Bausch & Lomb Balopticons C. W. Courtney Company 731 South Hope St. | Los Angeles, California es a ey sue] oJ Jessy, quo] 29 Yosneg YIM UAB], “x ‘N ‘raysoyooy ‘SyIOM QUOT 3 Yosneg Jo ydvigoj0yd [ley Balopticons and Accessories Copyrighted 1920, by Bausch & Lomb Optical Co. Revised Sept. 1923, and Feb. 1924 Bausch & Lomb Optical Co. ochiester, aN aie New York Chicago San Francisco Washington London - DD-5, I-24, 7M Branches and Forein Agencies We maintain branch offices in New York, Chicago, Washington and San Francisco, where sample lines of our products are carried for the inspection of our customers. Our representatives will be found well versed in all the phases of our business, glad to extend every courtesy and to give any desired information. Our products are supplied also by dealers in the United States and Can- ada and by our agents in foreign countries. Branches NEW YORK: Bausch & Lomb Optical Co., Pershing Square Building, Park Avenue and 42nd Street. WASHINGTON, D. C.: Bausch & Lomb Optical Co., 613 Fifteenth St. N.W. Cuicaago, Iuu.: Bausch & Lomb Optical Co., 5 No. Wabash Ave. SAN FRANcIScOo, CAu.: Bausch & Lomb Optical Co. of Cal., 28 Geary St. ENGLAND, Lonpon: Bausch & Lomb Optical Co., Ltd., 37 and 38 Hatton Garden, E. C. Foreign Agencies AUSTRALIA, SYDNEY, N.S. W.: Donald Ross & Co., Ltd., Angel Place, off 12 ea itte st. BRAZIL, RIO DE JANEIRO: J. Pinho, Caixa Postal 1126. CHINA, SHANGHAI: Edward Evans & Sons, Ltd., 30 North Szechuen Road. ITALY, MILANO: Henry Coe & Clerici, Via Settembrini 11. Andrews & George Co. JAPAN . TOKYO: Central P. O, Box F-25 OSAKA: 119 Nichome Yedobori, Minanidori, Nishiku. KOREA, SEOUL: Andrews & George Co. MANCHURIA, DAIREN: Andrews & George Co. PHILLIPINE ISLANDS, MANILA: Clark & Co., Escolta 90-94. NEW ZEALAND, WELLINGTON: Waterworths Limited, 286 Lambton Quay. BAUSCH & LOMB OPTICAL CO. EXECUTIVE OFFICE AND MANUFACTORY ROCHESTER, N. Y. *j Lic Poems ¢ ge, $ — TH 7 CENTER Preface Although this is not a complete catalog of all our projection line, in that it does not include our micro-projection apparatus and other instru- ments for special work, it contains all the models required for ordinary projection purposes. We shall be glad to send our complete projection catalog, or information concerning any equipment not listed here, upon request. During the remarkable development of motion pictures in recent years “still” projection has more than held its own. It is today more widely recognized than ever before as a necessary adjunct to the more serious purposes of visual instruction and entertainment. ‘To meet all the varied requirements of both purposes in the most efficient manner possible has been our constant aim throughout the twenty years in which we have been developing this line. The user of projection apparatus will find in the following pages much information of interest and value regarding the various possibilities and applications of optical projection. The trade name, ‘‘Balopticon’’, by which we designate our lanterns, has long since become standardized among those interested in the highest grade projection apparatus. The prefix, ‘“‘Bal’’, is derived from the Greek verb, “ballein’’, meaning to throw or project. Incidentally it contains the initials of our company and is rightfully used only by us. Back of our projection apparatus, as all of our products, are nearly seventy years of scientific and productive experience as optical manufactur- ers. The different instruments offered have resulted from the combined efforts of our Scientific and Technical Bureaus, working constantly in co- operation with the users of such apparatus, whose suggestions are always given serious attention. In the actual manufacture we enjoy the advantage of producing practi- cally all parts, mechanical as well as optical, in our own works. This now includes our basic raw material, optical glass, the manufacture of which we successfully developed, before and during the war, for the first time in Amer- ica. We are thus enabled not only to assure the effective co-ordination of the different parts, but to give all of our Balopticons and accessories the unqualified guarantee which our name conveys. BAUSCH & LOMB OPTICAL CO. Terms When ordering from this catalog, please give catalog number, name of article and size. Use code words in telegraphing. Credit and Financial Standing. To avoid delay, purchasers with whom we have no account and who have no mercantile rating, should ac- company their first order with commercial references or remittance in cash, money orders, or New York or Chicago current funds, as your local check may be subject to collection charges. Under an arrangement made by the Western Union Telegraph Co. orders can now be sent by telegraph between points in the United States, in the same message with remittance. Code words or catalog numbers may be used. Information may be secured on application to nearest Western Union manager. Cc. O. D. Shipments. No C. O. D. shipments will be made unless sufficient funds to cover delivery charges both ways accompany the orders. Goods made on special order, or to be sent on memorandum account, will not be forwarded C. O. D. Quotations. Our prices are f. o. b. Rochester, N. Y. Transportation for goods sent on memorandum or for examination is at the expense of the customer. Liability. In packing we double check all goods, and obtain proper receipts from the transportation companies. Unless otherwise specified, we shall use our best judgment in mode of shipping, prepaying transportation if requested and adding amount to invoice. Our responsibility ceases when we have delivered a shipment to the carriers. All claims for breakage should be reported to the transportation companies at once, as we cannot be held responsible for losses or damage to goods in transit. Please examine all pack- ing minutely for small items. Guarantee. We exercise the utmost care in manufacturing and pack- ing. In case of faulty goods inadvertently reaching our customers, we shall feel under obligation if our attention is called thereto. Returning of Goods. Goods being returned for any reason should be plainly tagged with the sender’s name and address. Special identification tags are furnished on request. Wherever possible, please give date of invoice on which the goods were originally billed. Notice. Prices in this catalog are subject to change without notice. We make no charge for boxing or packing and no allowance for freight, express or parcel post charges. BAUSCH & LOMB OPTICAL CO BAUSCH & LOMB OPTICAL COMPANY Introductory HILE optical projection, in a crude form, was known as far back as 1700, its scientific and universal application is of comparatively re- cent development. Unappreciated and undeveloped for generations, it has come into its own at last, till today it is an agency of widely known value in the scientific and educational world and in many other fields of usefulness. A projection lantern is now a recognized necessity in every completely equipped church, Sunday school, school or lecture hall. Since there are models that project either lantern slides or opaque objects, or both, their range of usefulness is very wide. The bodies of our Balopticons are of sheet metal, stamped out by special forming tools, making a light but durable instrument. They are finished with a dull, black lacquer thoroughly baked in a high temperature oven. This treatment produces a rich, black finish which is both serviceable and appropriate. Construction. There are a number of different illuminants that can be utilized to supply the light for projection purposes: the gas-filled Mazdas, the most recently and highly developed; the hand-feed arc lamp; and the acetylene burner. Wherever possible, we recommend that a Mazda lamp be used, for such a lamp is the most convenient to operate and gives the best results. The 6-volt lamp, for use with a storage battery, makes possible the use of a Mazda lamp even where electricity is not available. Illuminants. The condensing lenses play an important part in the optical system of any projection apparatus, as the uniformity of illumi- nating and the size of the illuminated field are dependent on the purity of the glass they are made from and on the correctness of their focal length. The condensing system furnished with the Balopticons shown in this catalog is a double system, consisting of two plano convex lenses with the convex sides facing each other. Optical Parts Improvements on the optical parts of our Balopticons have been in keeping with the mechanical development, as evidenced by our series of Balo projection lenses. These superior objectives are of an entirely new type of construction, particularly well corrected for flatness of field and critical definition. They are made in three series as described under ‘‘A ccessories.”’ In purchasing an apparatus for the projection of either lantern slides or opaque objects a point which should receive careful attention is the selection of an outfit with the correct focal length of lens to meet the specific requirements satisfactorily. The focal length of the projection lens, all other conditions being equal, determines the size of picture on the screen. In selecting an apparatus, therefore, one Hi Size of Picture should determine the distance at which the lantern is to be placed from the screen and the size of picture desired. With these two factors given, the focal length of lens required can readily be determined by reference to one of the tables here given. We would particularly caution Baloptican users not to make the mistake, too often made when working with a projection lantern, of deciding upon too large a picture. Any picture out of proportion in size to the distance at which it is being viewed appears unnatural and lacking in perspective and is a strain to the eyes of the observer. Where the regular lighting circuits are available, lamps for 110 volts are ordinarily used. For higher voltages, the 220-volt resistance, p. 40, must be used in series with the lamp, as it has not been found practical to make this type of lamp for high voltage, since that would necessitate the use of a more fragile filament and a larger light source. The focal lengths here tabulated are those which are listed with some one of our different Balopticons for either lantern slides or opaque objects. The tables give in feet the length of one side (the longer in case of lantern slides) of the screen image to be obtained at the different projection dis- tances and with the different lens foci indicated. Table 1: For Lantern Slides, 234 x 3-inch Mat Opening Distance from Lantern to Screen Focus of Lens 15 ft.| 20 ft.| 25 ft.| 30 ft.| 35 ft.) 40 ft.| 45 ft.| 50 ft./ 60 ft.) 70 ft.| 80 ft. 6-inch 744 | 10 12% 8-inch 544| 7%| 94%) 11%) 13 15 10-inch 44| 6 1419 104% | 12 13% 12-inch 5 644 | 74%| 834] 10 1144 | 12%] 15 15-inch 4 5) 6 7 8 4) 10 12 14 16% 18-inch 5 534 | 644| 714%] 8%) 10 li yds Example:—A 10-inch lens used at a distance of 40 feet from the screen will project an image measuring 12 feet on its longer side. Table 2: For Opaque Objects, 6 x 6-inch Opening Distance from Lantern to Screen Focus of Lens 15 ft. | 20 ft. 25 ft. 30 ft. 35 ft. 15-inch 54% 7% 9% 11% 18-inch 414 6 8 914 Tt See page 34 for longer focus lenses. For lantern slide projection only the white opaque screens will be found entirely satisfactory. With such a screen the room need be only partially darkened. When projecting opaque objects we strongly recommend the use of an aluminum coated screen, as that will materially increase the brilliancy of the image. The room in which such an apparatus is used should be totally darkened. BAUSCH & LOMB OPTICAL COMPANY Balopticon Model A In simplicity, compactness and portability, this little in- strument is unexcelled for lan- tern slide projection in class rooms, small auditoriums, and in the home. While it is a truly portable lantern, none ) of the optical and mechanical features so essential to best projection results have been sacrificed. Essentially this instrument is constructed along the lines of our Model B Balopticon, which has long occupied a premier position among small lantern slide projectors. It has the same lamp housing, lamp, reflector and optical parts, but the carrying case is an integral part of the equipment, serving as a supporting base and bellows when the lantern is in operation. The Balo projection lens, of 12-inch focus and 12 or 232. inch diameter, is fastened to a plate behind a spring door which opens in the front of the case. It is adjustable by means of a spiral focusing mount. On the rear of the case is a door which lets down to a horizontal position, allowing the lamp house easily to slide in and out of the case on metal tracks, a stop being provided to give it the correct location for use with the 12-inch focus lens. In front of the lamp housing are mounted the two plano-convex condens- ing lenses. They are 432, inches in diameter, sufficiently large to illuminate evenly the entire surface of the slide. The case, when closed, measures 131% inches long, 11 inches high and 61% inches wide. It is provided with a strong handle and because of the even balance of the outfit is extremely easy to carry. Code Word Cat. No. Specifications Price Daabs AM 12q Model A Portable Balopticon with 110-volt, 400- watt Mazda lamp with ground and polished glass reflector; 15 feet of extension cord and connect- ing plug; 15 in. diam., 12 in. focus projection lens; 4;°; in. condensers; double slide carrier and carrying case. $70.00 Daact AM 12 Same, but with 25-in. diam.., ‘12-in. focus lens. 75.00 Daadv AM 6V 12q Same as AM 12q but with 6- ‘volt, 24-watt Mazda lamp for use with storage battery. . st: 67.00 Daafw AM 6V 12 Same, but with 2;5 in. diam., 12-in. focuslens... .. 72.00 Daahy AM 30V 12q) Model A Portable Balopticon, as described, but with 30-volt, 14-ampere Mazda lamp for use on individual Bene circuits, 1% in. diam., 12 in. focus lens. . us 75.00 Duajz AM 30V 12 | Same, but with Qi in. diam., 12 in. focus lens. . 80.00 Daakb AG 12q Model A Portable Balopticon as described, but with acetylene burner, 15 in. diam., 12 in. focus lengins id: Sclode sactina Merc eae ee ie ee 67.00 Daalc AG 12 Same, but with 2;5 in. diam., 12 in. focuslens.. ... 72.00 9 BAUSCH & LOMB OPTICAL COMPANY Model B Balopticon ee a i Model B with Mazda Lamp and 2;;-Inch Diameter Lens This compact, efficient little instrument met with instant success when placed upon the market a few years ago and has increased in popularity con- stantly until it is now one of the most widely known for use with lantern slides only in school rooms, small auditoriums, Sunday school rooms, lodges and in the home. Because of its demonstrated merit it has been adopted as standard equipment by several organizations which distribute large numbers of lanterns. It is constructed throughout of a substantial weight of sheet metal, the - various-parts being made with special forming tools, thus providing light- ness in weight, rigidity and durability. The finish is a smooth black through- out. The top of the lamp house is removable, permitting easy access to the illuminant, and the base is provided with an adjustable plate in which may be interchanged the 400-watt, 110-volt lamp, which is entirely silent and automatic, and can be attached to any ordinary lamp socket, the 6-volt lamp or the acetylene burner. The 30-volt, 14-ampere lamp requires a special plate, as it must be provided with a mogul socket. The condensing lenses, two plano-convex, fit in a square mounting con- necting the lamp house and slide carrier support. Each condenser is held in place by a metal guide, while the hinged cover of the mounting has two clips, which hold the condenser in position and prevent their shaking about during shipment. The cover is fastened down by a small set screw. Our well-known Balo projection lenses are supplied with this instrument They are made in diameters of either 1°, or 27° inches. The former are made in 6, 8 and 10-inch focal lengths, mounted in either a spiral or rack and pinion focusing mount, and the latter in 10, 12 or 15-inch focal lengths, in rack and pinion focusing mount. The larger diameter is particularly re- commended, because of the fact that the illumination is increased approxi- mately 40 per cent. over that of the smaller diameter. A very compact metal case, into which the lantern may be easily placed, is regularly supplied with each equipment, affording an easy means for carry- ing the instrument and a dust-proof cabinet in which to store it when not in use. BAUSCH & LOMB OPTICAL COMPANY Specifications Base—Consists of front and rear metal standards, front standard fitted with elevating device, carried on sliding rods which have extension to accom- modate 15-in. lens. Lamp House—Of sheet metal with special ventilation; measures 614 x 7 x 5 in. with removable top; all illuminants interchangeable in one housing. Illuminant—Our 400-watt, 110-volt, gas-filled Mazda lamp, 30-volt, 14- ampere Mazda, 6-volt Mazda, or two-jet acetylene burner. Condensing System—Our regular double system, 4;5-in. diameter, in special ventilated mount from which lenses can be easily removed for cleaning. Slide Carrier—Our double carrier, No. 4430, with elevating device. Bellows—Mounted on metal frames which slide in metal ways. Projection Lens—Balo lens of 15¢ or 2;5-in. diameter and of focus as listed below. Dimensions—Length (ready for operation), 22 in.; height, 934 in. Weight—Complete in case, 13-15 lbs., depending on equipment. Case—Sheet metal, 7144 x 91% x 15 in., lacquered in black; with carrying strap. *The quick changing slide carrier, No. 4449, giving a dissolving effect, may be substi- tuted for $3.00 extra. Wecan supply to order carriers for small slides, so that one may use either the standard slide or the special small size now being offered. With Mazda Lamp Code Word | Cat. No. Specifications Price Dhurj BM 6qs | Model B Balopticon with 400-watt, 110-volt Mazda lamp, with ground and polished glass re- flector; 15 feet of extension cord with connecting plug and switch; double slide carrier; metal carry- ing case; and 154-in. diam., 6-in. focus projec- tion lens in spiral focusing mount.............. | $54.00 Dhusk BM 8qs | Same as above, but with 8-in. focus lens......... 54.00 Dhutl BM 10 qs _ | Same as above, but with 10-in. focus lens........ 54.00 Dhuom BM 6q Same as above, but with 6-in. focus projection lens in rack and pinion focusing mount.............. 57.00 Dhuxp BM 8q Same as above, but with 8-in. focus lens........ 57.00 Daanf BM 10q Same as above, but with 10-in. focus lens........ 57.00 Daapg BM 10 Same as above, but with 2;7;-in. diam., 10-in. focus projection lens in rack and pinion focusing mount | 65.00 Daarh BM 12 Same as above, but with 12-in. focus lens........ 65.00 Daasj BM 15 Same as above, but with 15-in. focus lens........ 65.00 Daatk BM 30 V10 |} Model B Balopticon with 30-volt, 14-ampere (420- watt) Mazda lamp with ground and polished glass reflector; 4 feet of extension cord with switch and connector; double slide carrier; metal carrying case; and 2;-in. diam., 10-in. focus projection lens in rack and pinion focusing mount.......... 70.00 Daal BM 30 V12/| Same as above, but with 12-in. focus lens........ 70.00 Daazn BM 30 V15| Same as above, but with 15-in. focus lens........ 70.00 Daazr BM 6V10!| Model B Balopticon with 6-volt Mazda lamp with silvered globe, supplementary condenser and six feet of extension cord fitted with switch and con- necting lugs for attaching to storage battery; double slide carrier; metal carrying case; and 2;3- in. diam., 10-in. focus projection lens in rack ANd pINion 1OCUsINS MOUND.) cscs eee ee or 63.00 Daebt BM 6V12| Same as above, but with 12-in. focus lens........ 63.00 Daecy BM 6V15| Same as above, but with 15-in. focus lens........ 63.00 tig Code Word Daedw Daegy Daehs BAUSCH & LOMB OPTICAL COMPANY Cat. No. BG 10 BG 12 BG 15 With Acetylene Burner Specifications Model B Balopticon with two jet acetylene burner, fitted with ground and polished glass reflector and 6 feet of rubber hose; double slide carrier; metal carrying case; and 2;;-in. diam., 10-in. focus projection lens in rack and pinion focusing mount Same as above, but with 12-in. focus lens........ Same as above but with 15-in. focus lens ........ Illuminants for Model B Balopticon No. 4461 No. 4462 No. 4502 Price Code Word Cat. No. Specifications Daemf Daeng Daeph Daerj 4461 4462 4515 4502 400-watt Mazda Lamp with reflector, socket, 15 feet of extension cord, connecting plug and switch for use on Model. B. «2 .....20.p4) 03); 10 oe 2-jet Acetylene Burner with ground and polished glass reflector, mounted on a base to interchange with socket for 400-watt lamp on Model B; with 6 feet of rubber. hose... ... 1...) . 52) 30-volt, 14-ampere (420-watt) Lamp with re- flector, mogul socket and clamp for attaching to sliding plate on bottom of lamp house, 4 feet of ex- tension cord and connector for use on Model B.. 6-volt Mazda Lamp with silvered bulb supple- mentary condenser on support to interchange with socket of 400-watt lamp, 6 feet of extension cord, switch and connecting lugs... .. . i... @oeeeee Price $13.50 10.50 18.50 11.50 NotE—To those who desire a 30-volt lamp to interchange with the regular 110-volt, 400-watt lamp, we can supply a 30-volt, 250-watt lamp with medium screw base at the same price as the regular 400-watt lamp. For extra bulbs see page 38. 12 BAUSCH & LOMB OPTICAL COMPANY Special Travelling Outfits . The Model B Balopticon naturally ap- peals to those who travel with a stereopti- con because of its compactness and light weight. For this purpose we have designed a special carrying case of wood covered ‘with leatheret, with metal corners and locks. This outfit can be shipped as bag- - gage or by express with perfect safety. Space is provided in this case for the Balopticon, together with a separate com- partment in which an acetylene burner, an extra Mazda lamp or a quantity of slides may be carried. The top of the case is fitted with a partition to form a compart- ment in which a sateen screen may be car- ried. Another feature of this portable equip- ment is the accessory carrying case for a 10-cu. ft. acetylene tank, which may be attached to the bottom of the regular carrying case for use when one is traveling where electricity is not available. In many cases the traveling lecturer will be unable to obtain a table of suitable height for the support of the lantern, so we have arranged to utilize the case for this purpose by attaching to its end the board which forms the compartment for the screen. The elevating rods fitted to the front standard of the Balopticon make it possible to tip the lantern to bring the picture on the screen. Code Word | Cat. No. Specifications Price Daejb BMP 12 Model B Balopticon with 400-watt, 110-volt Mazda lamp, 27;-in. diam., 12-in. focus lens in rack and pinion mount; in special carrying case of wood covered with black leatheret, with metal corners aNdalOGKS fiery nate ae aa amet eh ee es EN $92.50 Diacs BMP 6V12 | Same as above, but with 6-volt, 24-watt Mazda lamp in place.of the 400-watt lamp..............:.--. 90.50 Daekce BGP 12 Same as above, but with double-jet acetylene burner in place of Mazda lamp and with special glass re- Hector fittedm lamp house...) q.ceuer eee 89.50 Diabr BMGP 12 | Model B Balopticon with 400-watt, 110-volt Maz- da lamp and with acetylene burner to interchange with Mazda lamp; with lens and carrying case as described above: pati wk. Nees cae tet eae ee 102.00 Daeld 4529 Accessory Carrying Case for 10-cubic-foot acetylene tank-as described! svia-y. oe ae ee ee 17.50 NOTE—We are listing with this outfit the 12-inch focus lens, which is the one generally required. The 10 or 15-inch focus lens can be supplied at the same price. If one of these is preferred, substitute “10” or ‘15’ for the numeral ‘'12” in the above catalog numbers. We recommend that an extra Mazda lamp be included in traveling outfits to guard against possible breakage or burning out. For prices see page 38. 13 BAUSCH & LOMB OPTICAL COMPANY Model BC Balopticon Model BC with Mazda Lamp and 2;%-Inch Diameter Lens This new Balopticon follows the general lines of Model B, but is enough larger to accommodate the 600-watt tubular-shaped. Mazda lamp—the most powerful illuminant allowed on an ordinary lighting circuit by the Board of Underwriters. With this lamp, the only illuminant regularly supplied for this model, ample illumination is provided for screen images up to 12 feet in width. The highly corrected Balo projection lenses are fur- nished in either 10, 12, 15 or 18-inch focal lengths, depending upon the projection distance and the size of the picture required. A spherical glass reflector with a mounting by means of which it is attached directly to the lamp bulb is supplied, thereby assuring the user of the great- est efficiency from the Mazda lamp. This instrument is highly recommended and will prove an ideal instru- ment for class rooms and moderate sized auditoriums where the regular 110-volt lighting system only is available. Specifications Base—Consists of front and rear metal standards, front standard fitted with elevating device, carried on sliding rods which have extension to accom- modate 15-in. lens. Lamp House—Of sheet metal with special ventilation; measures 934 x 7144 x 8 in., with removable top; all illuminants interchangeable in one housing. Iluminant—Our 600-watt, 110-volt, tubular-shaped, Mazda lamp. Condensing System—Our regular double system, 4;%-in. diameter, in special ventilated mount from which lenses can be easily removed for cleaning. *Slide Carrier—Our double carrier, No. 4430, with elevating device. Bellows—Mounted on metal frames which slide in metal ways. 14 BAUSCH & LOMB OPTICAL COMPANY Projection Lens—Balo lens of 2;-in. diameter, and of 10, 12, 15 or 18-in. focus. Dimensions—Length (ready for operation), 26-in.; height, 13 in. Weight— Without case, 141% lbs. Case—Can be used as carrying case or dust-proof cabinet. *The quick changing slide carrier, No. 4449, giving a dissolving effect, may be sub- stituted for $3.00 extra. We can supply to order carriers for small slides, so that one may use either the standard slide or the special small size now being offered. Code Word | Cat. No. Specifications Price Daesk BCM 10 | Model BC Balopticon with 600-watt, 110-volt, tu- bular-shaped Mazda lamp, with ground and polished glass reflector; 15 feet of extension cord with connecting plug and switch; double slide carrier; metal carrying case; and 2;;-in. diam., 10-in. focus projection lens in rack and pinion TOCISING NOUN tanta ey ee ani eee eon eae So $75.00 Daetl BCM 12 | Same as above, but with 12-in. focus lens........ 75.00 Daevm BCM 15 | Same as above, but with 15-in. focus lens........ 75.00 Daexp BCM 18 | Same as above, but with 18-in. focus lens........ 77.00 15 BAUSCH & LOMB OPTICAL COMPANY Model BB Dissolving Balopticon Model BB with Dissolving Rheostat and 2;3;-inch Diameter Lenses. It is an accepted fact that the most pleasing way of projecting lantern slides is with a dissolving view lantern, by means of which the “racing” of the slide across the screen or a short interval of darkness between slides is entire- ly eliminated. This not only relieves eyestrain, but the dissolving of one view into the succeeding one produces a very pleasing effect. A number of devices have been produced for use on a single lantern for which claims of producing dissolving views have been made, but they either show movement of the slide upon the screen or produce momentary darkness. True dissolving effects can only be produced by the use of two lanterns fitted with a device by means of which the pictures are projected alternately by one lantern and then the other. Believing that this feature in a projecting lantern makes a strong appeal, we have designed the Model BB Balopticon, which is very compact and extremely simple to operate. This is truly two lanterns in one, as there are two light sources and two complete optical systems side by side in the one lantern body. This construction makes possible the maximum compact- ness and eliminates the setting up and adjusting of the average double dis- solving lantern. No more adjustments are required than in the ordinary lantern, except the adjustment of the lenses by means of sliding plates on the front standard, so that the pictures are superimposed on the screen. By means of the construction employed the complete equipment can be put in one carrying case—a decided advantage to travelling lecturers or to those who cannot leave their apparatus permanently installed. The dissolving effect, or the change from one picture to the next, is ac- complished by a resistance with sliding contact, which gradually cuts off the current to one lamp and turns it on in the other at a corresponding rate so that the screen is never dark. The effect produced with this device is a very pleasing one because there is no abrupt change, as one picture gradually dis- solves into the succeeding one. Two 400-watt Mazda lamps are used, but due to the particular way in which they are connected up, there are never more than 400 watts drawn at 16 one time, so that the apparatus requires only one lead of wire and can be connected to any regular lighting socket. In addition to this advantage the cutting off of the lamp when not required increases the length of service and materially reduces the heat. Specifications Base—Consists of front standard supporting projecting lenses, and sliding rods connecting with lamp house. Lamp House—Of sheet metal, specially ventilated, with removable top fo1 access to lamps; measures 7 x 95% x 1014 in. Illuminant—Two 400-watt gas-filled Mazda lamps with glass reflectors connected with dissolving rheostat. Condensing System—Two regular double systems, 435 in. diameter, in special ventilated mount from which lenses can be easily removed for cleaning. Slide Carrier—Permanently fastened in front of condensing system, with grooves for either American or English size of slide. Bellows—Mounted on metal frames which slide in metal ways. Projection Lens—Two of our regular Balo lenses, either 15¢ in. diameter or 2°; in. diameter, as desired. Dimensions—Length (ready for projection with 15-in. focus lenses) over all, 261% in. Weight—Complete in case with 23% in. diameter lenses, 30 lbs. Case—Sheet metal, 15% x 10% x 1014 in., lacquered in black; with hinged side door, two catches and carrying strap. Code Word | Cat. No. Specifications Price Daigz ‘| BBM 10q | Model BB Dissolving Balopticon with two 400- watt, 110-volt Mazda lamps with ground and polished glass reflectors; two 154-in. diam., 10-in. focus projection lensesin rack and pinion mounts; dissolving rheostat with 15 feet of extension cord, switch and connecting plug; metal carrying case |$134.00 Dathb BBM 10 Same as above but with 2;,-in. diam., 10-in. focus projection lenses ei 7..u yc ee ee ee 150.00 Daikd BBM 12 Same as above but with 12-in. focus projection lenges etc yy ties at eee ae ee ee ee 150.00 Dailf BBM 15 Same as above but with 15-in. focus projection lonsés.y. 23 See as Ce ee eee 150,00 i Stereoscopic Projection with Model BB Balopticon The Model BB Balopticon can be used for stereoscopic projection as well as regular projection purposes. Two slides, made from stereoscopic negatives, are used, the two pictures being superimposed on the screen. A blue-green glass filter is placed over one lens and a red glass filter, the com- plement of the blue-green, over the other lens, while the screen is viewed through spectacles having red and green lenses corresponding to the filters over the lenses. True stereoscopic effect is produced in this manner, objects appearing in correct relation to each other. This apparatus will be found of particular value in the departments of Biology, Anatomy and the like, where the third dimension is of such vital importance. When using the instrument for this purpose, the dissolving resistance must be eliminated, as both lamps have to be operated at full brilliancy, which is accomplished by means of an extra extension cord. Code Word | Cat. No. Specifications Price Daimg 4262 Pair of Complementary Glass Filters, one red and one green, in mountings to fit on front of pro- jection lens...) 0s a ee $7.50 Dainh 4264 Pair of Spectacles with red and green lenses... . 2.25 Daipj 4266 Extension. Cord. . ) 20. 0.5....4..: 310 Lvs 18 BAUSCH & LOMB OPTICAL COMPANY =) Model C Balopticon No. CA 10—Model C with Arc Lamp The Model C Balopticon was the first projection lantern to be made en- tirely of sheet metal by means of forming tools. It at once met with general approval and is still one of the most popular instruments for lantern slide projection. The interchange of illuminants has been made very simple, as each of the various illuminants is provided with a saddle support which slides on the two rods at the side of the lamp house. The rear of the lamp house is fitted with a hinged shield or door, which may be raised and the illuminant with- drawn for adjustment or interchange. 7 eee i e as No. CM 10—Model C with Gas-Filled Mazda Lamp Five different illuminants, the 90° hand-feed arc lamp, 400-watt, 110- volt Mazda lamp, 30-volt, 420-watt Mazda lamp, 6-volt, 24-watt Mazda lamp and the acetylene burner, all fitted with a base providing ready inter- changeability, may be used with this equipment. The 400-watt, 110-volt lamp is recommended for general use where electricity is available, while the 30 volt, 420-watt lamp can be used on individual lighting plants and the 6-volt, 24-watt lamp or acetylene burner where electricity is not avail- able. For long distance projection, where a large picture is to be projected, the arc lamp, which must be used with a rheostat, is recommended. Selec- tion of the rheostat should be made according to conditions. See page 39. 19 BAUSCH & LOMB OPTICAL COMPANY The projection lenses are of our Balo series, the highest grade lenses made for lantern slide projection. They are made in two diameters for use with the arc lamp, 154 and 2; in., but the 235 in. is recommended for use with the other illuminants. Double Dissolving Model C with Are Lamps Two Model C units can be connected, one above the other, as shown in the above illustration, by means of special connecting parts and the lenses fitted with a pair of iris dissolvers so arranged that one diaphragm closes as the other opens. If the 400-watt, 110-volt Mazda lamp is used, the dis- solving rheostat regularly supplied with the Model BB can be used instead of the iris diaphragm. Either of these combinations produces a perfect dis- solving effect, making such an equipment ideal for auditorium use. As the two units can be easily,disconnected, they can be used also as single lanterns in different rooms. Specifications Base—Consists of metal feet on bottom of lamp house and front metal standard of one piece with front board, the whole carried on sliding rods; front standard provided with elevating device for tilting instrument as desired. | Lamp House—Of sheet metal, fitted with our special, patent, light-tight ventilator and provided with two observation windows; measures 614 in. long, 11 in. high and 6 in. wide, asbestos lined. Illuminant—Hand-feed are lamp for direct or alternating current with adapters for small carbons, gas-filled Mazda lamp or acetylene burner. Condensing System—Our regular double system in ventilated mount; diameter, 43% in. 20 BAUSCH & LOMB OPTICAL COMPANY *Slide Carrier—Our double carrier, No. 4430, with elevating device. Bellows—Mounted on metal frames which slide in metal ways, with ex- tension sufficient for 18-inch focus lens. Projection Lens—Our Balo lens with rack and pinion adjustment. Dimensions—Length, extended, 27 in. without lens; height, 11 in. Weight—Alone, 14 lbs.; in case, 24 Ibs. Case—Of metal, neatly lacquered in black, measuring 2234 x 12 x 7 in. and provided with carrying strap. *The quick-changing slide carrier, No. 4449, giving a dissolving effect, may be substi- tuted for $3.00 extra. We can supply to order carriers for small slides, so that one may use either the standard slide or the special small size now being offered. With Arc Lamp Code Word | Cat. No. Specifications Price Dairk CA 8q | Model C Balopticon with hand-feed are lamp, double slide carrier, and 154-in. diam., 8-in. focus lens in rack and pinion focusing mount.... | $56.50 Daisl CA 10q | Same as above, but with 10-in. focus lens........ 56.50 Daitm CA 10 Same as above, but with 2;;-in. diam., 10-in. fo- 4 CUS Projecticnslens a tes een ere ees 61.50 Daivn CA 12 Same as above, but with 12-in. focus lens........ 61.50 Daixr CA 15 Same as above, but with 15-in. focus lens........ 61.50 Daizt | CA 18 Same as above, but with 18-in. focus lens........ 63.50 With Mazda Lamp Code Word | Cat. No. Specifications Price Daobw CM10 Model C Balopticon with 400-watt, 110-volt Mazda lamp with ground and polished glass re- flector and 2;3-in. diam., 10-in. focus lens.... | $65.00 Daody CM12 Same as above, but with 12-in. focus lens........ 65.00 Daofz CM15 Same as above, but with 15-in. focus lens........ 65.00 Daogb CM18 Same as above, but with 18-in. focus lens........ 67.00 Daohce CM6V10 Model C Balopticon with 6-volt, 4-ampere lamp with silvered globe and supplementary condenser, and 2;;-in. diam., 10-in. focus lens.......... 61.00 Daojd CM6V12 | Same as above, but with 12-in. focus lens........ 61.00 Daokf CM6V15_ | Same as above, but with 15-in. focus lens........ 61.00 Daolg *CM30V10 | Model C Balopticon with 30-volt, 14-ampere (420 watts) lamp with ground and polished glass re- flector, and 2;;-in. diam., 10-in. focus lens.... 69.00 Daomh CM30OV12 | Same as above, but with 12-in. focus lens........ 69.00 Daonj CM30V15 | Same as above, but with 15-in. focus lens........ 69.00 Daopk CM3OVI18 | Same as above, but with 18-in. focus lens........ 71.00 *If an outfit with the 30-volt, 14-ampere lamp is to be used on the regular circuit, a transformer or rheostat must be used in series with it. See page 39. NOTE—For extremely long distances lenses of longer focus than those listed can be supplied on special order. Sizes up to and including 22-inch focus will be supplied at the same' price as the 18-in. lens. For longer focal lengths special fittings are necessary and an extra charge of $7.50 will be made. 21 BAUSCH & LOMB OPTICAL COMPANY With Acetylene Burner Code Word | Cat. No. Specifications Price Daorl CG10 Model C Balopticon with double jet acetylene burner, ground and polished glass reflector and 2,-in. diam., 10-in. focus projection lens... | $62.00 Daosm CG12 Same as above, but with 12-in. focus lens... ... 62.00 Daotn CG15 Same as above, but with 15-in. focus lens...... 62.00 Double Dissolving Outfits In ordering a double dissolving outfit, prefix the catalog number with the word “Double.’’ The price of the double outfit will be twice that of the single instrument, plus $5.00 for the necessary connecting parts, and plus the cost of the iris dissolver or dissolving rheostat as may be required. Un- less otherwise specified, the iris dissolver will be supplied with all orders for this outfit. Code Word | Cat. No. Specifications Price Dautp 4490 Iris Dissolver. 0.23001 Ls ee Dauzxt 4484 Dissolving Rheostat, with connecting cord... .. 30.00 22 BAUSCH & LOMB OPTICAL COMPANY Model CL Balopticon Model CL with Mazda Lamp The Model CL Balopticon, which has been especially designed for lantern slide projection at relatively long distances where large size pictures are required, is an ideal instrument for use in auditoriums or other large rooms where the lantern must necessarily be so placed with reference to the screen. It is fitted with a light-tight lamp house with hinged side door, which com- plies in every way with the Underwriters’ requirements for a housing for high power are lamps. Either a 90° hand-feed arc lamp, with which a maximum of 35 amperes of current can be used, or a 1000-watt, 110-volt Mazda lamp can be had for ordinary use. Ample illumination for pictures up to 12 feet in width is given by the 1000-watt, 110-volt lamp, but for larger size pictures the arc lamp or the low volt Mazda with resistance is recommended. This apparatus is very substantially constructed throughout; the con- densers are mounted in a square frame, which connects the slide carrier support with the lamp house, thus making this part very rigid. Space is provided between the condensers for air cooling. A water cell can be in- serted if desired, and is recommended if the slides are to remain in place for an unusually long period of time. Each condenser is held in place by a metal ‘guide in the frame, while the hinged cover of the mounting has clips to hold the condensers in position and prevent their shaking about during shipment. The cover is fastened down by a small set screw. A carrying case is not regularly supplied with this equipment, but one can be had as an extra. (See price list.) Two of these units can be connected, one above the other, as shown in the illustration, by means of special connecting parts, and the lenses fitted with an iris diaphragm dissolver or a dissolving switch, making an ideal dissuiving view equipment. The two units can be disconnected easily and used alone. 23 BAUSCH & LOMB OPTICAL COMPANY Double CLM Balopticon Specifications Base—Consists of metal feet on bottom of lamp house and front metal standard of one piece with front board, the whole carried on sliding rods; front standard provided with elevating device for tilting instrument as desired. Lamp House—Measures 134 in. long, 14 in. high and 71% in. wide, light- tight, constructed of double walls with air space between and provided with large light-tight door on the side—conforms to most rigorous re- quirements of Boards of Underwriters. Illuminant—Hand-feed arc lamp for direct or alternating current with adapters for small carbons, 1000-watt, 110-volt, gas-filled Mazda lamp, 30-volt, 30-ampere (900-watt) Mazda. Condensing System—Our regular double system in ventilated mount; diameter, 41% in. *Slide Carrier—Our double carrier, No. 4430, with elevating device. Bellows—Mounted on metal frames which slide in metal ways, with ex- tension sufficient for 18-inch focus lens. Projection Lens—Our Balo lens with rack and pinion adjustment. Dimensions—Length, extended, 33 in. without lens; height, 14 in. Weight— Without case, 25 lbs. *The quick-changing slide carrier, No. 4449, giving a dissolving effect, may be substi- tuted for $3.00 extra. We can supply to order carriers for small slides, so that one may use either the standard slide or the special small size now being offered. 24 BAUSCH & LOMB OPTICAL COMPANY With Arc Lamp Code Word | Cat. No. Specifications Price Daovp CLA 8q | Model CL Balopticon with hand-feed arc lamp; ; double slide carrier; 154-in. diam., 8-in. focus projection lens in rack and pinion focusing mount | $89.50 Daoxs CLA 10q | Same as above, but with 10-in. focus lens........ 89.50 Daozv CLA 10 Same as above, but with 2;;-in. diam., 10-in LOCUS CNS 7 Fae Fie ere At Ee 6 oh een 97.50 Daucy CLA 12 Same as above, but with 12-in. focus lens........ 97.50 Daudz CLA 15 Same as above, but with 15-in. focus lens........ 97.50 Daufb CLA 18 Same as above, but with 18-in. focus lens........ 99.50 With Mazda Lamp Code Word | Cat. No. Specifications Price Dauge CLM 10 Model CL Balopticon with 1000-watt, 110-volt, Mazdalamp with ground and polished glass reflector and 2;3-in. diam., 10-in. focus projection lens | $95.00 Dauhd CLM 12 Same as above, but with 12-in. focus lens........ 95.00 Daujf CLM 15 Same as above, but with 15-in. focus lens........ 95.00 Daukg CLM 18 Same as above, but with 18-in. focus lens........ | 97.00 NOTE—For transformers or rheostat for these lamps see page 39. Carrying Case for CL Balopticon Code Word | Cat. No. Specifications Price Daurm 4376 Carrying Case of lacquered metal............... $9.00 Dausn 4374 Water Gell .s.e.60 ie al ee ee eee 12.00 Double Dissolving CL Balopticon When ordering a double dissolving outfit, prefix the catalog number with the word “Double’’. The price of the double outfit is twice that of the single instrument, plus $5.00 for the necessary connecting parts and plus the cost of the dissolving apparatus desired. Unless otherwise specified, dissolver will be supplied. Code Word | Cat. No. Specifications Dautp 4490 Iris Dissolver....... ee ee em ee ea See Oe Dauor 4487 Dissolving Switch with connecting cord.......... 25 the iris BAUSCH & LOMB OPTICAL COMPANY New Home Balopticon The New Home Balopticon has been designed primarily to meet the srowing demand for a thoroughly efficient and high grade apparatus for projecting post cards, photographs, solid objects, etc., in the home. Its scope, however, is not limited to the home. It is a very valuable asset for the schoolroom where it is possible to use the equipment within 9 to 12 feet of the screen in a room that can be well darkened. The outfit is made of sheet metal, finished in dull black, making it of light weight, but very durable. As the object holder occupies a horizontal position against the floor of the dark chamber, solid objects of many kinds can be projected on the screen. Pages from magazines and the like may be placed in position directly on top of the object holder and books or magazines which open flat may be readily placed in position. A single interior mirror brings the image always into correct position, from left to right, on the screen, so that reading matter appears unreversed. The exceptional strength of light makes this possible without detrimental loss of illumination. The lamp is a 400-watt, 110-volt, gas-filled Mazda, which can be attached to any ordinary lamp socket, operating automatically thereafter. The projection lens 1s of achromatic construction, designed to give maxi- mum illumination and a flat field. It projects a picture that is clearly de- fined to the extreme margin. An aluminum screen, 3 feet square, is included with the outfit. While a 3 ft. screen is regularly supplied, the illumination is sufficient for pictures up to 4 ft. in width with the 400-watt lamp. Code Word | Cat. No. Specifications Price Debot HRM-13 | Home Balopticon, for the projection of opaque objects only; with 400-watt, 110-volt, gas-filled Mazda lamp with specially corrected reflector, connecting cord and plug, and 3 ft. aluminum coated screen and two post card dolders....... | $50.00 Debuv 5333 Metal Carrying Case. »:........... 9. 7.00 Dhung 4378 Extra Post Card Holder~....... .. 53330 1.50 Aluminum coated screen. 44% x 41% ft. in place of 3 ft. sereen, $4.00 extra. 26 BAUSCH & LOMB OPTICAL COMPANY Combined Junior Balopticon This Balopticon has been ldesigned to meet the popular demand for a really efficient but inexpensive instrument, for the projection of opaque objects as well as lantern slides for use before small groups in the class room, Sunday School and home. The interchange between the projection of opaque objects and of lantern slides is instanta- neous, being effected by simply turning a convenient lever on the outside of the dark chamber. This lever operates an interior shield which cuts off the light from the lens for either form of projection not desired at the time. The supporting base measures 314 in. from the table top to the bottom of the dark chamber and 13 in. between front and rear feet, so that ample space for the insertion of average size illustrations and objects is provided. The horizontal object support is securely held in place against the floor of the dark chamber by strong springs, so that sheets of paper, books, irregu- larly shaped objects, etc., are readily placed and held in position. To facilitate the handling of post cards, small photographs and the like, two holders, which slide through the object support, are provided. Highly polished interior reflectors are so placed to utilize the maximum amount of light striking the object. By means of a first surface reversing mirror, the image appears in correct position from left to right. The lenses are of achromatic construction, designed to give maximum illumination and a flat field,—that is, the picture produced is clearly defined to the extreme margin. An aluminum coated screen, 54 inches square, is regularly supplied with this instrument. However, in a totally darkened room it is possible to very satisfactorily project pictures up to six feet in width at a distance not greater than 15 feet. This unusually good illumination is made possible by the use of an especially efficient 110-volt, 400-watt Mazda lamp and a highly corrected optical system. A 30-volt, 420-watt lamp, furnishing greater illumination than the regular bulb, may be used with this apparatus when connected by a transformer to the regular 110-volt circuit. ae Code Word Cat. No. Specifications Price Decar JCRM-13 Combined Jr. Balopticon for lantern slides, as well as for post cards, etc., complete with lan- - tern slide accessories, 400-watt, 110-volt, gas- filled Mazda stereopticon lamp, connecting cord and plug and 41%-ft. square aluminum SOTGOTI: ts Rees Lhe ae tae eee eRe ee ee $90.00 Deces JCRM-30V-13| Combined Jr. Balopticon, same as above but with 30-volt, 14-ampere lamp in place of 400- watt. D1LO-voltisc ce oe tee oe ee ee eee 95.00 Dexop 4499 Transformer for use on 110-volt alternating CUPLEN TA Me wee hee ee lain te ree ee 17.50 Dhung 4378 Extra Post Card Holder .................. 1.50 G.ftax 6 ft Screen >t eee extra 6.50 27 BAUSCH & LOMB OPTICAL COMPANY Combined Balopticon with 1000-watt Mazda Lamp CRM 18—Showing condenser in position for lantern slide projection. The constantly increasing demand for the Combined Balopticon with 1000-watt Mazda lamp has demonstrated that there is a positive need for a simple but high-grade and efficient apparatus with which it is possible to project postcards, photographs, drawings, maps, solid objects and the like, as well as lantern slides. This instrument has proven itself to be the ideal equipment for the school and the church, both from an educational and entertainment standpoint. One of the reasons for its popularity is the fact that the 1000-watt lamp, which was especially designed for this appar- atus, makes it so simple to operate that even the most inexperienced in the use of projecting machines have no difficulty with this equipment. 28 BAUSCH & LOMB OPTICAL COMPANY Since, unlike the arc, the lamp is enclosed, it can be brought very close to the object without danger. By means of a mirror with very high optical corrections an unusually large percentage of the available spherical candle power is utilized. Because of this special application of the illuminant it is possible to project images of opaque objects with a brilianecy considerably exceeding that possible with a 35-ampere arc lamp on alternating current, and equaling that of a 20-ampere arc on direct current. The advantages of this lamp are obvious. It operates on only 9 amperes of current, which means a considerable saving in current consumption and makes it available for use on many outlets without the carrying capac- ity to supply high-power are lamps. No rheostat is necessary with it, and, what is the most striking advantage of all, the lamp is entirely auto- matic, requiring no attention whatever. It works equally well on direct or alternating current, and the disagreeable noise so characteristic of the alternating current arc is absent. A final advantage is that the quality or color of the light is very pleasing to the eye and gives a better rendition of colors than that obtained with the alternating current arc. This model, CRM, has been constructed especially for use with the Mazda lamp, and the design is calculated to give the greatest possible efficiency. The lamp housing and the dark chamber have been brought together to allow the lamp to be placed as close to the object as possible. No condensers are used in illuminating the opaque object, but the spe- cially corrected glass reflector placed back of the lamp directs the light upon the object in parallel rays. By means of special methods of ventilation the temperature of the outfit is kept sufficiently low, so that there is positively no danger of scorch- ing the specimen; neither does the apparatus become uncomfortably hot for operating. The instrument is constructed of heavy sheet metal by means of special forming tools, so that it has a pleasing appearance and the proper rigidity, at the same time being sufficiently light to make it readily port- able from place to place. It is finished throughout in black enamel with a dull lustre, which is both serviceable and appropriate in such an appar- atus. The area of the opaque object that can be projected is ordinarily 6 x 6 inches, but by removing a plate from the bottom of the dark chamber the size can be increased to 7 x 7 inches. Much larger objects can be placed in position and shifted about so as to project any portion desired. The specimen is held in position against the bottom of the dark chamber by the object-holder, which is actuated by a spring-arm. To facilitate the rapid handling of small pictures, such as postcards, we supply two adjust- able carriers. The change from the projection of opaque objects to lantern slides, or vice versa, is made instantly by pushing in or pulling out a sliding rod located on the front of the dark chamber. This rod operates a shield in the dark chamber, which cuts off the light from the projection lens for opaque objects, or from the lens for lantern slide projection, and also 29 CRM 18—With changing device in position for opaque projection. brings the rear condenser, used for lantern slide projection, close to the lamp so that maximum efficiency of illumination for slides is secured. No movement of the lamp or lamp reflector is necessary in making the change, and there is consequently no jarring of the delicate lamp filaments during the operation. The projecting lenses are the Balo series, especially corrected for flat- ness of field and critical definition. The one for projecting the image of the opaque object is mounted on top of the dark chamber, together with a first-surface mirror which directs the light toward the screen and causes the picture to appear in correct position from left to right. The lens is 4 inches in diameter, of 15 or 18 inches focus, the selection depending on the projection distance and the size of the picture desired (see table, page 8). A lens is supplied for lantern slide projection, which is of the proper focal length to give approximately the same size picture as that obtained 30 with the projection lens for opaque objects. In order that the apparatus can be used conveniently for lantern slide projection at long distances, such as 50 feet, we have arranged for a supplementary lens to be used in conjunction with the regular lens, thus giving the effect of a long focus lens, without the disadvantage of a long supporting extension. (See price list). The mirror is fixed above the lens in an adjustable mount, which permits the images from both opaque object and lantern slide to be brought into coincidence on the screen. On account of the unavoidable loss of light in any projection of opaque objects, it is not possible to secure the same brilliancy as when using slides. Consequently, we would advise projecting a picture not larger than 10 feet square, if the distance will permit of such an arrangement. Particular attention should be given to the selection of a screen. A good quality, white, opaque screen, at least, should be used, and an alu- minum-coated screen is preferable. The latter, however, should not be used unless the audience can be placed within a total angle of about 60° from the center of the screen. Specifications Base—Consists of heavy sheet metal supports, front and rear, 10% in. wide, and carrying dark chamber at height of 514 in.; extreme length, 231% in.; each foot is provided with screw hole for fastening Balopticon to table, if desired. Lamp House and Dark Chamber—One continuous with the other; meas- ure 91% in. wide by 15 in. long; lamp house is 17 in. high; dark chamber 12% in.; light-tight and freely ventilated, constructed of double sheet metal walls, with an air space one inch in thickness between the two walls; roof of lamp house is fitted with our special patented ventilator; dark chamber provided with large, light-tight door on side convenient handle on outside of dark chamber at upper front controls shield by which light is cut off from opaque object lens or lantern slide lens, as desired Iluminant—1,000-watt, concentrated filament, gas-filled, Mazda stereop- ticon lamp, of special design; provided with ground and polished glass reflector, 8 in. in diameter, corrected to throw a parallel beam of light upon the specimen. Condensing System—Our regular double system, consisting of two plano- convex lenses, 41% in. in diameter, one mounted at the front of the dark chamber, the other on a sliding frame in dark chamber, for lantern slide projection only. Object Holder—-Square plate of sheet metal; held against opening in bottom of dark chamber by arm actuated by two strong springs; accom- modate objects of varying thickness and automatically brings them into proper plane for projection; opening in bottom of dark chamber permits area, 6 in. square, to be projected. (7 in. square by removing plate on bottom of dark chamber.) Slide Carrier—One double carrier, No. 4480, with elevating device. Post Card Carrier—Two adjustable carriers with wooden backs and frame, which fit object holder. ol Projection Lenses—Two of our new series of lenses, especially corrected to give a brilliant, flat field with the Mazda lamp; provided with rack and pinion adjustment; of such relative foci as to project images of approximately equal size from opaque objects and lantern slides; lens for opaque objects fitted with first-surface mirror to direct light to screen and cause picture to appear in proper position from left to right. Dimensions—Length, rear of lamp house to front of Jens for lantern slide projection, 27 in.; height to top of mirror, 33 in. Code Word | Cat. No. Specifications Price Decit CRM 15 | Combined Balopticon for projection of opaque ob- jects and lantern slides, with 4-in. diam., 15-in. focus lens for opaque objects and 15%-in. diam., 8-in. focus lens for lantern slides ; 1000-watt Maz- da stereopticon. lamp:.;...«. .:.-.).5 0 eee $200.00 Decov CRM 18 | Same as above, but with 18-in. focus lens for opaque objects and 154-in. diam., 10-in. focus lens for lantern. slides. 4.05.2. hija. seeds. oe Se 200.00 Dedas 4379 Extra Post Card Holder °7....%.2... 42 1.75 Long Distance Lantern Slide Projection In order to make it possible to use this apparatus for long distance lantern slide projection, we have developed a supplementary lens to be used in conjunction with the regular 15¢-in. diameter, 10-in. focus lens supplied on the CRM-18 outfit. This supplementary lens is furnished in a mounting, which fits between the extension adapter and the projection lens, giving the effect of a long focus lens without the long extension adapters which these would require. This combination of lenses makes it possible to use the apparatus up to a distance of 50 feet for lantern slide projection, producing a picture approximately 10 feet wide. Code Word|Cat. No Specifications Price Dedet 4404 Supplementary Lens in mounting for use with 15-in. diameter, 10-in. focus lens................. $11.50 If the apparatus is to be used to a considerable extent, we suggest that a 2is-in. diameter, 10-in. focus projection lens be substituted for the regular 15¢-in. diameter lens, which would mean an appreciable increase in illumination. The extra charge for this lens would be $7.50, and a larger supplementary lens would be required. Code Word/Cat. No. Specifications Price Dediv 4406 Supplementary Lens in mounting for use with 27.-in. diameter, 10-in. focus lens. ....4....,. 52.06 $14.50 32 BAUSCH & LOMB OPTICAL COMPANY Combined Balopticon for Projection at Long Distances CRM 25 This new model is offered in order to meet the demand of those who must of necessity use an instrument at a greater projection distance than is practical with the CRM-18, and to those who desire to project a somewhat larger object than is possible with any other model herein listed. Although the regular projection area is 7 in. x 7 in., by removing a plate from the bottom of the dark chamber, it is possible to project areas up to 7 in. wide by 9 in. long. For those wishing to project only 6 in. x 6 in. areas, we can supply a special plate on order, to be attached to the bottom of the dark chamber. For these large areas, it is quite essential to use specially corrected and long focus lenses,—not only from the standpoint of image quality but because of the advantageous working distance from the screen. Conse- quently this equipment is offered only with the 25 in. focus, 4 in. diameter focus lens for opaque objects, and a 12 in. focus, 235 in. diameter lens for lantern slides. | This equipment will particularly appeal to Architectural and Mechanical Engineering Departments, Schools of Journalism and Advertising and others where blueprints, layouts, and large areas of varied description must be projected. 33 When determining the size of the screen and the projection distance, one must take into consideration the longest side of the object, and reference should therefore be made to the following table, where the height of the picture is specified rather than the width as is usually customary with the shorter focus lenses. The table shows the height of the picture of the screen. tee, Distance from lantern to screen Opening 20 ft. 25 ft. 30 ft. 35 ft. 40 ft. 45 ft. 6” x 6” 44 5% 6% 8 9 10 TS Te 54 614 734 94 10% apse Wl 6% 84 10% The general design and specifications of this model are the same as for the CRM models described on the preceding pages, except that the dark chamber is two inches longer and the reversing mirror is mounted in a prism shaped box back of the projection lens. Code Word Cat. No. Specifications Price Decuw CRM 25 | Combined Balopticon, with 5-in. diam., 25-in. focus lens for opaque objects and 2;3;-in. diam., 12-in. focus lens for lantern slides ............ 290.00 Other Equipment In addition to the outfits listed in the foregoing pages, our complete projection line includes the Model D Balopticon with optical bed, a high type of lantern slide instrument which is also admirable for work in physics laboratories and the like; the Convertible Balopticon, providing in its complete form for practically all types of optical projection; the Large Opaque Balopticon with double illuminant, for projecting objects up to 12 inches square; and complete apparatus for microscopical projection, for drawing from microscopical objects, for work with polarized light, with the spectrum and with complementary colors. If interested in any of the above apparatus, write for a copy of our complete projection catalog, in which it is presented in full. 34 BAUSCH & LOMB OPTICAL COMPANY Balopticon Accessories Balo Projection Lenses This series of projection lenses has been designed to meet the requirements for lenses to project opaque objects as well as lantern slides. They are cor- rected for chromatic and spherical aber- ration and give critical definition to the extreme edges of the field. The lenses .of 158 and 2546 inches diameter are intended aecatalbedk: for lantern slide projection. The former, made in focal lengths up to 10 inches, : should be used only on outfits equipped with the arc lamp, while the latter should be used with the Mazda lamp and acetylene burner. The larger diameter lenses are especially con- structed for the projection of opaque objects. These lenses, very accurately mounted in heavy brass tubes with rack and pinion focusing adjustment, are finished in black and white engraving. Code Word Cat. No. | Diameter in Inches | Focus in Inches Price Dejey 4006 154 6 $ 15.00 Dejiz 4008 15% 8 15.00 Dejob 4010 1% 10 15.00 Dejuc 4020 25 10 23.00 Dekay 4022 Qa 12 23.00 Dekez 4025 25 15 23.00 Dekib 4028 255, 18 23.00 Dekoc 4045 4 15 82.50 Dekud 4048 4 18 82.50 Delaz 4055 5 25 140.00 Condensing Lenses Because of the quality of glass used and the superior workmanship our condensing lenses are considered standard. They are carefully annealed and finished. Although our patent, ventilated mount (see page 7) minimizes the danger of breakage, yet with all possible care condensers are still liable to break and it is well to have an extra set at hand. Code Word | Cat. No. Specifications Price Deleb 5095 Plano-Convex lens, 4-in. diam.; rear lens of the Model CL system, unmounted................. $ 1.40 Delic 5093 Plano-Convex lens 4-in. diam.; rear lens of the CRMFunmounted 20 ae cee ae cee 1.50 Delod 5096 Plano-Convex lens, 4;-in. diam;. front lens of the Models B, BB, BC and C systems. Be sure to state focus of projection lens when ordering.......... 1.50 Deluf 5102 Plano-Convex lens, 4;-in. diam.; rear lens of Home system, unmounted... 2.4.5. 44. a oo 1.50 Demab 5104 Plano-Convex lens, 4;-in. diam.; front lens of Home and CRM systems. Be sure to state focus of projection lens when ordering............... 1.50 Demec 5106 Plano-Convex lens, 4;-in. diam.; rear lens of Models B, BB, BC and C systems, unmounted .. 1.50 30 BAUSCH & LOMB OPTICAL COMPANY Illuminants Hand-feed Arc Lamp This lamp is carefully constructed, with screws and gears cut so as to prevent bind- ing even after being thoroughly heated. The carbons can be fed independently or simultaneously. A wide range of adjust- ment is provided for by accurate centering screws, and all adjusting and feeding screws are carefully insulated. Either direct or alternating current can be used, although the former is desirable as _.it gives greater illumination, is quieter in operation and more easily and accurately controlled. A rheostat must always be used with this lamp to regulate the current. Code Word | Cat. No. Specifications Price Denuh 4464 Hand-feed Arc Lamp, with centering support; for use in small lamp houses, Model C type......... {$21.50 Depad 4464L Same as above, but with long feeding and adjusting rods for use in large size lamp house............ .00 Gas-filled Mazda Lamps No. 4466—400-Watt Gas-Filled Mazda Lamp. The new gas-filled Mazda lamps with concentrated filament, which have been especially developed for projection purposes, furnish an automatic, steady-burning and very efficient and economical light source for the simpler types of Balopticons. The efficiency varies from 0.8 watt per candle power in the lower wattages to 0.55 watt per candle power in the higher wattages. They are rated by the manufacturer to have a life of approximately 100 hours and we stand ready to replace any that may prove defective or burn for an unduly short period. If the Mazda burned only one-half its rated life, the cost of operating this type, including renewals, would be much less than the 36 BAUSCH & LOMB OPTICAL COMPANY No. 4500 No. 4477 cost of an arc lamp giving equal illumination, when the saving in current and carbon consumption is considered. In addition, the Mazda is entirely automatic, noiseless and steady in operation and its efficiency per number of amperes used is higher than that of the A. C. arc. These lamps are not recommended for microscopical projection as they are not sufficiently con- centrated or homogeneous. No 4476—1000-Watt Gas-Filled Mazda Lamp The 400-watt and 1000-watt lamps are intended for use on regular circuits of 110-volts or 220-volts when used with resistance; the 30-volt, 14-ampere lamp can be used on individual lighting plants or on the regular circuit, when used in series with a transformer or rheostat, while the 6-volt lamp is intended for use with a storage battery. 37 BAUSCH & LOMB OPTICAL COMPANY Code Word | Cat. No. ! Specifications Price Depig 4466 400-watt Mazda Lamp with gas-filled globe, re- flector on support, 15 ft. of extension cable, con- necting plug and switch. ......;2. 2440s eee $18.50 Depoh 4479 400-watt Mazda Lamp, bulb only............ net 3.65 Depuj 4476 1000-watt Mazda Lamp, with gas-filled globe on support with glass reflector, 4 feet of extension cord and pass-through awitéh .. sc. # eee 27.75 Deraj 4478 1000-watt Mazda Lamp with gas-filled globe, clear; bulb: only.058 >... oe fe oe net (Py b) Dereg 4500 6-volt Mazda Lamp for use with storage battery, with silvered globe, supplementary condenser in mounting, 6 feet of connecting cord with switch and lugs for connecting storage battery............. 13.50 Derth 4504 6-volt, 24-watt Mazda lamp, silvered; bulb only net 1.25 Deroj 4477 30- volt, 14-ampere Mazda Lamp, with gas-filled | — globe on support with glass reflector, 4 feet of ex- tension cord and pass-through switch... :. ¢2aenee 22.50 Deruk 4492 30-volt, 14-ampere lamp; bulb only........... net 5.50 Deseh 4536 600-watt, 110-volt tubular-shaped Mazda _ lamp; bulb only hig whe cata segs es net 5.50 NOTE—On account of its size the 1000-watt lamp can only be used in the large, light tight model lamp houses. All illuminants listed above are fitted with sliding base suitable for use on such Balopticons as Model C or CL. Acetylene Lamp Acetylene is a convenient illuminant, as it is easily obtained or prepared and is portable. The illumination is sufficient for work at com- paratively short distances. Our lamp has a powerful double jet, mounted in front of our _ patent, optical mirror of silvered glass, which concentrates and steadies the light, nearly doubling the illumination. For the best result obtainable with this lamp a 10-inch focus pro- : -jection lens, of 23-inch diameter, giving an image 6 feet are at a distance of 20 feet, shenld be used. This burner consumes 2 cubic feet of gas per hour. Code Word | Cat. No. Specifications Price Desij 4467 Acetylene Lamp with reflector and 6 feet of rubber tubing (designed particularly foruse on Model C) | $13.00 38 BAUSCH & LOMB OPTICAL COMPANY Rheostats for Arc Lamps With every arc lamp there must be used a rheostat, selected according to the voltage available and the number of amperes re- quired. ) We construct our rheostats to meet the No. 4452—414-Ampere Rheostat strictest requirements of fire boards and underwriters and they have been approved by the National Board of Fire Underwriters’ Laboratory of Chicago. The wire in the resistance coils has practically no temperature coefficient and will not deteriorate with frequent heating and cooling. The cases are of perforated metal thus providing for the freest possible air circulation among the coils. There are no exposed contact points, and every means of insuring safety has been taken advantage of. The coils in rheostats of 15 amperes capacity and over are wound on asbestos board strips to prevent sagging or possible contact between coils. The coils in the 4144-ampere rheostats are carried on porcelain spools. The 414-ampere rheostats can be used satisfactorily with the electric wiring usually found in private houses, connecting with the ordinary lamp socket. Those of higher capacity generally require special wiring. When ordering be sure to specify voltage. No. 4450—15-Ampere Rheostat No. 4456—15 to 35-Ampere Rheostat 39 BAUSCH & LOMB OPTICAL COMPANY Code Word | Cat. No. Specifications Price Desok 4450 Fixed Form, 15 amperes, 110 volts............ $10.25 Desul 4451 ss 15 -amperes, 220.-volts.. co) eae 27.00 Detol 4452 ‘ 414 amperes, 110 volts, with cord, plug and pass through switch .......)./) 0. ase 8.75 Detum 4453 Fixed Form, 4/4 amperes, 220 volts with cord, plug and pass through switch...5, 5. 0 0. 12.50 Devaj 4458 Adjustable Form, 5-10 and 15 amperes, 110 volts. 18.00 Devek 4454 ts 15 to 25 amperes, 110 volts. 27.00 Devil 4455 3 a 15 to 25 amperes, 220 volts. 37.50 Devom 4456 ie 15 to 35 amperes, 110 volts. 50.00 Devun 4460 . Ly 15 to 35 amperes, 220 volts. 62.50 Transformers and Resistances for Mazda Lamps Any Mazda lamp, used on an electrical circuit whose voltage materially exceeds that for which the lamp is rated, must be provided with a suitable transformer or resistance to be connected with the lamp in order to reduce the voltage to that for which the lamp is rated. It has not been found practical to make these concentrated high power lamps for 220 volts or higher; hence, where high voltage prevails, the 110- volt lamps, as well as the 6 and 30-volt ones, must be used with a resistance. For the low voltage lamps, particularly those drawing rather high am- perage, a transformer should be used wherever alternating current is avail- able, as with this device the rate of current consumption on the main line is reduced to the point where all of the low volt lamps listed, with the ex- ception of the 30-volt, 30-ampere lamp, may be connected with the regular lighting socket. When operating on direct current a resistance must be used and an outlet, with an ampere capacity equivalent to that for which the lamp is rated, provided. Code Word | Cat. No. Specifications Price Dewak 4431 Transformer for 6-volt, 4-ampere lamp; 110 volts, 60 cycles, alternating current. .....:)..) 222.98 $ 7.50 Dewel 4433 Transformer for 6-volt, 4-ampere lamp; 220 volts, 60 cycles, alternating current.................. 11.25 Dewim 4434 Resistance for 6-volt, 4-ampere lamp; 110 volts, direct current...) io... See ee 8.75 Dewon 4436 Resistance for 6-volt, 4-ampere lamp; 220 volts, direct current. , 2... ..).s¢5n 500. 12.50 Dewup 4497 Transformer for 6-volt, 18-ampere lamp; 110 volts, 60 cycles, alternating current.................. 10.00 Dexal 4438 Resistance for 6-volt, 18-ampere lamp; 110 volts, direct current: . 2.05.4 .04 ) Gr 18.00 Dexem 4496 220-volt Resistance for 400-watt lamp.. ....... 9.50 Dexin 4498 220-volt Resistance for 1000-watt lamp.......... 14.00 Dexop 4499 30-volt, 14-ampere Transformer, for use on 110- volt, alternating current, with 15 feet of extension cord, switch and plug on primary cord from lamp on secondary sidé@..5. 20... 23 ec. . ee er 17.50 Dexur 4469 Rheostat for use on 110-volt, direct current with 30-volt, 14-ampere lamp with 2 feet of connecting cord attached to terminals. .......,) ssi. eee 22.00. 40 BAUSCH & LOMB OPTICAL COMPANY Cable “Code Word | Cat. No. Specifications Price Cable Deyam 5179 Rubber Covered Twin Cable, No. 12 copper wire, HOVE o amperes pers (OOL mae Lee eee cre. one $ .20 Deyen 5180 Rubber Covered Twin Cable, No. 10 copper wire, fori ZO. AMperes, Per 100t. wc oe ee es oS 725 Deyitp 5184 No. 14 Rubber Covered Portable Lamp Cord, per LOOUET nels EE ENA NAT Ee ce hee a 12 Deyor 5185 No. 16 Rubber Covered Portable Lamp Cord, per LOOT Meira ce ae eg ne FONE Bal ie .08 Carbons Code Word | Cat. No. Specifications Price Carbons Deyus 4470 Cored Carbons, ;% in. diameter, 6 inches long, per LED Serre a Pe eRe, Moen See ee revue ene, $ .40 Dezan 4471 Cored Carbons, 7% in. diameter, 6 inches long, per GTA spam ares e ent Nees pete) Mie Ney te cv aie 38 Dezep 4472 Cored Carbons, 3; in. diameter, 6 inches long, per LCL ee ee St cE Maes ene & Dae HE ican cn, .40 Dezir 4473 Cored Carbons, 14 in. diameter, 6 inches long, per A Ok ee ae Bet a Or EME ie Aa MO Ln Ra CEP ae nak oe Waco .38 Dezos | 4437 Solid Carbons, 4mm diameter, 6 inches long, each 04 Dezut | 4482 Solid Carbons, 5mm diameter, 6 inches long, each .04 Acetylene Tank Code Word | Cat. No. Specifications Price Dhabn 4483 Acetylene Tank, 10 cubic feet capacity.......... $13.00 Acetylene Generator This is a very compact generator, with a capacity of one pound of carbide. It is fitted with a needle valve, etc., for control of the gas flow. Code Word Cat. No. Specifications Price Dhacp 4587 Acetylene Generator as described; dimensions, approxamately® (x91 Ins. ee eee $14.00 4] BAUSCH & LOMB OPTICAL COMPANY Slide Carriers A satisfactory slide carrier, both con- venient and durable, is essential to a high grade projection apparatus. We supply several which have given such satisfac- tion. Particular attention is called to No. 4449, our new rapid-changing Rapid-Changing Slide slide carrier, which is a double carrier Carrier, No. 4449. . ; operated entirely from one side. As a new slide is fed forward, the preceding slide is automatically returned, and a metal shield, which travels with the slide, obliterates all movement of the slide on the screen, so noticeable in ordinary double carriers and other types of slide changers. This approximates a dissolving effect, thereby relieving all eyestrain. 3 Two carriers, Nos. 4430 and 4432, = are neatly finished wooden frames, pro- fe vided with an automatic elevating de- vice. This consists of loosely fitted metal pins beneath the center of the slides, which engage with an inclined plane at the end of the sliding movement, raising the slide so that it may be easily lifted out by its margin. No. 4430 is regularly supplied with our lantern slide equipments. We also make a convenient post card carrier for our apparatus project- ing opaque objects. Slide Carrier, No. 4480. Code Word | Cat. No. Specifications Price Dhish 4430 Slide Carrier, for two 344 x 4-inch slides with auto- $2.00 matic elevating device. 7s, .25. -. An. ee Dhit} 4432 Double Slide Carrier, for either 3144 x 344 or 34 x 25 4-inch slides with automatic elevating device. ... Dhivk 4449 Rapid-Changing Slide Carrier................. 5.00 Note—The semi-dissolving slide carrier, No. 4449, may be substituted on any equip- ment regularly supplied with No. 4430 for $3.00 additional. 42z BAUSCH & LOMB OPTICAL COMPANY Balopticon Tables No. 4259 To provide a suitable means of supporting the Balopticon we have developed a line of supporting tables, all of which are of a convenient height for operating the Balopticon and of a proper height for clearing the heads of the audience. No. 4259 stand, made of angle iron, is very rigid. 48 inches high. Wooden top 30 x 12 in. Very desirable for the smaller types of Balopticons. Stand No. 4257 is made of angle iron, strongly braced, and has a wooden top, the front of which may be raised or lowered. One of the unique features of this stand is that it may be folded up when not in use and stored in any small closet. It is of course folded when shipped. The front legs are fitted with casters, so that by lifting rear legs free of the floor it may be easily moved from place to place. Because of the method of bracing it is extremely rigid, and is recommended for such outfits as the CL and CRM. 43 Folding Balopticon Table No. 4257 in Two Positions No. 4253 stand is made with a heavy cast iron base with supporting columns, and a cast iron frame-work upholding the wooden top, which is provided with elevating screws at the front. This table is particularly rec- ommended for such apparatus as the Convertible. Specifications Code Word | Cat. No. Dhixm 4259 Dhizp 4257 Dhobs 4253 Balopticon Table of metal, 48 in. high; top of wood, 30 x 12 inchés . 00 ca dS ee Folding Balopticon Table, 47 in. high, with wood- en top 32 x 19-in. |. 8 ee Balopticon Table 44-in. high with strong casti on bare and frame, and heavy 40x 17-in. wooden top; space beneath for adding cabinet, if desired; provided with casters and leveling screws ...... 44 Price $15.00 27.50 2, CHEST RS OMe, BSD E c 5 < 2D, , ay BAUSCH & LOMB OPTICAL COMPANY oF. Kons SOFT oO CHESTER “*, Balopticon Table, No. 4258, with No. 4456 Rheostat and Knife Switch as supplied with Convertible Balopticon 45 | BAUSCH & LOMB OPTICAL COMPANY Screens Ordinary sheeting, or common cloth, is too translucent to furnish a satisfactory screen for projection work. Our screens are all made of heavy cloth, specially prepared and as nearly opaque as possible. ‘They are mounted on spring rollers. Code Word | Cat. No. Specifications Price Dhoct 4420 Screen, Gfeetx 6feet,each................. net | $ 8.75 Dhodv 4421 t CSRS ETE DS ETE: Ee net 12.00 Dhofw 4422 . auger. Sera ak Cees wert net 15.00 Dhohy 4423 : Qe Oe Oe puke alee ce toe en net 24.00 Dhojz 4425 y 10S RIDES Se ee aie eee net | 28.50 Dhokb 4426 ¥ 120" x12 Rs te... ae ae net 55.00 Larger sizes will be quoted upon request. Aluminum Screens These screens are made of heavy material with a metallic surface. They give a much more brilliant image than the ordinary screen and are recom- mended in all cases, but especially will their superiority be noted in project- ing opaque objects, microscopic specimens and in all work requiring brilliant illumination. Owing to their narrower field, however, due to the high re- flecting surface, they should be used only when the audience can be seated within an included angle of 60 degrees from the center of the screen. CodeW ord Cat. No. | Size Price ||CodeWord) Cat. No. Size Price Dhold 4420A 6x6ft.| $11.50 | Dhopg 4423A 9x 9ft $30.00 Dhomd 4421A | 7x7 ft. 15.50 Dhorh 4425A | 10x10ft 35.00 Dhonj 4422A = 8 x 8 ft. 20.00 Dhosj 4426A | 12x12ft. 65.00 These screens are supplied for portable outfits. Sateen Screens Sateen is as nearly opaque and highly reflecting a material as can be obtained, which at the same time is suitable for packing in a case. These screens are provided with eyelets for stretching and have reinforced borders. Code Word Cat. No. Specifications Price Dhotk 4420S Screen, 6 .x 6 feetci:.:.:..... ao pee net | $ 7.00 Dhovl 4421S £ 744 x 7146 feet:..4:4.... 50 ee net 10.00 Dhowm 4423S oe 9° °x 9° ‘feet..cc..5 4.42 ee net 18.00 Dhoxn 4426S if 12: x12. feet... ..4... 2.2; .. =. net 24.00 46 A, Model Balopticon Accessories, Balopticon Acetylene Generator Acetylene Lamp Acetylene Tank Aluminum Screens . Are Lamp, Hand Feed Balo Projection Lenses Balopticons Combined Combined Junior Double Dissolving Home . Model A Model B Model BB Model BC Model C Model CL Model CRM . Portable Model B B, Model Balopticon BB, Model, Dissolving Baloouicon BC, Model Balopticon . : Balopticon Accessories . Balopticon Tables C, Model Balopticon Cable Carbons . Carriers, Slide Carriers, Post Card CL, Model Balopticon . Combined Balopticon, CRM . Condensing Lenses . Construction, General . CRM Balopticon Dissolver, Iris Dissolving Rheostat Dissolving Switch Gas-filled Mazda Lamps Generator, Acetylene Hand-Feed Arc Lamp . Home Balopticon Iluminants Acetylene Lamp . . Are Lamp, Hand-Feed Mazda Lamps, Gas Filled Special for Model B . Iris Dissolver Lamps (see Tlaminants Lecturers’ Special Portable Outfit, Model B Lenses, Balo Projection Lenses, Condensing . Long Distance Lantern Slide Projection Magnification Tables Lantern Slide Opaque Objects Model A Balopticon Model B Balopticon Model BB Balopticon . Model BC Balopticon . Model C Balopticon Model CL Balopticon . Model CRM Balopticon Opaque Object Projection Tables Portable Outfit, Model B . Post Card Carriers . Projection Lenses, Balo Projection, Stereoscopic, with Model BB . Projection Tables ; Resistance for Mazda Lamps Rheostats Rheostat, Bicol’ Sateen Screen Screens Aluminum Sateen . White Opaque Slide Carriers Special Traveling Outfit Stereoscopic Projection with Model BB . Switch, Dissolving . Tables, Balopticon . Tables, Projection Termsii) 2 Traveling Outfit, Model B White Opaque Screens . 36-38 22, 25 7, 35 Other Products We append a partial list of our other products of possible interest to the reader of this catalog. Centrifuges Ophthalmic Lenses Colorimeters Optical Glass Drawing Apparatus Optical Machinery Field Glasses Photographic Lenses and Shutters (Stereo-Prism Binoculars) Photomicrographic Apparatus Magnifiers Reading Glasses Micro Projectors Refractometers Microscopes and Accessories Searchlight Reflectors Microtomes Saccharimeters Ophthalmic Instruments Spectacle and Eyeglass Frames, Mountings and Cases We shall be glad to furnish literature or information on any of the same upon request. 48 ag G ETTY CENTER LIBRARY win 3 3125 000