couples. From among 
 these listed it will be possible to select types and ranges suited to individual requirements. To insure getting the 
 proper outfit, it is advisable to inform us in regard to the service for which it is to be used. 
 
 PORTABLE INDICATING METERS. These are the highest grade D’Ar- 
 sonval type Milli-voltmeters designed especially for pyrometer work. They are 
 very sensitive high-torque meters, provided with: 
 
 1 Zero Temperature Adjustment which insures that the meter indicates cor¬ 
 rectly regardless of the temperature of the surrounding media. 
 
 2 Zero Adjustor which is a simple device for setting the pointer to agree with 
 the cold end temperature of the Thermo-couple. 
 
 3 Resilient Pivot Mounting which permits the utmost delicacy in adjustment 
 of the movement and by protecting it from the effects of jars and vibra¬ 
 tions, preserves its accuracy. 
 
 The case isjof aluminum, finished in black enamel. Over all dimensions are 
 6M X 6 X 3 inches. Scales are SYi inches. 
 
 FAHRENHEIT SCALES 
 
 
 CENTIGRADE 
 
 SCALES 
 
 Catalogue’No. 
 
 Range 
 
 Degrees per Division 
 
 Catalogue No. 
 
 Range 
 
 Degrees per Division 
 
 6397 " 
 
 32-1000 
 
 10 
 
 6397A 
 
 0-550 
 
 5 
 
 6398 
 
 32-1500 
 
 20 
 
 6398A 
 
 0-800 
 
 10 
 
 6399 
 
 32-2000 
 
 20 
 
 6399A 
 
 0-1100 
 
 10 
 
 6400 
 
 32-2550 
 
 25 
 
 6400A 
 
 0-1400 
 
 20 
 
 Nos. 6397 to 6400A 
 
 Price, with any of the above standard scales 
 
 $38.00 
 
CHEMISTRY AND BIOLOGY 
 
 475 
 
 Nos. 6402 to 6406A 
 
 WALL INDICATING METERS. These meters are essentially the same as 
 the Portable Meters above listed, except that they are designed with wall mounting. 
 The cases are of aluminum, finished in black enamel. Diameter, 6 inches, depth 
 3% inches. Scale arc, 5J4 inches. 
 
 FAHRENHEIT SCALES CENTIGRADE SCALES 
 
 Catalogue No. 
 
 Range 
 
 Degrees 
 per Division 
 
 Catalogue No. 
 
 Range 
 
 Degrees 
 per Division 
 
 6402 
 
 32-1000 
 
 10 
 
 6402A 
 
 0-550 
 
 5 
 
 6403 
 
 32-1500 
 
 20 
 
 6403A 
 
 0-800 
 
 10 
 
 6404 
 
 32-2000 
 
 20 
 
 6404A 
 
 0-1100 
 
 10 
 
 6405 
 
 32-2550 
 
 25 
 
 6405A 
 
 0-1400 
 
 20 
 
 Price, with any of the above standard scales 
 
 
 
 . . . $38.00 
 
 6407 THERMO-COUPLES. These thermo-couples generate an electro-motive force five times greater than 
 the costly platinum-rhodium couples, have a practically straight line temperature, — E. M. F. 
 relation, are heavy in cross section and are inexpensive. No. 14 B. & S. Gauge elements; length 
 of couple 3 feet. 
 
 Price includes handle and 10 feet of flexible leads. 
 
 For maximum temperature of 1000° F. (550° C.). 5.50 
 
 6408 -, for maximum temperature of 1500° F. (800° C.). 5.60 
 
 6409 -, for maximum temperature of 2000° F. (1100° C.). 5.50 
 
 For Extra Length Couples add,.r.Per Foot .60 
 
 6410 THERMO-COUPLES, same as above, but No. 8 B. & S. Gauge elements and with flexible leads 
 
 20 feet long. 
 
 For maximum temperature of 1000° F. (550° C.). 6.75 
 
 6411 -, for maximum temperature of 1500° F. (800° C.). 6.76 
 
 6412 -, for maximum temperature of 2000° F. (1100° C.). 6.76 
 
 6413 -, for maximum temperature of 2500° F. (1400° C.). 6.76 
 
 For Extra Length Couples add. Per Foot .86 
 
 6414 THERMO-COUPLES, same as No. 6407 but No. 6 B. & S. Gauge elements and with flexible leads 20 
 feet long. 
 
 For maximum temperature of 2000° F. (1100° C.). 8.35 
 
 6415 -, for maximum temperature of 2500° F. (1400° C.). 8.35 
 
 For Extra Length Couples add,.Per Foot 1.50 
 
 6420 
 
 PYROMETER TUBES, ALUNDUM. (See Index, “Alundum Ware,” for Characteristics.) Supplied 
 in lengths of 8, 12, 18, 24, 27, 30, 36, and 39 inches. When ordering Specify Catalogue Number, 
 Length, Bore, and Wall. 
 
 Bore, inch 
 
 a 
 
 7 A« 
 
 b 
 
 %e 
 
 c 
 
 X 
 
 a 
 
 %o 
 
 e 
 
 X 
 
 I 
 
 Vs 
 
 g 
 
 1 
 
 a 
 
 1 Vs 
 
 m 
 
 Wall, inch 
 
 Vs 
 
 %2 
 
 Vs 
 
 %« 
 
 X 
 
 X 
 
 X 
 
 Via 
 
 X 
 
 Per inch 
 
 $0.28 
 
 .34 
 
 .28 
 
 .28 
 
 .34 
 
 .34 
 
 .45 
 
 .45 
 
 .50 
 
 6425 
 
 RECALESCENT OUTFIT, — a simple and re¬ 
 liable apparatus for determining the proper 
 hardening temperatures of carbon steel (high 
 carbon steels only). The apparatus consists 
 of an Electric Furnace, a Pyrometer and a 
 Rheostat for regulating the furnace tem¬ 
 perature. 
 
 The operation is to clamp two small pieces of 
 steel to the end of the thermo-couple, place 
 them in the electric furnace and heat until 
 the “recalescent” or “critical” point is 
 passed as indicated by the pyrometer. 
 
 Outfit complete with Electric Furnace No. 
 6482A (see page 440), for 110 or 220 Volts 
 A. C. (60 cycles) or D. C. ........ 
 
 Note. — When ordering, specify Line Volt¬ 
 age and whether A. C. or D. C. 
 
 $70.00 
 
 PYKNOMETERS. See BOTTLES, SPECIFIC GRAVITY, Page 418. 
 
 No. 6425 
 
476 
 
 KNOTT APPARATUS CO 
 
 BOSTON 
 
 RADIOGRAPHS 
 
 The following list of RADIOGRAPHS has been carefully made from 
 the complete selection of one of our large hospitals, for the purpose of 
 showing, first, the possibilities of correct X-Ray examination and, second, 
 to show the formation of joints in the study of Physiology. 
 
 6430 FORMATION OF JOINTS, (a) Child’s Hand, showing Epiphy¬ 
 
 sis; (b) Adult Hand; (c) Elbow Joint (Lateral view); (d) Hip 
 Joint; (e) Knee (Lateral view); (f) Ankle (Lateral view). 
 
 6431 FRACTURES AND FOREIGN BODIES, (a) Hand (Fracture 
 
 Metacarpal Bones); (b) Fore Arm (Fracture Ulna and Radius); 
 (c) Leg (Fracture Tibia and Fibular); (d) Hand with Needle 
 Embedded; (e) Wrist (Typical Fracture); (f) Foot (Fractured 
 Metatarsal). 
 
 Each.$1.00 Choice, any six ... . $6.60 
 
 Complete Series, Nos. 6430 and 6431 . 10.00 
 
 6432 RADIOGRAPHS. A selected list of various articles photo¬ 
 
 graphed on one plate to show the different degrees of 
 
 radiability of diverse substances 
 
 1.76 
 
 No. 6430f 
 
 6435 
 
 6440 
 
 6446 
 
 6446 
 
 6448 
 
 6450 
 
 6460 
 
 6461 
 
 6463 
 
 6464 
 
 6466 
 
 6468 
 
 6472 
 
 Nos. 6445a-c 
 RECEIVERS, RETORT. 
 
 Capacity, ounces 4 8 16 
 
 Each $0.10 .14 .20 
 
 RETORTS, COPPER, for generation of oxygen, etc. a bed 
 
 Capacity, ounces 8 16 32 64 
 
 Each $2.25 2.60 3.36 3.96 
 
 RETORTS, GLASS, plain, without tubulations and glass stoppers. a b c 
 
 Capacity, ounces 8 16 32 
 
 Each ... ... ... 
 
 RETORTS, GLASS with glass stoppers ground in. a b c d e 
 
 Capacity, ounces 4 8 16 32 48 
 
 Each ... ... ... ... ... 
 
 RETORTS, IRON, for distilling mercury, etc. a be 
 
 Capacity, ounces 8 16 32 
 
 Each $2.25 2.50 2.95 
 
 RETORTS, VITRIFIED PORCELAIN, with tubulature and stopper. a be 
 
 Capacity, cc. 140 210 275 
 
 Each $2.60 4.00 4.36 
 
 RINGS FOR RING STANDS, Harcourt Open Side Filter Rings, short shank for use on small and 
 medium stands. a be 
 
 Diameter, inches 2 3 4 
 
 Each $0.13 .16 .20 
 
 RINGS FOR RING STANDS, Harcourt Open Side Filter Rings, long shank for use on 
 large stands. a bed 
 
 Diameter, inches 2 3 4 5 
 
 Each $0.14 .17 .21 .25 
 
 RINGS FOR RING STANDS, short shanks for use on small and medium stands. 
 
 Nos. 6436a-c 
 
 f 
 
 64 
 
 a b 
 
 Diameter, inches 2 3 
 
 Each $0.10 .13 
 
 RINGS FOR RING STANDS, long shank for use on large stands. 
 
 Diameter, inches 
 Each 
 
 EXTENSION RINGS, OPEN SIDE (Harcourt Open Side Filter Rings), 
 quire the use of Clamp Holder No. 4011. a b 
 
 Diameter, inches 2 3 
 
 Each $0.13 .15 
 
 RINGS, EXTENSION, for use with No. 4011 Clamp Holder. 
 
 a b 
 
 Diameter, inches 2 3 
 
 Each $0.11 .13 
 
 RINGS, CONCENTRIC, of cast iron, japanned, with clamp for use on ring 
 or retort stands, to support funnels, flasks, etc. a b 
 
 No. of rings 3 4 
 
 Diameter of Largest Ring, inches 6 8 
 
 Set $0.70 .90 
 
 Nos. 6460a-c 
 
CHEMISTRY AND BIOLOGY 
 
 477 
 
 6480 
 
 6482 
 
 6484 
 
 RODS, GLASS, in lengths of one meter. 
 Diameter, mm. 
 
 Per Pound 
 
 RODS, GLASS, Stirring Rods, finished ends. 
 Size, mm. 
 
 Per Dozen 
 
 6486 
 
 43-220 
 
 6490 
 
 a 
 
 4 
 
 $0.60 
 
 b 
 
 5 
 
 .60 
 
 c 
 
 6 
 
 .50 
 
 yt iso 
 
 $0.16 
 
 b 
 
 X 150 
 
 .20 
 
 r./ 
 
 % 
 
 1.25 
 
 f 
 
 3 /8 
 
 1.40 
 
 Per Box 
 Foot 
 
 d 
 
 7 
 
 .50 
 
 RODS, FUSED SILICA. (See index, “Fused Silica Ware,” for characteristics.) Can be 
 used for stirring and pouring at high temperatures, particularly in the case of high 
 melting metals and alloys which do not form basic oxides. In lengths up to 6 feet, 
 a bed 
 
 Diameter, inch Vk % M 
 
 Per Foot $0.40 .50 .75 1.00 
 
 RUBBER BANDS, assorted sizes. 
 
 RUBBER DAM, thin sheet rubber, best quality.Per Square 
 
 RUBBER DISCS, a tough sheet rubber especially selected for foot bellows. 
 
 Catalogue Number 3702 3702A 3702B 
 
 Diameter, inches 9% 1124 14J4 
 
 Each $0.95 1.36 1.95 
 
 RUBBER POLICEMEN for scraping precipitates from the sides of beakers, etc. For 
 use on glass rods. Pure rubber, without glass rod .Each 
 
 $0.15 
 
 .33 
 
 .08 
 
 No. 6490 
 
 THE KNOTT QUALITY 
 
 ANTIMONY RUBBER TUBING 
 AND STOPPERS 
 
 We early realized that the reason why France, Germany and England were supplying practically all of the rub¬ 
 ber tubing and stoppers used in chemical laboratory work, was due to research devoted to this branch of chemical 
 industry. We, therefore, secured the services of chemists eminently well fitted to undertake this line of work, in 
 order to find out the reason why rubber of equal quality could not be produced in this country. These researches 
 resulted in our well-known Formula “317,” on which our laboratory rubber for the past sixteen years has been based 
 Many laboratories have not yet appreciated the fact that cheap rubber is, in the end the more expensive Both 
 economy and efficiency in laboratory organization make it eminently desirable to use the be f rubber obtamable. 
 In ordering, specify Knott’s “317” Antimony Rubber, and thus be sure of obtaining a rubber of the highest quality. 
 
 6500 KNOTT’S “317” ANTIMONY RUBBER TUBING, regular 
 thickness of wall, extraordinary quality. 
 
 Inside diameter, inch 24 % 24 24 % % 
 
 Price per Foot $0.06 .08 .12 .16 .17 .26 
 
 6502 KNOTT’S “317” ANTIMONY RUBBER TUBING, same 
 quality as above, but extra thickness to withstand pres- 
 sures. _ . 
 
 Inside Diameter, inch 24 /% A 
 
 Price per Foot $0.10 .18 .20 
 
 6610 FLEXIBLE STEEL GAS TUBING, for gas supply, connec¬ 
 tions to hot plates, gas stoves, gas burners, etc. This 
 tubing is practically indestructible, is gas tight and will 
 not kink. Inside diameter 24-inch, and carried in stock 
 in two and three-foot lengths only, each length with 
 rubber ends for connecting to gas cock and burner 
 nipples. a b 
 
 Length, feet 2 ~ 
 
 Per Length $0.22 -30 
 
 .40 
 
 H 
 
 .25 
 
478 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 KNOTT’S “317” 
 
 ANTIMONY 
 RUBBER STOPPERS 
 
 No. 6515 
 
 In order to simplify the method of determining 
 the size of rubber stopper desired for a specific 
 purpose, our stoppers are given a number corre¬ 
 sponding to the small diameter in millimeters. 
 Hence, the stopper K25 means a stopper 25 milli¬ 
 meters in diameter. 
 
 In ordering specify the number according to 
 our list and insist on Formula “317” if you wish a 
 stopper of the very highest grade. 
 
 We carry in stock rubber stoppers, solid, with 
 one hole and with two holes as indicated below. 
 
 Size 
 
 Diameter 
 
 Mean 
 
 
 
 
 
 Price 
 
 Size 
 
 Diameter 
 
 Mean 
 
 
 
 
 Price 
 
 No. 
 
 Small End Diameter 
 
 Length 
 
 
 
 
 Per 100 
 
 No. 
 
 Small End Diameter 
 
 Length 
 
 
 Per 100 
 
 Kll 
 
 11 mm. 
 
 12 mm. 
 
 22 mm. 
 
 solid 
 
 or 
 
 1 hole 
 
 $3.00 
 
 K28 
 
 28 mm. 
 
 30 mm. 
 
 30 mm. 
 
 solid, 1 or 
 
 2 holes 
 
 $15.00 
 
 K13 
 
 13 
 
 15 
 
 22 
 
 solid 
 
 or 
 
 1 hole 
 
 4.00 
 
 K30 
 
 30 
 
 33 
 
 30 
 
 solid, 1 or 
 
 2 holes 
 
 20.00 
 
 K15 
 
 15 
 
 17 
 
 25 
 
 solid, 
 
 1 
 
 or 2 holes 
 
 5.00 
 
 K33 
 
 33 
 
 37 
 
 28 
 
 solid, 1 or 
 
 2 holes 
 
 23.00 
 
 K17 
 
 17 
 
 19 
 
 25 
 
 solid, 
 
 1 
 
 or 2 holes 
 
 6.00 
 
 K37 
 
 37 
 
 41 
 
 28 
 
 solid, 1 or 
 
 2 holes 
 
 31.00 
 
 K19 
 
 19 
 
 21 
 
 25 
 
 solid. 
 
 1 
 
 or 2 holes 
 
 7.00 
 
 K40 
 
 40 
 
 44 
 
 30 
 
 solid, 1 or 
 
 2 holes 
 
 40.00 
 
 K21 
 
 21 
 
 23 
 
 25 
 
 solid, 
 
 1 
 
 or 2 holes 
 
 9.00 
 
 K43 
 
 43 
 
 46 
 
 32 
 
 solid only 
 
 
 46.00 
 
 K23 
 
 23 
 
 25 
 
 30 
 
 solid. 
 
 1 
 
 or 2 holes 
 
 11.00 
 
 K47 
 
 47 
 
 50 
 
 32 
 
 solid only 
 
 
 48.00 
 
 K25 
 
 25 
 
 28 
 
 30 
 
 solid, 
 
 1 
 
 or 2 holes 
 
 14.00 
 
 K51 
 
 51 
 
 53 
 
 32 
 
 solid only 
 
 
 56.00 
 
 6516 RUBBER STOPPER, No. 1 Yi for Dr. Boles’ Hospital Bottle as used at Boston City Hospital. Each $0.36 
 
 6923 
 
 6520 
 
 6522 
 
 6524 
 
 6526 
 
 6530 
 
 6531 
 
 6532 
 
 6533 
 6535 
 
 SACCHAROMETER, DR. EINHORN’S FERMENTATION, with graduated test tube. With direc¬ 
 tions . 
 
 SCISSORS, for general utility, fine grade. 
 
 SCOOP, HORN, 4X2H inches. 
 
 SHEARS, METAL CUTTING, cutting blade 2 y 2 inches. 
 
 SHEARS, PAPER, superior quality. Cutting blade 10 inches long. 
 
 SIEVES, SEAMLESS BRASS FRAMES, BRASS GAUZE, substantially constructed for mixing or 
 separating substances into different grades of fineness. These sieves are made so that one will nest 
 with the other. Five inches diameter. a b c d e 
 
 Mesh 10 20 40 60 80 
 
 Each $1-20 1.25 1.36 1.46 1.66 
 
 SIEVES, SEAMLESS, BRASS FRAMES, BRASS GAUZE, same as above but 8 inches diameter. 
 
 a b c d e f 
 
 Mesh 10 20 40 60 80 100 
 
 Each $2.30 2.30 2.40 2.50 2.60 3.00 
 
 SIEVES, SEAMLESS, BRASS FRAMES, BRASS GAUZE, nested, 5 inches in diameter, 20, 40, 60, 80 
 
 and 100 mesh, with brass pan and cover. Same sieves as Nos. 6530b-f . Per Set of Five 
 
 SIEVES, SEAMLESS, BRASS FRAMES, BRASS GAUZE, nested, 8 inches in diameter, 20, 40, 60 
 80 and 100 mesh, with brass pan and cover. Same sieves as Nos. 6531b-f. . . Per Set of Five 
 
 $0.76 
 
 .65 
 
 .18 
 
 .76 
 
 1.00 
 
 f 
 
 100 
 
 1.70 
 
 8.40 
 
 14.60 
 
 SIEVES, WOOD FRAME, BRASS GAUZE, diameter 6 inches. 
 
 Mesh 
 
 Each 
 
 a 
 
 30 
 
 $0.70 
 
 b 
 
 40 
 
 .76 
 
 c d 
 
 60 80 
 
 .85 1.00 
 
CHEMISTRY AND BIOLOGY 
 
 479 
 
 No. 6586 Nos. 6580a-c No. 6560 No. 6562 
 
 32-200 SIPHON, GLASS, plain. $0.20 
 
 32-206 SIPHON WITH SUCTION TUBE, glass.36 
 
 SLEEVES. See OVERSLEEVES, Page 471. 
 
 6542 SOLDERING OUTFIT. Comprises one bar of solder, one box of resin, scraper and a special solder¬ 
 
 ing copper of sufficient size to retain heat and designed so that it may either be heated as an ordinary 
 
 soldering copper or, when attached to a gas burner, the gas will pass through a hollow tube within 
 
 the length of the handle and is ignited at emission holes immediately beneath the copper. In 
 wooden box. 1.00 
 
 6543 SOLDERING OUTFIT, similar to above, except that the soldering copper is not adapted to a gas 
 
 burner and is not quite so highly finished. In wood box. .76 
 
 6544 SOLDERING COPPER, with handle, one-half pound size. .60 
 
 6645 SOLDER, stick form.Per Pound .46 
 
 6646 SOLDER, Wire Form with Resin Cutter. No flux required.Per Pound .50 
 
 6547 SOLDERING PASTE, ACID. Box .25 
 
 6648 SOLDERING FLUID, ACID.Bottle .26 
 
 SOLDERING IRON, ELECTRIC. See ELECTRIC APPLIANCES, Page 436. 
 
 6550 SOLDERING IRON HEATER, for coal gas, a necessity for the laboratory work room. 1.60 
 
 6661 -, same as above for gasoline gas.. 1.86 
 
 SOXHLET’S APPARATUS. See EXTRACTION APPARATUS, Page 436. 
 
 6560 SPATULAS, HORN, double. a b c 
 
 Length, inches 4 5 6 
 
 Each $0.12 .16 .19 
 
 6562 SPATULA, RUBBER, OSTWALD’S. This is a superior instrument and will be found practically 
 
 indestructible. -40 
 
 6664 SPATULAS, STEEL with wood handle. Flexible polished steel blade. 
 
 a b c 
 
 Length, inches 3 4 6 
 
 Each $0.22 .27 .40 
 
 SPECIMENS AND SPECIMEN MOUNTS. See Page 480. 
 
 6670 SPLINTS, 100 in package, selected lengths.Per Package .16 
 
 6672 SPONGES for general laboratory use. These sponges are of excellent quality selected of convenient 
 
 size and to give long service.Each .18 
 
 6674 SPOONS, DEFLAGRATING, of heavy iron, handles 16 inches long. 
 
 a b 
 
 Diameter of Spoons, inch % 
 
 Each $0.08 .10 
 
 6576 SPOONS, DEFLAGRATING, of heavy brass, handles 16 inches long. 
 
 a b 
 
 Diameter of Spoons, inch Yi % 
 
 Each $0.12 .15 
 
 6678 SPOON, HORN, with Spatula End, length 5 inches.15 
 
 6580 SPOONS, PORCELAIN with SPATULA END, glazed. 
 
 a b c 
 
 Length, mm. 110 150 170 
 
 Each $0.20 .26 .30 
 
 6682 SPATULAS, PORCELAIN, with spatula on each end, glazed. 
 
 a b c 
 
 Length, mm. 105 130 160 
 
 Each $0.20 .25 .30 
 
 6686 SPOON, SODIUM, Sodium Capsule, after Brownlee and Others. With ramrod.3 
 
 
480 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 
 Nos. 6610a-d 
 
 6610 SPECIMEN MOUNTS, KNOTT’S PROTECTED BOTANICAL. Consist of two parts, — a thin plate 
 
 of photographic glass to which narrow flaps of linen morocco paper are neatly fastened, and a card¬ 
 board back to which is glued a thin layer of sterilized surgical cotton in which the specimens may be 
 embedded. abed 
 
 Size, inches 5X6 634 X 834 8 X 12 12 X 16 
 
 Each $0.24 .28 .42 .70 
 
 6611 SPECIMEN MOUNTS, KNOTT’S PROTECTED ENTOMOLOGY, suitable for mounting and pre¬ 
 
 serving specimens of butterflies, beetles and insects of all kinds, or of plants too large for Botanical 
 mounts. Consist of two parts, — the mounting part a heavy cardboard tray lined with a heavy pad of 
 cotton, and the cover, designed to fit dust-proof over the mounting part, is designed with a photo¬ 
 graphic glass top which permits of inspection of specimens. This cover portion is covered with 
 black binding cloth. 
 
 a b c d e f g h 
 
 Size, inches 234 X 3 334 X 434 4 X 5 5 X 6 634 X 634 634 X 834 8 X 12 12 X 16 
 Each $0.16 .18 .20 .24 .28 .36 .50 1.00 
 
 SPECIMENS 
 
 No. 6620 
 
 Much care has been expended on the preparation of our zoological material, so that it will be suitable for ele¬ 
 mentary courses. It is to be strongly recommended for its practical value. We try to keep live specimens and the 
 prices are approximately the same as those of the preserved material 
 
 National Biology Sheet. Each Dozen 100 
 
 a — R10 — Amoeba Microscopic Slides, specially prepared. $1.00 $10.00 $75.00 
 
 b — Z10 —- Grantia (Simple Sponge) . 10 .35 2.60 
 
 c — Z20 —• Hydra (fusca or viridis). 25 1.60 10.00 
 
 d —Z21 — Metridium (Sea-anemone). 25 2.00 15.00 
 
 e —-Medusa of Obelia, slides stained. (Admirable for showing Medusa structure) . . .60 7.00 
 
 f —-Medusa (Small, Gonionemus). 16 1.00 8.00 
 
 g —- Medusa (Large, Aurelia). 40 3.00 20.00 
 
 h-Coral (Species) ? . 10 .75 6.00 
 
 i — Z30 — Earthworm (Lumbricus). 10 .76 6.00 
 
 j — Z32 — Sandworm (Nereis viridis). 16 1.26 10.00 
 
 The sandworms are killed and hardened bv a special process which renders the tis¬ 
 sues firm. They are admirably suited for dissection and the preparation of cross- 
 sections. They are far superior to the ordinary formalin material. 
 
 k — Z40 — Starfish (Asterias) medium size, dry or formalin. 16 1.00 8.00 
 
 1-Sea Urchin. 16 1.00 8.00 
 
 m — Z50 — Crayfish (Cambarus). 16 1.00 8.00 
 
 n — Z52 —• Lobster (Homarus) chicken. 76 
 
 o — Z54 — Large Florida Grasshoppers. 20 1.60 10.00 
 
 These afford, in our opinion, the very best material for insect dissection. We so¬ 
 licit a trial order. 
 
 p —-Crickets. 10 .76 5.00 
 
 q —-Roaches. 10 .76 6.00 
 
 r —-Spider (Epeira). 10 .76 5.00 
 
 s — Z60 — Clam (Mya). 05 .60 3.00 
 
 t —-Snail (Large European). 10 .76 5.00 
 
 u —-Chart of Mollusca. 1.60 
 
 v —-Amphioxus . 26 1.50 10.00 
 
 w —-Necturus . 50 5.00 
 
 x — V21 — Frogs (very large). 50 6.00 
 
 v —-Medium Size. 20 2.00 
 
 
 
 > 
 
 
 6624 SCHOOL COLLECTION of 70 SPECIES OF INSECTS. Collection especially selected to represent 
 
 all of the Principal Order. Complete Collection. 6.00 
 
 
CHEMISTRY AND BIOLOGY 
 
 481 
 
 6630 
 
 6631 
 
 $0.05 
 
 STENCIL, HARCOURT IMPROVED. Consists 
 of a flexible transparent plate with various 
 “cut-outs” representing outlines of chemical 
 utensils as illustrated. The ruling edges of the 
 obtuse angle serves as convenient guides in 
 drawing delivery tubes. One edge has a metric 
 scale for dimensions. Recommended by prom¬ 
 inent teachers of chemistry in that its use 
 eliminates bad drawings, saves time, inspires 
 the pupil, holds his attention and induces ac¬ 
 curate thinking.Each $0.10 
 
 Per Dozen 1.00 
 
 STENCIL CUT-OUTS, three sizes Flat Bottom 
 Flasks, Erlenmeyer Flask, Bottle, Plain Beaker, 
 
 Griffin Beaker, Thistle Top, Funnel, Evaporat¬ 
 ing Dish, Bunsen Burner, Crucible and Re- No. 6630 
 
 tort. Of transparent material, same shapes and 
 
 sizes as cut-outs of stencil illustrated above. Per Package of 13 Cut-outs. 
 
 STERILIZERS 
 
 No. 6642 
 
 No. 6644 
 
 6640 STERILIZER, HOT AIR, of sheet iron, double wall with enclosed base and extra asbestos mat. In¬ 
 side measurements, 10 inches high, 12 inches wide and 10 inches deep. Extreme height, including 
 base, 2l l A inches. With two shelves.* • ' ‘ * 
 
 6642 
 
 6644 
 
 With two 
 
 STERLIZER, HOT AIR, of sheet iron, double wall, outer wall covered with asbestos. Heated by a 
 row of small Bunsen Burners around the sides of the base, insuring an even circulation of heat. I he 
 air is introduced through openings on each side. Inside dimensions, 19 inches high, 12 inches w , 
 
 9A inches deep. With three shelves. 
 
 STERILIZER. ELECTRIC, HOT AIR, automatic control. Constructed of asbestos board and with 
 heavy brass binding. Range 50 to 200 degrees Centigrade; regulation positive and control within 
 one degree. Consumption 5 amperes. All contact points are outside of the oven, thus eliminating 
 any possible danger when using a combustible substance. Heating units are independent and can 
 be renewed Sizf 10 X 10 X 12 inches wide. Complete for 110 volts either D. C. or A. C. with 
 6 feet of cord and with plug for any ordinary socket. 
 
Nos. 62-70a-e 
 
 62-70 STILLS (DISTILLING APPARATUS). 
 
 Consists of a heavy copper, tin-lined still 
 with removable head, connected with a 
 pure block tin worm, enclosed in a zinc 
 condensing vessel, having proper inlets 
 and outlets. 
 
 No. 62-80 
 
 a 
 
 Capacity, gallons 34 
 
 Still and Condenser $10.60 
 
 6661 STILLS, only, of above outfit. a 
 
 Capacity, gallons 34 
 
 Each $6.60 
 
 b 
 
 c 
 
 d 
 
 e 
 
 1 
 
 2 
 
 3 
 
 5 
 
 12.40 
 
 14.60 
 
 19.76 
 
 26.60 
 
 b 
 
 c 
 
 d 
 
 e 
 
 1 
 
 2 
 
 3 
 
 5 
 
 6.26 
 
 7.26 
 
 10.00 
 
 14.26 
 
 62-80 STILL, ACME. This still is a perfect apparatus for the production of pure water by distillation. 
 
 The distillate is cold, and aerated if desired. The apparatus is of first-class workmanship throughout 
 and is made of copper and brass, tin-lined and nickel-plated. The gas and water connections are 
 extremely simple. The Acme Water Still runs automatically and there is nothing to get out of 
 order. It is started and stopped in a moment. The “Acme” is comparatively the fastest and most 
 economical Water Still, as it produces a gallon of distilled water in about 134 hours, at a cost of 
 about 134 cents per gallon. It is the most durable still, and will practically last a life-time, as the 
 mineral and other matter that remains in the retort is drained off through the flushing outlet, this 
 being done in a moment without any trouble and without displacing the still or taking it to pieces. 
 
 The combustion of gas with our special burner is perfect and all the heat is fully utilized. Wall 
 space required 4X12 inches, extreme width 8 inches, projection 14 inches. 
 
 Still as illustrated with burner for coal or water gas, natural gas, or acetylene. $24.60 
 
 STILL, MERCURY, HARCOURT ECONOMY, for 
 use on any 110 volt A. C. or D. C. circuit, ready for 
 use as soon as filled and connected to lighting cir¬ 
 cuit current, automatically shut off when mercury in 
 the retort is exhausted. Operating cost approxi¬ 
 mately one cent per pound of distilled mercury. 
 
 The impure mercury is vaporized in an iron retort sur¬ 
 rounded by a heating unit having proper and ample 
 electrical and heat insulation. This entire unit is 
 surrounded with a polished metal casing which 
 serves both to protect the insulation surrounding the 
 heating unit and to prevent unproductive radiation. 
 
 The vaporized mercury passes down into the condensing 
 chamber located in the base. This chamber is entirely 
 surrounded by a water jacket in which a continuous 
 stream of cold water is allowed to circulate. Com¬ 
 plete condensation is produced and the clean distilled 
 mercury is drawn off as desired through the steel 
 spigot connected to the chamber. 
 
 The glass globe shown in the illustration and supplied 
 with the instrument is not an essential feature, but 
 is used as a precautionary measure to make doubly 
 
 sure that no mercury fumes can possibly reach the room atmosphere. $14.00 
 
CHEMISTRY AND BIOLOGY 
 
 483 
 
 Nos. 6662a-c 
 
 No. 6664 
 
 No. 6667 
 
 No. 6668 
 
 STOPCOCKS, BRASS. See KNOTT’S GAS COCKS, Page 446. 
 
 6660 STOPCOCK, GLASS, FRESENIUS’ FORM. Bore one mm.Each $1.26 
 
 6662 STOPCOCKS, GLASS, GEISSLER’S. Straight cocks carefully ground in by hand. 
 
 a b c 
 
 Diameter of Bore, inches 12 3 
 
 Each $0.96 1.20 1.40 
 
 STORAGE BATTERY HYDROMETERS. See Page 448. 
 
 6664 STOVE, GAS, top 12 X 12% inches, height 5 inches, finished in black, drip pan, drawing out in front, 
 
 valves and supply pipes nickel plated and polished. 4.60 
 
 6666 -, two burners, top 22% X 12 inches, height 5 inches. 6.60 
 
 6667 STOVE (HOT PLATE), ELECTRIC, ROUND. Operates on 110 or 220 Volts A. C. (60 cycles) orD. C. 
 
 Life of heating element guaranteed for one year. 
 
 Diameter, 6 inches, pressed steel top, heavy bent wire legs, “blued” steel finish. Boils one liter of water 
 from cold in 15 minutes. Maximum temperature 483° C. (900° F.). Current consumption 500 watts. 
 
 With 6 feet Twin Conductor Flexible Cord and detachable Connector Plug (110 or 220 volts A. C. 
 
 or D. C.). 6.76 
 
 6667A EXTRA HEATING UNIT for above.<. 3.36 
 
 Note.—W hen ordering specify Line Voltage and whether A. C. or D. C. 
 
 6668 STOVE (HOT PLATE), ELECTRIC, SQUARE, similar to above, but 12 inches square. Sheet steel 
 top, cast iron legs, “blued” steel finish. Centrally heated by spiral resistance unit covering circular 
 area 5% inches in diameter. 
 
 Maximum temperature at center, 260° C. (500° F.), temperature at edge 121° C. (250° F.). Current 
 consumption 500 watts. With 6 feet Flexible Twin Cord and detachable Connector Plug .... 9.00 
 
 6668A EXTRA HEATING UNIT for above. 3.36 
 
 Note. —When ordering specify Line Voltage and whether A. C. or D. C. 
 
484 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6670 
 
 6670 STOVES (HOT PLATES), THREE HEAT ELECTRIC 
 
 for use on 110 01 220 Volts A. C. (60 Cycles) or D. C. 
 Life of heating unit guaranteed for one year. 
 
 Sheet steel top and legs. “Blued steel” and black 
 enamel finish. 
 
 Renewable resistance units composed of three parallel 
 windings each connected by a snap switch on front 
 of plate, heat distribution uniform. Low heat ob¬ 
 tained with one switch on, medium, with two 
 switches on, high heat, with three switches on. 
 Low, 246° C. (475° F.); medium, 316° C. (600° F.); 
 high, 399° C. (750° F.) 
 
 Size of Plate, inches 
 
 t 
 
 Current Consumption, watts 
 Price, 110 or 220 Volts, A. C. or D. C. 
 
 Note. — When ordering specify Line Voltage 
 
 a 
 
 12 X 18 
 
 Low Medium High 
 600 1200 1800 
 
 $30.60 
 
 and whether A. C. or D. C. 
 
 Low 
 
 1200 
 
 b 
 
 18 X 24 
 Medium High 
 2400 3600 
 
 47.00 
 
 6671 EXTRA HEATING UNITS for above. 
 
 Note. — No. 6670a requires one unit, but No. 6670b requires two units. 
 
 Each $11.26 
 
 STOVES, GAS. See also pages 200 to 202. 
 
 STROP. See MICROTOME KNIFE STROP, Page 466. 
 
 No. 6687 
 
 No. 6689 
 
 SUGAR HYDROMETERS. See Nos. 6674A to C, Page 448. 
 
 6679 SUPPORT, FUNNEL, as designed at Harvard College. A strip of hardwood with four beveled holes 
 for 60° funnels. A V-Clamp attached to the index side of this strip permits of attaching to the 
 rods of supports Nos. 6691 and 6692 .$0.46 
 
 6681 SUPPORT, FUNNEL, for 6 funnels. H Metal Base, metal upright rod, wood funnel holder, with 
 
 clamp . 1.96 
 
 6681A WOOD FUNNEL HOLDER, as used on above stand. 1.10 
 
 6682 SUPPORT, FUNNEL, for 4 funnels.'. 1.80 
 
 6682A WOOD FUNNEL HOLDER, as used on above stand. .96 
 
 6683 SUPPORT, FUNNEL, for 2 funnels. 1.70 
 
 6683A WOOD FUNNEL HOLDER, as used on above stand.86 
 
 6686 SUPPORT, GAY-LUSSAC’S IMPROVED, of hardwood, cork-lined clamp with long J4~inch ex¬ 
 
 tension rod. 1.26 
 
 6687 SUPPORT, SCHELLBACH’S UNIVERSAL, of hardwood, cork-lined clamp with universal move¬ 
 
 ment, height of clamp adjustable. 1.33 
 
 6689 SUPPORT, PIPETTE, REVOLVING, for 12 pipettes, of hardwood. 2.20 
 
CHEMISTRY AND BIOLOGY 
 
 485 
 
 No. 6691 
 
 No. 6692 
 
 No. 6695b 
 
 No. 6701 
 
 6691 SUPPORTS', RING OR RETORT, with Rectangular Base and Rod. Base of iron, neatly japanned, cop- 
 
 
 pered steel rod. 
 
 a 
 
 b 
 
 c 
 
 
 
 Small 
 
 Medium 
 
 Large 
 
 
 Rod, inches 
 
 18 
 
 24 
 
 36 
 
 
 Rectangular Base and Rod 
 
 $0.32 
 
 .42 
 
 .60 
 
 6692 
 
 SUPPORTS, RING OR RETORT, with Tripod Base and Rod. Of iron 
 
 1 , tripod japai 
 
 
 pered steel. 
 
 a 
 
 b 
 
 c 
 
 
 
 Small 
 
 Medium 
 
 Large 
 
 
 Rod, inches 
 
 18 
 
 24 
 
 36 
 
 
 With Tripod, each 
 
 $0.30 
 
 .42 
 
 .58 
 
 6694 
 
 SUPPORTS, RING OR RETORT with HARCOURT OPEN SIDE FILTER RINGS. 
 
 
 
 a 
 
 b 
 
 c 
 
 
 
 Small 
 
 Medium 
 
 Large 
 
 
 No. of Rings 
 
 2 
 
 3 
 
 4 
 
 
 Diameter of Rings, inches 
 
 2 & 3 
 
 2, 3 & 4 
 
 2, 3, 4 & : 
 
 
 Rectangular Base, Rod and Rings 
 
 $0.55 
 
 .75 
 
 .96 
 
 6695 
 
 SUPPORTS, RING OR RETORT, with HARCOURT OPEN SIDE FILTER RINGS. 
 
 
 
 a 
 
 b 
 
 c 
 
 
 
 Small 
 
 Medium 
 
 Large 
 
 
 No. of Rings 
 
 2 
 
 3 
 
 4 
 
 
 Diameter of Rings, inches 
 
 2 & 3 
 
 2, 3 & 4 
 
 2, 3, 4 & 
 
 
 Tripod Base, Rod and Rings 
 
 $0.52 
 
 .70 
 
 .90 
 
 6697 
 
 SUPPORTS, RING OR RETORT with RINGS. 
 
 
 
 
 
 a 
 
 b 
 
 c 
 
 
 
 Small 
 
 Medium 
 
 Large 
 
 
 No. of Rings 
 
 2 
 
 3 
 
 4 
 
 
 Diameter of Rings, inches 
 
 2 & 3 
 
 2, 3 & 4 
 
 2, 3, 4 & 
 
 
 Rectangular Base, Rod and Rings 
 
 $0.55 
 
 .75 
 
 .96 
 
 6699 
 
 SUPPORTS, RING OR RETORT WITH 
 
 RINGS. 
 
 
 
 
 
 a 
 
 b 
 
 c 
 
 
 
 Small 
 
 Medium 
 
 Large 
 
 
 No. of Rings 
 
 2 
 
 3 
 
 4 
 
 
 Diameter of Rings 
 
 2 & 3 
 
 2, 3 & 4 
 
 2, 3, 4 & 
 
 
 Tripod Base, Rod and Rings 
 
 $0.52 
 
 .70 
 
 .90 
 
 6701 THE HARCOURT LECTURE TABLE RING STAND AND ATTACHMENTS. 
 
 Consists of extra large Ring Stand with 4 Clamp Holders, Universal Clamp No. 4000, Condenser Clamp 
 No. 4006, Quick Acting Condenser Clamp No. 4013, 3 Harcourt Open Side Rings, 2, 3 and 4-inch, 
 
 Nos. 6460a to 6460c, 2 Harcourt Open Side Extension Rings, 3 and 4-inch, Nos. 6466b and 6466c, 
 and Platform Support. Complete Outfit.V. $4.35 
 
486 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6710 
 
 No. 6711 
 
 No. 6713 
 
 No. 6716 
 
 No. 6719 
 
 No. 6724 
 
 No. 6722 
 
 No. 6720 
 
 No. 6726 
 
 TEST TUBE SUPPORTS. Our test tube supports have this distinctive feature, — they will hold 
 tubes one inch in diameter. 
 
 6710 
 
 6711 
 6713 
 
 6716 
 
 6717 
 6719 
 
 6720 
 
 6722 
 
 6724 
 
 6726 
 
 6727 
 6736 
 
 SUPPORT, TEST TUBE, for 4 tubes, with 4 drying pins. $0.22 
 
 -, for 6 tubes with 6 drying pins.. . .26 
 
 SUPPORT, TEST TUBE, for 12 tubes with 12 drying pins; 10 holes are 1 %e-inch diameter, 2 holes 1^6 
 
 inches diameter, with drain groove. .42 
 
 SUPPORT, TEST TUBE, for 13 tubes with drying pins. .40 
 
 SUPPORT, TEST TUBE, for 25 tubes, with drying pins. .66 
 
 SUPPORT, KNOCKED DOWN TEST TUBE. This support occupies a very small compass when 
 packed for shipment. It is very readily assembled, offering a substantial support. For sixteen tubes 
 with drying pins. .60 
 
 ——, same as above, for 25 tubes, with drying pins. 86 
 
 SUPPORT, TEST TUBE AND FUNNEL, after Irish for 8 tubes; with drying pins; two adjustable 
 
 funnel supports. .76 
 
 SUPPORT, TEST TUBE, WIRE, galvanized iron 
 wire rack for 36 test tubes. 
 
 SUPPORT, TEST TUBE, for drying tubes, with 50 
 drying pins. 
 
 -, with 25 drying pins. 
 
 SYRINGE, HYPERDERMIC, 1 to 26 minims. The 
 
 distinctive feature of this syringe is that the bar¬ 
 rel is ground to fit the metal parts and the syringe 
 may be dissembled for cleaning. With two steel 
 needles in pasteboard box. 
 
 1.26 No. 6736 
 
CHEMISTRY AND BIOLOGY 
 
 487 
 
 Nos. 6795a-h 
 
 No. 6800 
 
 6802 
 
 No. 6804 
 
 No. 6806 
 
 5642 
 
 6795 
 
 6798 
 
 6800 
 
 6802 
 
 6804 
 
 TABLES, LOGARITHM, a heavy board card, X 9 Y% inches, with four place tables of logariths 
 and antilogariths, with table of atomic weights, also Factors for Analysis. Computed by Dr. Hu¬ 
 bert G. Shaw. This card is of convenient size for students’ use in the laboratory. Used extensively 
 
 and for years at the Massachusetts Institute of Technology.Each 
 
 TEST GLASSES, on foot, clear colorless glass. a b 
 
 Capacity, ounces 2 4 
 
 Each $0.40 .45 
 
 TEST TUBES, colorless glass tubes of special glass, resistant to changes in temperature. 
 
 a b c d e f g 
 
 Length, inches 4 4 5 5 6 6 6 
 
 Diameter, inches K 5 A Yt % fs % 1 
 
 Per Gross $1.90 2.10 2.26 2.40 2.60 2.76 4.25 
 
 TEST TUBES, FUSED SILICA. (See index, “Fused Silica Ware,” for characteristics.) These test 
 tubes are of great service in laboratory work, as they withstand high temperatures and can be cooled 
 rapidly without breakage. a b c d e f 
 
 Size, inches 4XH 5XH 5 X Y 6 X % 6 X M 7 X V& 
 
 Each $0.85 1.00 1.20 1.45 1.75 2.26 
 
 TEST TUBES, BOSTON BOARD OF HEALTH, without flange, heavy wall, 5 inches long X i^j-inch 
 
 diameter..Per Gross $3.70 
 
 TEST TUBES WITH SIDE NECKS. a b c 
 
 Length, inches 6 8 10 
 
 Each $0.10 .12 .30 
 
 TEST TUBES ON FOOT, colorless glass tubes on pedestal bases. 
 
 $0.35 
 
 h 
 
 8 
 
 1 
 
 5.00 
 
 Height, inches 
 Diameter, inches 
 Each 
 
 a 
 
 4 
 
 Vi 
 
 $0.06 
 
 b 
 
 5 
 
 X 
 
 .08 
 
 c 
 
 6 
 
 H 
 
 .10 
 
 d 
 
 8 
 
 1 
 
 .20 
 
 6806 TEST TUBES, GRADUATED. 
 
 a 
 
 b 
 
 c 
 
 Capacity, cc. 
 
 10 
 
 20 
 
 30 
 
 Graduated to cc. 
 
 X 
 
 X 
 
 X 
 
 Each 
 
 $0.44 
 
 .52 
 
 .66 
 
 6816 TEST TUBE BASKETS for sterilizing in bacteriological work. Each 
 
 TEST TUBE BRUSHES. See BRUSHES, TEST TUBE, Page 419. 
 TEST TUBE CLAMPS. See CLAMPS, TEST TUBE, Page 423. 
 TEST TUBE RACKS. See SUPPORTS, TEST TUBE, Page 486. 
 
 $0.50 
 
 pisssis::^ 
 
 IniM 
 
 No. 6815 
 
 THERMIT REACTION APPARATUS 
 
 When the thermit is ignited in one spot, the combustion so started continues throughout the entire 
 mass without supply of heat or power from the outside and produces superheated liquid steel 
 and superheated liquid slag, attaining a temperature of about 4881° F. in less than 30 seconds. 
 
 The advantage of such a compound in iron and steel welding is at once apparent. 
 
 In order that science instructors may demonstarte the properties of such a compound, we offer com¬ 
 bination equipments for showing a few fundamental experiments. 
 
 6819A Thermit Welding a Small Piece of Steel to a Steel Plate.Complete outfit $2.45 
 
 6819B Thermit Burning a Hole through a Steel Plate.Complete outfit 21.00 
 
 6819C Thermit Welding a Large Boss to a Steel Plate.Complete outfit 22.25 
 
 6819D Thermit Used in Pipe Welding.Complete outfit 35.00 
 
 6820 THERMIT COMBINATION OUTFIT. Includes all material and equipment necessary to perform all 
 
 four experiments above listed. Shipping weight 270 pounds.Complete outfit 66.00 
 
 6820A THERMIT COMBINATION OUTFIT. Includes all material and equipment necessary to perform 
 
 experiments of Nos. 6819A to 6819C. Shipping weight 230 pounds.Complete outfit 31.00 
 
 6821 THERMIT, black.Per Pound .50 
 
 6822 IGNITING MIXTURE (8 ounces smallest quantity sold). Per Pound 1.30 
 
 THERMOMETERS. See Pages 213 to 216. 
 
 THERMO-REGULATORS. See GAS REGULATORS, Page 446. 
 
 6966 THISTLE TUBES a b ' c 
 
 Length, inches 10 12 15 
 
 Each $0.08 .12 .15 
 
 6826 TIN FOIL, regular thickness.Per Pound 1.25 
 
488 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6834 
 
 TONGS, CRUCIBLE. See CRUCIBLE TONGS. 
 6830 TRAYS, GLASS (Photo Trays), crystal glass. 
 
 
 a 
 
 
 b 
 
 
 
 c 
 
 
 Size, inches 
 
 4 X 
 
 6 
 
 SA x &A 
 
 
 8 
 
 x io y 2 
 
 
 Each 
 
 $0.22 
 
 .27 
 
 
 
 .66 
 
 
 TRAYS, FUSED SILICA, rectangular. 
 
 (See index, 
 
 “Fused Silica Ware, 
 
 ” for characteristics.) 
 
 
 
 a 
 
 b 
 
 c d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 Length, outside, inches 
 
 6A 
 
 
 10 12 % 
 
 14 
 
 iSK 
 
 16X 
 
 16X 
 
 Width, outside, inches 
 
 3 3 A 
 
 2Vs 
 
 7 6 
 
 4% 
 
 9y 2 
 
 HH 
 
 13% 
 
 Depth, outside, inches 
 
 7 A 
 
 1 
 
 Vi IK 
 
 1 
 
 I'A 
 
 1A 
 
 IK 
 
 Each 
 
 $2.00 
 
 2.26 
 
 3.26 3.60 
 
 3.60 
 
 4.26 
 
 6.76 
 
 7.00 
 
 Nos. 6840a-c 
 
 6840 
 
 TRIANGLES, “PIPE STEM,” iron wire, covered with porcelain, raised centers. 
 
 
 a 
 
 b 
 
 c 
 
 
 Small 
 
 Medium 
 
 Large 
 
 Length of side, inside, inches 
 
 2A 
 
 3 
 
 3H 
 
 Each 
 
 $0.08 
 
 .08 
 
 .08 
 
 TRIANGLES, PLATINUM. See PLATINUM WARE, Page 473. 
 
 No. 6842 
 
 No. 6843 
 
 6842 TRIANGLES, FUSED SILICA (Silica Tubes on Iron Wire). (See index, “Fused Silica Ware,” for 
 
 characteristics.) Will outwear innumerable pipe-stem triangles. 
 
 a bcdefghi jk 
 
 Length, inches 1 A 1% 2 2 X 2A 2 % 3 3A 3A 3 A 4 
 
 Each $0.13 .13 .13 .16 .16 .20 .20 .26 .26 .30 .30 
 
 6843 TRIANGLES, FUSED SILICA (All Silica Tubes). (See index, “Fused Silica Ware,” for characteristics.) 
 
 a bcdefghi j 
 
 Length, inches 1A 1% 2 2A 2'A 2% 3 3A 3A 3 % 
 
 Each $0.76 .76 .76 .90 .90 1.00 1.00 1.00 1.16 1.16 1.26 
 
 M 
 
CHEMISTRY AND BIOLOGY 
 
 489 
 
 6850 
 
 6852 
 
 6865 
 
 6860 
 
 e 
 
 10 
 
 12 
 
 .86 
 
 Diameters given are outside meas- 
 
 6862 
 
 TRIPOD, japanned iron, 8 inches high. Inside diameter of ring 3% inches, with three legs .... $0.28 
 
 TRIPODS, japanned iron, 8 inches high. 
 
 a bed 
 
 Inside diameter, inches 3 6 8 
 
 Outside diameter, inches 5 6 8 10 
 
 Each $0.35 .45 .66 .70 
 
 TRIPODS, CONCENTRIC RINGS, japanned iron, 8 inches high, 
 urements of largest ring. 
 
 a b c d e 
 
 No. of Rings 2 3 4 5_ 6 
 
 Diameter, inches 5 6 8 10 12 
 
 Set $0.48 .64 .84 1.20 1.60 
 
 TROUGHS, PNEUMATIC, heavy gauge metal, each size with sliding shelf and overflow tube. 
 
 a be 
 
 Length, inches 9 12 14^ 
 
 Width, inches 6 x /i 9 8% 
 
 Depth, inches 3% 5 5 
 
 Each $1.30 1.60 2.20 
 
 TROUGH, PNEUMATIC, of porcelain. 1.16 
 
 6868 TUBING, FUSED SILICA COMBUSTION. (See index, “Fused Silica Ware,” for characteristics.) 
 
 Fused Silica Combustion Tubes are largely employed in electric resistance furnaces for the determina¬ 
 tion of carbon, oxygen, and sulphur in iron, steel and other non-volatile metals; for the determina¬ 
 tion of sulphur in pyrites cinder, and for the determination of carbon, hydrogen, halogens and sul¬ 
 phur in organic compounds. 
 
 The superior heat and chemical resisting properties of Fused Silica have led to the general adoption 
 of tubes of this material to replace glass, porcelain and platinum in combustion work. 
 
 6872 
 
 6873 
 6875 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 Bore, mm. 
 
 1-2 
 
 3 
 
 4-5 
 
 6-7 
 
 8 
 
 9-10 
 
 11 
 
 Thickness of Wall, mm. 
 
 .5-3 
 
 .5-2.5 
 
 .5-2 
 
 .5-2 
 
 .5-2 
 
 1-2 
 
 1-2 
 
 Price per Foot 
 
 $0.25 
 
 .45 
 
 .76 
 
 .90 
 
 1.10 
 
 1.60 
 
 1.40 
 
 Extra Price per tube for Closed End 
 
 $0.10 
 
 .15 
 
 .20 
 
 .20 
 
 .20 
 
 .25 
 
 .25 
 
 
 h 
 
 i 
 
 j 
 
 k 
 
 1 
 
 m 
 
 n 
 
 Bore, mm. 
 
 12-13 
 
 14 
 
 15-16 
 
 17-18 
 
 19 
 
 22 
 
 25 
 
 Thickness of Wall, mm. 
 
 1-2 
 
 1-2.5 
 
 1-2.5 
 
 1-2.5 
 
 1-3 
 
 1-3 
 
 1-3 
 
 Price per Foot 
 
 $1.60 
 
 1.60 
 
 1.76 
 
 1.90 
 
 2.10 
 
 2.30 
 
 2.50 
 
 Extra Price per Tube for Closed End $0.25 
 
 .35 
 
 .36 
 
 .60 
 
 .60 
 
 .65 
 
 .76 
 
 TUBES, ABSORPTION, Bunsen’s, graduated to 180 millimeters. $0.75 
 
 TUBES, ABSORPTION, Bunsen’s, with Bulb. Graduated to 170 millimeters 1.00 
 
 TUBES, ARSENIC, hard glass. a bed 
 
 $0.06 .06 .06 .06 
 
 .22 
 
 Set of Four 
 

 490 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 No. 6880 
 
 No. 6920 
 
 No. 6882 
 
 No. 6900 
 
 No. 6887 No. 6888 
 
 No. 6902 
 
 No. 6911 
 
 6880 
 
 6882 
 
 6884 
 
 6887 
 
 6888 
 
 6890 
 
 6896 
 
 6900 
 
 6902 
 
 TUBES, CALCIUM CHLORIDE, U-Shape, Plain. a b 
 
 Size, inches 3 X % 4 X % 
 
 Each $0.14 .16 
 
 TUBE, CALCIUM CHLORIDE, 6 inches long, designed’to lay flat on the table 
 
 and useful type. 
 
 TUBES, CALCIUM CHLORIDE, U-SHAPE, with side tubes. 
 
 Size, inches 
 Each 
 
 TUBES, CALCIUM CHLORIDE, straight with one bulb. 
 
 Size, inches 
 Each 
 
 TUBES, CALCIUM CHLORIDE, straight with two bulbs. 
 
 Size, inches 
 Each 
 
 TUBES, CALCIUM CHLORIDE, Marchard’s. a 
 Size, inches 4 X % 
 
 Each $0.25 
 
 TUBE, CHLORINE, after Newell’s “Descriptive Chemistry” (Experiment 23) 
 TUBES, CONNECTING, BRASS, for reducing from Vie to % 2 inch .... 
 
 5]X % 
 
 .18 
 
 A most 
 
 d 
 
 6XM 
 
 .20 
 
 convenient 
 
 a 
 
 b 
 
 c 
 
 4 X M 
 
 6 XlH 
 
 8XM 
 
 $0.26 
 
 .32 
 
 .60 
 
 a 
 
 b 
 
 c 
 
 4X K 
 
 6X% 
 
 8 XH 
 
 $0.10 
 
 .14 
 
 .16 
 
 a 
 
 b 
 
 c 
 
 Small 
 
 Medium 
 
 Large 
 
 4 X H 
 
 6XH 
 
 8 XH 
 
 $0.10 
 
 .16 
 
 .18 
 
 b 
 
 
 
 6XH 
 
 
 
 .33 
 
 
 
 $0.48 
 
 $0.77 
 
 .16 
 
 
 Diameter, inch 
 
 % 
 
 X 
 
 X 
 
 
 
 Each 
 
 $0.27 
 
 .32 
 
 .40 
 
 
 6904 
 
 TUBES, CONNECTING, BRASS, Y Shape. 
 
 a 
 
 b 
 
 c 
 
 
 
 Diameter, inch 
 
 % 
 
 Vs 
 
 X 
 
 
 
 Each 
 
 $0.27 
 
 .32 
 
 .40 
 
 
 6906 
 
 TUBES, CONNECTING, GLASS, T Shape. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 
 Diameter, inch 
 
 M 
 
 % 
 
 X 
 
 X 
 
 
 Each 
 
 $0.08 
 
 .10 
 
 .13 
 
 .16 
 
 6908 
 
 TUBES, CONNECTING, GLASS, Y Shape. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 
 Diameter, inch 
 
 x 
 
 X 
 
 X 
 
 X 
 
 
 Each 
 
 $0.08 
 
 .10 
 
 .13 
 
 .16 
 
 6910 
 
 TUBE, CONNECTING, LEAD, Y Shape, Xi inch 
 
 
 
 
 
 6911 
 
 TUBE, CONNECTING, WHITE METAL, Y Shape, for V 8 -mch rubber tubing 
 
 
 
 6920 
 
 TUBES, CULTURE, of medium heavy glass, round bottom, 
 
 no lip. 
 
 
 
 
 
 a 
 
 b 
 
 c 
 
 
 
 Size, inches 
 
 4 xy 2 
 
 5 xYi 
 
 6X 3 A 
 
 
 
 Per Dozen 
 
 $0.24 
 
 .32 
 
 .40 
 
 
 $ 0.22 
 
 .26 
 
 TUBES, DISTILLING, see DISTILLING TUBES, Page 436. 
 
CHEMISTRY AND BIOLOGY 
 
 491 
 
 No. 6925 
 
 No. 6923 
 
 Nos. 6935a-c 
 
 No. 6966 No. 6962 No. 6960 No. 6960 
 
 6923 TUBE, FERMENTATION, with graduated test tube. (Dr. Einhorn’s Saccharometer.) 
 
 With directions .$0.75 
 
 6926 TUBES, FERMENTATION, ungraduated, on foot. 
 
 6620 
 
 Length, inches 
 Diameter, inch 
 Each 
 
 Diameter of Top, mm. 
 
 Each 
 
 TUBES, GAS, for collecting gases over mercury. 
 Capacity, cc. 
 
 Subdivided, cc. 
 
 Each 
 
 6935 TUBES, IGNITION, ordinary hard glass. 
 Length, inches 
 Diameter, inch 
 Each 
 
 Length, inches 
 Diameter, inch 
 Each 
 
 6945 TUBES, NESSLER’S, for ammonia tests in water analyses; of colorless glass. 
 
 a be 
 
 Graduated, cc. 50 100 50 & 100 
 
 Each $0.65 .80 .96 
 
 6960 TUBE, SAFETY, thistle top, one bulb in bend, length 12 inches. $0.17 
 
 6952 TUBE, SAFETY, thistle top, bend in stem. Length 12 inches. .22 
 
 TUBES, SPECIMEN. See VIALS, Page 492. 
 
 6965 TUBES, THISTLE. a b c 
 
 Length, inches 10 12 15 
 
 Each $0.08 .12 .15 
 
 6960 TUBE, VINEGAR, Massachusetts Board of Health, for determining the percentage of alcohol 
 
 a 
 
 b 
 
 
 SH 
 
 6 X 
 
 
 X 
 
 X 
 
 
 $0.27 
 
 .33 
 
 
 :ms ground to a point. 
 
 
 
 a 
 
 b 
 
 c 
 
 25 
 
 30 
 
 35 
 
 $0.24 
 
 .56 
 
 .64 
 
 y. a 
 
 b 
 
 
 50 
 
 100 
 
 
 X 
 
 X 
 
 
 $1.45 
 
 1.80 
 
 
 a 
 
 b 
 
 c 
 
 4 
 
 6 
 
 8 
 
 X 
 
 X 
 
 1 
 
 $0.05 
 
 .07 
 
 .14 
 
 glass, best for generating oxygen. 
 
 
 a 
 
 b 
 
 c 
 
 4 
 
 6 
 
 8 
 
 X 
 
 X 
 
 1 
 
 $0.12 
 
 .16 
 
 .32 
 
 No. 5620b 
 
 No. 6945 
 
 $0.45 
 
 Nos. 6970 and 6971 
 
 6970 TUBING, GLASS, best quality, free from lead, especially adapted for glass blowing and bending, usual 
 
 wall for chemical laboratory purposes. The following sizes are carried in stock, — 4, 5, 534, 6, 6J4. 7, 
 
 8, 9, 10, 12, 15, 18, 20, 22, and 25 millimeters outside diameters.Per Pound $0.54 
 
 6971 TUBING, GLASS, same as above in quality, but larger in diameter. The following sizes are carried 
 
 in stock, — 30, 35 and 40 millimeters outside diameter.Per Pound .66 
 
 Note. — In ordering Glass Tubing, always specify the diameter desired. 
 
 6973 TUBING, GLASS CAPILLARY, outside diameter 6-7millimeters, bore 1 and IK millimeters. (In 
 
 ordering specify bore desired.)...Per Pound .76 
 
 6976 TUBING, GLASS BAROMETER, outside diameter 8-9 millimeters, bore 3 millimeters Per Pound .76 
 
492 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 
 
 
 Nos. 6977 to 6979 
 
 6977 TUBING, ALUNDUM (See Index, “Alundum Ware,” for characteristics). Length 12 inches. 
 
 6978 
 
 6979 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 Bore, inch 
 
 34 
 
 
 H 
 
 1 
 
 Wall, inch 
 
 Vs 
 
 Vs 
 
 Vs 
 
 Vs 
 
 Each 
 
 $2.26 
 
 2.25 
 
 2.35 
 
 2.60 
 
 —, length 18 inches. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 Bore, inch 
 
 
 % 
 
 V* 
 
 1 
 
 Wall, inch 
 
 Vs 
 
 Vs 
 
 Vs 
 
 Vs 
 
 Each 
 
 $3.60 
 
 3.60 
 
 3.76 
 
 3.90 
 
 —, length 24 inches. 
 
 a 
 
 b 
 
 c 
 
 d 
 
 Bore, inch 
 
 Vi 
 
 
 H 
 
 1 
 
 Thickness, inch 
 
 Vs 
 
 Vs 
 
 Vs 
 
 Vs 
 
 Each 
 
 $6.00 
 
 5.00 
 
 5.20 
 
 5.35 
 
 Note. — Alundum Tubes up to 10-inch bore by )4-inch wall can be obtained. Prices on application. 
 A charge of 10 per cent, additional to above prices will be made for closing one end of the tube. 
 
 6982 
 
 TUBING, GLASS COMBUSTION, of hard glass, melting point 800° C. Outside diameter 8, 10, 13, 19 
 and 25 millimeters. (In ordering specify sizes desired).Per Pound 
 
 $1.35 
 
 6984 
 
 6990 
 
 TUBING, PORCELAIN COMBUSTION. Glazed inside and outside. Will stand a temperature of 
 1800 degrees Fahrenheit and is practically gas tight. In 24-inch lengths. 
 
 a b c d e f 
 
 Diameter, inch Z A % % 1 1 V 1)4 
 
 Per length $1.80 2.20 2.50 3.00 3.60 4.20 
 
 TUkERIC PAPER.Per Sheet 
 
 Per Quire 
 
 $0.04 
 
 .66 
 
 
 No. 7076 
 
 Nos. 7080a-f 
 
 7075 
 
 VASCULUM OR COLLECTING CASE, of metal, with leather shoulder straps. Size 18 X 6)4 X 4)4 
 inches . 
 
 7080 
 
 Capacity, drams 
 Height, mm. 
 Diameter, mm. 
 Per Dozen 
 
 tit wall, 
 
 for use with corks. 
 
 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 f 
 
 1 
 
 2 
 
 3 
 
 4 
 
 6 
 
 8 
 
 45 
 
 55 
 
 60 
 
 65 
 
 70 
 
 75 
 
 15 
 
 17 
 
 19 
 
 21 
 
 23 
 
 25 
 
 $0.12 
 
 .15 
 
 .18 
 
 .20 
 
 .30 
 
 .40 
 
 $1.75 
 
CHEMISTRY AND BIOLOGY 
 
 493 
 
 7085 
 
 7090 
 
 7095 
 
 7100 
 
 VISCOSIMETER, SCOTT’S, for determining the viscosity of oils, etc. 
 paring very favorably with those of much higher price. 
 
 A reliable instrument com- 
 
 .$14.25 
 
 VISES for laboratory use, 
 
 with hardened anvil and jaws. 
 
 a 
 
 b 
 
 Length of Jaw, inches 
 
 m 
 
 2 
 
 Jaws open, inches 
 
 2 
 
 2V 2 
 
 Dimensions of Anvil 
 
 H X 1 
 
 1 x 1H 
 
 Each 
 
 $0.66 
 
 .95 
 
 VOLUMETRIC FLASK. See FLASKS, VOLUMETRIC. 
 WARMING TABLE. See Page 466. 
 
 WASHING BOTTLES. See BOTTLES, Page 418. 
 
 WATCH GLASSES, thin and well annealed. 
 
 a be 
 
 Diameter, inches 1 2 
 
 Per Dozen $0.18 .20 .26 
 
 d e 
 
 2 a 3 
 
 .48 .54 
 
 f g 
 
 3'A 4 
 
 .76 .88 
 
 h i 
 
 5 6 
 
 1.50 2.60 
 
 WATCH GLASSES, SYRACUSE, designed so that one may be placed above another; outside diam¬ 
 eter 70 mm., inside diameter 53 mm.Per Dozen $0.60 
 
 7110 WATCH SPRINGS 
 
 Per Dozen .20 
 
 7116 WAX, SEALING, in sticks 
 
 Per Pound .44 
 
 7120 WAX TAPERS .Per Box $0.10 
 
 WEIGHTS. See pages 58 to 63. 
 
 WICKS for Alcohol Lamps. See Page 462. 
 
 WIRE, all kinds. See pages 311 to 313. 
 
 WIRE GAUZE. See page 446. 
 
 60-80 WATER HEATER WITH BURNER. Will heat water to 
 boiling point in three minutes. Consists of a solid flame 
 burner on which is placed the water heater. This heater 
 consists of a coil of copper tubing encased in a finished 
 metal casting. The cold water enters this heating tube 
 and by regulating flow of water and height of flame, the 
 issuing water may be obtained either boiling, hot, warm 
 or cold. Total height 9 inches. With Burner, complete $9.50 
 
 60-81 WATER HEATER only, same as above but without burner 6.60 
 
 WATER HEATER, ELECTRIC. See ELECTRIC APPLI¬ 
 ANCES, Page 436. 
 
 No. 60-80 
 
494 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 ALUNDUM WARE 
 
 Alundum is fused aluminum oxide. When bonded with ceramic materials and given proper heat treatment, 
 refractory articles can be obtained that have many desirable properties. Pure alundum, which is more than 99 per 
 cent, aluminum oxide, melts at 2050° C. and the bonded shapes at temperatures somewhat less than this depending 
 on the character of the mixtures. 
 
 Alundum is a very inert substance and the bonded articles are not readily attacked by chemically active solu¬ 
 tions. 
 
 Alundum is a poor conductor of electricity and is, therefore, particularly valuable in electrical constructions. 
 
 PROPERTIES. 
 
 Coefficient of Expansion — 0.0000071 per degree C. 
 
 Specific Electrical Resistance. 
 
 130 megohms at 528° Centigrade 
 
 16 
 
 <C 
 
 “ 730° 
 
 U 
 
 5.3 
 
 U 
 
 “ 892° 
 
 a 
 
 1.8 
 
 it 
 
 “ 1020° 
 
 tt 
 
 Porosity: — Three mixtures may be obtained, — 36 .9 per cent., 40.7 per cent, and 47.4 per cent. We carry in 
 stock mixtures of 40.7 per cent, porosity. 
 
 Filter Cones have special mixtures and may be specified as dense, medium or coarse. We carry in stock a mix¬ 
 ture giving the medium porosity. 
 
 All Filter Discs have a porosity of 43.9 per cent. 
 
 Alundum articles listed in this catalogue are carried in stock for immediate shipment. Muffles, other articles, 
 and special pieces can be obtained. We should be most pleased to correspond regarding special needs. 
 
 “PYREX” GLASSWARE 
 
 “PYREX” Glassware was recently developed in this country and holds promise of still greater extensive use 
 than at present. 
 
 1. It contains no heavy metals nor metals of the magnesium — lime — zinc group. 
 
 2. Under numerous tests for determining stability in comparison with best other glasses “Pyrex” Glassware 
 
 has proved greatly superior. 
 
 3. “Pyrex” Glassware does not commence to soften below 800° C. and a rod heated to 300° C. and then 
 
 plunged into cold water will not break. 
 
 4. Its chief characteristic is that of thick walls, a construction made possible by the very low expansion 
 
 coefficient of 0.0000032 (porcelain has an expansion coefficient of 0.0000036). This characteristic greatly 
 increases the durability of the vessels without diminishing the resistance to sudden heating and cooling. 
 
 Our stock of “PYREX” Glassware as listed through this catalogue is complete. We offer it as resistance ware 
 well comparable with Jena Glassware that cannot now be obtained. 
 
 FUSED SILICA WARE 
 
 The unusual properties of Pure Fused Silica Ware make it suitable for most analyses where platinum has here¬ 
 tofore been necessary. These properties are: 
 
 1. Its melting point is above 1500° C. 
 
 2. Its coefficient of expansion is extremely small being .00000059, which is about VL 7 th that of glass. Crucibles 
 
 or other dishes may be heated to red heat and then plunged into cold water without cracking or breaking. 
 
 3. It is not attacked by acids. 
 
 4. It is absolutely constant in weight. 
 
 5. It is insoluble in water. 
 
 On account of the increased cost of platinum the various laboratory vessels and utensils listed in this catalogue 
 may profitably receive the careful consideration of every chemist. 
 
CHEMISTRY AND BIOLOGY 
 
 495 
 
 ROYAL WORCESTER PORCELAIN WARE 
 
 Royal Worcester Porcelain Ware has been most carefully tested to ascertain its suitability for laboratory use 
 in comparison with similar ware so readily obtained before the European War. 
 
 The National Physical Laboratory of Teddington, England, has directed tests to ascertain 
 
 1. The Effect of Chemical Reagents. 
 
 2. The Behavior of the Glaze at High Temperatures. 
 
 3. Constancy of the Weight of the Ware. 
 
 4. Resistance to Sudden Changes of Temperature. 
 
 1. THE EFFECT OF CHEMICAL REAGENTS. 
 
 (a) Strong Sulphuric Acid. 
 
 After a four-hour test the acid acting on 209 square centimeters a dish gained 0.0016 gram,— (a gain 
 of 0.0008 gram per 100 square centimeters. 
 
 (b) 10 per cent. Solution Caustic Soda at 90°-100° C. (Concentration of solution by evaporation prevented 
 by conducting the experiment in a closed oven.) 
 
 After a four-hour test, the caustic soda solution acting on 209 square centimeters, a dish lost in weight 
 -0.0308 gram, — a loss of 0.0147 gram per 100 square centimeters. 
 
 (c) 10 per cent. Solution Sodium Carbonate at 90°-100° C. (Concentration of the solution by evaporation 
 prevented by conducting the experiment in a closed oven.) 
 
 After a four-hour test, the sodium carbonate acting on 209 square centimeters, a dish lost in weight 
 -0.0018 gram, — a loss of 0.0009 gram per 100 square centimeters. 
 
 2. BEHAVIOR OF THE GLAZE AT HIGH TEMPERATURES. 
 
 (a) A few broken pieces of Royal Worcester Porcelain were placed in a Royal Worcester Porcelain Dish 
 and heated for four hours in a large gas muffle the temperature of which was kept constant at 1000° C. 
 
 Fragments of porcelain adhered to the dish but were readily removed by slight pressure of the fingers, 
 but the glaze of the dish was but slightly affected. The dish was not at all discolored and the brightness of 
 the glaze was not appreciably dimmed. 
 
 3. CONSTANCY OF THE WEIGHT. 
 
 (a) A dish weighing 22 grams was first gently heated, cooled and weighed. It was then heated for one and 
 one-half hours in a muffle at a temperature of 850° C. 
 
 After cooling the dish showed a loss of but 0.0002 gram. 
 
 4. RESISTANCE TO SUDDEN CHANGES OF TEMPERATURE. 
 
 * • 
 
 (a) A dish was first filled with wax which was melted and heated gradually to a temperature of 160° C. It 
 was then allowed to cool to 150° C. to secure that the temperature of the dish was equal to that of the wax. 
 
 The dish, when plunged with contents into water at 15°, remained unbroken. 
 
 This treatment was continued in a similar way at successively higher temperatures up to 230° C., the 
 dish remaining intact. 
 
 (b) A dish was heated in a muffle at a temperature of 850° C. It was then removed with a thick pair of cold 
 iron tongs and placed on a cold stone bench to cool. 
 
 . No cracking or chipping even of the glaze was observed. 
 
 As a result of these tests, we ordered a sample line of this ware and have had it tested by men of the 
 highest reputation in this country. Their reports enable us to recommend this ware, confident that it in every 
 way meets the most exacting demands of Chemists. 
 
496 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 NATIONAL LOOSE-LEAF NOTE-BOOKS 
 
 BIOLOGY — CHEMISTRY 
 
 By Arthur S. Dewing, Ph.D. 
 
 The effort has been to prepare these laboratory instructions in a manner to give students only such assistance 
 as will enable them to observe and think for themselves. The author has avoided most carefully the “Verification 
 Method” of teaching science by which the student is told exactly what he is to find or what conclusion to draw. The 
 pupil is guided right to follow an individual channel in constructive observation and from a suggested sequence of 
 thought learns to observe accurately and think clearly. 
 
 The Loose-leaf System has long been recognized as one that affords the greatest latitude for choice and one that 
 is best adapted to individual requirements. A teacher is enabled to select from a series of experiments greater than 
 required, the experiments adapted particularly to individual conditions. One may select a series adapted to meet 
 State requirements, local educational requirements, etc., etc. We have endeavored to keep in file courses of labora¬ 
 tory instruction satisfactorily meeting in actual use the many requirements. We should be pleased, therefore, to 
 send, upon request, a note-book containing a series of direction sheets in Chemistry, Biology or Physics (See page 
 27) outlining a course found entirely adequate in meeting similar requirements. Such service is entirely gratis. 
 
 NATIONAL BIOLOGY DIRECTION SHEETS 
 
 This series covers Botany, Zoology and Physiology, 118 sheets. A number of these direction sheets are in 
 the nature of introductory exercises concerning the general nature of organisms and their simple chemical processes 
 and they should, when possible, precede the work in any of the special exercises. Larger amounts of matter are 
 given in every case than can ordinarily be undertaken, the author believing that a variety of conditions requires a 
 variety of methods and subjects. 
 
 A FEW NOTES AND COMMENTS 
 
 Wallace, Idaho, Independent School District No. 8. 
 
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 A FEW NOTES AND COMMENTS 
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CHEMISTRY AND BIOLOGY 
 
 497 
 
 LIQUID STAINS AND REAGENTS 
 
 Aniline Water . 
 
 Bismarck Brown, aqueous solution (Weigert). 
 
 Bismarck Brown, alcoholic solution. 
 
 Carmine Alcohol (P. Mayer). 
 
 Carmine Alum (Grenacher). 
 
 Carmine Ammonia (Gerlach’s). 
 
 Carmine Borax (Grenacher). 
 
 Carbol Fuchsin (Ziehl’s). 
 
 Carbol Gentian Violet (Oppenheim Sach’s). 
 
 Carmalum (P. Mayer). 
 
 Chenzinsky — Plehn’s Stain (Eosin and Methylene Blue) . 
 
 Congo Red (indicator). 
 
 Corallin Soda Solution (Strassburger). 
 
 Eosin in Ethylic Alcohol. 
 
 Eosin in Methylic Alcohol . . .. 
 
 Ehrlich’s Acid Haematoxylin. 
 
 Ehrlich’s Diazo Reaction No. 1. 
 
 Ehrlich’s Diazo Reaction No. 2. 
 
 Esbach’s Reagent . •.. . . 
 
 Fehling’s Reagent No. 1 and No. 2 (Copper and Alkali) . . 
 
 Fuchsin basic in Ethylic Alcohol. 
 
 Fuchsin Acid in Ethylic Alcohol. 
 
 Fuchsin, basic aqueous solution. 
 
 Gentian Violet Amline Water (Gram’s). 
 
 Gabbett’s Stain (Methylene Blue Sulphuric Acid) . . . . 
 
 Gabbett’s Stain (Carbol Fuchsin). 
 
 Giemsa Stain for Malaria. . ... . 
 
 Giemsa Stain for Spirochaeta. 
 
 Gunzberg Solution. 
 
 Haematoxylin (Delafield’s). 
 
 Haematoxylin Iron (Heidenhain’s). 
 
 Haematoxylin Lithium Carbonate, one solution (Weigert) . . 
 
 Hayem’s Solution for Blood. 
 
 Haines’ Solution for Sugar in Urine. 
 
 Jenner Stain. 
 
 Leischman Stain ... 
 
 Lugol’s or Gram’s Iodine Solution. 
 
 Methylene Blue Alkaline (Loeffler). 
 
 Methylene Blue Borax (Unna). 
 
 Methylene Blue, aqueous solution. 
 
 Methylene Blue, Ethylic Alcohol Solution. 
 
 Methylene Blue Polychrome (Unna). 
 
 Meyer’s Albumen Fixative. 
 
 Obermeyer’s Reagent. 
 
 Purdy’s Reagent (for sugar) . 
 
 Piero Carmin (Ranvier). 
 
 Phenolphthalein (Indicator) . 
 
 Uffelman’s Reagent (Milk Sugar in Stomach Contents) . . . 
 
 Toepf^r Solution. 
 
 Toison Solution. 
 
 Weigert Stain (Borax Potassium Cyanide Solution) . . . . 
 
 Weigert Stain (Fuchsin Solution). 
 
 Wright Stain (Blood Stain). 
 
 DRY STAINS 
 
 Azur1 . 
 
 Azur 11 . . . . 
 
 Azur 11 Eosine . 
 Congo Red .. . . 
 
 Eosine. 
 
 Fuchsin Basic 
 Gentian Violet . . 
 Malachite Green 
 Methylene Blue . 
 Methyl Violet . . 
 Primuline . . . 
 
 Per 
 
 Per 
 
 Per 
 
 25 cc. 
 
 100 cc. 
 
 Pound 
 
 $0.30 
 
 $0.50 
 
 
 .25 
 
 .60 
 
 
 .35 
 
 .76 
 
 
 .56 
 
 1.35 
 
 
 .60 
 
 1.25 
 
 
 .35 
 
 .76 
 
 
 .45 
 
 1.10 
 
 
 .60 
 
 1.25 
 
 
 .50 
 
 1.25 
 
 
 .36 
 
 .75 
 
 
 .50 
 
 .95 
 
 
 .35 
 
 .90 
 
 
 .60 
 
 1.60 
 
 
 .55 
 
 1.20 
 
 
 .76 
 
 1.66 
 
 
 1.00 
 
 1.80 
 
 
 .60 
 
 1.60 
 
 
 .60 
 
 1.60 
 
 
 
 .60 
 
 
 .55 
 
 1.00 
 
 
 .55 
 
 1.00 
 
 
 .55 
 
 1.00 
 
 
 .55 
 
 1.00 
 
 
 .65 
 
 1.00 
 
 
 .60 
 
 1.00 
 
 
 .50 
 
 1.25 
 
 
 .60 
 
 1.35 
 
 
 1.25 
 
 4.00 
 
 
 2.00 
 
 6.00 
 
 
 .60 
 
 1.60 
 
 
 .60 
 
 1.35 
 
 
 .60 
 
 1.35 
 
 
 .60 
 
 .75 
 
 $2.00 
 
 .55 
 
 1.66 
 
 
 .65 
 
 1.80 
 
 
 .50 
 
 .90 
 
 
 .60 
 
 1.60 
 
 
 .60 
 
 1.05 
 
 
 .50 
 
 .90 
 
 
 .90 
 
 1.95 
 
 
 .90 
 
 1.80 
 
 
 .60 
 
 
 
 .60 
 
 .90 
 
 2.00 
 
 .60 
 
 1.65 
 
 
 .76 
 
 
 
 .60 
 
 1.60 
 
 
 .50 
 
 1.00 
 
 
 .60 
 
 1.00 
 
 
 .76 
 
 1.60 
 
 
 .60 
 
 1.20 
 
 
 .60 
 
 1.95 
 
 
 Per 
 
 Per 
 
 Per 
 
 Gram 
 
 $4.50 
 
 10 Grams 
 
 Ounce 
 
 3.00 
 
 
 
 3.76 
 
 $2.60 
 
 $4.00 
 
 
 2.60 
 
 4.00 
 
 
 2.60 
 
 4.00 
 
 
 4.00 
 
 
 
 2.60 
 
 4.00 
 
 
 2.50 
 
 4.00 
 
 
 2.50 
 
 4.00 
 
 
 2.50 
 
 4.00 
 
498 
 
 L. E. KNOTT APPARATUS CO., BOSTON 
 
 INDEX 
 
 A 
 
 PAGE 
 
 PAGE 
 
 PAGE 
 
 Abbe Camera Lucidae.460 
 
 Abbe Condensers .459 
 
 Absorption Apparatus, Hydrogen, 
 
 Hall .403 
 
 Absorption Screen .206 
 
 Absorption Troughs.272 
 
 Absorption Tubes.489 
 
 Acceleration Apparatus ... 101-106 
 
 Acceleration Apparatus, Inclined 
 
 Wire .103 
 
 Acetylene Gas Bunsen Burner . . 200 
 
 Achromatic Lenses.259 
 
 Achromatic Objectives .... 458, 459 
 Achromatic Prisms . . 261, 262, 271 
 
 Acid Bottle .415 
 
 Acid Brush.419 
 
 Acid Burettes .468 
 
 Acid Dish.430 
 
 Acid Funnel .468 
 
 Acid Measures .468 
 
 Acid Pipettes.468 
 
 Acid Pump.474 
 
 Acme Water Still.210 
 
 Acoustic Reaction Wheel .... 197 
 
 Action and Reaction Apparatus . 87-90 
 
 Action and Reaction Apparatus, Hall 141 
 Action and Reaction Strip, Hall 141 
 
 Adhesion Disc . 73 
 
 Adjustable Resonator and Bell . . 197 
 
 Adjustable Spark Gaps .383 
 
 Agateware Casseroles .421 
 
 Agateware Dishes.430 
 
 Air Condensers.388 
 
 Air Impulse Attachment. 82 
 
 Air Pump Plates .151 
 
 Air Pumps.149-153 
 
 Air Storage Tanks.153 
 
 Air Testers.406 
 
 Air Thermometer Bulb.218 
 
 Air Thermometers .217, 218 
 
 Alcohol Burners .201 
 
 Alcohol Lamps .452 
 
 Alcoholometers .448 
 
 Alcohol, Solid .406 
 
 Alcohol Stoves .202 
 
 Alkaline Tablets, Farrington’s . . 468 
 
 Alternating Current Demonstration 
 
 Apparatus. 376, 399 
 
 Alternating Current Meters .... 353 
 
 Aluminum Beakers .413 
 
 Aluminum Block .129 
 
 Aluminum Cylinder.129 
 
 Aluminum Leaf.293 
 
 Aluminum Leaf Cutting Apparatus 293 
 
 Aluminum Milk Dishes .432 
 
 Aluminum Shot.229 
 
 Alundum.406 
 
 Alundum Capsules.421 
 
 Alundum Cement.406 
 
 Alundum Combustion Boats . . . 425 
 
 Alundum Combustion Boat Shields 425 
 
 Alundum Crucibles.427 
 
 Alundum Extraction Thimbles . . 436 
 
 Alundum Filter Cones.437 
 
 Alundum Filter Crucible.428 
 
 Alundum Filter Dishes.432 
 
 Alundum Incinerating Dishes . . . 432 
 
 Alundum Pyrometer Tubes .... 475 
 
 Alundum Tubing .492 
 
 Alundum Ware.494 
 
 Amber Specimen .289 
 
 Amici’s Direct Vision Prisms . . . 261 
 
 Ammeters . 350-353 
 
 Ammonium Hydroxide .403 
 
 Ampere’s Frame.328 
 
 Ampere’s Law Apparatus . . . 327, 328 
 
 Ampere’s Law Stand .327 
 
 Amyl-Acetate.246 
 
 Analytical Balances.46^18 
 
 Andrews Plate Base. 12 
 
 Anemometers.168 
 
 Aneroid Barometers.161, 162 
 
 Anglegraph. 43 
 
 Animal Parchment .156 
 
 Anode, Platinum .473 
 
 Anodes, Copper, Nickel, Silver . . 403 
 
 Antimony Rubber Stoppers . . . 478 
 
 Antimony Rubber Tubing .... 477 
 
 Anvil Vise Attachment, T-Beam . 26 
 
 Anvil Vise, T-Beam. 26 
 
 Apparatus A .203 
 
 Applied Physics Apparatus . 121-127 
 
 Apron .406 
 
 Aquaria .406 
 
 Aquaria Jars.406 
 
 Aquarium Table.406 
 
 Aquarium Tank .406 
 
 Arago’s Magnetic Rotation Appa¬ 
 ratus . 83 
 
 Archimedes’ Principle .128 
 
 Arch Model.126 
 
 Arc Lamp, Demonstration . . 159, 404 
 
 Armatures, Iron, T. & H.279 
 
 Arsenic Tubes. 407, 489 
 
 Artificial Light Circuit.312 
 
 Asbestos.407 
 
 Asbestos Boards.407 
 
 Asbestos Chimney.240 
 
 Asbestos Gauze.446 
 
 Asbestos Wool.407 
 
 Aspirator Bottle.415 
 
 Aspirators. 153, 407 
 
 Astatic Galvanometer.334 
 
 Astatic Needle.285 
 
 Astronomical Telescope Model . . . 266 
 
 Astronomical Telescopes . . . 264-266 
 
 Atomic Weight Chart.422 
 
 Attachment, Burette.419 
 
 Attachment Clamps, T-Beam ... 26 
 
 Attachments, Burner.420 
 
 Atwood’s Attachment for Accelera¬ 
 tion .103 
 
 Augur Bits.405 
 
 Automatic Microtomes .... 464, 465 
 Automatic Overflow Pipettes . . . 472 
 
 Automatic Pipettes .468 
 
 Automatic Zero Burette.419 
 
 Auxanometers.408 
 
 Avoirdupois Weights. 61 
 
 B 
 
 Babcock Milk Testers .... 467, 468 
 
 Babcock Test Bottles.468 
 
 Bag, Ice.204 
 
 Bags, Rubber for Gas.445 
 
 Balance Cradle Attachment, T-Beam 26 
 
 Balance Cradles. 57 
 
 Balance, Inertia. 93 
 
 Balance Level. 44 
 
 Balances and Weights.45-63 
 
 Balance Support. 20 
 
 Balance Wheel, Demonstration . . 66 
 
 Balancing Columns Apparatus . . 130 
 
 Balancing Columns Tube, M. G. & 
 
 B.155 
 
 Ball and Ring.223 
 
 Ballistic Coil.343 
 
 Ball Race.301 
 
 Balls, all kinds. 86 
 
 Balsam Bottles.415 
 
 Barker’s Mill.143 
 
 Bar Magnets.278 
 
 Barograph.162 
 
 Barograph Charts.162 
 
 Barometer Apparatus .148 
 
 Barometer Mounting Board .... 160 
 
 Barometers.160-162 
 
 Barometer Tubes.148 
 
 Barometer Tubing.491 
 
 Baroscope Balance.144 
 
 Baroscope Bell Glass.145 
 
 Baroscope Bottle.145 
 
 Baroscopes.144, 145 
 
 Baro-Thermo Recorder.165 
 
 Baro-Thermo Recorder Charts . . . 165 
 
 Bar, Soft Iron.279 
 
 Bases.11, 12 
 
 Basic Clamps, T-Beam .... 25, 26 
 
 Baths, all kinds. 409-411 
 
 Batteries. 320-325 
 
 Batteries, Leyden Jar.303 
 
 Batteries, Thermo-Electric .... 220 
 
 Batteries, Water. 297, 324 
 
 Battery Call Telephone.401 
 
 Battery Connectors . . . 312, 313, 326 
 
 Battery Elements. 320-325 
 
 Battery Jars . .. 326, 451 
 
 Battery Rheostat and Switch . . . 316 
 
 Battery Stands. 320, 321 
 
 Beads, Glass. 229, 411, 446 
 
 Beaker Brush. 419 
 
 Beakers, all kinds .... 204, 412, 413 
 
 Beckmann's Differential Thermome¬ 
 
 ters .216 
 
 Bed Clamp for Motor Generator, T. 
 
 & H.390 
 
 Beehive Shelves.445 
 
 Beetz Electroscope.302 
 
 Bell and Adjustable Resonator . . 197 
 
 Bell Chimes. 300, 301 
 
 Bell, Electric, Mounted.158 
 
 Bell Glasses, all kinds.154 
 
 Bell Glass with Sliding Rod .... 158 
 
 Bell in Stirrup.158 
 
 Bell in Vacuo Apparatus . . . 144, 158 
 
 Bellows. 202, 414 
 
 Bells, Electric.319 
 
 Belting, Leather, Round. 21 
 
 Bench Vise Clamp. 90 
 
 Bending Beam Apparatus. 94 
 
 Bennett's Electroscope.294 
 
 Bent Arm Lever and Supporting 
 
 Table.127 
 
 Bent Wire, Mounted.248 
 
 Bent Wire with Insulating Handle 
 
 and Binding Post.284 
 
 Bent Wire with Weighted Support 
 
 and Binding Post.284 
 
 Beveled Glass Tube, T. & H. 209 
 
 Bezold’s Tuning Fork.180 
 
 Bibbs, Demonstration.144 
 
 Bichromate Potassium Tablets. . . 468 
 
 Bi-filar Pendulum.105 
 
 Binding Posts.314, 315 
 
 Binocular Microscopes.457 
 
 Biology Direction Sheets.496 
 
 Biology Furniture.444 
 
 Biology (General) Collection Micro¬ 
 scopic Slides.463 
 
 Biot's Hemispheres ........ 299 
 
 Bi-polar High Frequency Coil . . . 380 
 
 Bi-Prism, Fresnel’s.272 
 
 Biram's Anemometer.168 
 
 Birds' Eggs.413 
 
 Bird Skins, unmounted.413 
 
 Birds, mounted.413 
 
 Bit Brace.405 
 
 Bits, Augur. 405 
 
 B-K Solar Calculator.173, 174 
 
 Black and White Opaque Screen with 
 
 Square Opening, F. & B. ... 248 
 
 Blackboard Divider or Compass . . 71 
 
 Blackboard Drawing Instruments. . 71 
 
 Blackened Plate of Glass.249 
 
 Black Opaque Screen. 245, 248 
 
 Blackprint Paper.280 
 
 Blades, Hack Saw.405 
 
 Blast Apparatus.413 
 
 Blast Lamps .. 201, 202 
 
 Blast Lamps, Gasoline.414 
 
 Block, Aluminum.129 
 
 Block and Bent Wire.248 
 
 Block Microscopes.457 
 
 Block Plane.405 
 
 Blocks, Charcoal.422 
 
 Blocks, Waterproofed.128 
 
 Block with White Face.249 
 
 Block, Wood.109 
 
 Blower Nets.414 
 
 Blowers. 414 
 
 Blowpipe Forceps. Platinum Tipped 473 
 
 Blowpipe Mouthpieces.414 
 
 Blowpipes.414, 415 
 
 Blowpipes, Brazing.414 
 
 Blowpipes, Dissecting.433 
 
CATALOGUE OF SCIENTIFIC INSTRUMENTS 
 
 499 
 
 PAGE 
 
 Blowpipes, Glass Blowers’.415 
 
 Blueprint Paper.280 
 
 Board, Connection, F. & B. ... 316 
 
 Board, Resistance.355 
 
 Board Support for Composition of 
 
 Forces. 97 
 
 Boats, Combustion .425 
 
 Bohnenberger’s Gyroscope .... 85 
 
 Boilers, Steam.238 
 
 Boiling Point of Alcohol Tube, M. & 
 
 G.209 
 
 Bologna Phials. 73 
 
 Boltwood Mercury Pump.151 
 
 Bomb, Freezing.225 
 
 Bone Cutting Forceps.433 
 
 Bone Saw.433 
 
 Borers, Cork.426 
 
 Botanical Mounts.480 
 
 Botany Microscope Slides . . . 462 , 463 
 
 Bottle Brush.419 
 
 Bottle Clamp. 19 
 
 Bottle Racks.444 
 
 Bottles, all kinds.415-418 
 
 Bottles, Milk and Cream Test . . 468 
 
 Bottles, Specific Gravity.130 
 
 Bourdon Gauge, Demonstration . . 146 
 
 Bovie’s Auxanometer.408 
 
 Bow, Double Bass.199 
 
 Boxes, Resistance. 357-362 
 
 Boxes, Slide.461 
 
 Box with Wire Screen, T. & H. . . 245 
 
 Boyle's Law Apparatus .... 147, 148 
 
 Brace.405 
 
 Brain Models.469 
 
 Brass Wire.311 
 
 Brazing Blowpipes.414 
 
 Breaking by Expansion and Contrac¬ 
 tion Apparatus.224 
 
 Breaking Magnet.278 
 
 Breaking Strength of Wires Apparatus 96 
 
 Breast Drill.405 
 
 Breeding Cages.418 
 
 Bridge Model, Davis' .124 
 
 Bridge Sight Clinometer Compass . 287 
 
 Bridge Truss.124 
 
 Bristle Stylus and Fixative .... 191 
 
 Brush, Camel's Hair. 60 
 
 Brushes.419 
 
 Buchner Funnel.439 
 
 Bulb, Connecting, Hopkins' .... 419 
 
 Bulb Expander. 419 
 
 Bulb, Osmosis.145 
 
 Bulbs, Gas Ammonia.445 
 
 Bulbs, Potash.419 
 
 Bull’s Eye Condensers.460 
 
 Bunsen Blast Lamps.202 
 
 Bunsen Burners. 200, 201, 420 
 
 Bunsen Cell . ..323 
 
 Bunsen Photometers. 243, 244 
 
 Bunsen Screen.248 
 
 Bunsen's Ice Calorimeter.227 
 
 Buoyancy of Liquids Apparatus . . 135 
 
 Burette Attachment.419 
 
 Burette, Automatic Zero.419 
 
 Burette Brush.419 
 
 Burette Caps.419 
 
 Burette Clamps.423 
 
 Burette Float.419 
 
 Burette Funnels.419, 439 
 
 Burettes.419 
 
 Burettes, Acid.468 
 
 Burette Supports.484 
 
 Burner Attachments.420 
 
 Burner, Illuminating. 240, 244 
 
 Burner, Monochromatic Flame . . . 240 
 
 Burners, all kinds. 200-202 , 420 
 
 Burners, Cluster.420 
 
 Burners, Gang.420 
 
 Burners, Glass Blowers’.415 
 
 Bursting Squares.157 
 
 Buzzer.319 
 
 C 
 
 Cabinet, First Aid.405 
 
 Cabinet Makers' Clamps.423 
 
 Cabinets. 6, 7 
 
 Cabinet, Tool.405 
 
 Cady Insulated Pinch Connector . . 313 
 
 Cages, Breeding for Insects .... 418 
 
 Calcium Chloride Holder for Balances 421 
 
 Calcium Chloride Jar.451 
 
 Calcium Chloride Tubes.490 
 
 Caliper Arms with Vernier .... 37 
 
 Caliper Gauges.'. 35 
 
 Caliper Rule. 37 
 
 Calipers.35-37 
 
 Calorimeters .*. 226-229 
 
 Calorimetric Thermometer .... 216 
 
 PAGE 
 
 Camera Lucid®.460 
 
 Camera Obscura.242 
 
 Candelabrum Trough.244 
 
 Candle Experiment.302 
 
 Candle Holders. 244, 248 
 
 Candles.239 
 
 Candle, Standard.246 
 
 Capacity Test Key.318 
 
 Capillary Plates. 74 
 
 Capillary Tubes.74, 75 
 
 Capillary Tubing.491 
 
 Caps, Burette.419 
 
 Capstan Arm with Capstan .... 115 
 
 Capsules.421 
 
 Carbon and Zinc Battery Connectors 326 
 
 Carbon Bisulphide Prisms.262 
 
 CO 2 Apparatus.406 
 
 Carbon Dioxide Freezing Attachment 466 
 
 Carbon Electrodes.403 
 
 Carbon Filters.491 
 
 Carbon Paper.101 
 
 Carbon Pencils.159 
 
 Carboy Pump.474 
 
 Cardboard Index Strip, F. & B. . . 266 
 
 Carey-Foster Bridge.369 
 
 Carpenter's Level. 44 
 
 Carre's Freezing Apparatus ... 211 
 
 Cars, Inclined Plane.118, 121 
 
 Cartesian Diver.137 
 
 Cartilage Knife.433 
 
 Cartridges, Extraction.436 
 
 Case of Drawers.444 
 
 Casseroles.421 
 
 Catch Bucket.128 
 
 Cathode, Platinum.473 
 
 Cathode Ray Tubes. 308, 309 
 
 Cat Skins.289 
 
 Cell, Floating.328 
 
 Cells, Primary and Storage . . 320-325 
 
 Cells, Selenium.401 
 
 Celluloid Friction Strip.289 
 
 Celluloid Rule. 33 
 
 Cement, Alundum.406 
 
 Center of Gravity Apparatus ... 100 
 
 Center of Gravity Arc.100 
 
 Center of Gravity Board.100 
 
 Center of Gravity System .... 100 
 
 Centrifugal Dryer. 80 
 
 Centrifugal Force Apparatus . . 77-85 
 
 Centrifugal Globe. 80 
 
 Centrifugal Hoop. 79 
 
 Centrifugal Railway.106 
 
 Centrifugal Separator. 80 
 
 Centrifugal Tube. Hall. 80 
 
 Centrifuge Accessories.422 
 
 Centrifuge for Rotator. 80 
 
 Centrifuges.422 
 
 Chain, Egg and Disc. 79 
 
 Chains, Conductor.301 
 
 Chamois Skin.403 
 
 Chapman’s Aspirators. 153, 407 
 
 Charcoal Blocks.422 
 
 Charge and Discharge Key .... 318 
 
 Charging Box, Constant Voltage 296 
 
 Charging Rods.289 
 
 Charles Law Tubes.225 
 
 Chart, Atomic Weight.422 
 
 Chart, Graph. 71 
 
 Chart, Locomotive.235 
 
 Chart, Metric . 29 
 
 Chart, Periodic Law .422 
 
 Charts, Barograph.162 
 
 Charts, Baro-Thermo Recorder 165 
 
 Charts, Electro-Dynamic.398 
 
 Charts, Spectrum.267 
 
 Chart, Star.172 
 
 Charts, Thermograph.165 
 
 Chart. Twilight. 172 
 
 Cheese Cloth Bag.280 
 
 Chemical Harmonica.183 
 
 Chemical Labels.452 
 
 Chemical Thermometers . . . 214-216 
 
 Chemistry Direction Sheets .... 496 
 
 Chemistry Tables. 8 
 
 Chimes, Bell.300 
 
 Chimney, Asbestos.240 
 
 Chimney, Burner.420 
 
 Chimneys, Lamp.207 
 
 Chisel.405 
 
 Chladni's Figures Apparatus .... 194 
 
 Chladni’s Plate Attachment. T-Beam 26 
 
 Chladni’s Plate Clamps.194 
 
 Chladni's Plate Sand.194 
 
 Chlorine Tube.490 
 
 Circle Area Demonstration Apparatus 68 
 
 Circular Protectors. 43 
 
 Clamp Holders.423 
 
 Clamp, Pendulum, T. & H. 104 
 
 Clamps, all kinds. 13-26, 423 
 
 PAGE 
 
 Clamps, Chladni’s Plate.194 
 
 Clamps, Stone's Tension. 97 
 
 Clasp and Hook Rod, Culler's. . . 105 
 
 Clay Pipes.471 
 
 Clinometer Compass.287 
 
 Clinostats.424 
 
 Clips for Holding Mirrors to Blocks 249 
 
 Clock Balance Wheel. 66 
 
 Clock Contact. 64 
 
 Clocks. 64, 66 
 
 Coated Paper for Vibrograph . . . 191 
 
 Cobalt Bottle.415 
 
 Coddington Magnifier.452 
 
 Coefficient of Friction.109 
 
 Cohesion Discs. 73 
 
 Coil, Ballistic.343 
 
 Coil, Induction, M. G. & B. . . . 370 
 
 Coil, Magnetic Induction.329 
 
 Coils, Electromagnetic, F. & B. . . 330 
 
 Coils, Electromagnetic, M. G. & B. 330 
 
 Coils, Gilley Induction.330 
 
 Coils, High Frequency .... 378-380 
 
 Coils, Induction. 373-375 
 
 Coils, Primary and Secondary . . . 372 
 
 Coils, Repulsion.329 
 
 Coils, Resistance. 354-356 
 
 Coils, Self Induction.387 
 
 Coils, Temperature.354 
 
 Collars. 16 
 
 Collecting Case.492 
 
 Collections, Minerals and Rocks . . 469 
 
 Collectors, Gas.445 
 
 Collision Ball Apparatus. 89 
 
 — Color Apparatus.268 
 
 Color Discs. 81 
 
 Colored Glass Plates.267 
 
 Combination Rule and Level ... 44 
 
 Combustion Boats.425 
 
 Combustion Boat Shields.425 
 
 Combustion Boats, Platinum . . . 473 
 
 Combustion Furnace.440 
 
 Combustion Tubing. 489, 492 
 
 Commutators.319 
 
 Comparative Thermometer .... 213 
 
 Comparing Scale. 34 
 
 Compasses. 70, 71 
 
 Compasses, Magnetic. 286, 287 
 
 Compensating Pendulums. 65 
 
 Compensation Apparatus.221 
 
 Composition of Force and Motion 
 
 Apparatus. 99 
 
 Composition of Force Boards . . 97—99 
 
 Composition of Forces.96-99 
 
 Compound Achromatic Prisms . 261, 271 
 
 Compound Bars .223 
 
 Compound Lever and Jackscrew . . 126 
 
 Compound Levers.109, 126 
 
 Compound Magnets.278 
 
 Compound Microscopes .... 454-457 
 
 Compound Rod.207 
 
 Compressed Air Outfits.152 
 
 Compression Bibbs, Demonstration . 144 
 
 Compression Pump for Boyle’s Law 147 
 
 Compression Pumps.151, 152 
 
 Concave and Convex Cylindrical 
 
 Mirror. 249 
 
 Concave and Convex Mirrors . . . 249 
 
 Concave and Convex Spherical Mirror 249 
 Concave Galvanometer Mirrors . . 348 
 
 Concave Glass Mirror, Mounted . . 244 
 
 Concave Lenses. 258, 259 
 
 Concentric Rings.,. . . 476 
 
 Condenser Attachment, Culler's . . 227 
 
 Condenser Clamps.423 
 
 Condenser Plate Attachment, Elec¬ 
 
 troscope.294 
 
 Condenser Plates.304 
 
 Condensers.425 
 
 Condensers, Air.388 
 
 Condensers, Bull's Eye.460 
 
 Condensers, Liebig's.211, 425 
 
 Condenser, Soxhlet's.425 
 
 Condensers, Paper, Mica.388 
 
 Condensers, Plate.304 
 
 Condensers, Substage Abbe .... 459 
 
 Condensers, Wireless. 383 
 
 Condenser, Wireless Fixed.384 
 
 Condensing Lenses . . • ■ 258, 259 
 
 Conduction Tube, Liquid.208 
 
 Conductivity of Water Apparatus . 208 
 
 Conductivity Rods.• • 207 
 
 Conductometers. 207, 208 
 
 Conductor Chains. . 301 
 
 Conductors, Electrostatic . . . 298-300 
 
 Cone and Plane.106 
 
 Cone, Dissectible. 
 
 Cone, Sphere and Cylinder .... 68 
 
 Conical Graduates.44' 
 
 Conical Net, Faraday’s Net .... 300 
 
5oo 
 
 L. E. KNOTT APPARATUS CO 
 
 > 
 
 BOSTON 
 
 PAGE 
 
 PAGE 
 
 PAGE 
 
 Conjugate Foci Screen.245 
 
 Connecting Tips.312, 313 
 
 Connecting Tubes.490 
 
 Connection Board, F. & B.316 
 
 Connector, High Potential .... 313 
 
 Connectors, Binding Post . . . 314, 315 
 
 Constant Voltage Charging Box . . 296 
 
 Constant Volume Air Thermometers 218 
 Constant Volume Hydrometer Tube, 
 
 M. G. & B.131 
 
 Constant Weight Hydrometer Tube, 
 
 M. G. & B.131 
 
 Contact Keys ..317 
 
 Controller Model.397 
 
 Convectional Current Apparatus . . 207 
 
 Convex and Concave Mirrors . . . 249 
 
 Convex Glass Mirror, mounted. . . 244 
 
 Convex Lens and Wire Screen, 
 
 mounted, M. G. & B.248 
 
 Convex Lenses. 258 , 259 
 
 Cooling Cup, T. & H.206 
 
 Coplin’s Staining Jar.451 
 
 Copper Anode.403 
 
 Copper Beakers.413 
 
 Copper Electrodes.403 
 
 Copper Plating Outfit.403 
 
 Copper Shot.229 
 
 Copper Sulphate.403 
 
 Copper Wire.311 
 
 Cord, Pulley . . . . •.Ill 
 
 Cores, Wooden with Attached Bind¬ 
 ing Posts, F. & B.313 
 
 Cork Borers.426 
 
 Cork Borer Sharpeners.426 
 
 Cork Knife.426 
 
 Cork Mats.426 
 
 Cork Presses. 426 
 
 Corks.426 
 
 Cork Screw.426 
 
 Cork Sheet.426 
 
 Corrosive Sublimate Tablets .... 468 
 
 Counterpoise for Trip Scale .... 55 
 
 Counterpoise Gyroscope. 85 
 
 Coupling, Brass.156 
 
 Couplings, Hydrant. 153 , 407 
 
 Cover Glasses.461 
 
 Cover Glass Forceps.433 
 
 Cowen's Expansion Apparatus . . . 221 
 
 Crane Boom, F. & B.120 
 
 Crane Demonstration Apparatus . . 120 
 
 Crane, Hoisting.123 
 
 Creamometer Jar.468 
 
 Cream Test Bottles.468 
 
 Crooke's Radiometers .204 
 
 Crooke’s Tubes. 308, 309 
 
 Cross Bars, Metal. 10 
 
 Cross Cut Saw.405 
 
 Cross Section Paper. 70, 101 
 
 Crova’s Disc. 82 
 
 Crowfoot Gravity Cell.322 
 
 Crown, Burner.420 
 
 Crown Glass Prisms. 261, 271 
 
 Crucible Blocks.429 
 
 Crucible Funnels. 428, 429 
 
 Crucible Furnaces. 440, 442 
 
 Crucible Rubber Tubing.429 
 
 Crucibles, all kinds. 427-429 
 
 Crucibles, Platinum.473 
 
 Crucible Tongs.429 
 
 Cryophorouses.211, 212 
 
 Crystallizing Dishes.430 
 
 Crystal Models. 68 
 
 Cube, Paraffine. 129 
 
 Cube Root Block. 68 
 
 Cubes, Glass . ..256 
 
 Cubes, Wood. 31 
 
 Cubical Expansion Bulb.212 
 
 Cubical Mirror. 82 
 
 Cubic Foot Block. 30 
 
 Culler’s Index of Refraction of Water 
 
 Apparatus.256 
 
 Culler's Lever, Pulley, Pendulum, 
 
 Clasp and Hook Rod. 105 
 
 Culler’s Principle Focus Box . . . 248 
 
 Culture Tubes.490 
 
 Cups, Porous.429 
 
 Curtis Naturalistic Models . . 175-178 
 
 “ Cut-off” Clamps.423 
 
 Cutters, Glass.447 
 
 Cylinder, Aluminum.129 
 
 Cylinder and Bucket.128 
 
 Cylinder, Hollow Brass, M. G. & 
 
 B. 68 
 
 Cylinder, Loaded, Waterproofed . 128 
 
 Cylinders, Graduated . . . 429, 447, 451 
 Cylinders, Hydrometer .... 429. 451 
 
 Cylinder Wheel, Loaded. 100 
 
 Cylindrical Diaphragm.239 
 
 Cylindrical Glass Vessel.135 
 
 Cylindrical Iron Armature, T. & H 1 . 279 
 
 Cylindrometer. 37 
 
 D 
 
 Dairy Thermometer.468 
 
 Dancing Balls and Holder .... 301 
 
 Daniell Cell.322 
 
 Darning Needles.279 
 
 D'Arsonval Galvanometer, M. G. & 
 
 B. 342 
 
 D'Arsonval Galvanometers . . 337-346 
 
 Davis’ Model Bridge.124 
 
 Davy’s Safety Lamp.208 
 
 Deflagrating Spoons.479 
 
 Deflection Magnetometer.282 
 
 De La Rives Apparatus.308 
 
 Demonstration Aneroid Barometer . 161 
 
 Demonstration Arc Lamps . . 159 . 404 
 Demonstration Batteries . . . 320, 321 
 Demonstration Dip Needle .... 285 
 
 , Demonstration Electromagnets . . 331 
 
 Demonstration Hydraulic Ram . , 139 
 
 Demonstration Hydrometer .... 131 
 
 Demonstration Incandescent Lamp 159 
 Demonstration Inclined Plane ... 118 
 
 Demonstration Induction Coils . . 373 
 
 Demonstration Lenses .... 258, 259 
 
 Demonstration Lever ..109 
 
 Demonstration Leyden Jar .... 303 
 
 Demonstration Metallic Thermometer 213 
 Demonstration Microscope, M. & G. 266 
 Demonstration Motor-Dynamo . . 391 
 
 Demonstration Organ Pipes .... 184 
 
 Demonstration Telephone Receiver . 400 
 
 Demonstration Transformer .... 370 
 
 Demonstration Wheatstone Bridges 
 
 366. 367 
 
 Density Apparatus.128-131 
 
 Density by Flotation.129 
 
 Density Cubes. 31 
 
 Density Indicating Ball .130 
 
 Derrick.124, 125 
 
 Dessicator Dish.430 
 
 Dessicator Plates.430 
 
 Dessicators.430 
 
 Detents for Meter Stick. 88 
 
 Dewar Beaker, Unexhausted .... 208 
 
 Dewar Bulb.208 
 
 Dewing’s Air Tester.406 
 
 Dew Point Apparatus.212 
 
 Diagonal Scales. 34, 40-42 
 
 Diamagnetic and Paramagnetic Study 
 
 Apparatus.333 
 
 Diamagnetic and Paramagnetic Sub¬ 
 stances .279 
 
 Diamond for Writing on Glass. . . 430 
 
 Diamond Ink.450 
 
 Diaphragms.239 
 
 Diaphragm with One Cm. Opening, 
 
 T. & H.248 
 
 Dibdin Bunsen Photometer . . 243, 244 
 
 Differential Pulley Hoists.113 
 
 Differential Thermoscopes.217 
 
 Diffraction Gratings.273 
 
 Diffusion Shells. 75, 145 
 
 Digesting Shelves.430 
 
 Digestion Flasks.438 
 
 Digestors, Papin . . . ..209 
 
 Dip Needles.286 
 
 Direction Sheets, Biology.496 
 
 Direction Sheets, Chemistry .... 496 
 
 Direction Sheets, Physics. 27 
 
 Direct Vision Pocket Spectroscope 269 
 
 Direct Vision Prisms. 261, 263 
 
 Disc, Brass, M. G. & B. 68 
 
 Dischargers.’. . . 298, 301 
 
 Disc, Magnetized.278 
 
 Disc, Revolving.302 
 
 Discs, Cohesion and Adhesion ... 73 
 
 Discs, Rubber, for Blowers . . 414. 477 
 
 Dishes, all kinds. 430-432 
 
 Dishes, Platinum.473 
 
 Dissected Clock. 64 
 
 Dissectible Cone. 68 
 
 Dissectible Hand Power Dynamo 
 
 and Motor.394 
 
 Dissectible Induction Coil.373 
 
 Dissectible Transformer.371 
 
 Dissecting Instruments .... 433, 434 
 Dissecting Microscopes .... 457, 458 
 
 Dissecting Pan.433 
 
 Dissecting Sets.434 
 
 Distillation FlasksJ .438 
 
 Distillation Tubes, Fractional . . . 435 
 
 Distilling Apparatus. 435, 482 
 
 Diverging Ray Attachment .... 254 
 
 Dividers. 70 
 
 Diving Bell Model.157 
 
 Dixon’s Crucibles.427 
 
 Double Bass Bow.199 
 
 Double Connectors.315 
 
 Double Contact Keys.317 
 
 Double Dishes.432 
 
 Double Meter Stick. 32 
 
 Doublet Magnifiers.453 
 
 Double Wall Calorimeters . . . 227, 228 
 
 Double Wall Funnels.439 
 
 Douglass’ Double Contact Key . . 317 
 
 Drawing Boards. 70 
 
 Drawing Instruments .69-71 
 
 Drawing Sets.'. 69 
 
 Drill, Breast.405 
 
 Drive Pulley for Round Belt ... 78 
 
 Drive Wheel and Clamp. 21 
 
 Dropping Bottles.415 
 
 Dry Cell.325 
 
 Drying Ovens.435 
 
 Drying Paper.472 
 
 Drying Table, Section.466 
 
 Drying Tower.451 
 
 Drying Tubes.490 
 
 Dry Measures. 32 
 
 Duff's Acceleration Apparatus . . . 101 
 
 Dynamo and Motor, Hand Power . 394 
 Dynamometers ......... 56-57 
 
 Dynamo-Motor.390 
 
 Dynamos and Motors .... 389-397 
 
 Dynamos, Small. 389, 390 
 
 E 
 
 Ear Model.469 
 
 Earth Induction Apparatus .... 83 
 
 Earth Inductor.288 
 
 Ear Trumpet . .187 
 
 Eccentric Leveling Bases. 12 
 
 Eggs, Birds’.413 
 
 Eight-in-One Apparatus ..136 
 
 Einhorn's Saccharometer.478 
 
 Elasticity of Wire Apparatus ... 95 
 
 Electric and Steam Power Plant. . 238 
 
 Electric Appliances.436 
 
 Electric Bell, Mounted.158 
 
 Electric Bells.319 
 
 Electric Calorimeters.228 
 
 Electric Centrifuges ..422 
 
 Electric Compressed Air Outfit . . 152 
 
 Electrical Density Apparatus . . . 299 
 
 Electric Driven Tuning Fork . . . 181 
 
 Electric Furnace Cores.443 
 
 Electric Furnaces .... 404, 440—443 
 
 Electric Gong.319 
 
 Electric Incubators.450 
 
 Electric Iron.436 
 
 Electric Lamp.240 
 
 Electric Mortar.302 
 
 Electric Rotator. 78 
 
 Electric Screen.299 
 
 Electric Soldering Iron.436 
 
 Electric Stoves. 436, 483, 484 
 
 Electric Water Baths.411 
 
 Electric Water Heater. 436 
 
 Electrodes, Carbon, Copper, Plati¬ 
 num .403 
 
 Electrodynamic Apparatus . . . 376, 398 
 
 Electrodynamic Charts.398 
 
 Electrolysis Apparatus .... 402 , 403 
 Electrolysis Apparatus, Lantern . . 403 
 
 Electrolysis Tube Supports .... 403 
 
 Electrolytic Interrupters.375 
 
 Electrolytic Rectifiers.385 
 
 Electromagnetic Coils, F. & B. . . 330 
 
 Electromagnetic Coils, M. G. & B. 330 
 
 Electromagnets. 330-333 
 
 Electromagnets, mounted . . . 332, 333 
 Electrometer Charging Box .... 296 
 
 Electrometer, Quadrant.302 
 
 Electrometers. 293-296 
 
 Electrophorouses.290 
 
 Electroplating Materials.403 
 
 Electroplating Outfit.403 
 
 Electroscope, Beetz.302 
 
 Electroscopes. 293-296 
 
 Electrostatic Motor.302 
 
 Electrostatic Sets. 201, 302 
 
 Electrostatic W r hirl.301 
 
 Electrotyping Letters, T. & H. . . 403 
 
 Elements, Battery. 320-325 
 
 Ellipsoidal Conductor.299 
 
 Emery, Powdered.403 
 
 Endless Screw.120 
 
 Endosmometer.75. 145 
 
 End Supports. 13 
 
 Engines, Gas.232 
 
 Engines, Hot Air.231 
 
 Engines, Steam. 233-238 
 
CATALOGUE OF SCIENTIFIC INSTRUMENTS 
 
 50i 
 
 PAGE 
 
 Geometric Stands. 15 
 
 Geometrical Wooden Forms .... 67 
 
 German Silver Wire. 311 
 
 Gilder’s Knife, Pad and Tip . . 293 
 
 Gilley Coils. 330 
 
 Gilley Gramme Machine.392 
 
 Gilley Low Form Bunsen Burner . 200 
 
 Gilley Skidmore Battery.320 
 
 Gimlet.405 
 
 Glass Beads. 229, 411, 446 
 
 Glass Beakers.412 
 
 Glass Blowers’ Blowpipes. 415 
 
 Glass Cutters. 447 
 
 Glass Cutting File. 437 
 
 Glasses, Bell, all kinds.154 
 
 Glasses, Test. 446, 487 
 
 Glass Friction Rods.289 
 
 Glass, Hand and Bladder.154 
 
 Glass Models of Crystals. 68 
 
 Glass Mortars.470 
 
 Glass Penetrating Apparatus. . . . 302 
 
 Glass Plate Lacquered Black on Back 249 
 
 Glass Plates.472 
 
 Glass Retorts.476 
 
 Glass Rods.477 
 
 Glass Slides, Microscopic.461 
 
 Glass Stopcocks ..483 
 
 Glass Tube and Steel Filings . . . 278 
 
 Glass Tube Cutters.447 
 
 Glass Tubing.491 
 
 Glass Wool.447 
 
 Glazed Paper.471 
 
 Gold Beaters' Skin.. . 447 
 
 Gold Leaf.293 
 
 Gold Leaf Cutting Apparatus . . 293 
 
 Gong, Electric.319 
 
 Gooch Crucibles.428 
 
 Gooch Crucibles, Platinum. . . . 473 
 
 Gotham Cell.321 
 
 Gotham Demonstration Battery . . 321 
 
 Graduated Arc with Clamp . . 89, 90 
 
 Graduated Cardboard Screen . . 245 
 Graduated Cylinders . . . 429, 447, 451 
 
 Graduated Flask.406 
 
 Graduated Pipettes.406 
 
 Graduated Rods, Metal. 10 
 
 Graduates, all kinds.447 
 
 Graph Chart. 71 
 
 Graphic Analysis of Sound Waves . 196 
 
 Gratings, Diffraction .273 
 
 Graphite Crucibles.427 
 
 Graphite Resistances.365 
 
 Gravesend Ball and Ring.223 
 
 Gravity and Motion Apparatus . . 106 
 
 Gravity Cell.322 
 
 Grenet Batteries.323 
 
 Guard Plugs, Brass.156 
 
 Guinea and Feather Tube.102 
 
 Gummed Labels.452 
 
 Gyroscopes.84, 85 
 
 Gyroscopic Outfit. 85 
 
 PAGE 
 
 Entomological Mounts.480 
 
 Equilateral Prism, M. & G. 256 
 
 Equilaterial Prisms .... 260-263, 271 
 
 Equilibrium Apparatus. 100 
 
 Equipotential Apparatus.284 
 
 Erdmann’s Float.419 
 
 Erlenmeyer Flasks.438 
 
 Ether Freezing Attachment .... 466 
 
 Eudiometers.436 
 
 Evaporating Dishes.431 
 
 Exciting Pads . ..289 
 
 Expander, Bulb.419 
 
 Expansion and Contraction appara¬ 
 tus, Packard’s.224 
 
 Experimental Barometer Vacuum and 
 
 Geissler Tube .......... 307 
 
 Extension Clamps. 14 
 
 Extension Rings.476 
 
 Extraction Apparatus, Soxhlet's . . 436 
 
 Extraction Cartridges.436 
 
 Extraction Flasks.438 
 
 Extraction Thimbles.436 
 
 Extraction Tubes, Soxhlet’s .... 436 
 
 Eyeglass Protector.310 
 
 Eye Models. 259, 469 
 
 Eye Shades.245 
 
 F 
 
 Falling Body Apparatus . 101-103 
 
 Falling Body Apparatus, M. & G. 102 
 
 Faraday’s Net.300 
 
 Faraday’s Ring.370 
 
 Faraday’s Shield.299 
 
 Farrington’s Alkaline Tablets . . . 468 
 
 Faucets, Water. 9 
 
 Fechner’s Electrometer.294 
 
 Fermentation Tubes.491 
 
 Ferron Detector.384 
 
 Fessel's Gyroscope . '.. 85 
 
 Field Tray.284 
 
 Filaments for Demonstration Incan¬ 
 descent Lamp . . . .'.159 
 
 Files. 405, 437 
 
 Filings Sifter. ..280 
 
 Film Demonstration Apparatus. . . 73 
 
 Filter Cones, Alundum.437 
 
 Filter Cones, Platinum.473 
 
 Filter Crucibles.428 
 
 Filter Dishes.432 
 
 Filtering Flasks.438 
 
 Filter Paper, all - kinds.437 
 
 Filter Plates. 437, 472 
 
 Filter Pumps. 153, 407 
 
 Filter Tubes.491 
 
 Fire Engine Pump.140 
 
 Fireless Cooker.208 
 
 Fire Syringe.231 
 
 First Aid Cabinet.405 
 
 Fitz Air Tester.406 
 
 Flannel Cap with Attached Silk 
 
 Cords, M. & G.289 
 
 Flannel Exciting Pad.289 
 
 Flask, Graduated.406 
 
 Flasks, all kinds. 438, 439 
 
 Flexible Steel Gas Tubing .... 477 
 
 Flexible Wire.311 
 
 Flexure of Beam Apparatus .... 94 
 
 Flint Glass Prisms. 261, 271 
 
 Float, Burette.419 
 
 Floating Helix and Cell.328 
 
 Floating Magnets.279 
 
 Florence Flasks.438 
 
 Fluorescent Geissler Tubes . . 305, 306 
 
 Fluoroscopes.310 
 
 Flush Plates. 12 
 
 Foil, Platinum.473 
 
 Foil. Tin. 293, 487 
 
 Folding Rule. 34 
 
 Foot Blowers or Bellows . . . 202, 414 
 
 Forceps.439 
 
 Forceps. Balance. 60 
 
 Forceps, Bone Cutting.433 
 
 Forceps, Cover Glass.433 
 
 Forceps, Dissecting.433 
 
 Forceps, Platinum Tipped.473 
 
 Force Pumps.140 
 
 Forces in a Uniform Metal Bar with 
 
 a Sliding Load. 126 
 
 Fortin Cistern Barometers .... 160 
 
 Foucault’s Pendulum. 79 
 
 Foucault's Prisms.275 
 
 Fountain in Vacuo.153 
 
 Four Way Gas Turret, Mounted . 445 
 
 Fractional Distillation Tubes. . . . 435 
 
 Fractional Weights.59, 61 
 
 Franklin’s Palm or Pulse Glass . . 211 
 
 Freas' Osmosis Apparatus . . . 75, 145 
 
 PAGE 
 
 Free Fall Acceleration Apparatus 102, 103 
 
 Freezing Apparatus .... 159, 211, 212 
 
 Freezing Attachments.466 
 
 Freezing Bomb.225 
 
 Frequency Indicator.398 
 
 Fresenius’ Burettes . . . 1 .419 
 
 Fresnel’s Bi-Prism.272 
 
 Fresnel's Mirrors.272 
 
 Friction Apparatus.109 
 
 Friction Block.109 
 
 Friction Board.109 
 
 Friction of Air Apparatus.146 
 
 Friction of Water Apparatus, Hall 73 
 Friction Rod and Magnet Support . 279 
 
 Friction Rods.289 
 
 Fruit Jars.451 
 
 Fuller Bibb, Demonstration .... 144 
 
 Fuller Cell.322 
 
 Funnel, Acid.468 
 
 Funnel, Burette.419 
 
 Funnel, Mercury Storage .... 146 
 
 Funnels, all kinds.439 
 
 Funnels for Hot Filtrations ... 439 
 
 Funnel Supports. 484, 485 
 
 Funnel, Wood for Porosity ... 72 
 
 Furnace Cores.443 
 
 Furnace, Electric.404 
 
 Furnaces . 440-443 
 
 Furniture. Laboratory .... 2-9, 444 
 
 Fused Silica Beakers.413 
 
 Fused Silica Capsules.421 
 
 Fused Silica Casseroles.421 
 
 Fused Silica Combustion Boats . . 425 
 
 Fused Silica Crucibles.428 
 
 Fused Silica Dishes.432 
 
 Fused Silica Evaporating Dishes . . 431 
 
 Fused Silica Plates.472 
 
 Fused Silica Rods.477 
 
 Fused Silica Trays.488 
 
 Fused Silica Triangles.488 
 
 Fused Silica Tubing.489 
 
 Fused Silica Ware.494 
 
 Fuse Wire.311 
 
 G 
 
 Galileo’s Telescope Model.266 
 
 Galton’s Whistles.184 
 
 Galvanometer Accessories . . . 348, 349 
 
 Galvanometer Mirrors.348 
 
 Galvanometers. 334-346 
 
 Galvanometer Suspension Filaments 348 
 
 Galvanometer Telescope and Scale 349 
 
 Galvanoscopes.334 
 
 Gas Ammonia Bulbs.445 
 
 Gas Apparatus.445 
 
 Gas Bags . . . ..445 
 
 Gas Bottle Generator.445 
 
 Gas Cocks.9. 445 
 
 Gas Collectors.445 
 
 Gas Engine Model.232 
 
 Gas Engines.232 
 
 Gas Generators.445 
 
 Gas Holders.446 
 
 Gas Lamp.240 
 
 Gas Measuring Tubes.446 
 
 Gasoline Burner.202 
 
 Gasoline Gas Generator.445 
 
 Gasometers.446 
 
 Gas Pressure Apparatus.146 
 
 Gas Pressure Regulator.446 
 
 Gas Regulators.446 
 
 Gas Sample Tubes.445 
 
 Gas Stopcocks.445 
 
 Gas Stoves.483 
 
 Gas Tubes. 446. 491 
 
 Gas Tubing.477 
 
 Gas Turrets.445 
 
 Gauge Calipers. 35 
 
 Gauges, Pitch. 405 
 
 Gauges, Pressure.155 
 
 Gauges, Pressure and Vacuum ... 146 
 
 Gauge, Pressure, for Apparatus A . 203 
 
 Gauge, Thorpe.229 
 
 Gauges, Wire. 39 
 
 Gauze, all kinds.446 
 
 Gauze Top, Burner.420 
 
 Gay Lussac’s Support.484 
 
 Geared Wheels. 120 
 
 Geissler’s Burettes.419 
 
 Geissler Tube, Experimental .... 307 
 
 Geissler Tube Holder. 301, 307 
 
 Geissler Tube Rotators.307 
 
 Geissler Tubes. 305-308 
 
 Geissler Tubes, Unequally Evacuated 307 
 
 Generator, Gas Bottle.445 
 
 Generators.397 
 
 Genus Covers . . . -.472 
 
 H 
 
 Hackeling's Tellurian.170 
 
 Hack Saw.405 
 
 Hack Saw Blades.405 
 
 Haematokrit.422 
 
 Half Meter Stick. 32 
 
 Half Meter Wheatstone Bridges . . 368 
 
 Hammers .405 
 
 Hammers, Rubber. . 179 
 
 Hand Air Pumps.149, 151 
 
 Hand and Bladder Glass.154 
 
 Hand Balances. 56 
 
 Hand Balance Support. 20 
 
 Hand Bellows.202 
 
 Hand Drive Centrifuges.422 
 
 Hand Microtome.464 
 
 Hand Power Dynamo and Motor . 394 
 
 Hand Screw Clamp.423 
 
 Harcourt Ball-bearing Pulleys . 110, 111 
 Hardened Steel Rods ...... 279 
 
 Hare’s Apparatus.130 
 
 Harmonic Motion Apparatus. . . 93 
 
 Harness for Trip Scale. 55 
 
 Hatchet. 405 
 
 H-Bases. 12 
 
 Head Models.469 
 
 Heart Model.469 
 
 Heater, Hot Water.201 
 
 Heaters, Soldering Iron.479 
 
 Heating Coil Attachment for Calo¬ 
 rimeters.228 
 
 Heat Shield.211 
 
 Hefner Lamps.246 
 
 Heliopticons.239 
 
 Heliostats.239 
 
502 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • » 
 
 PAGE 
 
 PAGE 
 
 PAGE 
 
 Helix and Ring.331 
 
 Helix and Separable Magnetic Cir¬ 
 cuit .331 
 
 Helix Electromagnet.331 
 
 Helix, Wireless.383 
 
 Helix with Movable Coil.331 
 
 Helmholtz Resonators.197 
 
 Hero's Fountain.141 
 
 High Frequency Apparatus . . 378-382 
 
 High Frequency Coils .... 378-380 
 
 High Frequency Inductive Apparatus 379 
 
 High Frequency Phenomena Appa¬ 
 ratus . 380, 381 
 
 High Resistance Wire.311 
 
 High Temperature Thermometers. . 216 
 
 High Tension Keys.317, 318 
 
 High Vacuum Aspirator.407 
 
 Hoffman’s Clamp.423 
 
 Hoffman’s Electrolysis Apparatus 402 
 
 Hoisting Crane. 123, 124, 125 
 
 Holder, Calcium Chloride, for Bal¬ 
 ances .421 
 
 Holder, Electrostatic.301 
 
 Holder, Geissler Tube.307 
 
 Holder, Incandescent Lamp .... 244 
 
 Holders, Clamp.423 
 
 Hollow Induction Cylinder ... 299 
 
 Hollow Lenses.259 
 
 Hollow Prisms.262 
 
 Hollow Troughs ... .... 272 
 
 Holman’s Life Slide.461 
 
 Hook Collars. 16 
 
 Hooke’s Law Apparatus ... 95 
 
 Hooks and Chains, Dissecting . . 433 
 
 Hook, Threaded.120 
 
 Hook, U-shaped, T. & H. 109 
 
 Hoop, Centrifugal. 79 
 
 Hopkins’ Connecting Bulb. 419 
 
 Hopkins’ Forked Tube. 188 
 
 Horizontal Galvanometer.342 
 
 Horn Spatulas.479 
 
 Horn Spoons.479 
 
 Horse and Rider.100 
 
 Horseshoe Core, Soft Iron, M. G. & B. 279 
 
 Horseshoe Magnets.278 
 
 Hortvet's Apparatus.116 
 
 Hot Air Engines.231 
 
 Hot Plates. 409 , 483 , 484 
 
 Hot Water Heater.201 
 
 Household Thermometers . . . 163, 213 
 
 Humidity Apparatus.166, 167 
 
 Huyghenian Oculars.459 
 
 Hydrant Couplings.. 153 , 407 
 
 Hydraulic Presses. 138 
 
 Hydraulic Rams.139 
 
 Hydrodynamic Wheatstone Bridge . 366 
 
 Hydrogen Absorption Apparatus, 
 
 Hall.403 
 
 Hydrometer Jars. 131, 429 , 451 
 
 Hydrometers, all kinds .... 131, 448 
 
 Hydrometer Tubes. 131 
 
 “Hydrone" Cartridges.445 
 
 Hydrostatic Balances.53, 54 
 
 Hydrostatic Bellows. 138 
 
 Hydrometers.166, 167 
 
 Hygrophant.167 
 
 Hyperdermic Syringe.486 
 
 Hypsometers.203 
 
 Hvpsometer Thermometers.216 
 
 I 
 
 Ice Bag.204 
 
 Ice Calorimeter. 227 
 
 Iceland Spar.274 
 
 Ice Shredder and Shave.204 
 
 Ice Tray.204 
 
 Ignition Apparatus.302 
 
 Ignition Capsules.421 
 
 Ignition Tubes. 491 
 
 Illuminating Burners. 240, 244 
 
 Image on Rod.245 
 
 Image Plates.300 
 
 Images, Pith.300 
 
 Impactand Reflection Attachment . 88 
 
 Impact Apparatus.87, 90 
 
 Impenetrability Apparatus. 76 
 
 Incandescent Lamp, Demonstration 159 
 Incandescent Lamp Holder .... 244 
 
 Incidence and Reflection Apparatus 250 
 
 Incinerating Dishes.432 
 
 Inclined Plane and Cone.106 
 
 Inclined Plane Cars. 118 
 
 Inclined Plane Rollers.117, 121 
 
 Inclined Planes.117, 118 
 
 Inclined Wire Acceleration Apparatus 103 
 Incompressibility of Liquids Appa¬ 
 ratus .. . 76 
 
 Incubators. 449 , 450 
 
 Indelible Pencil.471 
 
 Index Block.249 
 
 Index of Refraction Apparatus 256, 257 
 Index of Refraction Plates .... 256 
 
 Index Strip, Mounted, Hall’s ... 94 
 
 Indicating Meters. 474, 475 
 
 Indicator, Frequency.398 
 
 Inductances.387 
 
 Induction and Distribution Spheres 
 
 298 299 
 
 Induction Coil, M. G. & B. ... 370 
 
 Induction Coils. 284, 373-375 
 
 Induction Coils, Gilley.330 
 
 Induction Cylinders. 298, 299 
 
 Induction Motors.396 
 
 Induction Study Apparatus .... 330 
 
 Inductive Apparatus, High Fre¬ 
 quency .379 
 
 Inertia Accessories, Magnetometer . 281 
 
 Inertia Apparatus. 76 
 
 Inertia Balance. 93 
 
 “Influence Machines. 290-292 
 
 Ink, Diamond.450 
 
 Inoculating Needle.470 
 
 Insect Cages.418 
 
 Insect Pins.471 
 
 Insect Specimens.480 
 
 Inside Calipers. 35 
 
 Instantaneous Hot Water Heater 201, 493 
 
 Instructor's Tables.5, 405 
 
 Instruments, Dissecting .... 433, 434 
 
 Instrument Shelters.169 
 
 Instruments, Telegraph.400 
 
 Insulating Stands.297 
 
 Insulating Stools.297 
 
 Interference Apparatus .... 187, 188 
 
 Interference Mirrors.272 
 
 Interference of Light Plates, M. & 
 
 G.273 
 
 Interference Tubes.188 
 
 Interhooking Laboratory Weights . 62 
 
 Intermittent Fountain.137 
 
 Interrupter, Make and Break . . . 372 
 
 Interrupters, Electrolytic.375 
 
 Interrupting Wheel.318 
 
 Interval Timer. 64 
 
 Inverse Squares Model.242 
 
 Inverted Show Jars.451 
 
 Iron Armatures, T. & H.279 
 
 Iron Clad Magnets.331 
 
 Iron Crucibles.427 
 
 Iron, Electric.436 
 
 Iron Filings.280 
 
 Iron Mortars.470 
 
 Iron Retorts.476 
 
 Iron Weights. 62, 63, 127 
 
 Iron Wire.311 
 
 J 
 
 Jackscrew and Compound Lever . . 126 
 
 Jack Screws.119 
 
 Jar, Creamometer.468 
 
 Jars, all kinds.451 
 
 Jars, Aquaria.406 
 
 Jars, Glass.131 
 
 Jars, Hydrometer . . : 131, 429 , 451 
 
 Jars, Rectangular, Battery .... 326 
 
 Jars, Round, Battery.326 
 
 Jenkins’ Specific Gravity Apparatus 72 
 
 Joints, Models.470 
 
 Jolly Balances. 56 
 
 Jolly Photometer, F. & B.243 
 
 Junker’s Calorimeter.229 
 
 K 
 
 Kaleidoscopes.251 
 
 Kempe's Charge and Discharge Key 318 
 
 Kerosene Lamps.240 
 
 Key and Sounder, Combined . . . 400 
 
 Key Hole Saw.405 
 
 Key Parts, Telegraph.400 
 
 Keys, High Tension.317, 318 
 
 Key, Telegraph.400 
 
 Kittredge Clamps. 109 
 
 Kjeldahl Flasks.438 
 
 Kjeldahl’s Digesting Shelves .... 430 
 
 Knife Back, Microtome.466 
 
 Knife, Cork.426 
 
 Knife Edge Attachment, T-Beam . 26 
 
 Knife Edge Bracket. 16 
 
 Knife Edge Clamps.16, 26 
 
 Knife Edge Contact Piece .... 94 
 
 Knife Handle. Microtome.466 
 
 Knife Strop, Microtome.466 
 
 Knife Switch Pole Changer .... 319 
 
 Knitting Needles.279 
 
 Knives, Microtome.466 
 
 Koch's Funnel.439 
 
 Kolbe Harcourt Optical Disc . 252, 254 
 
 Kuehne’s Eye Model.259 
 
 Kullmer Star Chart.172 
 
 Kundt’s Apparatus.199 
 
 Kundt’s Interference Apparatus . . 187 
 
 Kymograph Record Sheets.192 
 
 Kymographs.192 
 
 L 
 
 Labels, Chemical.452 
 
 Labels, Gummed.452 
 
 Labels, Microscopic Slide.452 
 
 Laboratory Clock. 64 
 
 Laboratory Furniture.2-9 
 
 Laboratory Microtomes .... 464, 465 
 
 Laboratory Stand. 14 
 
 Laboratory Steelyard.126 
 
 Lactometers. 448, 468 
 
 Ladle.452 
 
 Lambert’s Capacity Test Key . . . 318 
 
 Laminated Magnet High School Gal¬ 
 vanometer .342 
 
 Laminated Magnet Lecture Table 
 
 Galvanometer.341 
 
 Lamp and Scale.348 
 
 Lamp Board.363 
 
 Lamp Chimneys.207 
 
 Lamp Cord.311 
 
 Lamp, Demonstration Arc . . 159 . 404 
 
 Lamp, Demonstration Incandescent 159 
 
 Lamp, Electric.240 
 
 Lamp, Gas.240 
 
 Lamp, Microscope.460 
 
 Lamps, Alcohol. 201, 202, 452 
 
 Lamps, Blast. 201, 202 
 
 Lamps, Hefner.246 
 
 Lamp, Single Filament for Galvanom¬ 
 eter .348 
 
 Lamps, Kerosene.240 
 
 Lamps, Projection.241 
 
 Lamp Wicks.452 
 
 Lantern Electrolysis Apparatus . . 403 
 
 Lantern Slides, Physics. 28 
 
 Larynx Phantom, Model.470 
 
 Larynx Models.470 
 
 Lead Cylinder with Conical Top 229 
 
 Lead Dishes . X .432 
 
 Lead Shot.229 
 
 Lead Sinker.128 
 
 Lead Wire.311 
 
 Leaning Tower.100 
 
 Leather Belting, round. 21 
 
 LeClanche Battery.322 
 
 Lecture Table, Biology.444 
 
 Lecture Table Clasps ....... 312 
 
 Lecture Table Connectors . . . 312, 313 
 Lecture Table Galvanometers . 338-341 
 
 Lecture Table Hardware Outfits 22, 23 
 Lecture Table Rheostat and Resis¬ 
 tance Frame.363 
 
 Lecture Table Ring Stand .... 485 
 
 Lecture Tables. 4, 5 
 
 Lenses. 258, 259 
 
 Lenses, Mounted. 259, 460 
 
 Lens Holders. 22, 245, 248 
 
 Leslie’s Cubes.206 
 
 Leveling Screws. 16 
 
 Leveling Table for Charles Law Tube, 
 
 Hall.225 
 
 Levels. 44 
 
 Lever and Supporting Table.... 127 
 
 Lever Clamps. 109 
 
 Lever Indicator. 94 
 
 Levers. 109, 126, 127 
 
 Lever Screw Compressor Clamp . . 423 
 
 Lever Support, Culler's.105 
 
 Leyden Jar Batteries.303 
 
 Leyden Jars. 301, 303 
 
 Leyden Jars. Resonant.377 
 
 Leyden Jar Dischargers .298 
 
 Liebig’s Condensers.211, 425 
 
 Life Slide.461 
 
 Lifting Magnets.332 
 
 Lift Pumps.140 
 
 Light Box. 255 . 
 
 Lightning Conductor.302 
 
 Lightning Jars.451 
 
 Lightning Plate.301 
 
 Lightning Spiral Tube.301 
 
 Light Screens. 245, 248 
 
 Lilliputian Projection Lamp .... 241 
 
 Lime Water.406 
 
 Linear Expansion Apparatus 221-224 
 
CATALOGUE OF SCIENTIFIC INSTRUMENTS 
 
 503 
 
 PAGE 
 
 PAGE 
 
 PAGE 
 
 Linen Tester. 259, 452 
 
 Lines of Force Apparatus.280 
 
 Liquid Conduction Tube.208 
 
 Liquid Interrupters.375 
 
 Liquid Interrupting Induction Coil 
 
 374, 375 
 
 Liquid Level Apparatus.137 
 
 Liquid Level Tubes.137 
 
 Liquid Measures. 32 
 
 Liquid Pressure Gauges.133 
 
 Liquid Pressure Tube, loaded, grad¬ 
 uated, F. & B.135 
 
 Liquid Pressure Tubes.135 
 
 Lissajous’ Curves Apparatus. . . . 193 
 
 Liter Blocks.29, 30 
 
 Liter Cases. 30 
 
 Liter Measures. 32 
 
 Litmus Paper. 452, 471 
 
 Litmus Pencil.452 
 
 Loaded Cylinder.100 
 
 Locomotive Chart.235 
 
 Lodestones.278 
 
 Lodestone Stirrup.278 
 
 Logarithm Tables. 452 , 487 
 
 Low Form Bunsen Burner.200 
 
 Low Temperature Thermometers 216 
 
 Luminous Cascade.251 
 
 Luminous Leyden Jar.303 
 
 Lummer-Brodhun Photometer . . . 246 
 
 Lungs, Models.469 
 
 Lycopodium Powder 194 
 
 Lyon's Car.103 
 
 M 
 
 Magdeburg Hemispheres. 157 
 
 Magnet and Friction Rod Support 279 
 Magnet and Meter Rod Supports . 281 
 
 Magnet Boards.279 
 
 Magnetic Compasses. 286, 287 
 
 Magnetic Distribution Apparatus. . 283 
 
 Magnetic Fields of Force Apparatus 
 
 279, 280 
 
 Magnetic Induction Coil.329 
 
 Magnetic Needles, mounted .... 285 
 
 Magnetic Pole Rotation Apparatus. 282 
 Magnetic Rotating Apparatus ... 83 
 
 Magnetic Screens.279 
 
 Magnetized Steel Disc.278 
 
 Magneto.395 
 
 Magnetometers . .. 281, 282 
 
 Magnetoscope.282 
 
 Magnets. 278, 279 
 
 Magnets, Floating.279 
 
 Magnets, Molecular. 278, 279 
 
 Magnet Stirrup.279 
 
 Magnet Supports.279 
 
 Magnifiers. 259 , 452 , 453 
 
 Make and Break Interrupter . . . 372 
 
 Manikins.453 
 
 Manometers.155 
 
 Manometer Tubes.133, 155 
 
 Manometric Flame Apparatus . . . 195 
 
 Manometric Flame Capsule .... 82 
 
 Marine Compass ..287 
 
 Mariotte’s Bottle.136 
 
 Marker Clamp and Stylus .... 95 
 
 Mason's Hygrometer.166 
 
 Material for Making Slides .... 463 
 
 Mathematical Models.67, 68 
 
 Mats, Cork.426 
 
 Maximum and Minimum Therrqome- 
 
 Maximum Density of Water Appara 
 
 tus.225 
 
 Maximum Density of Water Bulb 212 
 
 Measures of Length.31-37 
 
 Measuring Tapes. 34 
 
 Mechanical Equivalent of Heat Ap¬ 
 paratus . 230, 231 
 
 Mechanical Equivalent of Heat Tube 231 
 Mechanical Powers Apparatus . 109, 127 
 Mechanical Powers Support, Culler’s 105 
 Mechanical Powers, Weights for 62-63, 127 
 
 Mechanical Rotators.21, 77 
 
 Mechanical Stage.460 
 
 Medicine Droppers.472 
 
 Melting Point Tube.212 
 
 Mercury Pendulum. 65 
 
 Mercury Pole Changer.319 
 
 Mercury Pumps. 151 
 
 Mercury Still.482 
 
 Mercury Storage Funnel.146 
 
 Mercury Tube.306 
 
 Mercury Well. 148 
 
 Metalaphone.185 
 
 Metallic Coated Pith Balls .... 293 
 
 Metallic Thermometer.213 
 
 Metal Snips.478 
 
 Metalurgical Microscopes.457 
 
 Meteorological Equipments .... 169 
 
 Meteorological Thermometers . 163-165 
 
 Meter Rod Caliper Arms. 37 
 
 Meters, Indicating. 474, 475 
 
 Meter Stick Attachment, T-Beam . 26 
 
 Meter Stick Clamps.19, 26 
 
 Meter Stick, Comparative. 31 
 
 Meter Sticks . . 31, 32 
 
 Meter Stick Supports, metal ... 88 
 
 Meter Stick with Loop for String . 88 
 
 Metric Chart. 29 
 
 Metric Rules.32, 33 
 
 Metronome. 66 
 
 Mica Condensers.388 
 
 Micrometer Calipers.35, 36 
 
 Micrometer Screw Attachment, T- 
 
 Beam. 26 
 
 Micrometer Screws.38, 39 
 
 Microphone. 401 
 
 Microscope, Demonstration, M. & 
 
 G.266 
 
 Microscope Lamp.460 
 
 Microscope Model.266 
 
 Microscope Nosepieces.459 
 
 Microscopes. 454-458 
 
 Microscopic Slide Labels.452 
 
 Microscopic Slides ... 461, 462, 463 
 
 Microtome Freezing Attachment . . 466 
 
 Microtome Knife Back.466 
 
 Microtome Knife Handle.466 
 
 Microtome Knife Strop.466 
 
 Microtome Knives.466 
 
 Microtome Ribbon Carrier .... 465 
 
 Microtomes. 464, 465 
 
 Milk Dishes, Aluminum.432 
 
 Milk Pipettes.468 
 
 Milk Preservatives.468 
 
 Milk Test Bottles.468 
 
 Milk Testers. 467, 468 
 
 Milk Testing Apparatus . . . 467, 468 
 
 Miller-Cowen Attachment for Gilley 
 
 Gramme Machine.393 
 
 Miller Lantern Slides. 28 
 
 Millimeter Scale, mounted .... 95 
 
 Minder’s Manikin.453 
 
 Mineralite Thermopiles.219 
 
 Minerals and Rocks.469 
 
 Miner’s Compass.286 
 
 Minot’s Slide Cabinet.461 
 
 Mirror Attachment for Torsion Pen¬ 
 dulum . 92 
 
 Mirrors.249 
 
 Mirror, Scale and Support, M. G. & 
 
 B. 95 
 
 Mirrors, Concave and Convex, 
 
 mounted.244 
 
 Mirrors for Lissajous’ Curves ... 181 
 
 Mirrors, Galvanometer.348 
 
 Mirrors, Interference.272 
 
 Mirrors, Mounted. 22 
 
 Mirrors, Rotating.82, 83 
 
 Mixing Cylinders ... 429 . 447, 451 
 
 Model, Arch.126 
 
 Model, Arc Lamp.404 
 
 Model, Bridge, Davis’ ...... 124 
 
 Model, Controller.397 
 
 Model, Diving Bell.157 
 
 Model, Gas Engine.232 
 
 Model, Microscope.266 
 
 Model, Screw.119 
 
 Models, Crystal. 68 
 
 Models, Eye.259 
 
 Models, Naturalistic.175-178 
 
 Models, Physiological. 469, 470 
 
 Models, Pump.140 
 
 Models, Sectional of Steam Engine 
 
 233—235 
 
 Model, Steam Chest.233 
 
 Models, Telescope.266 
 
 Models, Turbine.142 
 
 Models, Valve.141 
 
 Models, Water Wheel.142 
 
 Model, Three Phase Current Motor 399 
 
 Model, Wedge.119 
 
 Mohr’s Burettes.419 
 
 Mohr’s Pinchcocks.423 
 
 Mohr's Pipettes.472 
 
 Molecular Magnet Model.279 
 
 Momentum Apparatus. 90 
 
 Monkey Wrench.405 
 
 Monochromatic Flame Burner . . . 240 
 
 Morse's Sympathetic Vibration Ap¬ 
 paratus .183 
 
 Mortar, Electric.302 
 
 Mortars .470 
 
 Motor-Dynamo Demonstation Ap¬ 
 paratus .391 
 
 Motor, Electrostatic.302 
 
 Motor Generators. 386, 390 
 
 Motors, A. C. and D. C.396 
 
 Motors and Dynamos .... 389-397 
 
 Motors, Small. 389, 390 
 
 Motors, Water.143 
 
 Mounted Transmission of Sound 
 
 Tube.185 
 
 Mounted Tuning Forks . 179, 181, 182 
 
 Mounting Board, Barometer . . . 160 
 
 Mounting Paper.472 
 
 Mounts, Microscopic. 462, 463 
 
 Mounts, Specimen.480 
 
 Muencke’s Aspirator. 153 , 407 
 
 Muffle Furnaces. 440-442 
 
 Muffles.470 
 
 Multiple Image Apparatus.250 
 
 Multiple Range Rotary Meter . . . 352 
 
 Multiple Range Self-Cooling Rectifier 385 
 
 Museum Jars.451 
 
 Mutual Action of Parallel Currents 283 
 
 N 
 
 National School Sonometer .... 189 
 
 Naturalistic Models.175-178 
 
 Natural Magnets.278 
 
 N. & F. Apparatus for Optical Disc 254 
 
 Needle, Inoculating.470 
 
 Needle Holder, Dissecting.433 
 
 Needles.279 
 
 Needles, Dissecting.433 
 
 Nessler’s Jars. 451, 470 
 
 Nessler’s Tubes.491 
 
 Net, Faraday’s. . 300 
 
 Nets, Blower.414 
 
 Newton’s Combination Disc .... 81 
 
 Newton's Rings.273 
 
 Nichol’s Pascal's Vase Apparatus 134 
 
 Nicholson's Hydrometers.131 
 
 Nickel and Ammonium Sulphate 403 
 
 Nickel Anode.403 
 
 Nickel Crucibles.427 
 
 Nickel Evaporating Dishes .... 431 
 
 Nickel Strip.279 
 
 Nickel Suspension Filaments . . . 348 
 
 Nicol’s Prisms.275 
 
 Nipper.405 
 
 Nipple, Brass.156 
 
 Nodon Valve.385 
 
 Normal Tuning Forks. 180 
 
 Normal Weights. 58 
 
 Nosepieces.459 
 
 O 
 
 Odd Angle Glass Prisms.260 
 
 Objectives, Achromatic .... 458, 459 
 
 Oculars.459 
 
 Oersted's Law Apparatus.327 
 
 Oil for Air Pumps.150 
 
 Oil-Sealed Air Pumps.150 
 
 Oil Stone. 405, 471 
 
 Oil Testers. •••••• 471 
 
 One Ohm Resistance, M. & G. 354 
 
 Opaque Screen, Black and White, 
 
 with Square Opening, F. & B. 248 
 Opaque Screen with Crossed Opal- 
 
 escent Square Opening, F. & B. 248 
 
 Opalescent Screen.245 
 
 Optical Bench Clamps.• 17 
 
 Optical Benches. 244-248 
 
 Optical Bench Outfits .... 247, 248 
 Optical Disc Accessories . . . 251-254 
 
 Optical Disc Glass Parts . . . • ■ 255 
 
 Optical Discs. 252 255 
 
 Optical Light Box.255 
 
 Optically Plane Mirror.348 
 
 Ores and Minerals.4bJ 
 
 Organ Pipes. J®* 
 
 Osborne’s Electrolysis Apparatus 402 
 
 Osmosis Apparatus. 75, 145 
 
 Osmosis Bulb.J’O 
 
 Osmotic Pressure Tube.140 
 
 Outside Calipers. 35 
 
 Overflow Can. 138 
 
 Overflow Pipettes.4/2 
 
 Ovens, Drying.435 
 
 Oversleeves.4 / * 
 
 "Oxone” Cartridges.440 
 
 Oxygen Gas Generator. 445 
 
 Ozone Generator Tube.3// 
 
 Packard’s Electrolysis Apparatus . 
 Packard’s Falling Body Apparatus 
 
 4(Xt 
 
 101 
 
504 
 
 L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 • > 
 
 PAGE 
 
 PAGE 
 
 PAGE 
 
 Page Motor Apparatus ....... 395 
 
 Palm or Pulse Glass, Franklin's . . 211 
 
 Pans, Agateware.471 
 
 Pan, Dissecting.433 
 
 Paper, Blackprint.280 
 
 Paper, Blueprint.280 
 
 Paper Brush.301 
 
 Paper, Carbon .101 
 
 Paper, Coated for Vibrograph . . . 191 
 
 Paper Condensers.388 
 
 Paper, Cross Section. 70, 101 
 
 Paper, Drying.472 
 
 Paper, Filter.437 
 
 Paper, Genus Covers.472 
 
 Paper, Litmus. 452 . 471 
 
 Paper. Mounting.472 
 
 Paper, Pole Test.300 
 
 Paper, Touch.207 
 
 Paper, various kinds.471 
 
 Papin Digestors.209 
 
 Parabolic Reflectors. 186, 205 
 
 Paraffine Baths.409 
 
 Paraffine Candles.239 
 
 Paraffine Cube.129 
 
 Parallel Current Apparatus .... 283 
 
 Parallel Current Repulsion Coils . . 329 
 
 Parallel Rule. 70 
 
 Parallelogram of Force Table ... 98 
 
 Paramagnetic and Diamagnetic 
 
 Study Apparatus.333 
 
 Paramagnetic and Diamagnetic Sub¬ 
 stances .279 
 
 Parchment Paper. 156, 471 
 
 Parr's Standard Calorimeters . . . 226 
 
 Pascal’s Vase Apparatus. . . . 134, 135 
 
 Pencil Compasses. 70 
 
 Pencil, Indelible.471 
 
 Pencil, Litmus.452 
 
 Pendulum Apparatus.104 
 
 Pendulum Balls. 86 
 
 Pendulum Bobs, Cylindrical .... 104 
 
 Pendulum Clamp, T. & H.104 
 
 Pendulum Clamps. 20 
 
 Pendulum, Foucault's, for Rotator . 79 
 
 Pendulum, Mercury. 65 
 
 Pendulums.104, 105 
 
 Pendulums, Compensating. 65 
 
 Pendulums, Seconds. 65 
 
 Pendulum Support, Culler's .... 105 
 
 Pendulums, Torsion.92, 93 
 
 Pendulum, Y or Sand.194 
 
 Penfield Goniometers. 41 
 
 Periodic Law Chart.422 
 
 Petri Dishes.432 
 
 Petri Dish Holder.471 
 
 Phenolphthalein Solution.406 
 
 Phials, Bologna. 73. 
 
 Phosphor Bronze Filaments .... 348 
 
 Phosphorescent Geissler Tubes . . . 306 
 
 Phosphorescent Mercury Tube . . . 306 
 
 Phosphorous Pentoxide.156 
 
 Photometers and Accessories . 242-248 
 
 Photometric Outfits ...... 247, 248 
 
 Photo Trays.488 
 
 Physics Direction Sheets. 27 
 
 Physics Tables. 2, 3 
 
 Physiological Models. 469, 470 
 
 Physiology Microscope Slides . 462, 463 
 
 Piano Wire.199, 311 
 
 Pickering Polariscope.274 
 
 Picture Wire.311 
 
 Pilz Manikins.. . . . 453 
 
 Pinchcocks.423 
 
 Pin Holder.248 
 
 Pin Hole Camera.242 
 
 Pipes, Clay.471 
 
 Pipestem Triangles.488 
 
 Pipettes, Acid.468 
 
 Pipettes, all kinds.472 
 
 Pipettes, Automatic.468 
 
 Pipettes, Graduated.406 
 
 Pipette Stand ..472 
 
 Pipette Support.484 
 
 Pins, Insect.471 
 
 Pitch Gauges.405 
 
 Pith.466 
 
 Pith Balls.293 
 
 Pith Ball Klectrometers.293 
 
 Pith Ball Electroscopes.293 
 
 Pith Images.300 
 
 Plane.405 
 
 Plane Mirrors.249 
 
 Plano-Convex Lenses. 258, 259 
 
 Plant Press.472 
 
 Plate Base, Andrews’. 12 
 
 Plate, Lightning.301 
 
 Plate, Colored Glass.267 
 
 Plates, Dessicator.430 
 
 Plates, Filter.437 
 
 Plates, Flush. 12 
 
 Plates, Glass.472 
 
 Plates, Image.300 
 
 Plates, Interference of Light . . . 273 
 
 Plates, various kinds.472 
 
 Plates with Projecting Needles, Hall 249 
 
 Platform Balances.54, 55 
 
 Platform Counter Scale. 54 
 
 Platforms. 15 
 
 Platinum Ware.473 
 
 Platinum Wire.311, 473 
 
 Pliers.405 
 
 Pliers, Side Cutting.474 
 
 Plotting Scales.33, 42 
 
 Plug Pole Changer.319 
 
 Plumb Bobs. 44 
 
 Plummets, Specific Gravity .... 130 
 
 Plunge Batteries. 323, 324 
 
 Pneumatic Troughs.489 
 
 Pocket Aneroid Barometers .... 162 
 
 Pocket Compasses, Magnetic. . 286, 287 
 
 Pocket Levels. 44 
 
 Pocket Magnifiers. 452, 453 
 
 Pocket Measuring Tapes. 34 
 
 Pocket Spectroscope.269 
 
 Pohl’s Commutator.319 
 
 Point Switches.316 
 
 Polariscopes.274 
 
 Polariscope Specimens.276 
 
 Polarization Study Apparatus . . . 274 
 
 Polarized Light Accessories .... 276 
 
 Polarized Light Attachments. . . . 254 
 
 Pole Changers.319 
 
 Pole Test Paper.300 
 
 Policemen, Rubber.477 
 
 Polyprisms. 262, 263 
 
 Porcelain Base Switches.316 
 
 Porcelain Beakers.413 
 
 Porcelain Casseroles.421 
 
 Porcelain Combustion Boats .... 425 
 
 Porcelain Crucibles. 427-429 
 
 Porcelain Evaporating Dishes . . . 431 
 
 Porcelain Funnels.439 
 
 Porcelain Mortars.470 
 
 Porcelain Plates. 472 
 
 Porcelain Retorts.476 
 
 Porcelain Spoons.479 
 
 Porcelain Tube, F. & B.313 
 
 Porcelain Tubing.492 
 
 Porosity Demonstration Apparatus . 72 
 
 Porous Cups. 429, 474 
 
 Porte Lumieres.239 
 
 Portraits of Scientists. 28 
 
 Potash Bulbs.419 
 
 Potassium Cyanide.403 
 
 Potential Bar.289 
 
 Practical Physics Apparatus . . 121-127 
 
 Pratt Institute Applied Physics Ap¬ 
 paratus . 121-127 
 
 Pratt Institute Inclined Plane . 117, 121 
 Pratt Institute Index of Refraction 
 
 Apparatus.257 
 
 Precision Weights. 59 
 
 Preparation Dishes. 432, 481 
 
 Primary and Secondary Coils . . . 372 
 
 Prince Rupert Drops. 73 
 
 Principal Focus Box, Culler's . . . 248 
 
 Prism, Equilateral, M. & G. . . . 256 
 
 Prism Gratings.273 
 
 Prisms. 260-263 , 271 
 
 Prisms, Foucault’s.275 
 
 Prisms, Mounted.263 
 
 Prisms, Nicol's.275 
 
 Prisms, Triangular, wood. 94 
 
 Preservatives, Milk.468 
 
 Press, Plant.472 
 
 Presses, Cork.426 
 
 Pressure of Gas Apparatus .... 146 
 
 Pressure Gauge for Apparatus A. . 203 
 
 Pressure Gauge Projection Holder . 133 
 
 Pressure Gauges. 133, 146, 155 
 
 Pressure Syringes.132 
 
 Pressure Tubes.133, 155 
 
 Pressure U-Tubes.135 
 
 Projection Apparatus.277 
 
 Projection Apparatus, Magnetic 
 
 r«! Lines of Force.280 
 
 Projection Electroscopes . . . 294, 295 
 
 Projection Frequency Indicator. . . 398 
 
 Projection Galvanometer.340 
 
 Projection Holder'.133 
 
 Projection Lamps.241 
 
 Proof Plane.298 
 
 Protectors, X-Ray Tube.310 
 
 Protractors, Instrument for Making 43 
 Protractor Rule and Square .... 40 
 
 Protractors.40-42 
 
 Protractor Triangles. 40 
 
 Psychrometer.166 
 
 Pulley Assortments. Ill 
 
 Pulley Attachment, T-Beam .... 26 
 
 Pulley Cord • • Ill 
 
 Pulley Demonstration Apparatus 114, 115 
 Pulley, Drive, for Round Belt ... 78 
 
 Pulley Hoists, Differential.113 
 
 Pulley in Frame.117 
 
 Pulley Rope.112 
 
 Pulleys.110-117 
 
 Pulleys, mounted. 22 
 
 Pulley Support, Culler’s.105 
 
 Pumice.403 
 
 Pump, Carboy.474 
 
 Pump Models.140 
 
 Pump Oil and Can.156 
 
 Pump Plates.151 
 
 Pumps, Air.149-153 
 
 Punch.405 
 
 Push Buttons.316 
 
 Pyknometers . . •■.130, 418 
 
 Pyrex Glassware.494 
 
 Pyrex Glass Beakers.412 
 
 Pyrometers. 220, 474, 475 
 
 Pyrometer Tubes.475 
 
 Q 
 
 Quadrant Electrometer .... 296, 302 
 
 Quadrant Protractors. 43 
 
 Quart Measure. 32 
 
 Quartz Prisms . . ..261 
 
 Quick Acting Clamp.423 
 
 Quincke's Tubes.188 
 
 R 
 
 Racks for Bottles.444 
 
 Radiation Apparatus.302 
 
 Radiation Screens.206 
 
 Radio Active Substances.297 
 
 Radio Electroscopes. 294-296 
 
 Radiographs.476 
 
 Radiometers.204 
 
 Radio Micrometer.345 
 
 Rain Gauges.167 
 
 Rams, Hydraulic.139 
 
 Ratio Box.360 
 
 Rayboum Quadrant Electrometer . 296 
 
 Razors, Section.433 
 
 Razor Strop.466 
 
 Reaction Gas and Flame Wheel . . 141 
 
 Reaction of Gas Apparatus .... 141 
 
 Reaction of Liquids Apparatus . . 141* 
 
 Reaction Wheel, Acoustic.197 
 
 Reading Lens. 259, 452 
 
 Reagent Bottles.416, 417 
 
 Reagents and Stains.497 
 
 Recalescent Outfit.475 
 
 Receivers, Retort.476 
 
 Receivers, Telephone.400 
 
 Receivers, Wireless Head Band . . 384 
 
 Recording Barometer.162 
 
 Recording Drums.192 
 
 Recording Thermometers.165 
 
 Recording Tuning Fork.181 
 
 Record(Sheets, Kymograph .... 192 
 
 Rectifiers. Electrolytic.385 
 
 Reflecting Level. 44 
 
 Reflecting Sextants.267 
 
 Reflection Apparatus.250 
 
 Reflection of Heat Apparatus . . . 205 
 
 Reflection of Sound Apparatus. . . 186 
 
 Reflectors, Parabolic ..... 186, 205 
 
 Refraction Tank for Optical Disc . 254 
 
 Refraction Tanks. 256, 257 
 
 Registering Anemometers.168 
 
 Registering Rain Gauge.167 
 
 Regulating Rheostats. 363. 364 
 
 Regulator, Gas Pressure.446 
 
 Regulators, Gas.446 
 
 Relay, Telegraph.. 400 
 
 Relief Models.175-178 
 
 Repulsion Coils.329 
 
 Resin.199 
 
 Resistance Board.• 355 
 
 Resistance Boxes. 357-362 
 
 Resistance Coils. 354-356 
 
 Resistance Frame.363 
 
 Resistances, Spool.354 
 
 Resistances, Standard. 355, 356 
 
 Resistance Units. 363 , 365 
 
 Resonance Apparatus.190, 191 
 
 Resonance Tubes.190, 191 
 
 Resonant Leyden Jars.377 
 
 Resonators.197 
 
 Respiration Models.469 
 
 Retorts.476 
 
CATALOGUE OF SCIENTIFIC INSTRUMENTS 
 
 505 
 
 PAGE 
 
 Retort Stands.485 
 
 Reversible Pendulums.104, 105 
 
 Reversing Key . ..318 
 
 Revolving Disc.302 
 
 Revolving Dustproof Nose-Pieces . 459 
 
 Revolving Mirror.82, 83 
 
 Rheochords.355 
 
 Rheostats. 363, 364 
 
 Ribbon Carrier, Microtome ... 465 
 
 Richards' Aspirators. 153 , 407 
 
 Richards’ Blast Apparatus .... 413 
 
 Richmond’s Slide Rule.468 
 
 Rider Block.109 
 
 Rider Weights. 59 
 
 Right Angle Clamps .... 16. 17, 19 
 
 Right Angle Prisms. 260-263 
 
 Riker Mounts.480 
 
 Ring Burners.420 
 
 Rings, Ring Stand.476 
 
 Ring Stand Rings.476 
 
 Ring Stands.485 
 
 Rintoul’s Dynamometer.57 
 
 Rip Saw.405 
 
 Ritchie Photometer.242 
 
 Ritchie Reversing Key.319 
 
 Rocks and Minerals.469 
 
 Rods for Torsion.92, 94 
 
 Rods, Friction.289 
 
 Rods, Glass, Fused Silica . v . . . 477 
 
 Rods, Support.: . . 10 
 
 Rod, Steel, M. G. & B. 94 
 
 Rod V-Clamp Attachment, T-Beam 26 
 
 Rod, Waterproof.129 
 
 Roentgen Ray Apparatus . . . 309, 310 
 Rollers, Inclined Plane . . . . 117, 121 
 
 Roof Truss. 123 
 
 Rope, Pulley.112 
 
 Rose’s Crucible .•.429 
 
 Rotary Compressors. 152 
 
 Rotary Converters.386 
 
 Rotary Field Apparatus for A. C . . 399 
 
 Rotary Meter for D. C.352 
 
 Rotary Microtome. 464, 465 
 
 Rotating Mirrors.82, 83 
 
 Rotator Globe and Dish. 80 
 
 Rotators.21, 77, 78 
 
 Rotators, Geissler Tube.307 
 
 Rouge.403 
 
 Rouge Cloth.403 
 
 Round Bases. 11 
 
 Round File.437 
 
 Round Leather Belt. 21 
 
 Royal Worcester Porcelain Ware 495 
 
 Rubber Bags. 156, 445 
 
 Rubber Bands. 477 
 
 Rubber Base Switches. ...... 316 
 
 Rubber Cord.108 
 
 Rubber Cord for Inertia Experiment, 
 
 Hall.118 
 
 Rubber Dam or Thin Sheet . . 156, 477 
 
 Rubber Discs for Blowers . . . 414, 477 
 
 Rubber Friction Rod.. . 289 
 
 Rubber Gaskets for Alundum Cru¬ 
 cibles .428 
 
 Rubber Gaskets for Filter Cones 437 
 
 Rubber Hammers. 179 
 
 Rubber Policemen.477 
 
 Rubbers, Friction Rod.289 
 
 Rubber Spatula.479 
 
 Rubber Stoppers.478 
 
 Rubber Tubing. 200, 477 
 
 Rubber Tubing for Gooch Crucibles 429 
 
 Ruhmkorff Cods.373 
 
 Ruled Cardboard Strip. F. & B. 266 
 
 Rule, Parallel. 70 
 
 Rules.32, 33 
 
 Rumford’s Photometer.243 
 
 Rutherford’s Prisms. 261, 271 
 
 S 
 
 Saccharometer. 
 
 .478 
 
 Safety Lamp, Davy’s . . 
 
 .208 
 
 Safetv Tubes. 
 
 .491 
 
 St. Louis Motor . . . . 
 
 .391 
 
 Sand Apparatus .... 
 
 .302 
 
 Sand Baths. 
 
 .409 
 
 Sand, Chladni's Plate . . 
 
 .194 
 
 Sand Crucibles. 
 
 .429 
 
 Sand Paper . 
 
 .471 
 
 Sand Pendulum .... 
 
 .194 
 
 Savart's Wheels .... 
 
 . 81 
 
 Saws. 
 
 .405 
 
 Scale Pans. 
 
 ... 94, 109 
 
 Scales . 
 
 
 Scalpels. 
 
 .433 
 
 Scheibler’s Dessicators 
 
 .430 
 
 Scissors. 
 
 .478 
 
 PAGE 
 
 Shellbach’s Burettes.419 
 
 Schellbach’s Support. 484 
 
 Scissors, Dissecting.433 
 
 Scoop, Horn.478 
 
 Screen, Electric.299 
 
 Screen Holders.. . 245, 248 
 
 Screens, Absorption and Radiation 206 
 
 Screens, Magnetic.279 
 
 Screens, Optical Bench .... 245, 248 
 
 Screen with Apertures.245 
 
 Screen with Vertical Slit.245 
 
 Screw Compressor Clamps .... 423 
 
 Screw, Cork.426 
 
 Screw Drivers.405 
 
 Screw Gauge. 39 
 
 Screw Jack with Wheel, Base and 
 
 Bar.127 
 
 Sealing Wax.493 
 
 Seasonal Twilight Chart. 172 
 
 Secondary Basic Attachment, T- 
 
 Beam. 26 
 
 Secondary Supports. 13 
 
 Second Law of Motion Apparatus . . 90 
 
 Seconds Pendulums. 65 
 
 Section Lifters.433 
 
 Section Razors.433 
 
 Selenium Cells.401 
 
 Self Induction Apparatus.387 
 
 Self Induction Coils.387 
 
 Self Leveling D’Arson val Galva¬ 
 nometer. 344, 345 
 
 Self Registering Thermometers . 163, 164 
 
 Semi-blast Wynne Burner.201 
 
 Separatory Funnels.439 
 
 Set Square, Universal. 70 
 
 Seven-in-One Apparatus.138 
 
 Sextants.267 
 
 Sharpener, Cork Borer.426 
 
 Shear Legs.122 
 
 Shears.478 
 
 Shears, Metal.405 
 
 Sheet Cork.426 
 
 Sheeting, Rubber.156 
 
 Shell Vials.492 
 
 Shelters, Instrument.169 
 
 Shelves, Digesting.430 
 
 Shocking Handles.301 
 
 Shocking Handles and Cords . . . 298 
 
 S-Hook. 55 
 
 Short Circuit Keys.318 
 
 Shot, Lead, Copper, Aluminum . . 229 
 
 Show Jars, Inverted.451 
 
 Shredder and Shave, Ice.204 
 
 Shunts.347 
 
 Sieves.478 
 
 Sifter, Filings.280 
 
 Sight Compasses, Magnetic .... 287 
 
 Silica Beakers.413 
 
 Silica Capsules.421 
 
 Silica Casseroles .421 
 
 Silica Combustion Boats.425 
 
 Silica Crucibles.428 
 
 Silica Dishes.432 
 
 Silica Evaporating Dishes.431 
 
 Silicon Detector.384 
 
 Silk Exciting Pad.289 
 
 Silver Anode.403 
 
 Silver Chloride.403 
 
 Singing Flame Apparatus.183 
 
 Single Contact Key.317 
 
 Single Plug Switch.318 
 
 Single Rod Attachment, T-Beam . 26 
 
 Sinker, Lead.128 
 
 Siphons. 137, 479 
 
 Siren Discs.81, 82 
 
 Sirens, Caignard-La-Tour.188 
 
 Six’s M. & M. Thermometer ... 163 
 
 Skidmore Battery.320 
 
 Skin Model.469 
 
 Skins, Birds'.413 
 
 Skull and Brains, Model of ... . 470 
 
 Slide Boxes.461 
 
 Slide Cabinet.461 
 
 Slide, Holman’s Life.461 
 
 Slide Making Material.463 
 
 Slide Rule, Richmond’s for Milk 468 
 
 Slide Rules. 42 
 
 Slides, Microscopic.461 
 
 Slides, Prepared Microscopic 462, 463 
 
 Slide Wire Bridges. 368, 369 
 
 Sliding Caliper. 36 
 
 Sling Psychrometer.166 
 
 Slit Diaphragm.239 
 
 Slope Level. 44 
 
 Smith School Squares. 40 
 
 Smoke Condensation Apparatus . . 301 
 
 Snips, Metal.405 
 
 Sodium Capsule.479 
 
 Sodium Spoon.479 
 
 PAGE 
 
 Soft Iron Bar.279 
 
 Soft Iron Horseshoe Core, M. G. & 
 
 0 B.279 
 
 Soil Sieves.478 
 
 Soil Thermometer. 164 
 
 Solar Calculator.173, 174 
 
 Solder.479 
 
 Soldering Copper. 1 . . 479 
 
 Soldering Fluid.479 
 
 Soldering Iron, Electric.436 
 
 Soldering Iron Heaters.479 
 
 Soldering Outfits.479 
 
 Soldering Paste.479 
 
 Solenoid Magnet.331 
 
 Solenoid with Movable Coil .... 331 
 
 Solid Alcohol.406 
 
 Sonograph.196 
 
 Sonometer Attachment, M. G. & B. 117 
 
 Sonometers. 189 
 
 Sonometer Wires.189 
 
 Sounder Parts, Telegraph.400 
 
 Sounder, Telegraph.400 
 
 Soun4 Lens. 187 
 
 Soxhlet’s Copper Condensers. . . . 425 
 
 Soxhlet’s Extraction Apparatus . . 436 
 
 Soxhlet’s Extraction Tubes .... 436 
 
 Spark Gaps, Wireless.383 
 
 Spatulas.479 
 
 Spatulas, Platinum.473 
 
 Specific Gravity Apparatus . . 128-131 
 
 Specific Gravity Apparatus for gases 72 
 Specific Gravity Balances . . . . 53. 54 
 Specific Gravity Bottles .... 130, 418 
 Specific Gravity Plummets .... 130 
 
 Specific Gravity Specimens . . 128, 129 
 Specific Heat Apparatus, Tyndall's 229 
 
 Specimen Bottles.418 
 
 Specimen Jars.451 
 
 Specimen Mounts. 480 
 
 Specimens, Polariscope.276 
 
 Specimens, Slide Making.463 
 
 Specimens, Zoological.480 
 
 Spectral Apparatus and Goniometer 269 
 
 Spectrometer.270 
 
 Spectroscopes. 269, 270 
 
 Spectroscopic Prisms. 261, 271 
 
 Spectrum Charts.267 
 
 Spectrum Tubes.271 
 
 Speed and Power Rotator. 78 
 
 Speed Indicator for Rotator .... 79 
 
 Speed Indicators. 67 
 
 Speedometers. 67 
 
 ■ Spheres, all kinds. 86 
 
 Spherometers. 38 
 
 Spindle and Clamp. 21 
 
 ‘‘Spinning Tops”. 85 
 
 Spiral Hygrometer.166 
 
 Spiral Spring.108 
 
 Spirometer. 138 
 
 Splints.479 
 
 Splint Ring Pole Charger.319 
 
 Sponges.479 
 
 Spool Resistances.354 
 
 Spoons.479 
 
 Spreader for Trip Scale. 55 
 
 Spring and Weight Holder, M. G. & 
 
 B. 95 
 
 Spring Balances.56, 57 
 
 Spring Magnetometer.282 
 
 •Spring Punch.405 
 
 Squares.40-42 
 
 Staining Box, Glass.461 
 
 Staining Jar : . . ..451 
 
 Staining Jar, Coplin's.451 
 
 Stains and Reagents.497 
 
 Standard Candle.246 
 
 Standard Cells.325 
 
 Standard Meter. 34 
 
 Standard Resistances. 355, 356 
 
 Standard Sources of Light .... 246 
 
 Standard Thermometers.215 
 
 Stand, Electrostatic.301 
 
 Stands, Insulating.297 
 
 Stands, X-Ray Tube.310 
 
 Stand Tops. 14 
 
 Stand Tubes. 13 
 
 Stand, Universal. 87 
 
 Star, Burner.420 
 
 Star Chart.172 
 
 Static Electrometers.293 
 
 Steam Boiler and Engine.237 
 
 Steam Boilers. 203, 238 
 
 Steam and Electric Power Plant . 238 
 
 Steam Chest Model. 233 
 
 Steam Engine Models .... 233-235 
 
 Steam Engines. 233-238 
 
 Steam Power Plants. 237, 238 
 
 Steam Traps.204 
 
 Steam Water Baths.411 
 
L. E. KNOTT APPARATUS CO 
 
 BOSTON 
 
 506 
 
 • > 
 
 PAGE 
 
 Steel Filings in Glass Tube .... 278 
 
 Steel Mortar.470 
 
 Steel Rules. 33 
 
 Steel Spatulas.479 
 
 Steel Suspension Filaments .... 348 
 
 Steelyard.109 
 
 Steelyard, Laboratory.126 
 
 Stencil.481 
 
 Stencil Cut-Outs.481 
 
 Stender Dishes. 432, 481 
 
 Sterilizers.481 
 
 Stills.210, 482 
 
 Stirrer for Calorimeter.227 
 
 Stirrup, Magnet.279 
 
 Stone’s Tension Clamps. 97 
 
 Stone’s Tension Clamps, T-Beam . 26 
 
 Stools, Insulating.297 
 
 Stop Clock. 66 
 
 Stopcock, Gas.445 
 
 Stopcocks, Brass.156 
 
 Stopcocks, Glass.483 
 
 Stoppers. Rubber.478 
 
 Stop Watch. 66 
 
 Storage Batteries.325 
 
 Storage Battery Hydrometers . . . 448 
 
 Storage Jars.451 
 
 Storage Tanks, Air.153 
 
 Stove, Electric.436 
 
 Stoves. 201, 483 , 484 
 
 Straight Edge Rule. 33 
 
 Streak Plate.472 
 
 Stretching Block with Pillar and 
 
 Binding Post. 95 
 
 Strip with Two Hooks, T. & H. 115 
 
 Strop.466 
 
 Students' Optical Disc.255 
 
 Students’ Table, Biology.444 
 
 Stylus and Fixative.191 
 
 Substage Condensers.459 
 
 Substances, Radio Active.297 
 
 Sulphuric Acid Cryophorous .... 212 
 
 Sulphur Specimen.128 
 
 Sun Dial. 66 
 
 Sun Dial and Compass.287 
 
 Sunlight Projectors.239 
 
 Sun Spectrum Chart.267 
 
 Support Blocks, Wood, M. G. & B. 94 
 
 Support Board for Composition of 
 
 Forces. 97 
 
 Support, Brass.129 
 
 Supporting Boards, Magnet .... 279 
 
 Support, Magnet and Friction Rod. 279 
 
 Support Rods. 10 
 
 Supports.11-16 
 
 Supports, Trip Scale. 55 
 
 Supports, Tube.403 
 
 Supports, various kinds .... 484-486 
 
 Surface Tension Apparatus . . . 73-76 
 
 Suspension Filaments, Galvanometer 348 
 Swiftest Descent Apparatus .... 106 
 
 Switches, Electrical.316 
 
 Swivel Post Attachment, T-Beam 26 
 
 Sympathetic Tuning Forks.182 
 
 Sympathetic Vibration Apparatus . 183 
 
 Syracuse Watch Glasses.493 
 
 Syringe, Hyperdermic.486 
 
 Syringes, Pressure.132 
 
 T 
 
 Table, Aquarium.406 
 
 Table Clamps .... 13, 16, 21, 25, 26 
 Table for Parallelogram of Forces . 98 
 
 Tables, Biology.444 
 
 Tables, Laboratory.2-5, 8, 444 
 
 Table, Microtome.464 
 
 Table Top on Rod.245 
 
 Tablets, Composite Test, for Milk . 468 
 
 Table, Warming.466 
 
 Tackle Blocks. 112 
 
 Tangent Galvanometers .... 335, 336 
 
 Tangent Scale. 43 
 
 Tank, Aquarium.406 
 
 Tanks, Air Storage.153 
 
 Tantalus Cup.137 
 
 Tap and Die Set.405 
 
 Taper Gauge, Inside. 39 
 
 Taper Gauge, Outside. 39 
 
 Tapering Zinc Element, T. & H. . 320 
 
 Tapers, Wax.493 
 
 Tapes, Measuring. 34 
 
 T-Beam Basic Tank.140 
 
 T-Beam Clamps and Attachments 24-26 
 
 T-Beam Water Pumps.140 
 
 Teeth Model.469 
 
 Telegraph Instruments.400 
 
 PAGE 
 
 Telegraph Key Parts.400 
 
 Telegraph Sounder Parts.400 
 
 Telephone, Battery Call.401 
 
 Telephone Receiver.400 
 
 Telephone Transmitter.400 
 
 Telephonic Microphone.401 
 
 Telescope and Scale.349 
 
 Telescope Clamp. 21 
 
 Telescope for Radio Active Work . 295 
 
 Telescope Models.266 
 
 Telescopes. 264-266 
 
 Tellurian.170 
 
 Temperature Coils.354 
 
 Tenacula.433 
 
 Tensile Strength of Wires Apparatus 96 
 
 Tension Clamps, Stone’s. 97 
 
 Terrestrial Telescope Model .... 266 
 
 Tesla Motor.399 
 
 Test Glasses. 446 , 487 
 
 Test Tube Basket.487 
 
 Test Tube Brushes.419 
 
 Test Tube Clamps.423 
 
 Test Tubes, all kinds.487 
 
 Test Tube Supports.486 
 
 Theater Cable.311 
 
 Thermit Reaction Apparatus. . . . 487 
 
 Thermo-Couples.475 
 
 Thermo-Electric Batteries.220 
 
 Thermographs. 165 
 
 Thermograph Charts.165 
 
 Thermometer, Dairy.468 
 
 Thermometers, all kinds . . . 213-218 
 
 Thermometer, Soil. 164 
 
 Thermometers, Maximum and Min¬ 
 imum . 163, 164 
 
 Thermometers, Meteorological . 163-165 
 
 Thermometers, Recording.165 
 
 Thermopiles.219 
 
 Thermoscopes.217 
 
 Thimbles, Extraction.436 
 
 4Q1 
 
 Thousand Ohm Resistance,' M. & G. 354 
 
 Thorpe Gauge.229 
 
 Threaded Hook.120 
 
 Three Phase Current Motor Model 399 
 
 Three Rod Attachment, T-Beam . 26 
 
 Time Marker. 192 
 
 Tin Foil. 293, 487 
 
 Tip, Burner.420 
 
 Toepler-Holtz Machines .... 290. 291 
 
 Tongs, Crucible.429 
 
 Tool Cabinet and Tools.405 
 
 Tool Holders.405 
 
 Tools.405 
 
 Torrentium Oil.150 
 
 Torricellian Law Apparatus .... 136 
 
 Torsion Apparatus.91-93 
 
 Torsion of Beams Apparatus. . . 91, 92 
 
 Torsion of Beams Attachments, T- 
 
 Beam. 26 
 
 Torsion Pendulums.92, 93 
 
 Torso Model.470 
 
 Total Reflection Apparatus .... 251 
 
 Total Reflection Prisms . . 260-263, 271 
 
 Touch Paper.207 
 
 Tourmaline Tongs.275 
 
 Transformer, Demonstration .... 370 
 
 Transformer, Dissectible.371 
 
 Transformers, Wireless.383 
 
 Transformers, Wireless Oscillating . 383 
 
 Translucent Screen.245 
 
 Transmission Diffraction Gratings . 273 
 
 Transmission of Sound Tube, 
 
 mounted.185 
 
 Transmitter, Telephone.400 
 
 Traps, Steam or Water.204 
 
 Trays.488 
 
 Tray, Ice.204 
 
 Trevelyan’s Rocker.198 
 
 Triangle Demonstration Apparatus 68 
 
 Triangle Holders, Platinum .... 473 
 
 Triangles, Platinum.473 
 
 Triangles, various kinds . . . 40, 70, 488 
 
 Triangular File.'. . . 437 
 
 Triple Beam Balance. 54 
 
 Triple Connectors.315 
 
 Triple Tandem Pulleys.112 
 
 Tripod Bases. 11 
 
 Tripod, Burner.420 
 
 Tripod Magnifier.452 
 
 Tripod, Rod, Clamp and Holder, M. 
 
 1 G. & B. 148 
 
 Tripods, various kinds.489 
 
 Tripoli.403 
 
 Trip Scales. 55 
 
 Trip Scale Supports. 55 
 
 Troughs, Absorption.272 
 
 Troughs, Glass.262 
 
 Troughs, Pneumatic.489 
 
 PAGE 
 
 Trough, Wave.108 
 
 Trowbridge Galvanometer.334 
 
 Troy Weights. 61 
 
 Trumpet.187 
 
 Trunk Model. 470 
 
 Trusses. 123 
 
 T-Square. 70 
 
 T-Tubes.490 
 
 Tube, Beveled Glass, T. & H. . . 209 
 
 Tube, Boiling Point of Alcohol, M. 
 
 & G.209 
 
 Tube, Brush.419 
 
 Tube, Burner.420 
 
 Tube Clamp. 19 
 
 Tube Cutters, Glass ....... 447 
 
 Tube Furnaces. 440, 441, 443 
 
 Tube Gauge. 39 
 
 Tube, Hopkins’ Forked.188 
 
 Tube, Lightning Spiral.301 
 
 Tube, Manometer.133, 155 
 
 Tube, Mechanical Equivalentof Heat 231 
 
 Tube, Melting Point.212 
 
 Tube, Ozone.377 
 
 Tubephone.185 
 
 Tubes, all kinds. 489-491 
 
 Tubes, Arsenic.407 
 
 Tubes, Barometer. 148 
 
 Tubes, Cathode Ray or Vacuum 308 , 309 
 
 Tubes, Charles Law.225 
 
 Tubes, Crooke’s. 308, 309 
 
 Tubes, Extraction, Soxhlet’s .... 436 
 
 Tubes, Fractional Distillation . . . 435 
 
 Tubes, Gas Measuring.446 
 
 Tubes, Gas Sample.445 
 
 Tubes, Geissler. 305-308 
 
 Tubes, Liquid Level.137 
 
 Tubes, Liquid Pressure.135 
 
 Tubes, Pressure. 133, 155 
 
 Tubes, Pyrometer.475 
 
 Tubes, Quincke’s Interference . . . 188 
 
 Tubes, Resonance.190, 191 
 
 Tubes, Spectrum.271 
 
 Tube Supports.403 
 
 Tubes, Vapor Tension.209 
 
 Tubes, Waterman’s Charles Law . 225 
 
 Tubes, X-Ray.309 
 
 Tube, Tyndall’s Sound.198 
 
 Tube, Vapor Pressure.209 
 
 Tube, Volume Coefficient, M. G. & B. 225 
 
 Tubing, Alundum.492 
 
 Tubing, Fused Silica.489 
 
 Tubing, Glass. 491 
 
 Tubing, Glass Combustion .... 492 
 
 Tubing, Porcelain.492 
 
 Tubing Rubber.200 
 
 Tubing, Vacuum.156 
 
 Tumeric Paper. 471, 492 
 
 Tuning Coil.384 
 
 Tuning Fork Apparatus.191 
 
 Tuning Forks.179-182 
 
 Tuning Forks, Unadjusted . . 181, 191 
 
 Tuning Forks, Sympathetic .... 182 
 
 Tuning Fork, Vibrograph.191 
 
 Turbines, Water.142 
 
 Turn Table.461 
 
 Turrets, Gas.445 
 
 Twilight Chart.172 
 
 Two-part Iron Armature, T. & H. 279 
 Tyndall’s Heat Attachment for Ro¬ 
 tator . 80 
 
 Tyndall’s Sound Tube.198 
 
 Tyndall’s Specific Heat Apparatus 229 
 
 U 
 
 Unadjusted Cast Iron Weights . 63, 127 
 
 Unadjusted Tuning Forks . . . 181, 191 
 Unequally Evacuated Geissler Tubes 307 
 
 Ungraduated Thermometer.213 
 
 Uniform Pressure Syringes .... 132 
 
 Uni-Polar High Frequency Coil . . 378 
 
 Universal Holder. 18 
 
 Universal Lecture Table Galvanome¬ 
 ter . 338, 339 
 
 Universal Pulleys.113 
 
 Universal Stand. 87 
 
 Universal Stand, Electrostatic . . . 301 
 
 Upward Pressure Apparatus . . 134, 135 
 
 U-Shaped Magnet.278 
 
 U-Shaped Wire Supporting Hook, 
 
 T.&H . 109 
 
 U-Tubes, Pressure.135 
 
 V 
 
 Vacuum Gauges. 146 
 
 Vacuum Pumps . . 149-153 
 
CATALOGUE OF SCIENTIFIC INSTRUMENTS 
 
 507 
 
 PACE 
 
 Vacuum Tubes. 308 , 309 
 
 Vacuum Tubing. 156 
 
 Valve Models.141 
 
 Valve Regulator. 80 
 
 Vapor Pressure Tube.209 
 
 Vapor Tension Apparatus.209 
 
 Vapor Tension Tubes.209 
 
 Vasculum. 492 
 
 Vase Shape Beaker.412 
 
 Vegetable Parchment.156 
 
 Velocity of Sound Apparatus . . . 199 
 
 Vernier Arc Model. 31 
 
 Vernier Caliper Model. 37 
 
 Vernier Calipers.36, 37 
 
 Vernier CaKper Strip. 31 
 
 Vernier Models. 31 
 
 Vertical Index Block.249 
 
 Vertical Laminated Magnet Galva¬ 
 nometer .343 
 
 Vertical Luminators.460 
 
 Vials.492 
 
 Vibration Apparatus for Sound . . 198 
 
 Vibration Frequency Apparatus . . 191 
 
 Vibration of Rod Apparatus . . 198 
 
 Vibrating Spiral Apparatus .... 283 
 
 Vibrograph.191 
 
 Vibrograph Tuning Fork.191 
 
 Vinegar Tube.491 
 
 Viscosimeter.493 
 
 Viscosity Apparatus. 72 
 
 Vise Clamp for Bench ....... 90 
 
 Vises.493 
 
 Volt-Ammeters.353 
 
 Voltmeters. 350-353 
 
 Volume Coefficient Tube. M. G. & B. 225 
 
 Volumetric Flasks.439 
 
 Volumetric Pipettes.472 
 
 Von Nardroff Color Apparatus . . 268 
 
 Vulcanite Friction Rod.289 
 
 W 
 
 Wall Bracket, Galvanometer . . . 346 
 
 Wall D’Arsonval Galvanometer . . 346 
 
 Wall Stand. 15 
 
 Warming Table.466 
 
 Washers, Leather.156 
 
 Washing Bottles.418 
 
 Waste Jars.451 
 
 Watch Glasses.493 
 
 PACE 
 
 Watch Springs.493 
 
 Water Baths.410, 411 
 
 Water Batteries. 297, 324 
 
 Water Faucets. 9 
 
 Water Friction in Pipes.141 
 
 Water Hammers.156 
 
 Water Heater.493 
 
 Water Heater, Electric.436 
 
 Water Lenses.259 
 
 Waterman's Charles Law Tubes . . 225 
 
 Water Motors. 143 
 
 Water Stills.210, 482 
 
 Water Thermometer.225 
 
 Water Traps.204 
 
 Water Turbines.142 
 
 Water Wave Apparatus.108 
 
 Water Wheel Model.142 
 
 Watt’s Governor. 80 
 
 Wave Motion Apparatus . . . 107, 108 
 
 Wave Trough.108 
 
 Wax Friction Rod.289 
 
 Wax, Sealing.493 
 
 Wax Tapers.493 
 
 Weather Bureau Barometer .... 160 
 
 Weather Bureau Hygrometers . 166, 167 
 Weather Bureau M. & M. Thermome¬ 
 ters . 163, 164 
 
 Wedges. 119 
 
 Wedge Shape Troughs .262 
 
 Weighing Bottles.418 
 
 Weight Hangers. 62, 63, 127 
 
 Weights.58-63 
 
 Weinhold’s Demonstration Prisms 
 
 262, 263 
 
 Weinhold’s Rotary Field Apparatus 399 
 Welsbach Gas Mantle, mounted . . 244 
 
 Westphal's Balance. 53 
 
 Wet and Dry Bulb Hygrometers . 166 
 
 Whatman Filter Paper.437 
 
 Wheatstone Bridges and Resistance 
 
 Boxes. 360-362 
 
 Wheatstone Bridges. 366-369 
 
 Wheel and Axle. 115 
 
 Whirl, Electrostatic.301 
 
 Whirling Tables.21, 77, 78 
 
 Whistles, Galton's.184 
 
 Whistle with Sliding Piston .... 183 
 
 Wicks, Lamp.452 
 
 Wilson’s Radio-Electroscope .... 295 
 
 Wimshurst Machines. 290, 292 
 
 Wing Top, Burner.420 
 
 PAGE 
 
 Wire, all kinds.311-313 
 
 Wire, Bent at Right Angles, Hall . 248 
 
 Wire Gauges. 39 
 
 Wire Guard.157 
 
 Wireless Adjustable Spark Gaps . . 383 
 
 Wireless Apparatus. 382-384 
 
 Wireless Condenser. 384 
 
 Wireless Detectors.384 
 
 Wireless Head Band Receivers . . 384 
 
 Wireless High Potential Condensers. 383 
 Wireless Oscillating Transformers 383 
 
 Wireless Receiving Outfit.382 
 
 Wireless Sending Outfit.382 
 
 Wireless Transformers.383 
 
 Wire Pentagon, T. & H. 99 
 
 Wire, Piano.199 
 
 Wire, Platinum.473 
 
 Wires, Galvanometer.348 
 
 Witch.100 
 
 Wollaston’s Cryophorous.211 
 
 Wollaston Steam Engine.233 
 
 Wollaston Wires.348 
 
 Wooden Strip with Two Hooks, T. 
 
 & H. 115 
 
 Wood Models of Crystals .... 68 
 
 Wool, Glass.447 
 
 Wrench.405 
 
 Wynne Burners.201 
 
 X 
 
 X-Ray Pictures.476 
 
 X-Ray Tube Protectors.310 
 
 X-Ray Tubes.309 
 
 X-Ray Tube Stands.310 
 
 Xylophone.185 
 
 Y 
 
 Young’s Modulus Apparatus ... 95 
 
 Y-Pendulum.194 
 
 Y-Tubes.490 
 
 Z 
 
 Zinc and Carbon Battery Connectors 326 
 
 Zinc Condensers.425 
 
 Zinc Wire.311 
 
 Zoological Material.480 
 
 Zoloogy Microscope Slides . . 462, 463 
 

 
 
GETTY CENTER LIBRARY 
 
 3125 00140 3159