A TREATISE SUBTERRANEOUS SURVEYING ETC. ETC. ETC. ELEMENTARY AND PRACTICAL TREATISE ON SUBTERRANEOUS SURVEYING, AND THE MAGNETIC VARIATION OF THE NEEDLE. BY THOMAS FENWICK, Colliery Viewer and Surveyor of Mln^. ALSO THE METHOD OF CONDUCTING SUBTERRANEOUS SURVEYS WITHOUT THE USE OF THE MAGNETIC NEEDLE, other BY THOMAS BAKER, C.E., Author of "Railway Engineering," "Theodolite Surveying, Levelling," &c., in Nesbit's " Surveying, Rudimentary, Land and Engineering Surveying, Statics and Dynamics, Elements of Mechanism, Mensuration, Integi-ation," in Weale's Series, &c, THE THIRD EDITION. LONDON: JOHN WEALE, 59, HIGH HOLBORN. 1861. LONDON : BRADBUEY AND EVANS, PRINTERS, "WHITEFRIAR3. PREFACE. THE mineral wealth of this kingdom had become of such great importance, ahout half a century ago, as to induce Mr. T. Fenwick, of Dipton, in the County of Durham, to compose a Treatise on Sub- terraneous Surveying (which forms the basis of the present Work) for the use and instruction of young men designed for the profession of mining agents' and surveyors, usually called colliery viewers : much more, then, is such a treatise now necessary, as these mineral productions have, up to the present time, been more than quadrupled in value ; and by the more general diffusion of mathematical, philosophical, and mechanical science, the working of mines has been conducted with greater skill and precision for the full development of their vast wealth. The general use of the magnetic needle in subter- raneous surveys has been found to be a great source of error, on account of ferruginous substances (which exist in almost all mines) attracting the needle, and causing it to give erroneous indications; whence, in general, old surveys are found to be extremely defec- tive. Indeed, Mr. Fenwick himself was so sensible M 1635 VI PEE FACE. of this deficiency of the needle, that he proposed, in the Second Edition of his Work, ahout forty years ago, to dispense with its general use ; though he still proposed to use it, at the first departure, or com- mencement of the survey, from the top to the bottom of the shaft of the mine. This Edition of the Work contains, in a small compass, the essentials of Subterraneous Surveying in all its branches, both with and without the use of the magnetic needle ; and to make it still more useful to that class of men for whom it is chiefly intended to convey information, there are added a great number of explanatory figures and examples. + PART I. contains the method of surveying, with the use of the magnetic needle, without attending to its variation, as being more readily intelligible to begin- ners; and the magnetic bearings being, at the same time, at once adapted to the use of the Traverse Tables. This part is arranged after Mr. Fenwick's plan (whose method and examples are still retained), in the following order : 1. Geometrical problems. 2. Theorems, and the methods of conducting sub- terraneous surveys. 3.- Of determining the magnitude of angles. 4. Of determining bearings, and reducing angles to the bearings which they form with the magnetic meridian, with a rule and examples. PBEFACE. Vll 5. The method of reversing bearings. G. Of reducing bearings to the angles they form with the magnetic meridian, with rules and examples ; and the manner of finding the magnitude of the angle that two bearings form with each other. 7. The method of reducing bearings and distances to the northing or southing, and easting or westing, they contain, by the Traverse Table, with a rule and examples. 8. The manner of surveying subterraneous exca- vations with the form of the survey-book. 9. The method of taking back sights. PART II. In this part, which treats extensively on conducting subterraneous surveys, without the use of the magnetic needle, Mr. Fenwick's examples are in several cases retained, with full directions for adapting them to the new method (they being already adapted to the use of the Traverse Table), which will con- stitute a useful exercise for the student in transferring the angles from their magnetic bearings to the angles which one line makes with the preceding one, as taken by the theodolite. This part has the following arrangement : 1. Mr. Fenwick's method of subterraneous sur- veying, without the use of the needle, except at the first departure or commencement of the survey. 2. Mr. Baker's method of commencing the survey by suspending two weights down the shaft in the direction Vlll PREFACE. of the first headway, and marking the same direction on the surface ; and afterwards conducting the survey with the theodolite, without the use of the needle. 3. Mr. Beauland's method of making the commence- ment of the survey by the help of a transit instrument, not using the needle, as in Baker's method. 4. Plotting and protracting surveys in various ways. 5. Of reducing the hearings and distances of a survey into one common hearing and distance, or any number of bearings and distances fewer than those that compose the survey, whether the angles be taken- with the needle, or the theodolite independent of the needle. 6. The method of plotting on the surface in various ways. 7. The method of making the survey where the excavation inclines from the horizon. 8. A promiscuous collection of practical examples, some of which relate to tunnelling. PART III. contains subterraneous surveys, under the necessary attention to the magnetic variation of the needle. As the magnetic meridian has been found to be in a state of variation from the true meridian for upwards of 300 years, and still continues to vary, therefore surveys made by the circumferentor, or any other instrument under magnetic influence, must vary accordingly as that meridian varies. For instance, suppose the bearing of any one known object to have PREFACE. IX been taken from a given point by the magnetic meridian in the year 1700, and recorded; and if the bearing of the same object be now retaken by the magnetic meridian from the same given point, these two bearings will be found, on comparison, to diifer about 14, the magnetic meridian having in that time changed thus far in its direction (see table, p. 96). It is also well known to directors of mines that the plans of their excavations, on examination, are always found to be erroneous, some even to a great extent. This frequently misleads the miner, adding expense to his subterraneous pursuits, and the cause of such errors originates through his inattention to the variation of the needle in the plotting from time to time of his surveys. This part, therefore, shows the method of rectifying the bearings of old surveys, in order to connect them with those made by the scientifically correct method laid down in the second part of this work. The third part is thus arranged : 1. Axioms and observations. 2. The method of finding the true and invariable meridian. 3. To determine the variation of the needle of the circumferentor or other instrument used in sur- veying. 4. To reduce bearings taken by an instrument, the needle of which has any known variation, to bearings with the true meridian, with rules and examples. 12 X PBEFACE. 5. To reduce bearings from one magnetic meridian to bearings with any other magnetic meridian, with rules and examples. 6. To find the kind of meridian by which a plan has been constructed, with rules and examples. 7. On planning surveys, and finding the magnitude of an error in plotting, caused by inattention to the magnetic variation, with examples. 8. On running bearings on the surface by the cir- cumferentor or theodolite without error. 9. To determine the antiquity of a plan by its delineated meridian. 10. On recording bearings. 11. The Traverse Tables, with examples of their use. 12. An expeditious method of calculating the pro- duce of coal strata of any given thickness, with examples. 13. Concluding examples in mining surveying. Having now described the plan, and enumerated the heads of this publication, I must leave it to practical colliery viewers of scientific skill to judge of its merits and utility, in its present improved form ; and I trust, from my own practical experience in surveys of almost every kind during the last forty years, that the diffi- culties and intricacies of such a work will, to candid and liberal minds, be sufficiently obviated. T. BAKER. CONTENTS. PART I. PAGE Geometrical Problems .,,.,...! Theorems, and the method of conducting a subterraneous survey . . 4 To find the magnitude of angles 9 To determine bearings, and to reduce angles to bearings . , . 10 To reverse bearings . . . , . , , , .15 To reduce bearings to angles . . . ib. To reduce bearings and distances to their northing and southing, and casting or westing . . , 21 Surveying and recording bearings . . . . . . . 25 To survey subterraneous workings, and to prove the work, with examples and form of survey-book 27 To take a back sight 39 PART II Subterraneous surveying without the general use of the magnetic needle (Mr. Fenwick's method) .41 Subterraneous surveying entirely without the use of the needle (Mr. Baker's method) . . 43 The same by Mr. Beauland's method ...... 44 Xll CONTENTS. PAGE To plot a survey on paper by the common method, with a description of the protractor 48 To plot a survey on paper by the use of the ~["' s< l uare an ^ drawing- board 51 To plot a survey, so that if an error be committed in any part of the work, it will not affect the following part, with an illustrative example 53 To reduce any number of bearings and distances to one bearing and distance equal to the whole, with several examples both with and without the use of the needle 63 To plot on the surface by the circumferentor or theodolite . . 70 To avoid an obstruction that interferes with the line of plotting on the surface, with several examples . . . . . . 73 To make a survey when the subterraneous excavation inclines from the horizon 82 The fallacy shown of putting two or more bearings into one, and thus plotting them .......... 84 A promiscuous collection of practical questions in mining and tunnelling . . . , . . . . . .85 PART III. Axioms and observations . . . . . . . . . 92 On the variation of the magnetic needle . . . . . .93 A table showing the variation of the needle from the year 1576 to the year 1858, both inclusive 94 A table showing the diurnal variation . . . . . .95 To find the true meridian . . . . . . . . 96 To find the true meridian astronomically . . . . .97 To determine the needle's magnetic variation in any instrument . . 98 To reduce bearings from a magnetic to the true meridian . . .99 To reduce bearings from one magnetic meridian to bearings with any other magnetic meridian 103 To find the meridian by which a plan has been constructed . .109 CONTENTS. Xill PAGE To plan subterraneous surveys correctly, and to find the amount of an error, arising in plotting, through inattention to the magnetic variation of the needle . . . . . . . . 115 To run bearings on the surface by any eircumferentor or other magnetic instrument without error . . . . . .124 To find the antiquity of a plan by its delineated meridian . . .127 To record the bearings of subterraneous surveys . . . .128 The use and application of the Traverse Tables 129 The use of the Table in reducing hypothenusal distances to horizontal distances , . . . 131 A Traverse Table to every degree of the quadrant . ... 133 To calculate the produce of coal-strata of any given thickness in tons . 157 Concluding questions in mining surveying ....... 160 EXPLANATION TEEMS AND EXPRESSIONS IN THIS WORK. Bearing to tJie right or left of a meridian. A. line is said to bear en the right or left of the north or south meridian, when it is to the right or left of a person, whose face is turned towards the north or south. Bearing on different sides of a meridian. Two lines are said to bear on different sides of a meridian, when the one bears on the east side, and the other on the west side thereof. A Bord is an excavation in a seam of coal driven in a direction across its fibres. A Drift is a narrow excavation driven in any direction in coal or stone. A Headway is an excavation in a seam of coal driven in the direction of its fibres. Different Meridians. When one line bears in a given direction with the north meridian, and another bears in a given direction with the south meridian, those lines are called bearing with different meridians. Also, when one line bears on the east side of the north meridian, and another on the west side of the south meridian, those lines are said to bear on different sides of different meridians, and vice vend. TREATISE ON SUBTERRANEOUS SURVEYING, ETC. PART I. 1.- GEOMETBICAL PROBLEMS. -To divide a given line AB into equal parts. WITH any distance greater than half AB, and one foot of the compasses on A and B, describe two arches cutting each other in C and D ; through the intersecting points CD draw a line CD, which will cut AB in I into equal parts. FIG-.!, \ / 2. To draw a line parallel to a given line CD, to pass through any assigned point A. From the given point A take the nearest distance to the given line CD ; with that n$} . distance, and one foot of E _* the compasses, any where /''' "\. towards C describe an / \ / arch O ; through A draw ' p . . _ .j_ , -_--_r.i '''^rai^i^'"''* Q a line AB, just to touch the arch O in O ; and the line AB will be the parallel required. STJBTEEBANEOTTS SURVEYING, ETC. 3. To rtiise a perpendicular from a given point P in a given line A3. FIG. 3. From the given point P describe the arch ED ; take PF, and set from F to C, and from C to D ; then with any con- venient distance from C and D describe the arches O, and through their point of inter- section from the point P draw the line PO, the perpendi- cular required. 4. To raise a perpendicular from a given point A, at the end of a given line AB. Set one foot of the compasses on A, and extend the no, 4, other to any point C, above the line AB ; on the centre C describe the semicircle FAP, to cut AB in F ; draw FC cutting the semi- circle in P ; then draw AP, which e perpendicular to AB. 5. From a given point P to let fall a perpendicular upon a given line AB. FIG 5 P -._ i _. ^r-- E On the given point P as a centre, describe the arch EF to cut AB in E and F; with any convenient distance, and one foofc of the compasses on E and F, describe two arches to cut each other in I; through P and I draw PI, which is perpendicular to AB - GEOMETRICAL PROBLEMS. Fl G . 6 . 6. To mnlce an angle ABC equal to a given angle ODE. With any convenient extent of the compasses, and one foot on D, draw the arch FGr ; equal to the measure of the given angle D draw a line BC, and with the distance DF de- scribe the arch HI ; then make the arch HI equal to the arch FGr, and through I draw the line BA, forming the angle ; so the angle ABC is equal to the angle CDE. 7, To lay down an angle FDGr equal to any determined number of degrees, which suppose 35 Draw the line D^ 1 at pleasure, and with 60 off the scale of chords describe the arch EH on the centre D ; from the same chords take 35 (the quantity of the angle), and lay upon the arch from E to H, through which from D draw the line DGr, and the angle FDGr will contain just 35. S. To determine the number of degrees contained in any angle, suppose angle FDGr. With 60, taken from the scale of chords, describe the arch EH ; then extend the compasses from E to H, and observe, on the same line of chords, what number of degrees the extension measures, which will be the measure of the angle EDH. Or, apply the centre of the protractor to the angular point D, and bring its straight edge upon the line DF, and the degree the other line cuts on the divided arch is the measure of the angle. B 2 SUBTEEEANEOUS SURVEYING, ETC. FIG. 8. A THEOEEMS. 1. Every right angle, as ACB, contains 90 degrees or equal parts. 2. Every circle ABDE, is supposed to have its peri- phery divided into, or to con- tain, 360 equal parts, called \ degrees, and those degrees "-|B are divided into 60 equal parts, / called minutes, and each mi- nute is divided again into 60 equal parts, called seconds, &c. 3. Every circle AD, con- tains four right angles, at angles ACB, BCD, DCE, and EC A, which, from theorem 1, must contain 90 each. 4. Every semicircle EAB, contains two right angles, as angles EGA and ACB, which, from theorem 1, must contain 90 each. Draw the diameter AD, which will divide the circle EABD into two equal parts EAB and EDB, each con- taining a semicircle, or 180 ; if, therefore, a line AC be drawn perpendicular to EB from the centre C, it will k divide the semicircle EAB into \ two equal parts, making two -j z ' right angles EGA, ACB. \ / 5. If any right line AY \ /' stands upon another right line X N. X ^/' DZ, it will make therewith ~~~E ** kwo right angles, or two angles whose sum is equal to two right angles. (Euc. b. 1, p. 13.) If a line AY, be drawn from any part Y of the circumference to A, it will FIG. 9. THEOREMS. divide the semicircle DXZ into two unequal parts, making the angles DAY, YAZ, unequal ; but these two angles are equal to a semicircle, or two right angle?. 6. If two right lines IL, KM, intersect each other, the opposite angles A and C, as also B FIG.lo. and D, are equal ; that is, the angle A = the angle C, and the angle B = the angle D. (Euc. b. 1, p. 15.) 7. If a right line OR, cuts two parallel right lines NP and SQ, the alternate angles KaE, QbO. are equal, and consequently the lines parallel. (Euc. b. 1, p. 29.) 8. If any side of a right-lined FIG u. triangle be continued, see fig. 12, the external angle is equal to the sum of the two opposite in- n a . ternal ones. (Euc. b. 1, p. 32.) f Let UST be the given tri- 5 / angle ; then the L STZ is = " A L SUT -f L UST, = the sum / of the opposite internal angles. /R 9. The three angles of any triangle are together equal to two right angles, or 180. (Euc. b. 1, p. 32.) See fig. 12. In the triangle STU, the L STU -*- L TSU + Z SUT = 180, or two right angles. 10. The sides of similar triangles are proportional, and the angles subtended by proportional or equal sides are equal. (Euc. b. 6, p. 45.) 11. In any four-sided right-lined figure, called a square parallelogram, rhombus, trapezium, &c., the sum of the no. SUBTEEEAKEOUS SUEYEYING, ETC. four angles is equal to four right angles, or 360. (Euc. b. 1, p. 32.) 12. The sum of all the angles of any right-lined figure (though it contain never so many sides) is equal to double as many right angles, abating four, as there are sides in the figure. (Euc. b. 1, p. 32.) 13. In right-lined triangles, equal sides subtend equal angles (Euc. b. 1, p. 5). The greatest side subtends the greatest angle (Euc. b. 1, p. 19), and the least side sub- tends the least angle. 14. An angle in a semicircle is a right angle ; or if two F i a ; i a , lines, as TE, SE, be drawn from T and S (the ends of the diameter) to E in the circumference, they will form, a right angle TES. (Euc. b. 3, p. 31.) 15. In any right-angled tri- angle, the square of the hypo- thenuse (or longest side) is equal to the sum of the squares of the other two sides or legs. (Euc. b. 1, p. 47.) 16. The compass is divided into four cardinal points, called nortb, south, east, and west ; the two first, north and south, are formed where the meridian cuts the horizon, and the other two, east and west, are each 90 degrees distant from the points north and south ; therefore they divide a circle into four equal w 1- E parts of 90 degrees each. 17. "When the face is turned to the north N, the right hand is to- wards the east E, and the left hand towards the west "W ; and when the face is turned towards the south S, the right hand is towards the west W, and the left hand towards the east E. N .F1C.I1-, THEOREMS. 18. The magnetic meridian is that line in which the magnetic needle of the compass settles ; and every par- ticular place on the earth has its respective magnetic meridian. 19. The magnetic needle is here assumed to retain its parallelism in every situation within the limits of a sub- terraneous survey. If in the situation A, a magnetic needle is placed, and is found to settle in the direction of ab, if tty same needle is removed to B or 0, it will settle itself in the direction of cd and ef, both FIG, 15, parallel to ab> But the magnetic meri- dian of places very distant from each other will not be parallel ; for the mag- netic meridian of London will vary a few degrees from its parallelism with that of Edinburgh. The magnetic needle has a small diurnal variation, being greatestabout noon, also a small annual variation, which seldom exceeds a few minutes of a degree. Part Eirst of this work consists of the manner of surveying under-ground, with- out attending to the magnetic variation of the needle, with several easy and ex- & el peditious modes of plotting the same. The instruments used in subterraneous surveying are the circumferentor, the theodolite, Grunter's chain, in the coal mines, which contains 100 links. In the lead mines, a chain, divided into 100 feet, is now frequently used instead of Grunter's chain. The manner of conducting a subterraneous survey ~by tlie magnetic needle. (1.) Place the circumferentor, or instrument used, where 8 SUBTERRANEOUS SURVEYING, ETC. the survey is intended to commence ; then let a person go forward in the direction of the line to be surveyed, with a lighted candle in his hand, to tne utmost distance his light can be seen through the sights of the instrument ; its bearing then is taken by the circumferentor (the manner of taking bearings will be shown hereafter), and noted down in the survey book ; proceed then to take the distance of the light or object from the instrument ; remove the instrument, and let a person stand on the exact spot where it stood, holding in his hand one end of the chain, while another, going towards the object, holds the other end, together with a lighted candle, in the same hand ; then being directed by the former until that hand which holds the candle and the chain is in a direct line with the object or light whose bearing was taken, there mark the first chain ; then he that stood where the instru- ment was placed comes forward to the mark at the end of tie first chain, the other advancing another chain forward, with the candle and chain in the same hand, directed as before, there mark the second chain, so proceeding in the same kind of way until the distance of the object is determined, which being noted down in chains and links in the survey book, opposite to the bearing, then the first bearing and distance is completed: Fix the instrument again where the light, as an object, stood, or at the ter- mination of the preceding bearing and distance, and take the second bearing, by directing the person to go forward as before, so far as his light can be seen, or at any shorter con- venient distance, and proceed as before until the whole is completed. There should not be fewer than five people employed in such surveys, to carry forward the work with expedition, viz., one to carry forward the survey, and make the necessary observations and remarks ; another to carry the instruments ; another to direct the chain ; another to lead it ; and another to go forward with a light, as an object, THEOREMS. from station to station. During the time of making the survey, be careful in not admitting any iron, steel, or other ferruginous substance, within ten feet of the instrument, for fear of attracting the needle ; I have seen the needle affected at almost twice the above distance, by a very massy piece of iron. Also if the glass of the instrument stand in need of cleaning, it must be rubbed as gently as possible, and not with any silken substance, for that will be apt to excite electrical matter, which will prevent the needle from traversing ; but if that matter should be excited, it may be very easily discharged, by touching the surface of the glass with the wet finger. In order for familiarising the young miner with this system of surveying, previous to his practising it in mines, it would be necessary for him to fix up a number of marks on the surface, and afterwards take their bearing and dis- tance from each other, according to the method before directed. But to approach nearer to the form of subter- raneous surveying, it would be much better to do it at night, by the assistance of candle-light ; many favourable evenings might be found for this mode of practising. Should the current of air be too strong for the naked flame of the candle, lanterns may be used. To find tlie magnitude of angles. (2.) Every circle, ABCD, is supposed to contain 300 (see theorem 2) ; each semicircle DAB and DCB contains 180 ; and each quadrant AB, BC, CD, and DA, contains 90. Draw the line ab ; and if Z A.ab contains 50 L Dab must contain 90 50 40, and L baC must contain 180 50 = 130 (see theorem 5). Also if ab makes an angle of 50 with the line AC, and ad an angle of 30 with the same line, the semicircle ADC containing 180, L A& = 50 + Z Cad = 30 = 80, then 180 - 80, leaves 100 = /. bad. Or thus, L AD = 90; then B3 10 SUBTEEEANEOUS STJEVETINa, ETC. 90 - 50 / Aab = 40' ' Z. baD ; also L DaC = 90 ; then 90 - 30 L daC = 60 L Dad; consequently Z. ball = 40 + L Dad = 60 = 100 L bad, as before. If al make an angle of 50 with A, and ac make another angle of B 75 with the same line a A, then the L cab 75 50= = 25 ; and if ab make an an- gle of 50 with #A, and ac an angle of 25 with the line ab, then 50 + 25 = 75 L (Buc. b. 1, p. 15.) The manner of determining bearings, and also reducing angles into bearings. (3.) The instrument used in subterraneous surveying is the circumferentor, mentioned as before, whose effect depends on the magnetic needle ; and the directions, courses, or bearings, are recorded according to the angles these direc- tions make with the magnetic meridian. (The magnetic meridian is the north and south line, as pointed out by the mag- netic needle ; see theo- rem 18.) If we pass round from the north N, to the east E, and continue moving from the east to the south S, and from thence to the west "W, and lastly from the west to the north N, from whence we first of all set out, THEOREMS. 11 we shall have made a circuit NESWJST of 60, which all circles are upposed to contain (see theorem 2) ; and as there are four cardinal points (see theorem 16) in that circle, north, east, sonth, and west, dividing it into four equal parts, consequently from north N to east E subtends an angle of 90 ; from east E to south S subtends an angle of 90 ; from south S to west "W subtends an angle of 90 ; and from west W to north N subtends an angle of 90. Now let NE, or the distance between north and east, also ES, or the distance between east and south, also SW, or the distance between south and west, and also "WN, or the distance between west and north, be each divided into 90 equal parts or degrees, then a line in direction of CIST may be called due north, and another in direction of CS may be called due south, another in direction of CE may be called due east, or north 90 east, or south 90 east, and another in direction of CW may be called due west, or north 90 west, or south 90 west ; likewise the line CD passing between S and W, or between south and west, is called south 50 west, being 50 towards the west from south, or to the westward or right-hand (see theorem 17) of the south meridian line. The line CE passing between JST and W, or between north and west, is called north 20 west, being 20 towards the west from north ; the line CA passing between N and E, or between north and east, is called north 30 east ; and the line CB passing between S and E, or between south and east, is called south 50 east ; for the bearing of any object from any point or place, taken by the circumferentor, is only the angle that object makes with the magnetic meridian of that point or place from which the bearing is taken : Therefore, if the bearing of B from C is required, it is nothing more than the direction and angle that B makes with the magnetic meridian of C ; CS is supposed the magnetic meridian of C, and BCS is the angle the object makes with that meridian. SUBTEEEANEOUS SUEYEYING, ETC. Let WE, represent a circumferentor, and NS the magnetic needle suspended on tbe pivot c as its centre of suspension and centre of motion ; AB are two horizontal arras fixed opposite to each other on the instrument; on the extremity FJG.I8. of each arm is the sight d and e perpendicular thereto, through which is seen the object whose bearing is wanted : The inner part of the circle to which the needle points is divided into degrees, beginning at JN", and numbered to 90 each way to "W and E ; and also beginning at S, and numbered to 90 each way to the same points "W and E. The whole of the instrument is fixed on a stand, having a ball and socket to allow of its being kept level and turned freely round. This instrument is manufactured in great perfection by Messrs. Elliott, Brothers, 30, Strand, London. To find the bearing of the line H (by fixing the instrument at the mark at J), which suppose N 1 W 5 chains : At 80 links is a bord 15 holed into the headways to the right, and to the left 90 links to the face; at 1'70 chains is a bord 16 holed into the headways to the right, and to the left 60 links to the face ; at 2'55 chains is a bord 17 holed into the headways to the right, and to the left 60 links to the face ; at 3'40 chains is a bord 18 to the right 50 links to the face, and to the left 55 links to the face. Take the bearing and distance of AM (by fixing the instrument at A), which suppose N 85 E 2'80 chains : At 1*30 chains is a headways X to the right and to the left, and a mark + to return to ; at 2*50 chains is a headways Q to the right and to the left, and a mark * to return to. Take the bearing and distance of the head- ways XP (by fixing the instrument at the mark X), which suppose S 5 E 3 '10 chains : At 75 links is a bord 19 to the right and left, and holed into the headways each way ; at 1'60 chains is a bord 20 to the right and left, and holed into the headways each way ; at 2'40 chains is a bord 21 to the right, and holed into the headways, and none to the left. Take the bearing and distance of the headways SG STTBTEHEAXEOTJS SUEVEYIXG, ETC. QO (by fixing the instrument at the mark Q), which suppose S 4 E 2-30 chains: At 80 links is a bord 22 to the right, and holed into the headways, and to the left 40 links to the face ; at 1'GO chains is a bord 23 to the right, holed into the headways, and none to the left. Take the bearing and distance of the headways XYZB (by fixing the instrument at the mark X), which suppose from X to Y N 2 W 2-80 chains : At 90 links is a bord 24 to the right and left, and holed into the headways each way ; at 1*70 chains is a bord 25 to the right and left, and holed into the headways each way ; at 2*60 chains is a bord 26 to the right and left, and holed into the headways each. Take the bearing and dis- tance of YZ (by fixing the instrument at Y), which suppose N 5 W 2 chains : At GO links is a bord 27 to the left, holed into the headways, and none to the right ; at 1*50 chains is a bord 28 to the left 30 links, and none to the right. Take the bearing and distance of ZB (by fixing the instrument at Z), which suppose N 3 "W" 2'30 chains, to a pit B. Lastly, take the bearing and distance of the head- ways QL (by fixing the instrument at the mark Q), which suppose N 2W 3'60 chains: At 80 links is a bord 29 to the left, holed into the headways, and to the right 30 links to the face ; at 1 link is a bord 30 to the left, holed into the headways, and to the right 20 links to the face ; at 2'60 chains is a bord 31 to the left, holed into the'head- ways, and none to the right. See the survey-book, where the whole is recorded ; THECEEMS. 37 SURVEY-BOOK. A SURVEY OP A PIT'S WORKINGS, COMMENCING AT THE PIT A. Bearings. Remarks to Left. Dist. Remarks to Right. Chains. S. 10 E. 3-10 . AC Bord holed 0-80 Bord holed Bord holed . . . 1-60 Bord holed Bord holed 2-40 Bord 1 chain from the headways S. 80 W. . .... 1-60 . . Act Headways 1-30 Headways And a chalk mark * at R to return to S. 70 W. . . . . 1-80 . aG 0-80 A headways b, and a chalk mark * to return to Headways V, and a 1-20 chalk mark * to return to S. 8 W. . . . 2-50 . . RD Bord holed 0-70 Bord holed Bord holed . . . 0-50 Bord holed Returned to the mark * atV S. 10 W. . . 2-40 .... VF Bord holed . . . 0-80 Bord 1-30 chain from the headways Bord holed 1-60 Bord 1 chain from the headways Returned to the pit A N. 10 W. . 4-20 . AK Bord holed 0-80 Bord holed Bord holed . . . 1-70 Bord holed Bord holed . 2-50 Bord holed None . . . . 3-30 Bord holed Returned to the mark * atll N. 2 W. 3-00 RI Bord holed . . . 0-80 Bord holed Bord holed 1-60 Bord holed Bord holed . . . 2-40 Bord holed Returned to the mark * at b N. 1 W. 5-00 . m Bord 90 links from 0'80 Bord holed the headways Bord 60 links from 1-70 Bord holed the headways SUBTERRANEOUS SURVEYING, ETC. Bearings. Remarks to Left. Dist. Remarks to Right. Chains. Bord 60 links from 2-55 Bord holed the headways Bord 55 links from 3-40 Bord 50 links from the headways the headways Returned to the pit A N. 85 E. . . . 2-80 AM Headways 1-30 Headways And a chalk mark * at X to return to Headways 2-50 Headways And a chalk mark * at Q to return to Returned to the mark * atX S. 5 E. . 3-10 . 4 XP Bord holed 0-75 Bord holed Bord holed . . . 1-60 Bord holed None 2-40 Bord holed Returned to the mark * atQ S. 4 E. 2-30 . . . QO Bord 40 links from 0-80 Bord holed the headways None 1-60 Bord holed Returned to the mark * atX N. 2 W. 2-80 . XY Bord holed 0-90 Bord holed Bord holed . . . 1-70 Bord holed Bord holed 2-b'O Bord holed N. 5 W. 2-00 . . . YZ Bord holed 0-60 None Bord 30 links from 1-50 None the headways N. 3 C W. . 2-30 To pit B ZB Returned to the mai'k * atQ K. 2 W 3-60 QL Bord holed 0-80 Bord 30 links from the headways Bord holed . . . 1-70 Bord 20 links from the headways Bord holed 2-60 None Note. When marks are made to be returned to in the survey* observe that they are returned to, otherwise the survey will be defective ; and when the new method of taking the angles, given in Arts. 20 and 21, is adopted, the angles, thus taken, must be inserted instead of the bearings, the column being headed "angles" instead of "bearings." THEOREMS. FIG 3! The Back-Sight. (18.) Suppose the bearing and distance of B from the pit A is required : Eix the instrument at B, instead of A (keeping the same sight foremost, and pointing towards b, when it is placed in the situation of B, as if it had been placed in the situation of A, for the purpose of taking the bearing of B) ; then apply the eye at the sight furthest distant from A, turning the same until the light at the pit A is cut by the perpendi- cular hair in the other ; observe then the bearing of A from B, which, suppose S 30 E, on being reversed (see p. 17), will become JST 30 W, for the bear- ing of B from A, the distance, being measured, is found to be 3 chains; making the bearing and distance of B from A X 30 ~\V 3 chains. Bearings taken in this way are taken in a direction contrary to the order of the survey, and the eye is applied at the contrary sight to that which it would be applied when direct bearings are taken. (19.) Suppose the bearing of ABCDFGr and H is required, c making use of the back-sight throughout the survey : Fix the instrument at B, instead of A, directing that sight towards A which, in the situation of A, would have been hindmost, FJC 32 40 SUBTEREANEOUS SURVEYING, ETC. in the manner before directed ; then the bearing A from B being found to be 1ST 45 E, on being reversed makes S 45 W, the bearing of B from A, which enter into the survey^book. The instrument standing at B, turn that sight towards C which pointed to a, and take the bear- ing of C from B, which being found N 75 "W, enter the same into the survey-book, without reversing, as it is not a backsight. Remove the instrument from B to D, and direct the sight back to C from D, in the same manner as from B to A : The bearing then of C from D being found S 10 W, which, being reversed, will be N 10 E, the bearing of D from C, which enter into the survey-book. Then take the bearing of E from D, which being found N 80 E, enter the same into the survey-book, without reversing. Lastly, remove the instrument to Gr ; then take the back-sight from G- to E, which being found S 15 E, on being re- versed will be N 15 W, the bearing of G- from E, which being entered into the survey-book, then take the bearing of H from G- ; which suppose N 30 E, which enter also into the survey-book, without reversing, and the survey is finished. By this mode of taking bearings, the instrument- is on]j removed half the number of times it would otherwise be, were the back-sights not taken. SURVEY-BOOK. The bearing of B from A, S. 45 W. C from B, N. 75 W. D from C, N. 10 E. F from D, N. 80 E. Gfrom F, N. 15 W. II from G, N. 30" E. PART II. ON SURVEYING SUBTERRANEOUS EXCAVA- TIONS WITHOUT THE GENERAL USE OF THE NEEDLE. IT has long been found that the conducting of subter- raneous surveys requires strict attention in guarding against the presence of ferruginous substances, which exist in almost all mines, and which, it is well known, affect the magnetic needle, so as to cause it to give erroneous indications. On this account Mr. Fenwick was induced, as long ago as 1822 (when the second edition of his work was published), to suggest to the surveyor of mines the following new method, in which the needle has no control except in the first departure. The use of the instrument.* Suppose the subterraneous excavation ABCDEF to be surveyed beginning at the pit A, and terminating at the pit F. (20.) Place the instrument at B, and turning it until the vanes at zero cut the lighted candle at the centre of the pit A, which suppose N 65 E ; and suppose AB to be 3 chains, the fixed sight at 0^ still remaining as ' before ; screw the instrument fast, and turn the moveable sights so as to cut a candle placed at C, taking care that the instru- * The improved Circurafereutor, by Elliott Brothers, 30, Strand, London, which is still much used, especially in secondary mining surveys ; but the modern improved theodolite is much to be preferred. See ff-.i Mathematical Instruments, Wealds Series. 42 SUBVEYING SUBTEBBANEOUS EXCAVATIONS ment has remained immovable. If so, read off the angle, which the index makes with the moveable circle, which sup- FIG. 33. pose .120 ; then the angle ABC is 120, that is, the excava- tions BC and AB make an angle of 120. Removing the instrument to C, turn the sights and index so as to cut the candle at B, keeping the instrument immovable ; then turn the sights to the candle at D, reading off the angle BCD, which suppose 80; and measure CB, which call 5 chains. Remove the instrument next to D, measuring the distance CD, which call 3 chains ; and turn the sights and index to the candle at C, the instrument, as before, being kept immovable ; turn the sights to the candle E, observe the angle CDE ? which suppose 70, and let the distance DE be 4 chains. Remove the instrument to E, and turn the sight and index to the candle at D, keeping the instrument immovable; turn the sight to the candle at E, and observing the angle DEF = 160 ; lastly, measure the distance EF, which call 6 chains, and the survey is completed. The following method of conducting subterraneous survey entirely without the use of the magnetic needle, was sug- gested by Mr. T. Baker (who has now made the present WITHOUT THE TJSE OF THE NEEDLE. 43 additions and improvements to the new edition of Mr. Fenwick's "Subterraneous Surveying"), at least 35 years ago ; but it was ridiculed by the then colliery surveyors ; yet is now recommended and adopted by several scientific mining surveyors ; among whom I may name Mr. H. Mackworth ; who has given more elaborate details for con- ducting these surveys than those in the preceding article : Mr. M.'s improvements on Mr. Baker's suggestion are given in the following article. (21.) To commence a survey without the magnetic needle, where there is only one shaft to the mine, the following plan should be adopted. Two thin copper wires, carrying heavy weights, must be suspended from a strong straight edge, at the surface of the shaft, and as near the edges of the shaft as not to touch them, the weights reaching nearly to the bottom of the shaft; while the weights must be immersed in buckets of water, or what would be still better, in vessels filled with mercury, to diminish oscillation, which will still continue, if the shaft is deep ; but in the latter case, for only a very short time. The observer standing behind the wires must next send a candle along the head- ing, as far as it can be seen, and have it fixed in a line with the wires. He should repeat the operation in the opposite direction, by placing a candle against one of the wires, that the whole may be checked by seeing that the three candles are exactly in a line. This line being the basis of the whole underground survey, must be permanently marked by four or more pegs driven into the roof, with nails in them, or by marks on cross timbers or masonry. Eeturning to the surface, permanent pegs should be placed at some chains' distance, on each side of the shaft, in a line with the wires, as G- and H (see last fig). "We then obtain a line on the surface exactly corresponding with the base line of our operation underground. The same process may be adopted, if there is more than one shaft to a mine ; but it is not generally desirable to repeat it at more than one 44 SURVEYING SUBTERRANEOUS EXCAVATIONS shaft. A few hours' labour in getting the fundamental lines permanently fixed and connected, before commencing the survey, is afterwards well repaid. The angular instrument used for this purpose ought to be the modern improved theodolite (see the foot-note to last article). Three tripods should be provided, and two lamps on stands, fitting on the tripod, of such a height that, when the lamp is replaced by the theodolite, the fulcrum of the axis of the telescope must be of the same height a& the top of the wick in the lamp, a tripod with a lamp being placed under the centre of the shaft, at some well-marked station ; the second tripod is fixed with the theodolite upon it, as far along the base-line as the light at the bottom oi % the shaft can be seen. The theodolite is clamped to zero. The third tripod with the other lamp on it, is sent as far forward as the light can be seen from the theodolite. The depth of the top of the wick in the first lamp below the top of the shaft having been ascertained, we carry on a series of levelling with the vertical arc of the theodolite all through the mine, at the same time as the horizontal angles and the measurement of the lines are taken. The telescope of the theodolite being directed to the top of the wick of the first lamp, the angle of elevation or depression is read. The lower limb being then clamped, and the upper relaxed, the horizontal angle is then read to the second lamp, and at the same time its angle of elevation or depres- sion is read. The distance having been carefully measured, the first tripod is taken up, and carried forward beyond the third tripod, a lamp is placed on the second tripod, and the theodolite on the third tripod, when the observation of the angles are repeated as before. (22.) The leading feature of Mr. A. Beauland's plan (see "Mining Surveys, Institute of Mining Engineers, ]S~ewcastle-upon-Tyne ") consists in a method of fixing a bearing, or meridian line at the bottom of the pit, the direction of which is determined, either with reference to WITHOUT THE USE OF THE NEEDLE. 45 Hie true meridian, or with respect to some line arbitrarily iixed on the surface, as PQ, fig. to Art. 20. By this means the underground survey can be commenced, and carried forward to any extent, by means of the theodolite/ and is properly connected with the surface, the whole process being effected without the aid of the magnetic compass. This method is Mr. B.'s own invention, or, at least, he is not aware that the idea has ever been carried out before, or has ever occurred to any one else, though of course it is quite possible that he may not be the first person who has thought of such a plan. The process is effected by means of a powerful transit instrument, mounted in the line of the shaft, either at the top or bottom as may be most convenient. For simplicity, suppose the instrument to be at the top of the shaft. It is -fixed and properly adjusted on a very firm support, which must be so arranged as not to interrupt the view of the telescope, when pointed vertically down the shaft. Two marks are then fixed at the bottom of the pit, as nearly as may be in the same vertical plane as the transit, so that each of them can be seen through the telescope, and appear in the centre of the field of view. These marks are rendered visible by the light of a strong lamp reflected upwards, and are likewise so arranged that both can be seen by a theodolite placed at the bottom in a horizontal line with them. They are made as small as will allow of their being observed by the transit at the top, and are of such form that they can be bisected by the wires with great precision, the marks being as far apart as possible. If now, on pointing the instrument downwards, each of the marks be exactly bisected by the middle wire, it is evident that the horizontal line, in which the marks are placed, coincides with the vertical plane of the instrument, and is, therefore, parallel to the position of the telescope when pointed horizontally. In this case, therefore, we have two lines, one at the top of the shaft, represented by 46 SURVEYING SUBTERRANEOUS EXCAVATIONS. the optical axis of the telescope when pointed horizontally the other the line joining the centres of the two illuminated marks at the bottom, and the bearing of the instrument being determined, either with respect to the meridian, or to some determinate line, which can be connected with the surface survey, that of the line of direction of the marks below is ascertained at the same time. This, however, is on the supposition, that each of the marks is seen precisely in the centre of the telescope.- If this condition is not exactly fulfilled, the marks being a little out of the centre of the field of view, the apparent distance of each mark from the middle wire is accurately measured by a micrometer, or some other means, and from these distances, the angular deviation of the line of the marks from the plane of the instrument is determined by calculation. Having found the amount of this deviation, the bearing of the line of marks is at once deduced from that of the instrument, and the connection between the surface and underground survey, made as in the former case. It is necessary, in order to complete the process, that permanent marks should be fixed above and below, the marks above ground being set out in some given direction, with respect to the plane of the telescope; those below, with respect to the illuminated marks, which, as well as the instrument, must be removed from their places in the line of the shaft, before the colliery can resume working. "Wherever the nature of the ground, or erections on the surface, admit of it, marks may be placed at once in the direction of the instrument above being set out in any convenient positions, coinciding with the middle wire of the telescope. These permanent marks should of course be placed so that one of them can be seen from the other, it is also desirable to have them conveniently placed for the commencement of the surface survey. Where, however, it is not practicable to set out a line in the direction of the transit, owing to obstructions, some PLOTTING STTEYETS. 47 other direction must be taken, one mark being fixed in the line of the instrument, and the other at any point at a con- venient distance, and visible from the first. The direction of the permanent line will, of course, be determined with respect to that of the transit, by setting up the theodolite at the nearer station, and measuring the angle between the direction of the transit and that of the further station. The permanent marks fixed at the bottom of the pit are fixed in like manner, and their direction determined from that of the illuminated marks, by the aid of the theodolite, which is placed at some point near the shaft, in the line of the illuminated marks, and from which a more distant point can be seen. A permanent mark is then fixed at the place occupied by the theodolite, and another at the more distant point referred to, which may be chosen convenient for the commencement of the underground survey. Mr. A. B. has thus endeavoured to explain, somewhat briefly, but he trusts with sufficient distinctness, the method by which the underground survey may be connected with the surface. It will scarcely be necessary for him to observe, that the whole process is one requiring great care, and an intimate acquaintance with the use and manipula- tion of the instruments, such as can scarcely be acquired without considerable expense. With proper management, however, and a transit of sufficient size and power, he believes the bearing may generally be fixed at the bottom of the pit without any error exceeding one minute of an arc, a degree of precision amply sufficient for all practical purposes. On plotting subterraneous surveys. (23.) Plotting may be divided into two kinds : The first kind, the communicating of bearings and distances of a subterraneous survey to paper, for the purpose of planning the same ; the second kind, the manner of running on the surface of the earth the different bearings or angles and distances, in the same order as they were taken under- STJEYEYIKG SUBTEEEANEOUS EXCAVATIONS ground in the survey. In the first mode, the protractor, for setting off the angles contained in each beariDg, and a scale of chains and links, for transferring the distances, are requisite ; and in the second mode, the circumferentor or theodolite, and Gunter's chain. Observe, in running off the bearings on the surface, that the same instrument be made use of as in the subterraneous survey ; and also let the same end of the needle, when used, determine the angles of the bearings as determined them under- ground. This last precaution is not necessary when the magnetic needle is not used. (24.) Let ABCD represent a protractor, which is a cir- cular rim of brass, and E its centre, of about 9 inches diameter, divided into degrees, and each de- gree in quarters of a degree, commencing from the north and south points A and B and numbered up to 90 atC and D. Also abc represents a semi- circular protractor, which for many pur- poses, is more com- modious than the circular one, ab re- presenting the meri- dian, and e its centre. These instruments are manufactured by Messrs. Elliott Bro- thers, 30, Strand, London. In using this in- strument in plotting bearings, the meridian line AB or ab, WITH OE WITHOUT THE USE OF THE NEEDLE. must be applied to the assumed meridian line drawn on paper; and if a line Ee is drawn from the centre E, through the 50fch degree or division from B to C, supposing AB the meridian, A the north, and B the south ; then Ee will be N 50 ~W (see theorem 17), and the line E/ 1 passing through the 20th degree or division, will be N 20 E. (25.) Suppose the following bearings and distances to be plotted on paper 10 chains. 7 6 FIC.35. AB, N. 45 W. . BC, N. 10 E. CD, S. 50 E. . Proceed thus : Draw the meridian line NS on the paper where the work has to be plotted, N for north, and S for south ; then fix on any place on that meridian line for the commencement of the work, as at the pit A; apply the meridian line AB of the protractor on the as- sumed meridian, with its centre E on A ; let nesw represent the protractor, n corresponding with N the north, and s with S the south, e will represent the east, and w the west; then draw the line AB from the centre of the protractor at A through the 45th degree from n towards w, or west, and it will represent N 45 "W" : Also from the scale of chains take 10 with the compasses, and setting the same from A to B, and AB will represent the first bearing and distance N 45 W, 10 chains : by the assist' ance of a parallel ruler, or any other method, draw the second meridian line ns, through B, parallel to that drawn through A ; apply the protractor 50 SURVEYING SUBTERRANEOUS EXCAVATIONS as before directed, with its centre on the point B ; draw the line BO from the centre of the protractor at B, through the 10th degree from n towards e, and it will represent N 10 E : Then from the scale of chains take 7 with the compasses, setting the same from B to C, and BC will represent the second bearing and distance ; then draw the third parallel line ns through C ; apply the protractor as before, with its centre on C ; draw the line CD through the 50th degree from s towards e, and it will represent S 50 E : Then take 6 chains from the scale, setting the same from C to D, and CD will represent the third bearing and distance ; and the whole will be plotted. Note. The student ought now to lay down on paper the several surveys, commencing at Art. 12, not only by the old method of bearings, taken by the magnetic needle, but also by the modern and more accurate methods, given in Arts. 20, 21, and 22 (the methods given in the several articles not differing materially except at the commencement of the surveys), that he may thus acquire a skilful and ready method of performing this impor- tant part of his profession. See the following article. (250.) Let the following angles and distances, taken in a coal-mine, be laid down on paper (see fig. to Art. 20). Let NS be the true meridian, obtained by making proper allowance for the magnetic variation ; and let the following distances be measured, and angles be taken in a coal-mine as below : DISTANCES. AB = 3 -.12 chains. BC = 4-96 ,, CD = 2-89 DE = 4-17 EF 6-02 ANGLES. NAB = 64 39' ABC 118 19' BCD = 79 15' CDE = 61 5' DBF = 158 57' Draw the meridian line NS, N representing the north point, and let A in the line NS be the pit where the work is to commence ; lay off from the meridian line NS by the protractor, the angle NAB=64 39 r , in the manner already directed; and from a scale of equal parts, lay off the dis- WITH OK WITHOUT THE USE OF THE NEEDLE. 51 tance AB = 3'12 chains, and extend the line, if necessary ; next apply the line AB of the protractor on the line AB on the plan, the centre E of the protractor being applied to the angular point B : then lay off the angle ABC=118 19' ; and the distance BC = 4'96 chains ; apply the protractor to the line BC, as before directed, lay off the angle BCD=r 79 15', and the distance CD=2'89 chains : lay off succes- sively the angles ODE = 61 5' and DEE = 158 57', and the distances DE=4-17 and EE = 6'02 chains; and the work will be completed, being a correct representation of the survey made in the mine. Next plot the surveys, given in Arts. 17, 18, and 19, by laying off the successive angles, as directed in Arts. 20 and 21, the bearings being previously reduced to the angles, which every two successive distances make with one another by Art. 6. Note. In the second column of the survey-book to Art. 17, the angles NAB, ABC, &c., must be entered, as shown in this article. Suppose the following subterraneous survey is to be plotted by the application of the T square : N. 54 W. . . .10 chains. S. 42 W. . . . 7 N. 30 W. . . .6 (26.) On the drawing-board, or table ABCD, fix the paper abed, on which the survey is to be plotted, and let SN represent the T square applied thereon, which also represents the magnetic meridian (N the north and S the south). Eix upon the point /for the commencement of the work ; apply the straight edge of the semicircular, pro- tractor sn against the arm of the T square NS, with its centre on the pointy/ then draw the line fg through the 54th degree of the protractor from north to west, setting off the distance 10 chains from / to g : Then fg is the first D 2 52 STJIIVEYINQ SUBTEHEAITEOUS EXCAVATIONS FIG 36 bearing and distance N 54 W 10 chains. Kemove the T square along the line AC until its arm SN meets the point y, where it represents the magnetic meridian ; then apply the protractor as before- directed, with its centre 011 g ; draw the line gli through the 42nd degree from south to west, setting off the distance 7 chains from g to h : and gli is the second bearing and distance S 42 W, 7 chains. Ke- move again the T square until its arm SN meets the point h, representing there the magnetic meridian; then apply the protractor with its centre on Ji; draw the line Tik through the 30th degree from north to west, setting off the distance 6 chains from Ji to Tc : And Jik is the third and last bearing and distance N 30 W, 6 chains. The work being finished, take the paper off the board. (27.) In the following subterraneous survey fgJik (see Pig. to last Article), I wish to know, by one single bearing and distance, the situation of k from f? V fg, N. 54 W. gh, S. 42 W. M, N. 30 W. 10 chains. 7 ,, 6 Protract the survey on the paper fixed to the drawing- board, as before-directed; then draw a line from f to Jc ; move the arm of the T square until it touches /, forming therewith the magnetic meridian ; then apply the protractor with its centre at f, observing what division or degree the line fh cuts which will be found to be the 71st nearly, which is the magnitude of the angle N/& : Measure the distance to 7c from / by the same scale as the work was WITH OE WITHOUT THE USE OF THE NEEDLE. 53 plotted from, which distance is found to be 16*70 chains ; then from rule, Art. 4, the bearing of k from / will be found to be N 71 "W, and its distance 16'70 chains. (28.) In the following survey of the subterraneous work- ing ABCDF (see Fig. to Art. 16), driven from the pit A towards Gr, I wish to know the bearing that the workmen must proceed in from F to hit the pit Gr, and likewise the distance between F. and Gr ? Plot the survey from the given data in Art. 16, by the use of the T square ; also by laying off the several angles, as directed in Arts. 20 and 21, which will verify the survey. Then the bearing of the pit Gc from F, from rule, Art. 4, will be S 65 30' E. Measure the length of the line FG by the same scale of equal parts as the work was protracted from which is found to be 8*60 chains ; hence the bearing and distance of the subterraneous working from F, to hit the pit G-, must be S 65 30' E 8*60 chains. ANOTHER METHOD. Which may le thought more eligible than the preceding \for if any error is made in this method of 'plotting, it only affects the particular part where it occurs, and is not carried throughout the remaining part of the work, as in the otner methods already described. (29.) Suppose the following survey to be plotted accord- ing to this method : Chains. AB, S. 36 E. . . .7-00 EC, S. 42 W. . . . 4-00 CD, S. 75 W. . . . 10-00 DF, N. 42 W. . . . 7-50 Prepare the survey by taking the northing, southing, easting and westing of all the bearings therein (see Art 10, ex. vii.), placing each separately in its respective column, in the following preparatory table : Thus the bearing and 54 SURVEYING SUBTEBEANEOUS EXCAYATIONS distance AB, S 36 E, 7 chains, will, from the traverse tables, contain 5-66 chains of southing, and 4'12 chains of easting ; and so of all the rest. The next thing is to determine the northing and south- ing of the bearings conjointly, from A the point of com- mencement of the survey : Thus let NS represent the magnetic meridian of A, the southing of the bearing AB S 36 E, 7 chains is 5-66 chains A ; which place in the 6th column of the preparatory table. The southing of the bear- ing BC, S 42 W, 4 chains is 2-97 chains al, which, being- added to 5'66 chains, makes 8'63 chains A.I for the south- ing of the bearings ABC ; which place in the 6th column : The southing of the bearing CD S 75 W, 10 chains is 2'59 FIG 37 chains lc, which, being added to 8'63 chains, makes 11-22 chains Ac for the southing of the bearings ABCD ; which place in the 6th column : The next, DF, N 42 W 7'50 chains, will produce 5'55 chains of northing ce from D, which, being subtracted from 11*22 chains, leaves 5 '67 chains Ae, the southing of the bearings ABCDF from the commence- ment A : Then determine the easting and westing distance of WITH OR "WITHOUT THE TTSE OF THE NEEDLE. 55 the end of each bearing from the assumed meridian of the point A, or point of commencement. The easting of the bearing AB, which is S 36 E, 7 chains from NS, the assumed meridian, will be found by the traverse tables to be 4'12 chains &B ; which place in the 7th column of the following table : The westing of the bearing S 42 W, 4 chains from B will be found to be 2' 68 chains /C, which, taken from the easting aB or &/4-12 chains, leaves 1'44 chains, 1C for the easting of the bearings ABC from NS, the assumed meri- dian of A : The westing of the bearing S 75 "W, 10 chains from C will be found to be 9 -66 chains C^, from which take 1-44 chains of easting 5C, leaves Ig or e?D 8'22 chains for the westing of the bearings ABCD from NS : The westing of the bearing N 42 W, 7*50 chains from D will be found to be 4*97 chains Dl, which, being added to 8'22 chains cD, makes d or eF 13 '19 chains for the westing of the bearings ABODE from NS. Now, to prepare the survey for plotting, the next thing is to assume another meridian, which shall be to the west of the westmost bearing of the survey from NS ; and from this second meridian find the easting of the end of each bearing from it (see the 8th column of the table). The greatest westing of the bearing from NS is eF, or cl 13-19 chains : Suppose, then, this second assumed meridian line to be ns 14 chains AO west of the first meri- dian line NS, place the 14 chains at the top of the 8th column of the following table, which is the distance that the point A is eastward of ns : Then 14 chains ha + 4' 12 chains B = 18-12 chains TiB, the distance that B is east of ns ; which place in the 8th column : Then 14 chains + 1'44 chains 5C = 15'44 chains 7cC, the easting of C from ns : Then 14 chains 8'22 chains cD = 5'78 chains 0D, the easting of D from ns : Lastly, 14 chains 13 f 19 chains cF = 81 links m~F, the easting of F from ns; which, being all entered in the 8th column of the following table, the survey will be prepared for plotting. 56 SURVEYING SUBTEEBAFEOUS EXCAVATIONS ||S* .W W pq H pq *i? i5 *J fl O (N --fi CO > 1 IH "^ rH O T-l -^ t>. OO 06 f 111 J^J CO JO ^ b illjr <1 PQ P PS llfd J W C^ ^H (M Ci o 7^ -* CM T-I ~ &> &> .2 -^ A^ co co ^'3^3 O r-t r O 5> w^^a *Q o o & *w ^ *-M -= * A . CO OQ CO OJ _U) *s CO Il g 'O CO t- .9 ^o to cs e ?* * * 1 < o ^ " 73 H S-^ O R J^ m .2 EATOR * be g 1 pj C 1 ! 6 "* : : i PQ 0> 1 1 2 e g H OS 3 PH fcb .3 CO t^ O .a co o o p s CO S u : i -3 ^ r5 a m 1 1 '3 V 5 S c* f Q xo O : : : 8 J5 EH PQ & 00 p | ? o f g 'S i>- ^ o t> , If 8 ^ p ^ II ?o c^ 2rs c< '1 CO <**** 1 CO CO CO {25 PQ P fe <1 PQ P WITH OR WITHOUT THE USE OF THE NEEDLE. 57 In order to plot the survey, fix the paper on the drawing- board or table G-HIK ; then draw the meridian line ns by the application of the T square, n representing the north and s the south ; let O be the point for the commencement of the work, and from the 6th column of the table set off the different southings ; 1st, 5'GG chains Aa from O to k, being the southing of the bearing AB ; 2dly, 8*63 chains Ab from O to &, the southing of the bearings and distances AB and BC ; 3rdly, 1T22 chains Ac from O to 0, the southing of the bearings and distances AB, BC, and CD; and 4thly, 5'67 chains Ae from O to m, the southing of the bearing and distances AB, BC, CD, and DF. This being done, apply the T square to the side G-K, its arm crossing the meridian line ns at right angles ; then from the 8th column of the table set off 14 chains of easting from O to A, and A denotes the place of commencement of the survey, or point of departure : Move the T square down the side GrK until its arm comes to Ti ; then set off 18*12 chains of easting from Ji to B, draw the line AB, and it represents the first bearing and dis- tance ; move the T square until the arm comes to &, then setting off 15*44 chains of easting from Tc to C, draw the line BC, and it represents the second bearing and distance ; move the T square to 0, then setting off 5*78 chains of east- ing from to D, draw the line CD, and it represents the third bearing and distance ; move the T square to m, then setting off 81 links of easting from m to F, draw the line DP, and it represents the fourth and last bearing and dis- tance. Then the whole survey will be plotted. Next plot this survey from the given data by laying off the several angles as directed in Arts. 20 and 21, the bearings being previously reduced to the angles which the successive distances make with one another by Art. 6 ; also plot the surveys, given in Arts. 30 and 31, in the same manner. (30.) Suppose the following subterraneous survey to be plotted, beginning at the pit A : 58 SUBYEYING SUBTEEBANEOUS EXCAVATIONS FIG, 3 8, Chains. AB, N. 42 E. 5-00 BC, E. 4-00 CD, N. 9 E. 4-00 At 4 chains is a mark * to return to. DF, S. 69 E. 5-66 Returned to mark *. DG, S. 36 E. 7-00 GH, S. 42 W. 4-00 TA Prepare the survey for plotting, by taking the northing, southing, easting, and westing of each bearing from the traverse tables. The northing and easting of the first bearing and distance N 42 E, 5 chains, will be northing 3*72 chains, and easting 3-35 chains (which see in the following preparatory table, together with the northing, southing, easting, and westing of all the others) . Then find the northing and southing of the bearings conjointly from the commencement of the sur- vey at the pit A* which is had from the 2nd and 3rd column of the table : The northing of the first bearing and distance will be found to be 3'72 chains ; which place in the 6th column of the table : That of the second bearing and dis- tance will be also 3'72 chains ; that of the third, 3'72 chains + 3*95 = 7*67 chains ; and so of all the rest. Also take the easting and westing of each bearing and distance from the meridian of the pit A, which is had from the 4th and 5th column of the table : The easting of the first bear- ing and distance will be found 3 -35 chains ; which place in the 7th column of the table : That of the second will be 3-35 + 4 chains z= 7'35 chains of easting ; and so of all the WITH OB WITHOUT THE USE OF THE NEEDLE. GO fl, H CO O> rH g *irl ** a / 13-19 + 5-67 = 14-36 AF,or the distance of F from A. As AG 5-67 . . . . -753583 Is to radius . . . . 10 '000000 So is GF 13-19 1-120245 To tang. Z A GG 45' . IQ'366662 Therefore the bearing and distance of F from A is N 06 45' E, 14-36 chains ; and if that bearing and distance is 66 SUBVEYING STJBTERB.O'EOTJS EXCAVATIONS run off by a circumferentor and chain, on the surface from A, it will determine the point thereon immediately vertical to the point F in the subterraneous excavation. Also, if the different bearings and distances ABCDF are protracted on paper, on which the triangle AGrF is con- structed, beginning at the point A, and making the side AGr the meridian, the end of the last bearing and distance DF will coincide with the angular point F of the triangle, if the survey is rightly protracted. (34.) In the subterraneous survey ABCDFG-H, com- mencing at the pit A, I wish to know the direct bearing and distance of the point D from A, and also the direct bearing and distance of the point H from A, so that a pit may be put down from the surface on each of those points ? AB, N. 42 E. BC, E. . CD, N. 9E. DF, S. 69 E. FG, S. 36 E. GH, S. 42 W. Chains. . 5-00 . 4-00 . 4-00 . 5-56 . 7'00 , 4-00 (See Preparatory Table opposite.) The point D has from A 7'67 chains of northing A.a, and 7*98 .chains of easting aD ; and the point H has from A 2-96 chains of southing A5 ; and 14*63 chains of easting Construct the triangle AD, and let Aa represent 7'67 chains of northing, and aD 7'98 chains of easting ; also construct the triangle AZH, and let A.b represent 2'96 chains of southing, and 6H 14'63 chains of easting : The side AD WITH OE WITHOUT THE USE OF THE NEEDLE. 67 PREPARATORY TABLE. Chains. N. 42 E. 5-00 E. . . 4-00 N. 9 E. 4-00 S. 69 E. 5-56 S. 36 E. 7-00 S. 42 W. 4-00 Northing. Southing. Easting. Westing. Chains. 3-72 3-95 Chains. 2-00 5-66 2-97 Chains. 3-35 4-00 0-63 7-98 5-21 4-12 Chains. 2-68 7-67 7-67 10-63 7'67 17-31 2-68 2-68 2-96 14-63 and /. NAD is required in the former triangle, and the side AH and L SAH in the latter. Then, as A 7 '67. Is to radius . . . . So is D 7-98 884795 10-000000 902003 To tang. A 46 8' 10-017208 And V 7'67 + 7'98 = 11-06 AD. Therefore the bearing and distance of a pit from A on the surface, to hit the point D under-ground, will be N 46 8' E, 11-06 chains. Also, as A6 2-96 . Is to radius So is 6H 14-63 . To tang. A 78 33' 471292 10-000000 1-165244 10-693952 And V 14-63 + 2 '96 = 14-92 AH. Consequently the bearing and distance of a pit from A 68 STTBVEYING SUBTEREANEOUS EXCAVATIONS on the surface, to hit the point H under-ground, will be S 78 33' E, 14-92 chains. (34#.) In the subterraneous survey ABCDEF, com- mencing at the pit A, it is required to find the direct bearing and distance of the point E from A, so that a pit may be sunk from the surface to the point E (see Eig. to Art. 20), the required bearing being taken both from the meridian NS, and also from a well defined line GH, passing through the fixed marks G- and H and the shaft A, and corresponding to a line in the headway AB, determined in the manner pointed out in Articles 21 and 22. Let the distances be measured, and the angles be taken by the theodolite as below : Distances. AB = 3-12 chains. BC = 4-96 CD = 2-89 DE = 4-17 EF = 6-02 Angles. ABC = 118 34' BCD = 79 15' CDE = 61 5' DEF = 158 57' Eeduce the angles at B, C, D and E to their bearings from GH by Art. 3 ; then find the northing or southing and the easting or westing from the Traverse Table by Art. 59 ; then proceed as in Art. 34 to find Kg and Ey ; whence by trigonometry, as shown in the last-named Article, the bearing of E from the fixed line GH, and the distance AF, will be readily found. Next reduce the angles A, B, C, D and E to their bearing from NS, then find the northing or southing and easting or westing from the Traverse Table, and proceed as in Art. 34 to find Am and Fwi ; whence by trigonometry, as already shown, the bearing of E from the meridian NS and the distance AE will be found. Or the bearings and distance in both cases may be found from the plan by measuring the angles GAF and NAF with the protractor, and the distance AE by the same scale WITH OE WITHOUT THE USE OF THE NEEDLE. of equal parts as that with which the plan was laid down. By doing the work by all these methods its accuracy may be further verified. It would conduce much to the improvement of the student to plot the surveys in the following Articles 35 and 36, by reducing the given bearings to the angles made by every two successive lines in each example, as practice of this kind will impart great facility in the exercise of his profession; and besides, enable him to reason for himself and not on every slight occasion to have recourse to authors. (35.) In the following subterraneous working ABCDF, beginning at the pit A, I wish to know the bearing and distance of the pit G from E, the bearing and distance of Gr from A being given : N FIG, 43. AB, S. 30' W. . BC, N. 50 W. CD, N. 50 E. . DF, N. 53 W. AG, N. 20 E. . 70 STJBYEYINa STJBTEBBANEOTTS EXCAYATIO^S PREPARATORY TABLE. Chains. S. 30 W. 4-00 N. 50 W. 8-00 N. 50 E. 9-00 N. 53 W. 8-00 N. 20 E. 24-00 Northing. Southing. Chains. 3-46 Easting. Westing. 6F Chains. 514 5-79 4-81 Chains. 6-89 Chains. 2-00 6-13 6-39 15-74 3-46 3-46 AZ> Ka 6-89 8-21 14-52 .6-89 12-28 22-55 7-63 aG or be 10-27 Then A.a 22-55 chains A5 12-28 chains = 10-27 chains 5or cGr, and P5 7*63 chains + aQr or Ic 8-21 chains = 15'84 chains ~Fc. The L nFGr, or bearing of the line FG from the mag- netic meridian ns, and the length of FG are both wanted ; and the sides J?c, cQ-, and the right L c are given to nnd them. As Fc 15-84 .... 1-1997552 Is to radius . . . 10 '0000000 So is Gc 10 -27 . . . 1-0115704 To co-tang. F 57 3' . . 9-8118152 "Which will be JS" 57 3' E with the magnetic meridian ns. Also v/ 15-84 + 10-27 = 18-87 EG. Therefore the bearing of the pit G from E will be N 57 3' E, and the distance 18-87 chains. Plotting on the surface ly the circumferentor, or theodolite. (36.) In this mode of plotting the bearings and distances are run off on the surface of the earth in the same order as taken in the subterraneous survey. Great care must be taken in running the length of each bearing as nearly hori- zontal as can be, where the surface is uneven and declining. WITH OB WITHOUT THE USE OF THE NEEDLE. 71 The first two examples show the different modes of commencing the plotting of a survey on the surface, by assuming a point to begin at ; and the others following show the manner of avoiding an obstacle, as a house, a lake, or any other thing that interferes with the line of survey. Let the following subterraneous survey be plotted on the surface, commencing at the centre of the pit A : FIG.44. Chains. S. 45 W. . 6-00 S. 80 W. . . . 6-00 N. ..... 5-00 N. 70 E. ... 4-00 N. 20 E. . 10-00 Fix the instrument as near the pit A as convenience will allow ; (observe to keep the same end of the instrument first in the plotting of the survey as was first in making it under-ground ; likewise the same end of the needle must determine the bearings in the plotting as determined them under-ground). Suppose a the place where the instrument is fixed, which is such a situation that, when the fore-sight is put in the direction of the first bearing, S 45 W, you may, by looking backward from a, cut exactly the centre of the pit A, the commencement of the survey, otherwise the instrument is not placed in a proper situation. (This first point A is obtained by shifting the instrument either to the right or left, until it is in the situation before-mentioned.) After the proper situation, of the commencement of the survey is found, let the assistant take the chain, and running 6 chains from the centre of the pit A, which STJRYEYINQ SUBTEBEANEOTJS EXCAVATIONS suppose to extend to B, then AB is the first bearing and distance plotted. Eemove the instrument to B, and put the fore-sight in direction of S 80 W, measuring the dis- tance from B to C 6 chains ; then BC is the second bearing and distance. Remove again the instrument to C, and put the foresight in direction of due north, measuring the distance from C to D 5 chains; then CD is the third bearing and distance. E/emove again the instrument to D, and put the fore-sight in direction of N 70 E, measuring from D to P 4 chains ; then DE is the fourth bearing and distance. Lastly, remove the instrument to I\ and putting the fore- sight in direction of N 20 E, measure 10 chains from F to Gr ; then FG is the fifth and last bearing and distance. If marks are made at B, C, D, F and G-, they will represent on the surface the excavation with all its windings. (37.) Suppose the following subterraneous survey ABCDF, to be plotted on the surface, commencing at the centre of the pit A : FIG-,45, S. 30' W. N. 50* W. N. 50 E. N. 53 W. Chains. 4-00 3-00 9-00 8-00 Instead of following the same mode of commencement, as shown in the former example, make any place on the surface the point of commencement, as a (the same not being far distant from the pit A), and run off from that assumed point a the first bearing and distance, in the same WITH OB, WITHOUT THE USE OF THE NEEDLE. 73 manner as if a was the centre of the pit A ; which first bearing and distance S 30 W 4 chains suppose to be represented by db. Before the instrument is removed, from a take the bearing and distance of the centre of the pit A from a, which suppose S 30 E 3 chains a A, and insert it in the column of remarks in the survey-book (for fear it should be forgot), as a deflection from the line of the subterraneous survey; which deflection must be accounted for before the whole of the survey is plotted. Now remove the instrument to b, and there turn the sights in the direction of S 30 E, running off 3 chains, which let #B represent ; then the line AB represents the first bearing and distance as if taken from the centre of the pit A (the line of deflection A is now repaid). Remove the instru- ment from b to B, and proceed to run off the second bearing and distance N 50 W 8 chains BC, according to the method described in the last example. Remove the instru- ment to C, and run off the third bearing and distance N 50 E 9 chains CD. Lastly remove the instrument to D, and run off the fourth bearing and distance N 53 W 8 chains DF. And if marks are put up at BCD and E, they will represent the course of the subterraneous excava- tion on the surface. Note. This survey ought also to be plotted by the new methods, given in Arts 20 and 21, in the manner directed in Art. 34a. To show the manner how to avoid an obstacle that interferes with the line of survey when plotting it on the surface of the earth. (38.) Suppose the following survey ABCD is to be plotted on the surface, commencing at the centre of the pit A : SUBTEEEANEOUS EXCAVATIONS S. 30 W. N. 5.0 W. A N. 50 E. Chains. 4-00 8-00 9'00 Fix ib/: instrument at the point #, as the assumed centre of the pit A, and run off the first bearing and distance from thence, which suppose to extend to I ; then take the bearing and distance of A from a for the deflection, which note down in the column of remarks in the survey-book: suppose it to be S 30 B 3 chains : Then remove the instrument to 5, and from thence run off S 30 E 3 chains SB, and the line AB will be the first bearing and distance as run off from A. Eemove the instrument to B, and proceed to plot the remaining part of the survey, Now the next bearing, N 50 W, will be found to run over the lake e ; therefore, to avoid this obstruction, let the plotter extend the line Be to such a distance that, in running the second bearing from e, he may avoid the obstruction. Suppose this line Be to be due west 6 chains, which being noted down in the survey-book, remove the instrument to c, and from thence let the bearing N 50 -W 8 chains be run, which suppose it to extend to d; then from d run off due east 6 chains (being the reverse of Be), which suppose to extend to C ; then BC will be the second bearing and distance. Remove the instrument to C, and run off the third bearing and distance, which suppose to extend to D ; then CD will represent N 50 E 9 chains, and the whole is plotted. The obstruction at e may be more easily avoided by WITH OR WITHOUT THE TTSE OF THE NEEDLE. 75 laying down the survey on paper, and drawing on it the lines AC AD, which must be measured, and their bearings from NS found ; thus the position of the points C and D may be determined ; also various other similar methods will readily suggest themselves to the student when the obstruc- tions are even more formidable than that at e. In plotting a survey, either on paper or on the surface of the earth, it matters not whether we "begin with the first or last bearing, the ending will le the same. (39.) Thus, suppose the subterraneous bearings and distances are required to be plotted, in order to determine on the surface the situation of the end D from the com- mencement A : FIG. 47. 1st, N. 10 W. 2nd, N. 40 E. 3rd, N, 45 W. Suppose A the point or place of commencement, and run off from thence the first bearing and distance to B, then AB will represent N 10 W 5 chains ; and from B run off the second bearing and distance to C, then BC will repre- sent N 40 E 7 chains ; and from C run off the third bearing and distance to D, then CD will represent N 45 W 6 chains, and the whole is plotted in the order of the survey. Now, to plot the same in a manner contrary to the order of the survey, begin at the point A, and run off E 2 76 SURVEYING STJBTERKANEOUS EXCAVATIONS the third bearing and distance N 45 W 6 chains, which let AJ) represent ; run off from & the second bearing and distance N 40 E 7 chains Ic ; also run off from c the first bearing and distance N 10 "W 5 chains cD ; which termi- nation will correspond with the point D in the former method, if the work be right. (40.) In the following subterraneous survey ABCDF; beginning at the pit A, I wish to have the same plotted on the surface, in order to determine the bearing and distance of E from A : FIC 48 Chains. AB, N. 42 E. . . 5-00 BC, E. . . 4-00 CD, N. 9 E. . . 4-00 DF, S. 69 E. . 5-56 Commence the plotting on the surface according as directed in the former examples; and running off the bearing and distance AB N 42 E 5 chains, remove the instrument to B, and run off the bearing and distance BC due east 4 chains ; remove the instrument to C, and run off the bearing and distance CD N 9 E 4 chains ; lastly, remove the instrument to D, and run off the bearing and distance DE S G9 E 5'56 chains, and there make a mark ; then return with the instrument to the pit A, and take the bearing of the mark at E, which suppose N 64 44' E j then measure the distance, which suppose 14*40 chains, which are the bearing and distance required. Or the circum- ferentor may be fixed at E instead of A, and the bearing of A taken from it ; which being reversed (see Art. 5), will become the bearing of E from A, the same as before. Note. In many cases, where the surveyor is desirous of plotting the subterraneous survey on the surface, it will be best to make choice of a WITH OR WITHOUT THE USE OP THE NEEDLE. 77 level piece of ground, sufficiently large to contain the whole, and plot the same thereon, assuming a point of commencement in the most advantage- ous place. (41.) In the following survey of the subterraneous working ABCDF, driven from the pit A, I wish to know by what bearing the miner must be conducted from F, the extreme point of the excavation, just to hit the centre of the pit G- ; and also what is the distance of G- from F ? FIG. 49 AB, N. 30 W. . Chains. . 5-50 BC, N. 45 E. . 7-00 CD, N. 50 W. . . 5-00 DF, N. 65 E. . 7-00 Commence the plotting at the pit A on the surface, as before directed, running off the distances in direction of their respective bearings: When the whole is run off to F, fix the instrument there, and take the bearing of the pit Gr from it, which suppose S 68 30' E ; then measure, by the chain, the distance of G- from F, which suppose 8*60 chains, the direction and distance required to hit the pit Gr. In the foregoing subterraneous survey, commencing at the pit A, I wish to know the bearing and distance on the surface of F from A, without plotting the same ? (42.) Reduce the bearings and distances of the survey to their northing or southing, and easting or westing (see Art. 10, Ex. VII.), in order to obtain the denomination of bearing of F from the pit A. Thus : 78 STJEVEYINa SUBTEEEANEOUS EXCAVATIONS PREPARATORY TABLE. Chains. N. 30 W. 5-50 N. 45 E. 7-00 N. 50 W. 5-00 N. 65 E. 7-00 Northing. Southing. Easting. Westing. Chains. 4-76 4-95 3-21 2-96 Chains. Aa Chains. 4-95 6-34 Chains. 2-75 8*81 6-56 15-88 11-29 6-56 4-73 aF The denomination of bearing of the extreme part of the excavation E from the pit A is 15 '88 chains of northing, and 473 chains of easting. Therefore, As Aa 15-88 . Is to radius So is aF 4-73 To tang. Z AF 16 35' 1-2008505 10-0000000 6748611 9-4740106 And V 15-88 + 4-73 = 16-56 = AF. Now fix the instrument at the pit A, and run off from thence the bearing and distance JST 16 35' E 16*56 chains, and the situation of E, with respect to the pit A, will be had on the surface. (43.) In the workings of the pit A, see fig. 30 to Art. 17, 1 wish to know how far each bord or excavation opQqrst is distant from the boundary cdfgmn ? To obtain what is required, fix the circumferentor at the pit A, and survey in direction of AGr, YE, and 5H, which are the excavations next the boundary, measuring the distance that each bord opQqrst is driven towards the boundary from the headways YE and H, entering them, according to the following form, in the survey-book. WITH OB, WITHOUT THE USE OF THE NEEDLE. 79 SURVEY-BOOK. Bearings. Remarks to Left. Distance. Remarks to Right. Chains. S. 80 W. . 1-60 . Aa S. 70 W. t 1-80 aG 0-80 A headways 6, and a chalk mark + to return to. A headways V, and a 1-20 chalk mark + to return to. Returned to . mark + at V. S. 10 W. 2-40 . VF 0-80 Bordj), 1'30 chains towards the boun- dary. 1-60 Bord o, 1 chain to- wards ditto. Returned to . mark + at b. N. 1 W. . 5-00 . . . . 6H Bord q, 90 links to- 0-80 wards the boundary Bord r, 60 links to- 170 wards the boundary Bord s, 60 links to- 2-55 wards the boundary Bord t, 55 links to- 3 '40 wards the boundary Note. The student must recollect to enter in this and all other survey- books in the first column the angles which every t\v^ successive lines in the survey make with one another when the new methou% given in Arts. 20 and 21, are used ; besides, not only this survey, but also *he following one, ought to be done without the use of the magnet. Now the survey underground being finished, fix the instrument at the pit A, on the surface, and run off the bearing and distance therefrom, in the order ac taken underground, the first S 80 "W. T60 chains A.a : Remove the instrument to , and run off the next bearing and distance S 70 W 1'80 chains Q- ; at 80 links make a mark on the surface, as represented by I ; also at I 1 20 chains make another, as represented by V; and at Gr make another: Then with the chain measure the distance G/, which sup- pose 1'30 chains, which is the distance the excavation Q- is 80 SUKVEIING SUBTEBBANEOTTS EXCAVATION'S short of the boundary, which must be recorded in the miner's book of memorandums. Return with the instru- ment to the mark made on the surface at V, and run off S 10 W 2-40 chains YF ; at 80 links, in direction from V to F, run off the bord p 1*30 chains to the right, per- pendicular to the headways YF, and there make a mark at p : Then measure the distance pe, which suppose 1 chain, which is the distance of the bord p from the boundary, which must be recorded. Also at 1/60 chains run off the bord o 1 chain to the right, similar to the former, and make a mark at o : Then measure the distance od, which suppose 70 links, which is the distance of the bord o from the boundary, which must also be recorded. Return with the instrument to the mark made on the surface at 5, and run off N 1 W 5 chains 5H, and there make a mark : Then mea- sure the distance Jin, which suppose 80 links, which is the distance of the headways- 5H from the boundary. At 80 links, in the direction from 1) to H , run off the bord q 90 links to the left, perpendicular to the headways 6H, and there make a mark at q : Then measure the distance qg, which suppose 70 links, which is the distance of the bord q from the boundary. From T70 chains run off the bord r 60 links to the left, and make a mark at r : Then measure the distance r7i, which suppose 1-10 chains, which will be the distance of the bord r from the boundary. From 2*55 chains run off the bord s 60 links to the left, and make a mark at s : Then measure the distance sk, which suppose 1-50 chains, which will be the distance of the bord s from the boundary. From 3'40 chains run off the bord t'55 links to the left, and make a mark at t: Then measure the distance tm, which suppose 1-80 chains, which will be the distance of the bord t from the boundary, and the whole will be finished. (44.) In the following subterraneous survey ABCDF, commencing at the pit A, I wish to know the bearing and distance of F from A : WITH OB WITHOUT THE USE OF THE NEEDLE, 81 FIG 50 N. 30 W. N. 45 E. N. 50 W. N. 65 E. Chains. 5-50 7*00 5-00 7-00 H Easting and westing dist- ance from the meridian of A. tfi ^" Is 2-20E. r-l i 1 CO CD III 5 T 1 J25 OS te CO oo 111 6^ C5 I 1 5 p > Ji w ; II 00 CO : , rf 10 _ tf il i ; OS : CO CO ii 1 ; : 00 6 . -C3 . .1 10 rH (0 c* S c "* s CO s 1 1? o o o o . S) S . ^ p o CO j Is 125 ^ 5 rf E 3 82 STJBYEYING SUBTEBBANEOT7S EXCAVATIONS Fix the instrument at A, and run off the line Kd 15 chains 88 links on the magnetic meridian of A (from the 6th column of the table), for the northing of F from A ; and also 4 chains 73 links d~F (from the 7th column of the table), for the casting of F from the magnetic meridian of A : Then at F fix up a mark, and take its bearing and dis- tance from A, which suppose IN" 16 35' E 16'56 chains, which is the bearing and distance required. This mode of plotting will be tedious, and liable to error, particularly where the surface is uneven. The manner of making a survey wliere tlie subterraneous excavation declines from the horizon. (45.) In making surveys where the distances measured are not horizontal, but rising or falling, or both, it will be necessary for the surveyor to reduce all his measurements to horizontal distances, which may be obtained by taking the angle that each separate distance makes with the horizon, noting the same down opposite its respective bear- ing, in a column made for that purpose in the survey-book. FIG 5! *. - -^- :r f i Suppose Ae and ad to be lines parallel to the horizon, and AS CD is the undulating excavation which is to be surveyed, commencing at A ; let the bearing and distance taken in such a situation as that of AZ> to be N 10 "W" 5 chains, and the angle fKb which such excavation makes with the horizon to be 30 ; and another in such a situation as that of 60 JST 20 W 6 chains, and the angle Cbc which it makes with the horizon to be 20 ; also another in the situation of CD JN" 20 E 12 chains, and the angle DCe which it makes with the horizon to be 10 ; which bearings, WITH OR WITHOUT THE USE OF THE NEEDLE. 83 distances, &c., must be inserted in the following survey book : Thus, the first column containing the bearings and declining distances, the second column the magnitude of the angle that each bearing forms with the horizon, and the third the declining distance of each bearing reduced by the traverse tables to horizontal distance. This third column may be made at the surveyor's leisure, but previous to its being plotted. SUKVET-BOOK. 1. 2. | 3. Rising and falling distances. Angle that each bearing forms with, the horizon. The horizontal distance of each bearing. i Chains. N. 10 W. 5-00 N. 20 W. 6-00 N. 20 E. 12-00 30 20 10 Chains. 4-33 A/ or a& 5-64 be '* Gf 11-82 C .or cd I shall protract the survey first without reducing the declining measurements to horizontal distances, from the first column of the foregoing survey-book ; and, secondly, by the same, reduced to horizontal distances, taken from the third column, in order to show the error arising from the protracting of declining or hypothenusal distances. Without reducing the declining dis m tances.~Let A.b represent N 10 W 5 chains, 1C N 20 W 6 chains, and CD 1ST 20 E 12 chains ; then A&CD will re- present the survey protracted according to the first column of the survey- book. Where the declining lengths of each learing are reduced to horizontal dis- 84 STTEYEYING SUBTEEEANEOUS EXCAVATIONS tance Let AM represent N 10 W 4'33 chains (from the 3rd column of the survey-book), Vc N 20 W 5 -64 chains, and cd N 20 E 11-82 chains ; then Mod will represent the true protraction, and A5CD the false one, and dD will be the amount of the error. As it is common among practical miners, when plotting- their surveys, to add a number of bearings and distances together, taking the mean sum of the degrees contained in the bearings so added for the common bearing of the whole, when they are all on the same side of the same meridian, and the sum of the lengths of all the bearings for the length of the whole, I shall therefore show the errors which result from such practices. (46.) Suppose AB N 30 W 10 chains, and BC N 50 W 20 chains to be plotted. FIG. 53, Hy the false method. N. 30 W. . .10 chains. N. 50 W. . 20 2)80 N. 40 W. , . 30 chains. Now it appears that N 40 "W 30 chains will be the bear- ing and distance equal to both, by this method. WITH OB WITHOUT THE USE OF THE NEEDLE. 85 By the true method. N. 30 W. N. 50 W. Chains. . 10-00 . . 20-00 Aa Northing. Westing. Chains. 8-66 12-86 Chains. 5-00 15-32 21-52 20-32 I aC As 21 -52 Is to radius So is 20 -32 . To tang. L AC 43 21' 1-3328420 10.0000000 1-3079240 9-9750820 FIG. 54. And V 21 '52 + 20 -32 = 29 -59 chains = AC. Then N 43 21' W 29-59 chains is the true bearing and distance of C from A, instead of N 40 W 30 chains ; and the magnitude of the error will be their difference, i. e. 30 2959=41 links; it is hence presumed that no sur- veyor will use the false method. A promiscuous collection of practical questions. (47.) EXAMPLE I. I wish to drive a drift or subter- raneous excavation from the point A to hit the pit C, which is on the other side of a river; now I run a line AB by the river side, N 85 E 20 chains long, which from the point A, I found C to bear N 42 E, and also from the point B, I found C to bear N 30 W ; I therefore desire to know what will be the length of the excavation or drift AC ? 86 /SURVEYING. SUBTERRANEOUS EXCAVATIONS From the rules for reducing bearings into angles, Z.A = 43, /. B = 65, and L C = 72 ; therefore, by trigonometry, the excavation AC will be 19*05 chains in length. EXAMPLE II. There is a pit C (see last fig.), on the other side of a river, to which I wish to drive a drift from a given point ; I took the bearing of the pit C from A, which was N 42 E, and after running a line AB by the river side in direction of N 85 E 20 chains, I also took its bearing again from B, which I found to be N 30 "W"; now I demand to know under what bearing I must set off a drift from a point D, 8 chains from A, along the line AB, so that I may hit C, and also what will be the length of the drift DC? L A = 43, L B = 65. The line D C, which is the direction of the drift or excavation, will be found to form an angle with the line DB of 65 33', and the line DB forms an angle of 85 to the left of the north magnetic meridian ; therefore, from the rule for reducing angles into bearings (Art. 3), the drift DC will bear N 19 27' E, and its length will be 14-29 chains. EXAMPLE III. There is an inaccessible point C (see fig. to Ex. I.), to which a drift is to be driven underground ; now the angle A is found to be 43, the angle B = 65, and the length of the drift AB = 20 chains: how far from A must a drift be set off to arrive at C by the shortest dis- tance possible ? The shortest distance between AB and the point C is a line perpendicular to AB, let fall from the point C. The point, from which the drift DC must be driven, by the shortest distance possible, will be 13'94 chains from A, as required. EXAMPLE IV. I made a survey along the side of a hill from A to B, under the following bearings and distances viz., A.a N 75 E 20 chains, ab S 80 E 19 chains, Ic N 73 E 15-60 chains, and cE S 71 E 18 '65 chains ; now I wish to make a straight tunnel from A to B ; therefore I demand to WITH OB WITHOUT THE USE OF THE NEEDLE, 87 know under what bearing it must be conducted, and what will be its length ? FI&.53. FIG. 5G. From the traverse tables, the point B will have 7'63 chains of southing Ad, and 65'17 chains of easting dE from A; and the angle SAB = 83 43', which is the angle that the line AB makes with the south meridian, and AB being the direction of the tunnel, therefore it must be conducted from A to B under the bearing of S 83 43' E, and its length will be 65-61 chains. EXAMPLE V. There is a vein of lead ore AB, which I find forms an angle CAB of 82 with the horizon ; now I wish to know how deep my shaft DB must be sunk before I cut the vein, if I set it off at the distance of 30 yards from A to D at the surface ? Ans. DB = 213-4 yds. EXAMPLE VI. There is a vein of lead ore AB (see last fig.), which forms an angle CAB of 70 with the horizon, on which I wish to sink a shaft DB ; I demand to know what distance AD the shaft must be set off from the vein at the surface, just to cut it at the depth of 141 yards ? w .The distance AD that the shaft must be set off at the surface from the vein AB, just to cut it at the depth of 141 yards, will be 51'3 yards. 88 SURVEYING SUBTERRANEOUS EXCAVATIONS FIG. 59 EXAMPLE VII. I have to set a drift BC from the bottom of a pit AB, which is to be driven truly level ; now I wish r . _ D to know at what F I W.JO. ,. . ,, ,T A. distance irom the pit B it will cut the stratum of coal DE, which dips so as to form an an- gle dDE of 20 C with the horizon, the drift BC being set from the bot- tom of the pit at B, 40 yards perpendicularly below the seam D, and driven in direction of the dip of the stratum ? Ans. BC = 109-9 yds. EXAMPLE VIII. I set off a drift at the side of a hill A, which was driven truly level, and cut a vein of lead ore at B, 100 yards distant from A, which vein I found to make an angle of 65 ABC with the horizon'; now I wish to know what depth a shaft at A must be sunk just to cut the vein at C ? Ans. AC = 214-4 #<&. EXAMPLE IX. In the sub- terraneous survey ABCD, in the form of a trapezium, are two shafts F and |E, joined by a fifth straight drift FE. Now this survey was made with a magnetic needle, which was afterwards found to be de- fective in its indications, on account of the presence of ferruginous substances both in the mine and on the surface ; therefore, how is the work to be plotted, since the angles WITH OR WITHOUT THE USE OF THE NEEDLE, 89 57. cannot be relied upon ; and only the lengths of five drifts, and the segments of the drifts AB and CD made by the drift EF, are given; moreover, the tops of the shafts F and E range with the sun at 1^ P.M. on the 18th of October, 1860 ? Note. The solution of this question will require a knowledge of the application of algebra to geometry and of spherical trigonometry to astronomy. EXAMPLE X. There is a vein of lead ore AC, which forms an angle aK.e of 80 with the horizon Ac ; now A EIG.GO. I have sunk a shaft AB on the vein at the surface, to the depth of 120 yards perpendicular; I desire to know what distance the bottom of the shaft B will be from the vein ? An*. BC=2M yds. EXAMPLE XI. I made a survey of a subterraneous excavation ABCDFG- (see the following bearings and distances), commencing at the pit A ; now I wish to know, on the surface, by one single bearing and distance, to be taken from the pit A, where I must sink a pit perpendicularly upon G-, the extreme end of the excavation ? 90 SUETEYIITG SUBTEKBAKEOUS EXCAVATIONS Chains. AB, N. 20 W. . . 15-50 BC, N. 60 E. . 12-00 CD, N. 15 E. . . 10-50 DF, N. 85 E. . 15-00 EG, s. 25 B. . . 16-60 The extreme point Gr of the excavation will have 16-98 chains of northing A#, and 29 '76 chains of easting Gr, from A ; therefore the line Ad will be found to bear N 60 IT E with SJX", the magnetic meridian of A, and its length will be 34-26 chains, the bearing and distance required. Note.' This Example ought also to be solved by taking the angles from the direction of the drift AB (the position of which is assumed to be fixed on the surface), by the method given in Art. 21. EXAMPLE XII. I have to drive an excavation from B towards A, which is to rise 1 inch in every 60 feet of its length; now I wish to put down an air- shaft P thereon, just 1600 yards from its mouth B ; what will be the depth of the ~- e shaft from the sur- face to the sole of the drift or excavation, when the surface at P, the place where it has to be sunk, is 350 feet above the level of B, the mouth of the excavation ? Anns. 343gjfe 1580 11 11 1750 17 54' 1612 6 10' U 1760 19 12' 1622 6 0' ( H< 1765 20 0' 1633 4 5' 1770 20 35' 1657 0' ) 1775 21 28' 1666 1 35' S 1777 21 57' 1672 2 30' 1779 22 4' 1683 4 30' 1780 22 26' . 1692 6 0' 1786 23 19' 1700 8 0' 1789 23 36' 1717 10 42' . 1793 23 51' 1724 11 45' 1797 24 2' 1730 13 0' 1800 24 6' 1735 14 16' 1803 24 9' 1740 15 40' j 1806 24 15' MAGNETIC VABIATION. VARIATION AT LONDON. Continued. 95 Year. Variation. Year. Variation. 1809 24 22' N 1835 23 32' 1812 24 28' 1838 23 19' 1815 24 35' 1841 23 6' 1818 24 41' 1844 22 52' 1820 24 32' k w. 1847 22 41' > W. 1823 24 20' f 1850 22 30' 1826 24 8' 1853 22 19' 1829 23 56' 1856 22 8' 1832 23 44' J 1858 22 2' Note. By the variation being east or west, is meant that the north end of the magnetic needle is on the east or west side of the true meridian ; and where the variation is called east or west in the following part of this work, it is to be understood that the north end of the magnet' c needle has east or west variation accordingly, except it is particularly mentioned to the contrary. From the table it appears the magnetic needle had east variation in the year 1576 ; that is, its north end was 11 15' on the east side of the true meridian of London ; and in 1657 the needle was in direction of the true meridian ; and since that time it has been veering about to the west, 'until it has got upwards of 24 to the westward thereof. Besides this annual variation just mentioned, it has a daily variation. I shall insert a table, showing the diurnal variation taken at different hours of the 27th day of June, 1759, by Mr. Canton. (Phil. Trans., vol. 51.) Hrs. Min. Declination west. Degrees of Fahrenheit's therm om. ' 18 18 2' 62 6 4 18 58' 62 Morning . 8 30 9 2 18 55' 18 54' 65 67 10 20 18 57' 69 I 11 40 19 4' 684 50 19 9' 70 1 38 19 8' 70 Afternoon . 3 10 7 20 19 8' 18 59' 68 61 9 12 19 6' 59 t 11 40 18 51' 574 96 TO FIND THE TEUE MEBIDIA.N. The mean variation of each month of the year . January . . 7' 8" February . . 8' 58' March . 11' 17' April . . . 12' 26 " May . . . 13' 0" June 13' 21" July . . .13' 14" August . . . 12' 19" September . . 11' 43" October. . . 10' 36" November . . 8' 9" December 6' 58" To find the true meridian. (50.) I shall lay down an easy and comprehensive rule to find the true meridian, which is preparatory to the deter- mining of the magnetic variation of the needle. It is well known that the sun, at 12 o'clock at noon, is due south in all northern latitudes ; and if a pole is set up perpendicular to the horizon, its shadow at that hour will bear exactly north, or in direction of the true meridian ; also the shadow of the pole will be shortest at that precise time. Let ABC be a board perfectly plain and clear of twist- ings, and of a triangular form, each side about 30 inches long, having a number of concentric circles cde about 1J inch asunder, drawn on its surface from a centre a. Now let this board be placed horizontal by means of a spirit level, with its angular point C towards the south ; and at a, the centre of the concentric circles, let there be fixed an upright pin about 10 inches long, exactly perpendicular to the board, and also perpendicular to the horizon. All this being done on a clear day, and before the sun arrives on the meridian of the place of observation, which I shall say about 11 o'clock, then observe carefully the first concentric circle that the end of the shadow of the pin fixed at a touches, which suppose to be at/, and there make a mark : Then ob- serve again carefully when the end of the same shadow touches on the same concentric circle, which will be about 1 o'clock, suppose it to be at g ; there make another mark : Then with a pair of compasses divide the distance fg, and TO FIND THE TRUE MERIDIAN. 97 FIG.: S3. the point in tlie middle between which, suppose h, will bo the direction of the shadow of the pin at 12 o'clock : Con- sequently ah is the direction of the true meridian. Then by placing an upright sight E, with a slit Tck in it, on the table, the centre of which coinciding with the point A, the pin at a paving an open- ing in it similar to Ib, with a perpen- dicular hair in direc- tion of the opening ; and by looking through the sight E, together with the hair in the centre of the opening in the pin placed at , the meridian may be ex- tended to any distance S on the surface ; in the direction of which line it will be proper to place two permanent marks, as represented by NS, whose distance may be from 100 to 300 yards, for the purpose of determining at all times the magnetic variation of the needle of the different instruments, made use of in surveying : Such a line every director of mines ought to have marked out in the situation of the mine he directs. (50a.) If the student be acquainted with the application of spherical trigonometry to astronomy, he will find the following method of finding the true meridian to be greatly preferable to that just given. Let S represent the place of the sun's centre, P the north pole, and Z the zenith ; these 98 TO FIND THE MAGNETIC VABIATION. three points being the angles of a spherical triangle SPZ (the student can readily draw the figure for himself), in which SZ represents the co-altitude of the sun, when he comes into the direction of the required bearing of the drift in the mine ; SP the sun's co-declination on the day of observation (which will be found in the Nautical Almanack for the year in which the observation is made) ; and PZ the co-latitude of the place of the mine (which is usually well known). Prom the given spherical triangle SPZ the angle Z may be readily found, which is the azimuth or bearing of the sun from the north at the time of observation, and also the bearing of the drift ; whence also the true meridian may be readily deduced for the following purpose. To determine the magnetic variation of the needle of any instrument. (51.) Suppose N and S to be marks representing the true meridian, S the south and N the north : place the in- strument (whose magnetic variation you would wish to know) at S, and turn the sights in N direction of SN until N is seen through them ; at the same time observe the bearing of the needle of the instrument, and whatever JS" is found to bear from due north, as much will the magnetic meridian differ from the true c meridian. Suppose the north end of the / needle to stand* in direction of Sc?, then the / true meridian SN will be to the east of the / magnetic as much as the angle dSN, which / suppose 23; then SN will bear JST 23 E with / the magnetic meridian : Consequently the / needle of the instrument may be said to have 23 of west variation, as the north end thereof is 23 to the west or left of the S true meridian SN. Or if the north end of the needle stand in direction of S0, then the true meri- SEDUCING BEAEINGS, ETC, 99 FIG. dian SX will be to the west of the magnetic as much as the angle eSX, which, if equal to 23, then SX will bear N 23 W : Then the needle may be said to have 23 of east variation, the north end thereof being' 23 to the east or right of the true meridian SX. The manner of reducing bearings from a magnetic to a true meridian. (52.) Let XS represent the true meridian, X the north and S the south, and ns a magnetic needle suspended on a centre c, representing the magnetic meridian, n the north and s the south ; then the arch na will be the variation of the magnetic meridian from the true meridian, which may be called west va- riation, the north end of the needle being to the west side of the true meridian : And if the angle nca is equal to 23, then the needle will have 23 of west variation, and the south end s will have 23 of east variation ; for 5 will be to the east of the true south meridian line as much as the north end n is to the west of the true north meridian line. (See theorem 3.) 1st. Suppose the circle WE to represent a circuin- ferentor, and that the bearing of the object O with the true meridian is required ; if ns is the needle representing the 100 EEDTTCING BEARINGS, ETC. magnetic meridian, and the object O is found to form an angle nca with it of 23, which (from the manner of determining bearings, Art. 2) may be called N 23 E, and, as before, the magnetic variation of the needle being 23 to the west of the true meridian, then 23 23 = ; therefore the bearing of O with the true meridian SdN" will be due north, for the needle ought to have stood in direction db. 2d. Suppose again the bearing of the object A with the true meridian is required ; the bearing of A with the mag- netic meridian will be equal to the angle ncA., which call N 10' "W; but as the magnetic meridian has 23 of west varia- tion, the bearing of A with the true meridian will be N 23 + 10 =33 W ; for angle acA. is equal to 33, which is the angle that cA. makes with the true meridian ScN. 3d. Suppose again the bearing of the object C with the true meridian is required ; the bearing of C with the magnetic meridian will be equal to the angle ncC, which call N 53 E ; but the variation of the needle being 23 to the west of true north, and ought to have stood in the direction of ab, consequently the bearing of C from c with the true meridian will be N 53 23 = 30 E ; for angle acC is equal to 30, which is the angle that the line cC makes with the true meridian line ScN. 4th. Suppose the bearing of the object D with the true meridian is required ; the bearing of D with the south mag- netic meridian will be equal to the angle scD, which call S 56 W ; but the south end of the needle having 23 of east variation, and ought to have stood in direction of ab the true meridian, consequently the bearing of D from c with the true meridian will be S 56 - 23 = 33 W; for angle foD is equal to 33, which is the angle that the line cD makes with the true meridian line NcS. 5th. Suppose again the bearing of the object B with the true meridian is required ; the bearing of B with the mag- netic meridian will be equal to the angle scB, which call S 15 E ; but the south end of the needle having 23 of east EEDUCING BEABINGS, ETC. 101 variation, consequently the true bearing of B will be S 15 + 23 = 38 E ; for angle bcE is equti 1 to 38, which, is> the angle that the line cQ makes with the true meridian HneNcS. Gth. Suppose again the bearing of the cbjeco F with the true meridian is required ; the bearing of F with the mag- netic meridian will be equal to the angle cF, which call N 13 E ; but the magnetic meridian has 28 of west variation, consequently the bearing of F with the true meridian, will be N 23 - 13 - 10 W ; for angle cF is equal to 10, which is the angle that the line cF makes to the left with the true meridian Sc~N. 7th. Suppose again the bearing of the object Gr with the true meridian is required ; the bearing of Gr with the magnetic meridian will be equal to the angle sc&, which call S 13 "W ; but the south magnetic meridian has 23 of east variation, consequently the bearing of Gr with the true meridian will be S 23 - 13 = 10 E ; for angle IcQr is equal to 10, which is the angle that the line cQt makes to the right with the true meridian NcS. 8th. Suppose again the bearing of the object K with the true meridian is required ; the bearing of K with the magnetic meridian will be equal to the angle ?zcK, which call N 80 W ; the magnetic meridian having 23 of west variation, the angle that cK will make with the true north meridian cN will be 80 + 23 = 103, acK; but as it exceeds 90, therefore 180 - 103 = 77, angle 5cK; then the bear- ing of K with the true meridian will be S 77 "W ; for angle ScK is equal to 77, which is the angle that the line cK makes with the true south meridian line NcS. N.B. The true bearing of any object is nothing more than the angle that the object makes with the true meridian, instead of the angle it forms with the magnetic meridian ; therefore, by the several cases of Art. 52, the method of solving the following examples will be readily seen : EXAMPLE I. If the following bearings, N 20 W, N 60 102 t BEABLNGS, ETC. E, N 70 "W, and N 13 E are taken by an instrument whose magnetic needle has 23 west variation, what will be their bearings 'with ihe -true meridian ? The '.first- bearing *!N" 20 "W will -form a bearing of N 20-*+ '-28' - 4SP-W- with the true meridian. The second bearing, N 60 E, will form a bearing of IN" 60 - 23 = 37 E with the true meridian. The third bearing, N 70 W, will form a bearing of 180 - 70 + 23 = 87, which will be S 87 W with the true meridian. The fourth bearing, N 13 E, will form a bearing of N 23 - 13 = 10 W with the true meridian. With the magnetic meridian. Thus, N. 20 W. N. 60 E. N. 70 W. N. 13 E. With the true meridian. N. 43 W. N. 37 E. S. 87 W. N. 10 W. EXAMPLE II. If the following bearings are taken by a meridian having 23 of west variation S 10 "W, N 10 E, JS" 50 E, and JST 20 W what will be their bearings with the true meridian ? With the magnetic meridian. S. 10 W. N. 10 E. N. 50 E. N. 20 W. With the true meridian. S. 13 E. N. 13 W. N. 27 E. N. 43 W. EXAMPLE III. If the following bearings are taken by a meridian having 10 of west variation N 50 "W, N 70 E, S 5 E 3 and S 60 W what will be their bearings with the true meridian ? With the magnetic meridian. N. 50 W. N. 70 E. S. 5" E. S. 60 W. With the true meridian. N. 60 W. N. 60 E. S. 15 E. S. 50 W. KEDTJCIKG BEABINGS, ETC. 103 EXAMPLE IV. If the bearings in the last example be taken by a meridian having 6 of east variation, what will be their bearings with the true meridian ? With the magnetic meridian. N. 50 W. N. 70 E. S. 5 E. S. 60 W. With the true meridian. N. 44 W. N. 76 E. S. 1 W. S. 66 W. The manner of reducing a /bearing from one magnetic meridian to its bearing with any other magnetic meridian of different variation. (53.) 1st. Suppose the bearing of the object P from C is taken by a circumferentor whose needle has 10 of west variation n's' y which bearing is to be reduced to the bearing it will form with another magnetic meridian ns, having 23 of west variation : Let NS represent the true p - meridian, and the bearing of CP therewith (from the man- 104 BEDTJCING BEAEINGS, ETC. ner of reducing bearings, &c., Art. 52) equal to the angle PCN 45, or N 45 W ; also the magnetic meridian to which the bearing PC is to be reduced equal to the angle ;iCN 23, or having 23 of west variation ; the object P and the magnetic variation of the meridian to which its bearing is to be reduced are both on the west side of the true meridian NS ; therefore L PCN 45 Z. CN 23 = Z. PCw 22; and as the angle PCN exceeds the angle nCN, the object P from C must bear N 22 W with the magnetic meridian ns. 2d. Suppose the bearing of the object from C is taken by an instrument whose needle has 10 of west variation n's', which is to be reduced to the bearing it will form with another magnetic meridian ns, having 23 of west variation: Let the bearing of CO with the true meridian be found equal to the angle OCN 8, or N 8 "W ; and the magnetic meridian to which the bearing CO is to be re- duced equal to the angle wCN 23, or having 23 of west variation ; the object arid the magnetic variation of the meridian to which its bearing is to be reduced are both on the west side of the true meridian NS ; therefore Z. wCN 23 - Z. OCN 8 = L OCn 15 ; and as the angle OCN is less than the anlge ?zCN, the bearing of O from C will be N 15 E with the magnetic meridian ns. 3d. Suppose the bearing of the object T from C is taken by a magnetic needle having 10 of west variation n's' 9 which bearing is to be reduced to the bearing it will form with another magnetic meridian ns, having 23 of west variation : Let the bearing of TC with the true meridian be found equal to the angle TCN 23, or N 23 W ; and the magnetic meridian to which the bearing TC is to be reduced equal to the angle rcCN 23, or having 23 of west variation ; then Z. TCN 23 Z. wCN 23 = ; therefore the bearing of T from C will be in the direction of the magnetic meridian ns, or due north. 4th. Suppose the bearing of the object Q from C is taken by a magnetic needle having 10 of west variation V, BEDUCIffG- BEARINGS, ETC. 105 which bearing is to be reduced to the bearing it will form with another magnetic meridian, ns, having 23 of west variation : Let the bearing QC with the true meridian NS be found equal to the angle QCN 15, or N 15 E ; and the magnetic meridian to which the bearing QC is to be reduced equal to the angle nCN 23, or having 23 of west variation ; now the object Q and the magnetic variation of the meri- dian to which its bearing is to be reduced are on contrary sides of the true meridian NS ; therefore Z. QGN 15 + Z. nCN 23 = / QCw 38 ; and also the bearing of Q will be on the contrary side of that magnetic meridian ns that its variation is on ; and as ns has west variation, therefore the bearing of Q from C will be N38 E with the meridian ns. 5th. Suppose the bearing of the object A from C is taken by the meridian n's', having 10 of west variation, which is to be reduced to the bearing it will form with another magnetic meridian ns, having 23 of west variation : Let the bearing of CA with the true meridian NS be found equal to the angle ACS 45, or S 45 E ; and the south magnetic meridian to which the bearing AC is to be re- duced equal to the angle sCS 23, or having 23 of east variation (see theorem 3, Art. 48) ; the bearing of the object A and the magnetic variation of the meridian to which its bearing is to be reduced are both on the east side of the true meridian ; therefore Z. ACS45 3 Z. sCS 23 = L ACs 22 ; the angle ACS exceeding the angle sCS, the bearing of A with the magnetic meridian ns will be S 22 E. 6th. Suppose the bearing of the object B from C is taken by a needle n V, having 10 of west variation, which is to be reduced to its bearing with another magnetic me- ridian ns, having 23 of west variation : Let the bearing of CB with the true meridian NS be found equal to the angle BCS 8, or S 8 E ; and the south magnetic meridian to which the bearing BC is to be reduced equal to the angle sCS 23, or having 23 of east variation (see theorem 3, 106 REDUCING- BEAEINGS, ETC. Art. 48) ; the bearing of the object B and the magnetic variation of the meridian to which its bearing is to be reduced are both on the east side of the true meridian ; therefore L CS 23 ^BCS 8 = Z. BCs 15 ; and as the angle BCS is less than the angle sCS, the bearing of B from C will be S 15 "W with the magnetic meridian ns. 7th. Suppose the bearing of the object D from C is taken by a needle n's', having 10 of west variation, which is to be reduced to its bearing with another magnetic me- ridian ns, having 23 of west variation : Let the bearing of CD with the true meridian NS be found equal to the angle DCS 15, or S 15 W ; and also the south magnetic meridian to which the bearing DC is to be reduced equal to the angle sCS 23, or having 23 of east variation (see theorem 3, Art. 48) ; and as the bearing of the object D and the magnetic variation of the meridian to which its bearing is to be reduced are on contrary sides of the true meridian NS, therefore ^DCS 15+sCS 23= Z DCs 38 ; and also the bearing of D will be on the contrary side of the magnetic meridian ns that its variation is on ; and as the south me- ridian ns has east variation, therefore the bearing of D from C will be S 38 W. 8th. Suppose the bearing of the object E from C is taken by the meridian n's', having 10 of west variation? which is to be reduced to the bearing it will form with another magnetic meridian ns, having 23 of west variation : Let the bearing EC with the*true meridian be found equal to the angle ECN 77, or N 77 E ; and the magnetic meridian to which the bearing EC is to be reduced equal to the angle raCN 23, or having 23 of west variation ; the bearing of the object E and the magnetic variation of the meridian to which it is to be reduced are on contrary sides of the true meridian NS ; therefore Z. ECN 77 + L wCN 23 = L ECra 100 ; but as the angle that the object E makes with the north magnetic meridian ns exceeds 90, its bearing in that case must be with the south or contrary REDUCING BEARINGS, ETC. 107 meridian ; then 180 100 = 80 / EC* ; consequently the bearing of the object E with the magnetic meridian ns wiU be S SO C E. . From the several cases of Art. 53, the student will have no dif- ficulty in solving the following examples, with respect to two different magnetic variations. EXAMPLE I. If the following bearings are taken by a meridian having 10 of west variation, N 50 W, N 70 E, S 5 E, and S 80 E ; what will be the bearing of each with a meridian having 23 of west variation ? With a meridian of 10 of variation. N. 50 W. N. 70 E. S. 5 E. S. 80 E. With a meridian of 23 of variation. N. 37 W. N. 83 E. S. 8W. S. 67 E. EXAMPLE II. If the following bearings are taken by a meridian having 10 of east variation, S 60 W, S 10 E, N 80 E, and N 10 W ; what will be the bearing of each with a meridian having 20 of west variation ? With a mwidian of 10 of east variation. S. 60 W. S. 10 E. N. 80 E. N. 10 W. With a meridian of 20 of ivest variation. Due west. S. 20 3 W. S. 70 E. N. 20 E. EXAMPLE III. The following bearings are taken by a meridian having 20 of west variation, S 60 W, N 5 W, N 30 W, and N 50 E ; what bearing wiU each form with a meridian having 10 of east variation ? With a meridian of 20 of west \ With a meridian of 10 of east variation. S. 60 W. N. 5W. N. 30 W. N. 50 E. variation. S. 30 W. N. 35 W. N. 60 W. N. 20 E. 108 REDUCING BEAKINGS, ETC. EXAMPLE IV. If the following bearings are taken by the true meridian, S 60 W, N 5 W, N 30 W, and N 50 E ; what bearing will each form with a meridian having 23 of west variation ? With the true meridian. S. 60 W. N. 5 W. N. 30 W. N. 50 E. With a meridian of 23 of variation. S. 83 W. N. 18 E. N. 7W. N. 73 E. EXAMPLE Y. I have to plot a survey on the surface of the following bearings and distances, N 25 "W 5 chains, N 63 W 10 chains, N 20 E 3 chains, N 70 E 6 chains, and S 84 E 9 chains, which has been taken by a eircum- ferentor having 20 of west variation ; now 1 find the circumferentor by which I have to plot the same has 23 of west variation, I demand to know the bearings under which the survey must be plotted, so that the same may be accurately clone ? With a meridian of 20 of west variation,. N. 25 W. N. 63 W. N. 20 E. N. 70 E. S. 84 E. Chains. . 5 . 10 3 , 6 9 The bearings under which the sur- vey must be plotted to be accu- rately done, ly a needle having 23 of west variation. Chains. N. 22 W. . N. 60 W. N. 23 E. N. 73 E. S. 81 E. 5 10 3 6 EXAMPLE VI. In a subterraneous survey of the fol- lowing bearings and distances, viz. N 20 W 10 chains, N 60 W 3 chains, S 12 W 5 chains, IS" 87 W 4 chains, and S 15 E 7 chains, surveyed by an instrument having 22 of west variation, which is to be plotted on a plan whose meridian has 12 of west variation, I wish to know EEDTJCTNG BEARINGS, ETC. 109 under what bearing each must be plotted on the plan, so that it may be accurately done ? The bearings by a meridian hav- The bearings with the plan's me- ing 22 of west variation. ridian having 12 of west va- riation. Chains. Chains. N. 20 W. . . 10 N. 30 W. . 10 N. 60 W. . . 3 N. 70 W. . . 3 S. 12W. . . 5 S. 2 W. . 5 N. 87 W. . . 4 S. 83 W. . . 4 S. 15 E. . . 7 S. 25 E. . 7 FIG 67 ,V To find what kind of a meridian a plan has leen constructed ~by. (54.) Where subterraneous excavations are to be added to some previously delineated on a plan, it will be neces- sary, first of all, to find what kind of meridian the plan has been constructed by, in order that the bearings to be plotted may previously be reduced thereto (see theorem 4, Art. 48). 1. Suppose N'S' to be the meri- dian of a plan whose magnetic varia- tion is required to be known ; let the bearing of the pit B from the pit A be taken on the plan with the meri- dian thereon', equal to the angle BA^40, or N 40 W; and let the bearing of the same two pits be taken on the surface by a circum- ferentor placed ab A, whose needle is known to have 23 of west varia- tion ns, and found to form an angle BA = 27, or N 27 W; then, if N'S' represent the true meridian, the line AB will form an angle therewith of 27 = 50 BAN, or N 50 W : From L BAN 50 110 BEDUCING BEABINGS, ETC. ' 40, leaves L WAN = 10, which is the angle that the plan's meridian makes with the true meridian; and as the angle ~BA.W, which is the bearing of the object with the plan's meridian, is to the left thereof, and less than the L BAN, which is the bearing of the same object, as taken by the circumferentor on the surface, with the true meridian, and to the left thereof also, it follows that L WAN, the variation of the plan's meridian, must be to the left of the true meridian ; therefore S'W must have 10 of west variation. 2. Suppose WS' to be the meridian of a plan whose magnetic variation is required to be known ; let the bearing of the pit B from A be taken on the plan with the meridian thereon, equal to the angle BA.ZV' 60, or N 60 W ; and let the bearing of the same two pits be taken on the surface by a circumferentor placed at A, whose needle is known to have 23 of west variation ns, and found to form an angle BArc = 27, or N 27 W ; then if NS represent the true meridian, the line AB will form an angle therewith of 27 + 23 = 50 BAN, or N 50 W: Then from L BA^ 60 - L BAN 50, leaves L WAN = 10, the variation of the plan's meridian; but as the L BA.ZV", which the bearing of the object makes to the left with the plan's meridian, is greater than the /. BAN, which is the angle that the same object, as taken by the circumferentor on the surface, makes to the left with the true meridian, the L -ZV'AN must be to the right of the true meridian ; there- fore jSWmust have 10 of west variation. 3. Suppose WS' to be the meridian of a plan whose magnetic variation is required to be known ; let the bearing of the pit B from the pit A be taken on the plan with the & BEDTJCING BEARINGS, ETC. Ill FI&.69. Bt rj meridian thereon, equal to the angle BAjY' 5, or N 5 E ; and let the bearing of the same two pits be taken on the surface by a circumferentor placed at A, whose needle has 23 of west variation ns, be found to form an angle BA?z = 18, or N 18 E ; then if NS represent the true meridian, the line AB will form an angle there- with of 23 - 18 = 5 L BAN, or N 5 W : Then L BA^' 5 + L BAN 5 = Z JV'AN 10, the variation of the plan's meridian ; and as AB bears on different sides of the two meridians N'S' and NS, and L BAN being to the left of the true meridian NS, L NAJV' must be to the left thereof also ; consequently the plan's me- ridian N'S' must have 10 of west variation. 4. Suppose N'S' (see last fig.), is the meridian of a plan whose magnetic variation is required to be known ; let the bearing of the pit B' from the pit A be taken on the plan with its meridian, equal to the angle N'A.'B' 83, or N 83 W ; and let the bearing of the same two pits be taken on the surface by a circumferentor placed at A, whose needle has 23 of w r est variation ns, be found to form an angle wAB' = 70, or N 70 W ; then if NS repre- sent the true meridian, the line AB' will form an angle therewith of 87 L B'AS S 87 W (see Art. 52) : Now L -Y'AB' 83 + L B'AS 87 = /. JV"AS 170, then 180 - 170 = 10 L NAJV', the variation of the plan's meri- dian ; and as L NAN' 10 is what L SA^ r falls short of 180, reckoning from the south meridian S, therefore it must be to the left or west of the north meridian N ; consequently the plan's meridian N'S' must have 10 of west variation. 112 EEDTJCING BEARINGS, ETC. F I C 70 N 5. Suppose N'S' to be the meridian of a plan whose magnetic variation is required ; let the bearing of the pit B from the pit A be taken on the plan with its meridian thereon, equal to the angle N'A^B 45, or N 45 W ; and let the bearing of the same two objects, taken on the surface by an instru- ment placed at A, whose needle has 23 of west variation ns, be found to be equal to the same angle *AB 45, or N 45 W, as before ; then if NS represent the true meridian," the line AB will form an angle therewith of 45 + 23 = 68 NAB, or N 68 W: Then L NAB 68 - L JVAB 45 = L NAJV' 23, the varia- tion of the plan's meridian; but as L -ZV'AB is to tlie left of the plan's meridian, and is less than L NAB, the L NAJV' must be to the left of the true meridian SN ; therefore the plan's meridian, will have 23 of west variation. When the bearing of two objects, taken on a plan by its delineated meridian, agrees with the bearing of the same two objects taken on the surface by an instrument, the variation of the plan's meridian will be the same as the magnetic variation of the needle of that instrument. 6. Suppose N'S' to be the meridian of a plan whose magnetic variation is required to be known ; let the bearing of the pit B from that of A be taken on the plan by its meridian thereon, equal to the angle NAB 68, or N 68 W: and let the bearing of the same two objects be taken by an instrument on the surface placed at A, whose needle has 23 of west variation ns, equal to the angle nKB 45, or N 45 W ; then the object will form an angle with the true REDUCING BEABISTGS, ETC. 113 meridian of 45 + 23 = 68, or N 68 W: Now, as the bearing of the two objects on the plan with its meridian, agrees with the bearing of the same two objects taken on the surface when reduced to the true meridian, therefore the plan's meridian must be the true meridian. From, the several cases in the last Article, where six examples are solved, the method of solving the following unsolved examples will be readily seen. EXAMPLE I. I wish to know the variation of a plan's meridian, when the bearing of two objects thereon with its meridian is N 30 W, and the bearing of the same two objects with each other on the surface is found, by an instrument whose needle has 20 of west variation, to be N19W? The objects on the surface will form a bearing with each other of N 39 "W by the true meridian. Then 39 30 = 9 ; therefore the plan's meridian has 9 of west variation. EXAMPLE II. I wish to know the variation of a plan's meridian, when the bearing of two objects thereon with its meridian is N 16 E, and the bearing of the same two objects with each other on the surface is found, by an instrument whose needle has 23 of west variation, to be N 10 E ? The objects on the surface will form, a bearing with each other of N 13 W by the true meridian. The 16 + 13 = 29 ; therefore the plan's meridian has 29 of west variation. EXAMPLE III. I have a plan which I wish to know by what kind of meridian it has been delineated : Now the bearing of two objects thereon with each other by its meri- dian is found to be N 80 "W, and the bearing of the same two objects, taken on the surface by an instrument whose needle has 21 of west variation, is N 74 W ? The bearing of the two objects on the surface with the true meridian will be S 85 W. 114 BEDUCiya BEARINGS, ETC. Then 180 80 + 85 = 15 ; therefore the plan has been delineated by a meridian having 15 of west variation. EXAMPLE IV. I wish to know the variation of a plan's meridian, when the bearing of two objects taken thereon by its meridian is found to be JST 40 E, and the bearing of the same two objects, taken on the surface by an instru- ment whose needle has 20 of west variation, is also N40E? Then the meridian of the plan will have the same magnetic variation as the needle by which the bearing of the objects was taken on the surface ; therefore the plan's meridian will have 20 of west variation. EXAMPLE V. I wish to know by what kind of meridian a plan has been constructed, when two objects thereon by its meridian form a bearing with each other of N 32 "W, and the bearing of the same two objects, as taken on the surface by an instrument whose needle has 22 of west variation, forms a bearing with each other of N 10 "W ? The two objects on the surface will form a bearing with each other of N 32 "W by the true meridian. Then the meridian of the plan will be the true meridian. EXAMPLE VI. I wish to know the variation of a plan's meridian, when the bearing of two objects thereon with its meridian is S 16 W, and the bearing of the same two objects with each other on the surface, taken by an instru- ment whose needle has 23 of west variation, is found to be S 10 W ? The plan's meridian will have 29 of west variation. EXAMPLE VII. I wish to know the variation of a plan's meridian, when the bearing of two objects thereon with its meridian is S 40 W, and the bearing of the same two objects with each other on the surface, taken by an instrument whose needle has 20 of west variation, is found to be S 23 "W? The plan's meridian will have 6 of east variation. EXAMPLE VIII. I wish to know the variation of a plan's meridian, when the bearing of two objects thereon REDUCING EEARI^GS, ETC. 115 with its meridian is N 65 W, and the bearing of the same two objects with each other on the surface, taken by an instrument whose needle has 23 of west variation is found to be N 20 W ? The plan's meridian will have 22 of east variation. EXAMPLE IX. I have a plan of a colliery workings, on which I took the bearing of two pits with each other by its meridian, which was N 5 W ; I also took the bearing of the same two pits on the surface by an instrument whose needle had 23 of west variation, which was N 5 E ; now I wish to know the variation of the plan's meridian by which it has been delineated ? The plan's meridian will have 13 of west variation. EXAMPLE X. I wish to know by what kind of meridian a plan of a colliery working has been constructed, when the bearing of two pits thereon with each other by its delineated meridian is found to be JST 5 E, and the bearing of the same two pits on the surface with the true meridiaji is found to be N 14 W ? The plan has been constructed by a meridian having 19 of west variation. How to plan surveys, and also the manner of determining an error arising in plotting, through inattention to the magnetic variation of the needle. (55.) It has been shown, in Art. 49, that the magnetic meridian is always changing ; therefore the bearings of the same objects, taken by such a meridian at [different times, must also vary from each other, except reduced to bearings with the true meridian. Let Ts"S represent the meridian of a plan, which is also supposed to be the true meridian ; and if a subterraneous excavation is to be plotted thereon from the pit A, which excavation is found to form a bearing of N 10 W 10 chains by an instrument whose needle had 20 of west variation ; 116 BEDTJCING BEAEINGS, ETC. now if the excavation N 10 W 10 chains is plotted on the plan by its meridian NS, which is the true meridian, it will FIG- 71 ^ e re P resen ted by -AB ; but the bearing being taken by a needle having 20 of west variation, therefore (according to the manner of reducing bearings from one magnetic meridian to their bearings with any other, Art. 53) it should form a bearing of N 30 W with the meridian NS, as represented by A5 ; then A.I will be the true direction of the excavation from the pit A, and b~B will be the magni- tude of the error (see theorem 8, Art. 48): \ Or, instead of reducing the excavation to s its bearing with the true meridian NS, it will be equally as true if ns is drawn on the plan, and made to represent the magnetic meridian of the needle by which the bearing was taken, with which AS will form a bearing of N 10 AV. I shall insert a few examples, illustrative of the error arising from plotting a subterranous survey on a plan without attending to the variation of the magnetic meri- dian, and also how its magnitude can be ascertained. EXAMPLE I. The following is a subterraneous survey, commencing at a pit called the B pit, N 30 W 6 chains, N 70 E 10 chains, N 30 E 5 chains, and N 25 W 8 chains, which was surveyed by an instrument whose needle had 24 of west variation ; under what bearings must the survey be plotted on a plan whose delineated meridian has 15 of west variation ? Eeduce the bearings, as taken by a meridian having 24 of west variation ; to bearings with a meridian having 15 of west variation : Thus, REDUCING BEAEINGS, ETC. 117 Bearings with a meridian of 24 of west variation. Chains. N. 30 W. 6 N. 70 E. . 10 N. 30 E. . . 5 N. 25 W. 8 Bearings with a meridian of 15 of west variation. Chains. N. 39 W. . . 6 N. 61 E. . .10 K 21 E. . . 5 N. 34 W. 8 FIG. The survey must be plotted under bearings with a magnetic meridian having 15 of west variation, as above, commencing at the B pit. EXAMPLE II. If the following subterraneous survey, N 9 W 8 chains, N. 30 E 7 chains, and N 21 W 8 chains, is made by an instrument whose needle has 23 of west variation, and plotted on a plan by a meridian having 5 of west magnetic variation, without being reduced thereto, what will be the magnitude of the error re- sulting by such neglect ? Suppose A, the point of com- mencement of the survey on the plan, and let the meridian of the plan here presented be N'"S"', hav- ing 5 of west variation with the true meridian NS; then the first bear- ing, IN" 9 "W 8 chains, will be re- presented by AB, the second, N 30 E 7 chains, by BC, and the third bearing, N 21 W 8 chains, by CD ; then ABCD will represent the survey plotted without attend- ing to the magnetic variation : But as the survey was made by an in- strument whose needle- had 23 of west variation, therefore each bear- ing, when truly plotted, must be set off from a meridian of that variation, which let ns represent ; 118 BEABINGS, ETC. then N 9 W 8 chains will be represented by A5, N 30 E 7 chains by lc } and N 21 "W 8 chains by cd ; then Abed will represent the survey truly plotted, and dD will be the magnitude of the error. Or the survey may be plotted by reducing the bearings, as taken by a meridian of 23 of west variation, to bearings, with a meridian of 5 of variation, as represented by N'S', and plotted from it accordingly, which will exactly coincide with A.bcd, as before. To discover, by calculation, the magnitude of the error reduce the bearings of the survey, as taken by a magnetic- meridian having 23 of west variation, to bearings with the true meridian, and also the same bearings, as if taken by a meridian having 5 of west variation, to bearings with the true meridian ; then determine the northing and easting of D from^: Thus, With a meridian of 23 of west variation. With the true meridian. With a meridian ' of 5 of west variation. With the true meridian. Chns. N. 9W. 8 N. 30 E. 7 N. 21 W. 8 Chns. N. 32 W. 8 N. 7E. 7 N. 44 W. 8 Chns. N. 9 W. 8 ' N. 30 E. 7 N. 21 W. 8 Chns. N. 14 W. 8 N. 25 E. 7 N. 26 W. 8 Chns. N. 32 W. 8 N. 7 E. 7 N. 44 W. 8 Northing. Southing. Easting. Westing. Chains. 678 6-94 5-75 Chains. Chains. 0-85 Chains. 4-23 5-55 19-47 Aa 9-78 0-85 ad 8-93 KEDTJCIIS'G , ETC. 119 Chns. N. 14 W. 8 N. 25 E. 7 N. 26 W. 8 Northing. Southing. Easting. Chains. 2-9*5 Westing. Chains. 1-93 3-50 Chains. 7-76 ' 6-34 7-19 Chains. 21-29 Ae 5-43 2-95 2-48 cD or af ad 8'93 chains af 2 '48 chains = fd 6'45 chains. Ae 21'29 chains A 19 '47 chains = ae or/D 1'82 chains. Then, as fd 6 -45 . . . -8095595 Is to radius. . . . 10 '0000000 Sois/D 1-82 . . . -2600714 To tang. /_ d 15 45' . . 9'4505117 From 90 15 45' = 74- 15', Z cidV. And V 6-45 + 1'82 = 67 c?D, or 6 '70 chains. Therefore the magnitude of the error, or the bearing and distance of D from d t will (from Art. 3) be N 74 15' E 670 chains with the true meridian. EXAMPLE III. If the following subterraneous survey S 30 "W" 4 chains, N 50 W 8 chains, N 50 E 9 chains, and IX" 53 W 8 chains, is surveyed by an instrument having 23 of west variation, and plotted on a .plan by the true meridian, without being reduced thereto, what will be magnitude of the error thereby ? Suppose A to be the point of commencement on the plan, and NS the true meridian thereon ; then ABCDF will be the erroneous representation of the bearings and distances, as plotted from that meridian, AB forming an angle of 30 therewith, BC an angle of 50 therewith, CD an angle of 50 therewith, and DF an angle of 53 therewith. 120 HEDUCING BEABINGS, ETC. To plot the survey accurately, draw on the plan a meri- dian line ns, having 23 of west variation ; each bearing and dis- tance being then plotted from it, and Abcdfwill represent the sur- vey accurately done, and/'F will be the magnitude of the error: Or, otherwise, if each bearing in the survey is reduced from the angle it formed with the mag- netic meridian it was taken by, to the angle of bearing it will form with the plan's meridian, which is the true meridian, and plotted accordingly, the result will be the same : Thus, With a meridian having 23 of west variation. Chains, S. 30 W. . . 4 N. 50 W. . 8 N. 50 E. . . 9 N. 53 W. , 8 With the true meridian. Chains. S. 7W. . . 4 N. 73 W. . 8 N. 27 E. . . 9 N. 76 W. , 8 Then A will represent S 7 W 4 chains, bo N 73 W 8 chains, cd N 27 E 9 chains, and cff, N 76 W 8 chains,, the same as before. EEDUCINQ BEAKINGS, ETC. 121 Chns. S. 30 W. 4 N. 50 W. 8 N. 50 E. 9 N. 53 W. 8 Northing. Southing. Easting. Westing. AF or ah Chains. 5 V 14 579 4-81 1574 3-46 Chains. 3-46 Ah Chains. 6-89 Chains. 2-00 6-13 6-39 14-52 6-89 7'63 12-28 Chns. S. 7 W. 4 N. 73 W. 8 N. 27 E. 9 N. 76 W. 8 Northing. Southing. Easting. Westing. Chains. 2'-33 8-01 1-93 12-27 3-97 Chains. 3-97 Chains. 4-08 Chains. 0-48 7-65 7-76 15-89 4-08 8-30 Aa 11-81 / From af ll'Sl ale 7'63 = fc/4'18. AA 12-28 Aa 8 -30 = ah or &F 3 -98. 6211763 10-0000000 5998831 9-9787068 Then, as kf 4 18 Is to radius So is JfcF 3-98 To tang. ^ / 43 35' . From 90 43 35' = 46 25' ^ nfF. And V418 + 3-98 = 5'77/F chains. Therefore the bearing of F from /with the true meri- dian will be N 46 25' E, and the distance will be 577 chains ; which is the magnitude of the error. EXAMPLE IV. If the following subterraneous survey, 122 EEDTJCING BEABINGS, ETC. FF&.74-. commencing at the pit A, S 30 ~W 4 chains, S 70 "W 10 chains, and S 50 E 5 chains, was surveyed by an instru- ment whose needle had 23 of west variation, and is plotted on a plan by a meridian having only 10 of variation to the west, without reduc- ing the bearings there- to ; what will be magni- tude of the error ? If NS represent the true meridian, ns the meridian, having 23 of west variation, by which the survey was taken, \ and IPS' the meridian \ of the plan, having 10 ^ of variation, by which the survey is to be plot- ted ; the ABCD will be the erroneous representation of the survey, as plotted by the meridian N'lS' without reducing tne bearings thereto. To plot the same truly, With a meridiem of 23 of west variation. Chains. S. 30 W, . .4 S. 70 W. . . 10 S. 50 E. . 5 With a meridian o/10 of west variation. Chains. S. 17 W. . .4 S. 57 W. . . 10 S. 63 E. , 5 Now make AJb form an angle to the west with the meri- dian -ZV'/S' of 17, lc an angle to the west of 57, and cd an angle to the east of 63 ; then Ated will represent the survey truly plotted, and the distance between D and d will be the magnitude of the error. EEDTJCIKG BEABIKGS, ETC. TO FIND THE MAGNITUDE OP THE ERROR. 123 With a meridian of 23 of west variation. With the true meridian. With a meridian of 10 of west variation. With the true meridian. Chns. S. 30 W. 4 S. 70 W. 10 S. 50 E. 5 Chns. S. 7 W. 4 S. 47 W. 10 S. 73 E. 5 Chns. S. 30 W. 4 S. 70 W. 10 S. 50 E. 5 Chns. S. 20 W. 4 S. 60 W. 10 S. 60 E. 5 Chns. S. 7 W. 4 S. 47 W. 10 S. 73 E. 5 Northing. Southing. Easting. Westing. ad Chains. Chains. 3-79 6-82 1-46 12-25 Chains. 4'- 7 8 Aa Chains. 0-49 7-31 7-80 4-78 3-02 Chns. S. 20 W. 4 S. 60 W. 10 S. 60 E. 5 Northing. Chains. Southing. Easting. Chains. 4-33 Ae Westing. eD Chains. 3-75 5-00 2-50 Chains. 1-37 8-66 10-03 4-33 11-25 5-70 Then Aa 12-25 Ae 11-25 = ae or fd 1. And eD 570 ad 3 '02 = /D 2'68. As/D 2-68 .... -4281348 Is to radius . . . . 10 '0000000 Sois/dl .... To tang. /_ D. 20 27' . . 9-5718652 From 90 20 27' = 69 83', _ fdV. And V 2-68 + 1 = 2'86 = Dd. 124 HOW TO RUN BEARINGS, ETC. Therefore the bearing of D from d with the true meridian will be N 69 33' W, and the distance will be 2-86 chains ; which is the magnitude of the error. EXAMPLE V. The following subterraneous survey, S 20 W 5 chains, S 70 W 10 chains, N 50 W 5 chains, and N 3 "W 8 chains, was taken by an instrument having 23 of west variation, which I have to plot on a plan, the magnetic variation of the meridian by which it has been constructed is unknown ; I therefore wish to know how the survey must be plotted, so that it may be accurately done? In order to find by what kind of meridian the plan has been constructed, I took the bearing of two pits thereon by the delineated meridian, which I found to bear with each other ]N T 25 W, and the same two pits on the sur- face I found to bear N 22 W by an instrument whose needle had 23 of west variation ; therefore the plan's meridian will have 20 of west variation, and the bearings of the survey must be reduced from a meridian of 23 of west variation to bearings with a meridian of 20 of the same variation, and plotted on the plan accordingly ; Thus, Searings with a meridian of 23 of west variation. Chains. S. 20 W. . .5 S. 70 W. . . 10 N. 50 W. . .5 N. 3 W. 8 Searings with the plains meridian of 20 of west variation. Chains. S. 17 W. . . 5 S. 67 W. . . 10 N. 53 W. . .5 N. 6 W. 8 Sow to run bearings on the surface l>y a circumferentor, without error. (56.) It frequently happens that the practical miner has to re-traverse on the surface the survey of a subterraneous excavation from bearings taken at some former time : Now, when that is the case, if the miner does it without attending to the change that has taken place with the magnetic meridian, between the taking of the survey and the re- HOW TO RUN BEARINGS, ETC. 125 traversing it, an error must inevitably be the result ; but where surveys are recorded without mentioning by what kind of meridian they were originally made, such surveys cannot be re-traversed with any degree of accuracy. Suppose the bearing of a subterraneous excavation AB, is found to be N 20 W, which is taken by the needle of an instrument placed at the pit A, whose magnetic meridian is represented by NS ; now, if the bearing of this excavation is run off on the surface from the pit A, immediately after it has been surveyed under-ground, and by the same instrument also, the excavation AB will be truly represented on the surface (see theorem 6, Art. 48) ; but if it should be ne- cessary, at any future time, to have the same excavation represented on the surface by the same survey already made, and in that in- terval of time between the survey being made and its second plotting on the surface, the magnetic meridian NS has changed its situa- tion to ns, the same excavation, IN" 20 "W, run off from the then magnetic meridian ns, will be represented by A&, which will be erroneous : Therefore, to do the work truly, the bearing of AB, as originally taken by the meridian NS, must be reduced to its bearing with the meridian ns, and plotted on the surface from it accord- ingly (see theorem 7, Art. 48). I shall insert a few examples relative to plotting bearings on the surface by different meridians. EXAMPLE I. The subterraneous excavation commencing at the pit A, N 20 W 5 chains AB, N 20 E 8 chains BC, N 70 E 5 chains CD, and S 70 E 5 chains DF, was surveyed by an instrument whose needle had 10 of west variation ns, and is to be plotted on the surface by another instrument whose needle has a different magnetic variation ; how must it be plotted with accuracy ? 126 HOW TO BUK" BEABINGS, ETC. First, find the magnetic variation of the needle of the instrument by which the survey is to be plotted (see Art. 51), which suppose it to have 23 of west variation N S ; then reduce the bearings, as taken by a meridian of 10 of west variation ns, to bearings with a meridian of 23 of west variation !N" S. EXAMPLE II. If the following survey of a subterraneous excavation, commencing at the pit A (see Eig. to Ex. IV. Art. 55), S 30 W 4 chains, S 70 W 10 chains, and S 50 E 5 chains, was surveyed by an instrument which had 10 of west variation ; what will be the magnitude of the error, if the survey is plotted on the surface by another instrument having 23 of west variation ? Let N'S' represent the magnetic meridian of the needle of the instrument by which the survey was made, having 10 of west variation, and let ABCD represent the survey as plotted on the surface thereby, also let ns represent the meridian of the instrument whose needle has 23 of west variation, and AJbcd the excavation as plotted according to that meridian; then AEOD will be the survey plotted truly, and A.lcd the same plotted erroneously : Therefore, from the manner of determining the magnitude of an error, arising from plotting a survey by a different meridian than that by which it was made (Art. 55), the error will be 2*86 chains, which is the distance of d from D. EXAMPLE III. I have the survey of a subterraneous excavation, commencing at a pit called the A pit; the bearings are recorded to be taken by the true meridian, viz., N SO W 5 chains, due north 8 chains, IN" 80 E 5 chains, JS T 45^ W 10 chains, and JS" 23J W 4 chains ; how is the survey to be truly delineated by an instrument on the surface, so that a pit may be sunk on the extreme point of the last bearing ? The first thing to be done, the surveyor must ascertain the magnetic variation of the needle of the instrument by which he intends delineating the survey (see Art. 49) TO FIND THE ANTIQUITY OF A PLAN, ETC. 127 which suppose to be 23 30' to the west, and reduce the bearings of the survey thereto : Thus, Bearings with the true meridian. Bearings with a meridian of 25 30' of west variation. Chains. N. 30 W. . .5 N 8 N. 80 E. . .5 N. 45f W. . . 10 Chains. N. 6|W. . . 5 N. 23f E. . . 8 N. 76| E. . . 9 N. 22 W. 10 N. 23| W. . . 4 N. ... 4 Then fix the instrument at the A pit, and run off the first bearing and distance N 6J W 5 chains, and the other following ones in regular order, and the end of the last N 4 chains, will be the place on the surface where the pit must be sunk, to hit the extreme point of the excavation. To find the antiquity of a plan ly its delineated meridian. (57.) As the magnetic meridian has, for a great number of years past, been veering about to the west, hence plans constructed at different times must have their magnetic meridians of different variation ; those that are of the most ancient construction will have their meridians more easterly than those of a more modern date. Should a plan be found to have been constructed by a meridian having 11 15' of east variation, it will be reasonable to suppose it has been made about the year 1576 ; for at that time the magnetic meridian had 11 15' of east variation (see Table, Art. 49) : Or, if its meridian is found to have 20 of west variation, from the same principle it may be supposed to have been made about the year 1765. EXAMPLE I. If a plan is found to have a magnetic meridian of 18 of west variation, in what year has it been constructed ? By looking in the table, Art. 49, it will appear to have been made about the year 1750. 128 MANNER OF BECOBDING STJBTEBEANEOFS SUBVEYS. EXAMPLE II. I have a plan on which is a delineated meridian ; I therefore wish to know iu what year it has been made ? First find the magnetic variation of the meridian on the plan according to the rules for finding the same, Art. 54, which suppose to be 6 of east variation; then, by the table, Art. 49, it will appear to have been made about the year 1^22. The manner of recording subterraneous surveys. (58.) As the necessity of recording surveys of subterra- neous workings frequently occurs, I shall therefore show how the same ought to be recorded, so that they may answer the intended design : Thus, A recorded survey of a subterraneous excavation, taken June lOfch, 1800, beginning at the centre of the A pit, in Blackburn colliery. Each bearing "being reduced to the true meridian. Chains. N. 10 W 5-50 N. 20 E 4-20 N. 75 E 10-10 E 4-40 S. 71 E 6-30 N. 50 E 5-90 A recorded survey of a subterraneous working, taken November 21st, 1801, beginning at the centre of the Venture Pit, in Tanfield colliery. Each bearing was taken by a needle having 23 of ivest variation, and recorded accordingly. Chains. S. 50 W 5-24 S. 30 W 2-20 S. 86 W 5-70 N. 40 W 12-60 Now, either of these recorded surveys may be truly re-traversed on the surface of the earth; at any future time NATURE AND USE OF TBAYEESE TABLES. 129 with accuracy, by an instrument whose magnetic needle may have any known variation whatever, by referring to Art. 56. The nature and use of the Traverse Tables. (59.) Thus, if it is required to know the northing and easting of IS" 18 E 56 links, look in the tables under the degree answering to the bearing, and to the right, opposite 56 in the column of bearing lengths, will be found 53 links and 26 hundred parts of a link of northing, and 17 links and 30 hundred parts of a link of easting. As the bearing length is links, the northing and easting must be links and parts of a link ; for in whatever denomination the bearing length is, in the same denomination must the integral part of the northing or southing and easting or westing be. Also, if it is required to know the northing and easting of N 18 E 5'65 chains, look in the table under the degree answering to the bearing, and opposite 5 chains in the bearing lengths will be found 4 - 76 chains of northing and 1*55 chains of easting ; then, for the remaining 65 links, look opposite 65 in the same column of bearing lengths, and there will be found 61' 82 links of northing, and 20*09 links of easting, which, added to the former northing and easting, will make 5*3782, or nearly 5-38 chains of northing, for the whole northing, and 1*7509 chains, or 1*75 chains nearly, for the whole easting. Suppose, again, the southing and westing of S 86 "W 98*20 chains is required, look in the tables under the degree of the bearing, and the southing and westing will be thus : Chains. Chains. Chains. For &8 '00 there is 6 '84 of southing and 97 '76 of westing. For 00-20 1 -40 of ditto 01 9 '95 of ditto. 98-20 6-85-40 of southing and 97 '95 '95 of westing. or, 6-85 of southing and 97 '96 of westing nearly. a 3 130 NA.TTJBE AND USE OF TEAVEESE TABLES. If the southing and easting of S 18J E 20 chains is required, take the southing and easting of the bearing length under 18, and also under 19, in manner before shewn, and half their sum will be the southing and easting required ; thus : Chains'. Chains. Chains. S. 18 E. 20 will have 19-02 of southing 6'18 of easting. S. 19 E. 20 will have 18 '91 of ditto. 6'51 of ditto. 2)37-93 12-69 18-96 of southing 6 '34 of easting. Therefore S 18J E 20 chains will have 18'96 chains of southing and 6'34 chains of easting. Again, if the northing and westing of N 75 1 W 10'35 chains is required, Chains. Chains. Chains. ; N. 75 W. 10-35 will have 2 '68 '06 of northing 9 -99 '81 westing. N. 76 W. 10-35 will have 2'50'47 of ditto. lQ-08'96 ditto. 2)5-18-53 20-08-77 N. 75|W. 10-35 will have 2-59-26 of nortiiing 10-04-38 westing, or nearly 2-59 of northing 10'04| westing. If the northing and easting of N 14 37' E 18 chains be required, take the northing and easting of the bearing length under 14 and the same under 15 ; take the difference of each, multiply the respective differences by the number of minutes, *. e. 37', and divide the products by 60 (the number of minutes in a degree), subtract the first quotient from the northing, and add the second to the easting ; and the sum and difference will be the northing and easting required ; thus NATURE AND USE OF TRAVERSE TABLES. 131 N. 14 E. 18 chains will have 17 "47 of northing, and 4 '35 of easting. N. 15 E. 17-39 of ditto, 4-66 of ditto. 08 diff. -31 diff. 37 37 60) 29-6 60)114-7 5 nearly. 19 nearly. 14-47 4-35 N. 14 37' E. 18 ch. will have 14'42 of northing, and 4-54 of easting. The use of the Traverse Tables in reducing hypothenusal or inclined distances to horizontal distances. (See Art. 45.) (60.) When the table is used for the before-mentioned PIC 75 purpose, the column called a bearing lengths represents the hypothenusal distance or longest side of a right-angled triangle, as CB ; the column called N or S distance repre- sents the horizontal distance AB ; and the column called E or "VV distance represents the perpendicular AC. If the horizontal distance AB or C# is required, when the hypothenusal distance CB is 10 chains, and the angle CB or CBA is 20, look in the table under 20, and Opposite 10, in the column of bearing lengths, will be found in the column of N or S distance 9-40, which will be 9'40 chains, equal to the horizontal distance AB or C. If the horizontal distance AB or C is required, when the hypothenusal distance CB is 8 chains, and the angle aCB or CBA is 50, look in the tables under 50, and opposite 8, in the column of bearing lengths, will be found 5'14 chains, in the column of N or S distance, which is equal to AB or Ca, the horizontal distance. The horizontal distance of a line 20'50 chains, run under an angle of 15 of elevation, is required ? Look in the tables under 15, and in the column of 132 NATURE AND USE OP TRAVEBSE TABLES. bearing lengths for 2O50 chains, the horizontal distance will be thus : Chains. Chains. For 20*00 of hyp. distance 19 '32 of horizontal distance. For 0*50 of hyp. distance '4 8 of horizontal distance. For 20'50 of hyp. distance 19 '80 the whole horizontal distance. Therefore, 2O50 chains of hypothenusal or inclining length will be equal to 19 chains 80 links, or 19'80 chains of horizontal distance. TRAVERSE TABLES; OR, TABLES OF THE NORTHING OR SOUTHING, AND EASTING OR WESTING ; WHEREIN THE DISTANCE IS EXTENDED TO ONE HUNDRED, FOR EVERY DEGREE OP THE QUADRANT. TBAVERSE TABLES. 135 r 1 *>." oof S *>J i *i sj ajf *l j si M if 3 C BJ g| si 1 C o| "s| C 5C si 2 t-. rj Q *- ;- c4 5| I! B| s| IJ ^a wS 3J 3 s'3 Sj &3 wS S5 i3 s'S i 1-00 001 51 51-CO 045 1 1-00 0-02 51 50-99 0-89 2 2-00 0-02 52 52-00 0-45 2 2-00 0-03 52 51-99 C-91 3 3-00 0-03 53 53-00 0-43 3 3-00 0-05 53 52-99 0-92 4 4-00 0-03 54 54-00 046 4 4'00 0-07 54 53-99 094 5 5-00 0-04 55 55-00 0-48 5 5-00 0-09 53 54-99 0-96 6 6-00 005 56 56-00 0-49 6 6-00 o-io 56 55-99 098 7 7-00 0-06 57 57-00 0-50 7 700 0-12 57 5699 0-99 8 800 007 58 58-00 0-51 8 8-00 0-14 58 57-99 1-01 9 900 0-08 59 59-00 0-52 9 900 0-16 59 58-99 1-03 10 10-00 0-09 60 6000 0-52 10 10-00 0-17 60 59-99 1-05 11 11-00 0-10 61 61-00 0-53 11 11-00 0-19 61 60-99 1-07 12 12-00 0-10 62 62-00 0-54 12 12-00 021 62 61-99 1109 13 13-00 0-11 63 63-00 0-54 13 13-00 0-22 63 62-99 1-10 14 14-00 0-12 64 64-00 0-55 14 14-00 0-24 64 6399 1-12 15 15-00 013 65 65-00 0-56 15 15-00 026 65 64-93 1-14 16 16-00 0-13 66 66-00 0-57 16 1600 0-28 66 65-99 1-16 17 1700 0-14 67 67-00 0-58 17 17-00 0-29 67 6699 1-17 18 18-00 0-15 68 6S-00 059 18 18-00 0-31 68 67-99 1-19 19 19100 0-16 69 69-00 0-60 19 19-00 033 69 68-99 121 20 20-00 0-17 70 70-00 0-61 20 20-00 035 70 69-99 122 21 2100 0-18 71 71-00 0-62 21 21-00 0-37 71 70-99 1-24 22 22-00 0-18 72 72-00 0-63 22 22-00 0-38 72 7199 1-26 23 23-00 0-19 73 73-00 0-63 23 23-00 0-40 73 7299 1-28 24 2400 0-20 74 74-00 0-64 24 24-0") 0-42 74 7399 1-29 25 2500 0-21 75 75-00 0-65 25 25-00 0-44 75 74-99 1-31 26 26-00 022 76 76-00 066 26 26-00 0-45 76 75-P9 1-33 27 27-00 023 77 77-00 0-67 27 27-00 0-47 77 76-99 1-35 28 28-00 0-24 78 78-00 0-fiS 28 28-00 0-49 78 77-99 1-36 29 29-00 0-25 79 79-00 069 29 29-00 051 79 7899 1-38 30 30-00 0-26 80 80-00 0-70 30 30-00 0-52 80 7999 1-40 31 31-00 0-26 81 81-00 0-71 31 31-00 054 81 80-99 1-42 32 32-00 0-27 82 82-00 072 32 32-flO 0-56 82 81-99 1-44 33 33-00 0-28 83 83-00 0-73 33 33-00 0-58 83 82-99 1-45 3t 34-00 C-29 84 84-00 0-74 34 3399 0-60 84 83-99 147 35 35-00 030 85 85-00 0-74 35 34-99 0-61 85 84-99 1-49 36 36-00 031 86 86-00 0-75 36 3599 0-63 86 8599 1-51 37 37-00 032 87 87-00 0-76 37 36-99 065 87 86-99 1-53 38 38-00 0-33 88 83-00 0-77 38 37-99 0-67 88 87-99 1-54 39 3900 0-34 89 89-00 0-78 39 3899 0-69 89 8899 1-56 40 40-00 0-35 90 90-00 0-79 40 39-99 0-70 90 89-99 1-57 41 4100 0-36 91 91-00 0-80 41 40-99 0-72 91 90-99 1-59 42 42-f-O 036 92 9200 081 42 41-99 0-74 92 9199 1-61 43 4300 0-37 93 93-00 0-81 43 4299 076 93 92-99 1-62 44 44-00 0-38 94 94-00 0-82 44 43-99 0-78 94 9399 1-64 45 45-00 039 95 95-00 0-83 45 4499 0-79 95 9499 1-66 46 46-00 040 96 96-00 0-84 46 45-99 0-81 96 95-99 1-C8 47 47-00 0-41 97 9700 0-85 47 4609 0-83 97 .96-99 1-69 48 48-00 0-42 98 98-00 0-85 48 47-99 0-84 98 97-99 1-71 49 4900 0-43 99 99-00 0-86 49 48-99 0-S6 99 98-99 173 50 50-00 0-44 100 10000 087 50 4999 087 ICO 9999 1-75 E.orW N.orS. E.orW N. or S. E. or VV N. or S. E.orW. N.orS. 89^ 89 136 TRAVERSE TABLES. 2 3 'E 5o II l\ E. or W. Distance. E &c * p j HQ Bearing Lengths. 1 H'Q Bearing Lengths. ll E. or W. Distance. 1 1-00 0-03 51 50-97 1-78 1 1-00 0-05 51 50-93 2-67 2 2-00 0-07 52 5197 181 2 2-00 0-1 1 52 5193 2-72 3 3-00 0-10 53 52'97 1-85 3* S'OO 0-16 53 52-93 2-77 4 4-00 0-14 54 53-97 1-88 4 399 0-21 54 53-93 283 5 5-00 0-17 55 54-97 192 5 4-99 0-26 55 54-93 288 6 6-00 0-21 56 5597 1-95 6 5-99 0-31 56 55-92 293 7 7-00 0-24 57 5697 1-99 7 6-99 0-37 57 5692 2-98 8 800 0-28 58 57-97 2-02 8 7-99 042 58 57-92 3-04 9 8-99 031 59 58-96 206 9 8-99 047 59 58-92 3-09 10 9-99 0-35 60 59-96 209 10 9-99 0-52 60 59-92 3-14 11 10-99 0-38 61 60-96 2-13 11 10-98 0-58 61 60-92 3-19 12 1199 0-42 62 61-96 2-16 12 11 -93 063 62 61 '92 3-25 13 1299 0-45 63 62-96 2-20 13 1298 0-68 63 62-92 3-30 14 13-99 0-49 64 6396 2-23 14 13-98 0-73 64 63-91 3-35 15 14-99 0-52 65 6496 2-27 15 1493 079 65 64-91 3-4) 16 1599 056 66 65-96 2-30 16 1598 0-84 66 65-91 3-46 17 16-99 059 67 66-96 2-34 17 1698 0-89 67 66-91 3-51 18 17-99 063 68 67-96 2-37 18 1798 0-94 68 6791 3-56 19 18-99 0-66 69 68-96 2-40 19 18-97 1-00 69 6891 361 20 19-99 0-70 70 6996 3-44 20 19-97 1-05 70 6990 366 21 20-99 0-73 71 70-96 2-47 21 2097 1-10 71 70-90 372 22 21-99 0-77 72 71-96 2-51 22 2197 115 72 71-90 3-77 23 22-98 0-80 73 72-96 2-54 23 22-97 1-20 73 72-90 3-82 24 23-98 0-84 74 73-95 258 24 23-97 1-26 74 73-90 3-88 25 24-98 0-67 75 74-95 2-61 25 24-97 1-31 75 74-90 3-93 26 25-98 091 76 7595 2-65 26 25-96 1-33 76 75-90 3-98 27 26-98 0-94 77 76-95 268 27 26-96 1-42 77 76-90 404 28 27-98 0-98 78 7795 2-72 28 2796 1-47 78 77-89 4-09 29 28-98 1-01 79 78-95 2-75 29 28-96 1-52 79 78-89 4-14 30 2998 1-05 80 7993 2-79 30 2996 1-57 80 7989 4-19 31 30-98 1-08 81 80-95 2-82 31 30-96 1-62 81 80-39 4-24 32 3193 1-12 82 81-95 286 32 31-98 1-68 82 81-89 4-29 33 32-98 1-15 83 8-295 289 33 32-95 1-73 83 82-89 4-35 34 33-98 1-19 84 8395 293 34 33-95 1-78 84 83-89 4-40 35 34-98 122 85 84-95 296 35 3495 183 85 8488 4-45 36 3598 1-26 86 8595 30) 36 3595 1-88 86 8588 4-50 37 36-98 1-29 87 86-95 3-03 37 3*595 1-94 87 86-88 4-56 38 37-98 1-33 88 87-95 307 38 3795 199 88 87-88 4-61 39 3898 1-36 89 8895 310 39 38-95 2-04 89 88-88 4-65 40 39-98 1-40 90 89-95 3-14 40 3995 2-09 90 89-88 4-71 41 40-98 1-43 91 90-94 3'17 41 40-94 2-15 91 90-88 4-76 42 4198 1-47 92 91-94 3-21 42 4194 220 92 91-87 4-82 43 42-98 1-50 93 9294 3-24 43 42-94 225 93 92-87 4-87 44 4397 1-53 94 93-94 3-28 44 4394 2-30 94 93-87 4-92 45 4497 1-57 95 94-94 331 45 41-94 236 95 94-87 4-97 46 45-97 1-60 96 9594 3-35 46 45'94 2-41 96 95-87 5-02 47 46-97 1-64 * 97 96-94 338 47 4694 2-46 97 9687 5-08 48 47-97 '1-67 98 9794 342 48 47-94 2-51 98 9787 5-13 49 4897 1-71 99 9894 345 49 48-93 2-57 99 9887 5-18 50 49-97 174 100 99-94 3-49 50 4993 2-62 100 99-86 6-23 E. orW. N.orS. E.orW. N.orS. E.orW. N.orS. E. or W. N.orS. 88 87 TRAVERSE TABLES. 137 4 5 sc - -S 8 >8 - S fe-4 MS 02 *' fc* iJD^ . j 1} |g M 11 i .S aa "^ a 'E S S l s| If EC 3 5 3 g| xu3 55 Q wS *! K"5 1,2 fc'S WQ 3^ fcS KG i i-oo 0-07 51 50-88 3-56 i i-oo 0-09 51 50-81 4-45 2 2-00 0-14 52 51-87 3-63 2 1-99 0-17 52 1-80 4-53 3 2-99 0-21 53 52-87 3-70 3 2-99 0-26 53 52-80 4-62 4 3-99 0-28 54 53-87 3-77 4 3-98 0-35 54 53-79 4-71 5 4-99 0-35 55 54-87 3-84 5 4-98 0-44 55 54-79 4-79 6 6-99 0-42 56 55-86 3-91 6 5-93 0-52 56 55-79 4-88 7 6-98 0-49 57 56-S6 3-98 7 6-97 0-61 57 56-78 4-97 8 7-98 0-56 58 57-86 4-05 8 7-97 0-70 58 57-78 5-06 9 8-98 0-63 69 58-86 4-12 9 8-97 0-78 59 58-78 5-14 10 9-98 0-70 60 59-85 4-19 10 9-96 0-87 60 59-77 5-23 11 10-97 0-77 61 60-85 4-26 11 10-96 0-96 61 60-77 5-32 12 11-97 0-84 62 61-85 4-32 12 11-95 1-05 Qs 61-76 5-41 13 12-97 0-91 63 62-85 4-39 13 12-95 1-13 63 62-76 5-49 14 13-97 0-98 64 63-84 4-46 14 1395 1-22 64 63-76 5-58 15 14-96 1-05 65 64-84 4-53 15 14-94 1-31 65 64-75 5-67 16 15'96 1-12 66 65-84 4-60 16 15-94 1-39 66 65-75 5-75 17 16-96 1-19 67 66-84 4-67 17 16-94 1-48 67 68-75 5-84 18 17-96 1-26 68 67-83 4-74 18 17-93 1-57 68 67-74 5-93 19 18-95 1-33 69 68-83 4-81 19 18-93 1-66 69 68-74 6-02 20 19-95 1-40 70 69-83 4-88 20 19-92 1-74 70 69-73 6-10 21 20-95 1-47 71 7 '83 4-95 21 20-92 1-83 71 70-73 6-19 22 21-95 1-54 72 71-82 5-02 22 21-92 1-92 72 71-73 6-28 23 22-94 1-61 73 72-82 5-09 23 22-91 2-00 73 72-72 6-36 24 23-94 1-68 74 73-82 5-16 24 23-91 2-09 74 73-72 6-45 25 24-94 175 75 74'82 5-23 25 24-91 2-18 75 74-72 6-54 26 25-94 1-82 76 75-81 5'3) 26 25-90 2-27 76 75-71 6-63 27 26-93 1-89 77 76-81 5-37 27 26-90 2-35 77 76-71 6-71 28 27-93 1-96 78 77-81 5-44 28 27-89 2-44 78 77-70 6-80 29 28-93 2-03 79 78-81 5-51 29 28-89 2-53 79 78-70 6-89 30 29-93 2-09 80 79-81 5-58 30 2^-89 2-61 80 79-70 6-97 31 30-92 2-16 81 80-80 5-65 31 30-83 2-70 81 80-69 7-06 32 31-92 2-23 82 81-60 5-72 32 31-88 2-79 82 81-69 7-15 33 32-92 2-30 83 82-80 5-79 33 32-88 2-88 83 82-68 7-24 34 33-92 2-37 84 83-80 5-86 34 33-87 3-96 84 83-68 7-32 35 34-91 2-44 85 84-79 5-93 35 34-87 3-05 85 84-68 7-41 36 35-91 2-51 86 65-79 6-00 36 35-86 3-14 86 85-67 7-50 37 36-91 2-58 87 86-79 6-07 37 36-86 3-22 87 86-67 7-58 38 37-91 2-65 88 87-79 6-14 38 37-83 3-31 88 87-67 7-67 39 38-90 2-72 89 88-78 6-21 39 38-85 3-40 89 88-66 7-76 40 39-90 2-79 90 89-78 -28 40 39-85 3-49 90 89-66 7-84 41 40-90 2-86 91 90-78 6-35 41 40-84 3-57 91 90-65 7-93 42 41-90 2-93 92 91-78 6-42 42 41-84 3-66 92 91-65 8-02 43 42-90 3-00 93 92-77 6-49 43 42-84 3-75 93 92-65 8-11 44 43-89 3-07 94 93-77 6-56 44 43-83 3-84 94 93-64 3-19 45 44-89 3-14 95 94-77 6-63 45 44-83 3-92 95 94-64 8-28 46 45 -S9 3-21 96 95-77 6-70 46 45-83 4-01 96 95-64 8-37 47 46-69 3-28 97 96-76 6-77 47 46-82 4-10 97 96-63 8-45 48 47-88 3-35 98 97-76 6-84 48 47-82 4-18 98 97-63 8-54 49 48-88 3-42 99 98-76 6-91 49 48-81 4-27 99 98-62 8-63 50 49-88 8-49 00 99-76 6-98 50 49-81 4-36 00 99-62 8-72 E.orW N.orS. E. or W. N. or S. E. or W. N.orS. E. or W. N. or S. 86 85 138 TEAVEESE TABLES. 6 7 e.3 j 'S *i *| if w>2 s -z d ft ITJ CO *J II ej ^3 y 3 s c V O> 3 i-3 Q a 5 2 fc3 11 WQ 3_5 Q KQ j 0-98 0-21 51 4989 10-60 1 0-97 0-22 51 4969 11-47 2 1-96 0-42 52 5086 10-81 2 1-95 0-45 62 50-67 11-70 3 2-93 0'62 53 51-84 11-02 3 2-92 0-67 53 51-64 11-92 4 3-91 0-83 54 52-82 11-23 4 3-90 0-90 54 52-62 12-15 5 4-89 1-04 55 53-80 11-44 5 4-87 1-12 55 53-59 12-37 6 5-87 1-25 56 54-78 11-64 6 5-75 1-35 56 54-57 12-60 7 6-85 1-46 57 55-75 11-85 7 6-82 157 57 55-54 12-82 8 7-83 1-66 58 56-73 12-06 8 7-79 1-80 58 56-51 13-05 9 880 1-87 59 57-71 12-27 9 8-77 2-02 59 57-49 13-27 10 978 2-08 60 58-69 12-47 10 9-74 225 60 58-46 13-50 11 10-76 2-29 61 59-67 12-68 11 10-72 2-47 61 59-44 13-72 12 lt-74 2-49 62 6065 12-89 12 11-69 2-70 62 60-41 13-95 13 12-72 2-70 63 61-62 13-10 13 12-67 2-92 63 61-39 14-17 14 13-89 2-91 64 6260 13-31 14 13-64 315 64 62-36 14-40 15 14-67 312 65 63-58 13-51 15 14-62 337 65 6333 14-62 16 15-65 3-33 66 6i-5ti 1372 16 15-59 360 66 64-31 14-85 17 10-63 353 67 6554 13-93 17 1656 3-82 67 65-28 1507 IS 1761 3-74 68 66-51 14-14 18 17-54 4-05 68 6626 15-30 19 18-58 3-95 69 67-49 14-35 19 18-51 4-27 69 67-23 1552 20 19-56 4-16 70 63-47 14-55 20 1949 450 70 68-21 15-75 21 20-54 4-37 71 69-45 14-76 21 20-46 4-72 71 69-18 15-97 22 21-52 4-57 72 70-43 1497 22 21-44 4-95 72 70'16 16-20 23 22-50 4-78 73 71-40 15-18 23 22-41 5-17 73 71-13 1642 21 23-48 4-99 74 72-38 15-39 24 23-38 5-40 74 7210 1665 25 24-45 5-20 75 73-36 15-59 25 24-36 5-62 75 73-08 1687 26 2543 5-41 76 74-34 1580 26 25-33 5-85 76 74-05 17-10 27 26-41 5-61 77 75-32 16-01 27 2631 6-07 77 75-03 17-32 28 27-39 5-82 78 76-30 16-22 28 27-28 6-30 78 76-00 17-55 29 28-37 6-03 79 77-27 16-43 29 28-26 6-52 79 76-98 17-77 30 29-34 6-24 80 78-25 1663 30 29-23 6'75 80 77-95 18-00 31 30-32 6-45 81 79-23 16-84 31 30-21 6-97 81 78-92 1822 32 31-30 6-65 82 80-21 17-05 32 31-18 7-20 82 7990 18-45 33 32-28 6-86 83 81-19 17-26 33 3215 7-42 83 80-87 18-67 34 33-26 7-07 84 82-16 17-46 34 33-13 765 84 81-85 18-90 35 34-24 728 85 83-14 17-67 35 34-10 7-87 85 82-82 1912 36 35-21 7-48 86 84-12 17-88 36 35-08 8-10 86 83-80 19-35 37 36-19 769 87 85-10 18-09 37 36-05 8-32 87 84-77 19-57 33 37-17 7-90 88 86-08 18-30 38 37-03 8-55 88 85-74 1980 39 38-15 8-11 89 87-06 18-50 39 3800 8-77 89 86-72 20-02 10 39-13 8-32 90 88-03 1871 40 3397 9-00 90 87-69 20-25 41 40-10 8-52 91 89-01 19-92 41 3995 922 91 88-67 20-47 42 4108 873 92 89-99 1913 42 40-92 9-45 92 89-64 20-70 43 42-06 8-94 93 90-97 19-34 43 41-90 9-67 93 90-62 2092 44 43-04 9-15 91 91-95 19-54 44 42-87 9-90 94 91-59 21-15 45 44-02 936 95 9292 19-75 45 43-85 10-12 95 92-57 21-37 46 4499 956 96 9390 19-96 46 4482 10-35 96 93-54 21-60 47 45-97 9-77 97 94-88 20-17 47 45-80 1057 97 9451 21-82 48 46-95 9-98 98 95-86 20-38 48 46-77 10-80 98 95-49 22-05 49 47-93 10-19 99 96-84 20-68 49 47-74 11-02 99 96-46 2227 50 48-91 10-40 100 97-81 2079 50 48-72 11-25 ICO 97-44 22-50 E.orW. N. or S. E.orW. N. or S. E. or W. N. or S. E.orW. N.orS. 71 i 7' r* 142 TRAYERSE- TABLES. 14 15 irl I *t el rfl *f hcj an I ^i *>2 o> OJ 2 1 "si? SI !-> 8 ..S 3 c Si *] Si 1 si = n} c S~ g| 3 so WQ 33 fc5 HQ S3 53 S w'S [5 fc'3 K"3 i 097 024 51 4949 1231 1 097 0-26 51 49-26 13-20 2 1-94 0-48 52 50-46 1258 2 193 0-52 52 5023 13-46 3 2-91 0-72 53 51-43 1282 3 2-90 0-78 53 51-19 13-72 4 3-88 0-97 54 5240 1306 4 8-86 1-04 54 52-16 13-98 5 4-85 1-21 55 53-37 1331 5 4-83 1-29 55 53-13 11-24 6 5-82 1-45 56 54-34 13-55 6 5-80 1-55 56 54-09 14-49 7 6-79 1-69 57 5531 13-79 7 6-76 181 57 55-06 14-75 8 7-76 1-93 58 56"28 14-03 8 7-73 2-07 58 56-02 15-01 9 8-73 218 59 57-25 14-27 9 8-69 2-33 59 56-99 15-27 10 9-70 2-42 60 58-22 1452 10 9'66 2'59 60 57-96 15-53 11 10-67 266 61 59-19 1476 11 10-63 2-85 61 58-92 1579 12 1164 290 62 60-16 15-00 12 11-59 311 62 5989 16", 5 13 12-61 3-14 63 61-13 15-24 13 12-56 336 63 60-85 16-31 14 13-58 3-39 64 62-10 15-48 14 13'5 i 3-62 64 61-82 16-56 15 14-55 3-63 65 6307 15-72 15 14-49 3-88 65 6279 16-82 16 15-52 387 64-04 15-97 16 15-45 4-14 66 63-75 17-08 17 16-50 411 67 65-01 16-21 17 16-42 4-40 67 64-72 17-34 18 17-47 435 63 6598 16-45 18 17-39 4-66 68 65 H8 17-60 19 18-44 4'60 69 66-95 16-B9 19 18-35 492 69 6665 17-86 20 19-41 4'84 70 67'92 16-94 20 19-32 518 70 67-61 1812 21 20-38 5-08 71 63-S9 17-18 21 20-28 5-44 71 6858 18-38 22 21-35 5-32 72 69-86 17-42 22 21-25 569 72 69-55 18-o3 23 22'32 5-56 73 70-83 17-66 23 22-22 5-95 73 70-51 18-89 24 23-29 5-81 74 7rso 17-90 24 23-18 6-21 74 71-18 19-15 25 24-26 6-05 75 72-77 18-14 25 24-15 6-47 75 72-44 19-41 26 25-23 6-29 76 73-74 18-39 26 2511 6-73 76 73-41 19-67 27 26-20 653 77 74-71 18-63 27 26-08 699 77 74-38 1993 28 27-17 6-77 78 7568 18-87 28 27-05 7-25 78 75-34 20-19 29 28-14 7-02 79 76-65 19-11 29 28-01 7-51 79 76-31 20-45 30 29-11 7-26 80 77-62 19-35 30 28-98 7-76 80 7727 20-71 31 30-08 7-50 81 78-59 19-60 31 2994 802 81 78-24 20-96 32 31-05 774 82 79-o6 1984 32 30-91 8-28 82 79-21 21-22 33 32-02 7-98 83 80-53 2008 33 31-88 8-54 83 80-17 21-48 34 32-99 8-23 84 81-50 20-32- 34 32-84 8-80 84 81-14 21-74 35 33-96 847 85 82-48 2056 85 33-81 906 85 8210 2200 36 34-93 8'71 86 8345 2081 36 3477 9-32 86 83-07 22-26 37 3590 895 87 8442 21-05 37 3574 9-58 87 84-04 22-52 38 33-87 9-19 88 8539 21-29 38 3671 984 88 851)0 22-78 39 37'84 943 89 86-36 21-53 39 3767 10-09 89 85-97 23-03 40 38'81 9-68 90 8733 21-77 49 88-64 10-35 90 8693 23-29 41 39-78 9-92 91 88-30 22-01 41 3960 10-61 91 87-90 23-55 42 40-75 1016 92 89-27 22-26 42 40-57 1087 92 88-87 23-81 43 41-72 10-40 93 90-24 22-50 43 41-53 11-13 93 89-83 24-07 44 42-69 1064 94 91-21 22-74 44 42-50 11-39 94 90-80 21-33 45 43-6 1069 95 92-18 2298 45 43-47 1165 95 91-76 24-59 48 4163 11-13 96 93-15 2122 46 4 1-43 11-91 96 92-73 2485 47 4560 11-37 97 94-12 2347 47 45-40 12-16 97 9369 25-11 43 46-57 11-61 98 95-09 23-71 48 4636 12-42 98 9466 25-36 49 47-54 11-85 99 9606 2395 49 47-33 12-68 99 95-63 2562 50 4851 12 10 100 9703 24-19 50 48-30 12-94 100 96-60 25-88 E. orW N.orS. E.orW. N.orS. E.orW. N. or S. E.orW. N.orS 76 76 TBAYEESE TABLES. 143 1 3 1 g i\ S'l If ui Si | c | 5- C3 SI -1 jf Si sjj o *-* 5 c -g o 5 c ?! K 5 c 1e c ~ 'ea,3 5 wa 3 KQ s3 w"5 % Q a-S j o-DT- 0-28 51 4902 14-06 1 0-96 0-29 51 48-77 14'91 2 1-92 0-55 52 4999 14-33 2 1-91 0-58 52 4973 15-20 3 2-88 0-83 53 50-95 14-61 3 2-87 o-ss 53 50-68 15-50 4 3-85 1-10 51 51-91 1488 4 3-83 1-17 54 51-64 1579 5 4-Sl 1-38 55 52-87 15-16 5 4"78 1-46 SS 52-60 16-08 6 5-77 1-65 56 53-83 15-44 6 5-74 175 56 53-55 16-37 7 6-73 1-93 57 54-79 15-71 7 6-69 2-05 57 54-51 16-67 8 7-69 2-21 58 55-75 15-99 8 7-65 2-33 58 55-47 10-90 9 865 2-48 59 56-71 16-26 9 8-61 2-63 59 5642 17-25 10 961 2-76 60 57-68 16-54 10 956 292 6) 57-38 17-54 11 10-57 3-03 61 58-64 16-81 11 10-52 3-22 61 53-33 17-83 12 11-54 3-31 62 59-60 17-09 12 11-48 3-51 62 59-29 18-13 13 12-50 3-58 63 6056 17-37 13 12-43 3-80 63 60-25 18-42 14 13-45 3-86 64 61-52 17-04 14 13-39 409 64 61-20 1871 15 14-42 413 65 62-48 17-92 15 14-34 439 65 62-16 19-00 16 15-38 4-41 66 63-44 1819 16 1530 4-68 66 6212 19-30 17 16-34 469 67 64-40 18-47 17 1626 4-97 67 64-07 1959 IS 17-30 4-96 68 6537 18-74 18 17-21 526 68 65-03 19-88 19 18-26 5-24 69 66-33 19-02 19 18-17 553 63 65-98 2017 20 19-23 5-51 70 67-29 19-29 20 1913 5-85 70 6694 2047 21 20-19 5-79 71 65-25 1957 21 20-08 6-14 71 67-90 20-76 22 21-15 6-06 72 69-21 1985 22 21-Ot 6-43 72 68-85 21-05 23 22-11 634 73 70-17 20-12 23 2199 6-72 73 69-81 21-34 24 23-07 6-62 74 71-13 20-40 24 22-95 7-02 74 70-77 21*64 25 24-03 6-89 75 72-09 20-67 25 23-91 7-31 75 7172 2193 26 2499 7-17 76 73-06 20-95 26 24-86 7-60 76 7268 22-22 27 2595 7-44 77 74-02 21-22 27 25-82 7-89 77 7364 22-51 28 26-92 7-72 78 74-98 21-50 28 26-78 8-19 78 7459 22-80 29 27-88 7-99 79 7594 21-78 29 27-73 8-48 79 75-55 23-10 30 28-84 8-27 80 76-90 22-05 30 28-69 8-77 80- 76-50 23-39 81 29-80 8-54 81 77-86 22-33 31 29-65 906 81 77-46 2368 32 30-76 8-82 82 78-82 22-60 32 30-60 9-36 82 7842 23-97 33 31-72 910 83 7978 22-88 33 31-56 9-65 83 79-37 24-27 34 32-68 9-37 84 80-75 23-15 34 3251 994 84 80-33 24-56 35 33-64 965 85 81-71 23-43 35 3.3-47 10-23 85 81-29 24-85 36 34-61 992 86 82-67 2370 36 34-43 10-53 80 82-24 25-14 37 35-57 1020 87 83-63 2398 37 35-38 10-82 87 8320 25-44 38 36-53 10-47 88 84-59 24-26 38 36-34 11-11 83 84-15 2573 39 37-49 10-75 89 85-55 24-53 39 37-30 11-40 89 8511 26-02 40 38-45 11-03 90 86-51 24-81 40 33-25 11-69 90 88-07 26-31 41 39-41 11-30 91 87-47 25-08 41 3921 11-99 91 87-02 26-61 42 40-37 1158 92 88-44 25-36 42 40-16 1228 92 87-98 26-90 43 4133 11 '&> 93 89-40 25-63 43 41-12 1257 93 8894 27-19 44 42-30 12-13 9t 90-36 25-91 44 4208 12-83 94 89-89 2748 45 4326 1240 95 91-32 26-19 45 43-03 13-16 90 90-85 27-78 46 44-22 12 GS 96 9228 26-46 46 43-99 13-45 o; 91-81 28-07 47 45-18 12-95 97 93-24 26-74 47 4495 1374 97 92-76 28-36 48 46-14 1323 98 94-20 27-01 48 45-90 1403 98 93-72 28-65 49 47-10 13-51 99 95-K3 27-29 49 4686 14-33 99 9467 28-94 50 48-06 13-78 100 93-13 2756 50 47-82 1462 100 95-63 29-24 E.orW. N. or S. E.orW. N. or S. E. or W. N.orS. E. or W. N.orS. 7 r 7 3 1 144 TEAVEBSE TABLES. 18 19 9 S 1 %z tn | J on I 8 S 00 I 3 II of 1 3 a S .l sj Iti aj C *j t-f 00 11 J ?! ttJ fc'S WQ OtS 53Q HP MJ fc'S WQ 33 w"3 j 095 031 51 4850 15-76 1 0-95 0-33 51 48-22 16-60 . 2 1-90 0-62 52 49-45 16-07 2 1-89 0-65 52 49-17 16-93 ' 3 2-85 0-93 53 50-41 16-38 3 2-84 0-98 53 50-11 17-26 4 3-80 1-24 54 51-36 16-69 4 378 1-30 54 51-06 17-58 5 4-76 1-55 55 52-31 1700 5 4-73 163 55 52-00 17-91 6 5-71 1-85 56 53-26 17-30 6 5-67 195 56 52-95 18-23 7 6-66 2-16 57 54-21 17-61 7 6-62 2-28 57 53-89 18-56 8 7-61 2-47 58 55-16 17-92 8 7-56 2-60 58 54-84 18-88 9 8-56 278 59 56-11 18-23 9 8-51 293 59 55-79 19-21 10 9-51 3-09 60 57-06 1854 10 9-46 3-26 60 56-73 19-53 11 10-46 3-40 61 58-01 1883 11 10-40 3-58 61 57-68 19-86 12 11-41 371 62 5897 19-16 12 11-35 3-91 62 58-62 20-19 13 12-36 4-02 63 59-92 19-47 13 12-29 423 63 5957 20-51 14 13-31 4-33 64 60-87 19-78 14 13-24 4-56 64 60-51 20-84 15 14-27 4-64 65 61-82 20-09 15 14-18 4-88 65 61-46 21-16 16 15-22 494 66 62-77 20-40 16 15-13 5-21 66 62-40 21-49 17 16-17 525 67 6372 20-70 17 1607 553 67 63-35 21-81 18 17-12 5-56 68 6467 21-01 18 17-02 5-86 68 64-30 22-14 19 18-07 5-87 69 65-62 21-32 19 17-96 6-19 69 6524 22-46 20 1902 6-18 70 66-57 21-63 20 18-91 6-51 70 66-19 2279 21 19-97 6-49 71 67-53 21-94 21 19-86 6-84 71 67-13 23-12 22 20-92 6-80 72 68-48 22-25 22 20-80 716 72 68-08 23-44 23 21-87 7-11 73 6943 22-56 23 21-75 7-49 73 69-02 23-77 24 22-83 7-42 74 70-38 22-87 24 22-69 7-81 74 69-97 24-09 25 23-78 7-73 75 71-33 23-18 25 23-64 8-14 75 70-91 24-42 26 24-73 8-03 76 72-28 23-49 26 24-58 8-46 76 71-86 24-74 27 25-68 8-34 77 73-23 23-79 27 25-53 8-79 77 72-81 25-07 28 26-63 8-65 78 74-18 24-10 28 26-47 9-12 78 73-75 25-39 29 2758 896 79 75-13 24-41 29 27-42 9-44 79 74-70 25-72 30 28-53 9-27 80 76-08 24-72 30 28-37 9-77 80 75-64 26-C5 31 29-48 9-58 81 77-04 25-03 31 29-31 1009 81 76-59 26-37 32 30-43 9-89 82 77-99 2534 32 30-26 10-42 82 77-53 26-70 33 31-38 10-20 83 78-94 2565 33 31-20 10-74 83 78-48 27-02 34 32-34 10-51 84 79-89 2596 34 32-15 11-07 84 79-42 27-35 35 33-29 10-82 85 80-84 2627 35 33-09 11-39 85 80-37 27-67 36 34-24 11-12 86 81-79 2658 36 3404 11-72 86 81-31 28-00 37 35-19 11-43 87 82-74 26-88 37 34-98 12-05 87 82-26 28-32 38 36-14 11-74 88 8369 27-19 38 3593 12-37 88 83-21 28-65 39 37-09 1205 89 84-64 27-50 39 3687 12-70 89 84-15 28-98 40 3804 12-36 90 85-60 27-81 40 37-82 13-02 90 85-10 29-30 41 3899 12-67 91 86-55 2812 41 38-77 13-35 91 86-04 29-63 42 39-94 1298 92 87-50 28-43 42 39-71 1367 92 8699 29-95 43 40-90 13-29 93 88-45 28-74 43 40-66 14-00 93 87-93 30-28 44 41-85 1360 94 89-40 29-05 44 41-60 14-32 94 88-88 30-60 45 42-80 1391 95 90-35 29-36 45 42-55 1465 95 89-82 30-93 46 4375 1421 96 91-30 2967 46 43-49 14-98 96 90-77 31-25 47 4470 14-52 97 92-25 29-97 47 44-44 1530 97 91-72 31-58 48 45-65 14-83 98 93-20 30-28 48 4538 15-63 98 92-66 31-91 49 46-60 15-14 99 94-15 30-59 49 46-33 15-95 99 9361 32-23 50 47-55 1545 100 95-11 30-90 50 47-28 16-28 100 9455 32-56 E. orW. N. orS. E.orW. N. orS. E. or W. N. or S. E. or W. N.orS. 72 71 1 TliAVEKSE TABLES. 145 20 21 >* ril *1 sa | | go *i i g>! ! $i E "tc s- 5 II sM A 5 So ci 8 03 &Q a S | wo II fci HQ i 0-93 0-37 61 47-29 19-10 1 0*92 0-39 51 46*95 19'93 2 1-85 0-75 52 48-21 19*48 2 1-84 0-78 52 47*87 20*32 3 2-78 1'12 53 49-14 19*85 3 2*76 1-17 53 48*79 20*17 4 3-71 1-50 54 50-07 20-23 4 3-68 1-56 54 49*71 21'10 5 4-64 1-87 55 51-00 20-60 5 4-60 1-95 55 50*63 21*49 6 5-56 2-25 56 51-92 20-98 6 5-52 2-34 56 51-55 21*88 7 6-49 2-62 57 52-85 21-35 7 6-44 2-74 57 52*47 22*27 8 7-42 3-00 58 53-78 21-73 8 7-36 3-13 58 53-39 22*66 9 8-34 3-37 59 54-70 22-10 9 8-28 3-52 59 54-31 23-05 10 9-27 3-75 60 55-63 22-48 10 9-21 3-91 60 55*23 23-44 11 10-20 4-12 61 56-56 22-85 11 10-13 4-30 61 56*15 23 '83 12 11-13 4-50 62 57-49 23-23 12 11-05 4-69 62 57*07 24-23 13 12-05 4-87 63 58-41 23-60 13 11-97 5-08 63 57*99 24-62 14 12-98 5-24 64 59-34 23-97 14 12-89 5-47 64 58-91 25'01 15 13-91 5-62 65 60-27 24-35 15 13-81 5-86 65 59-83 25-40 16 14*83 5-99 66 61-19 24-72 16 14-73 6-25 66 60-75 25-79 17 15-76 6-37 67 62-12 25-10 17 15-65 6-64 67 61-67 26-18 18 16-69 6-74 68 63-05 25-47 18 16-57 7-03 68 62-59 26-57 19 17-62 7-12 69 63-98 25-85 19 17-49 7-42 69 63-51 26-96 20 18-54 7-49 70 64-90 26-22 20 18-41 7-81 70 64-44 27-35 21 19-47 7'87 71 65-83 26-60 21 19-33 8'21 71 65-36 27-74 22 20-40 8-24 72 66-76 26-97 22 20-25 8-60 72 66-28 28-13 23 21-33 8-62 73 67-68 27-35 23 21-17 8-99 73 67-20 28-52 24 22-25 8-99 74 68-61 27-72 24 22-09 9-38 74 68-12 28'91 23 23-18 9-37 75 69-54 28-10 25 23-01 9-77 75 69-04 29-30 26 24-11 9-74 76 70-47 28-47 26 23-93 10-16 76 69-93 29-70 27 25-03 10-11 77 71-39 28-84 27 24-85 10-55 77 70-88 30-09 28 25-96 10-49 78 72-32 29-22 28 25-77 10-94 78 71-80 30-48 29 26-89 10-86 79 73-25 29-59 29 26-69 11-33 79 72-72 30-87 30 27-82 11-24 80 74-17 29-97 30 27-62 11-72 80 73-64 31-26 31 28-74 11-61 81 75-10 30-34 31 28-54 12-11 81 74-56 31-65 32 29-67 11-99 82 76-03 30-72 32 29-46 12-50 82 75-48 32-04 33 30-60 12-36 83 76-96 31-09 33 30-38 12-89 83 76-40 32-43 34 31-52 12*74 84 77-88 31-47 34 31-30 13-28 84 77-32 32-82 35 32-45 13-11 85 78-81 31-84 35 32-22 13-68 85 78-24 33-21 36 33-38 13-49 86 79-74 32-22 36 33-14 14-07 86 79-16 33-60 37 34-31 13-86 87 80-66 32*59 37 34-06 14-46 87 80-08 33-99 38 35-23 14-24 88 81-5) 32*97 38 34-98 14-85 88 81-00 34-38 89 36-16 14-61 89 82-52 33-34 39 35-90 15-24 89 81-92 34-78 40 37-09 14-98 90 83-45 33-71 40 36-82 15-63 90 82-85 35-17 41 38-01 15-36 91 84-37 34-09 41 37*74 16-02 91 83-77 35-56 42 38-94 15-73 92 85-30 34-46 42 38*66 16-41 92 84-69 35-95 43 39-87 93 86-23 34-84 43 39*58 16-80 93 85-61 36-34 44 40-80 16-48 94 87-16 35-21 44 40-50 17-19 94 86-53 36-73 45 41-72 16-86 , 95 88-03 35-59 45 41-42 17-58 95 87-45 37-12 46 42-65 17-23 96 89-01 35-96 46 42-34 17-97 96 88-37 37-51 47 43-58 17-61 97 89-94 36*84 47 43-26 18-36 97 89-29 37-90 48 44-50 17-98 98 90-83 36*71 48 44-18 18-76 98 90-21 38-29 49 45-43 18-36 99 91*79 37-09 49 45-10 19-15 99 91-13 38-68 50 46-36 18-73 100 92-72 37-46 50 46-03 19-54 100 9"-05 39-07 E. or W. N.or S. E.orW. N. or S. E.or W. N.orS. iE.orW. N. or S. 1 68 67 TEAYEltSE TABLES. 147 24 25 vl i cj 1 jj j *s t*J ^P,3 | ft II o 8* 3* p oo o ^ -a a o 5 si it *| s| fcS K s . II fc5 3 JsS WQ 1 0-91 0-41 51 46-59 20-74 i 0-91 0-42 51 46-22 21-55 2 1-83 0-81 52 47'50 21-15 2 1-81 0-85 52 47-13 21-98 3 2-74 1-22 53 48-42 21-56 3 2-72 1-27 53 48-04 22-40 4 3-65 1-63 54 49-33 21-96 4 3-63 1-69 54 48-94 22-82 5 4-57 2-03 55- 50-25 22-37 5 4-53 2-11 55 49-85 23-24 6 5-48 2-44 56 51-16 22-78 6 5-44 2-54 56 50-75 23-67 7 6-39 2-85 57 52-07 23-18 7 6-34 2-96 57 51-66 24-09 8. 7-31 3-25 58 52-99 23-59 8 7-25 3-38 58 52-57 24-51 9 8-22 3-66 59 53-90 24-00 9 8-16 3-80 59 53-47 24-93 10 9-14 4-07 60 54-81 24-40 10 9-06 4-23 60 54-38 25-36 11 10-05 4-47 61 55-73 24-81 11 9-97 4-65 61 55-28 25-78 12 10-96 4-88 62 56-64 25-22 12 10-88 5-07 62 56-19 26-20 13 11-88 5-29 63 57-55 25-62 13 11-78 5-49 63 57-10 26-62 14 12-79 5-69 64 58-47 26-03 14 12'69 5-92 64 58-00 27-05 15 13-70 6-10 65 59-38 26-44 15 13-59 6-34 65 58-91 27-47 16 14-62 6-51 66 60-29 26-84 16 14-50 6-76 66 59-82 27-89 17 15-53 6-91 67 61-21 27-25 17 15-41 7-18 67 60-72 28-32 18 16-44 7-32 68 62-12 27-66 18 16-31 7-61 68 61-63 28-74 19 17-36 7-73 69 63-03 28-06 19 17-22 8-03 69 62-54 29-16 20 18-27 8-13 70 63-95 28-47 20 18-13 8-45 70 63-44 29'60 21 19-18 8-54 71 64-86 28-88 21 19-03 8'87 71 64-35 30-01 22 20-10 8-95 72 65-78 29'28 22 19-94 9-30 72 65-25 30-43 23 21-01 9-35 73 66-69 29-69 23 20-85 9-72 73 66-16 30-85 24 21-93 9-76 74 67-60 30-10 24 21-75 10-14 74 67-07 31-27 25 22-84 10-17 75 68-52 30-50 25 22-66 10-57 75 67-97 31-70 26 23-75 10-58 76 69-43 30-91 26 23-56 10-99 76 68-88 32-12 .27 24-67 10-98 77 70-34 31-32 27 24-47 11-41 77 69-79 32-54 28 25-58 11-39 78 71-26 31-72 28 25-38 11-83 78 70-69 32-96 29 26-49 11-80 79 72-17 32-13 29 26-28 12-26 79 71-60 33-39 80 27-41 12-20 80 73-08 32-54 30 27-19 12-68 80 72-50 33-81 31 28-32 12-61 81 74-00 32-94 31 28-10 13-10 81 73-41 34-23 32 29-23 13-02 82 74-91 33-35 32 29-00 13-62 82 74-32 34-65 33 30-15 13-42 83 75-82 33-76 33 29-91 13-95 83 75-22 35-08 34 31-06 13-83 84 76-74 34-16 34 30-81 14-37 84 76-13 35-50 35 31-97 14-24 85 77-65 34-57 35 31-72 14-79 85 77-04 35-92 M 32-89 14-64 86 78-56 34-98 36 32-63 15-21 86 77-94 36-35 37 33-80 15-05 87 79-48 35-38 37 33-53 15-64 87 78-85 36-77 38 34-71 15-46 88 80-39 35-79 38 34-44 16-06 88 79-76 37-19 39 35-63 15-86 89 81-31 36-20 39 35-35 16-48 89 80-66 37-61 40 36'54 16-27 90 82-22 36-60 40 36-25 26-90 90 81-57 38-04 41 37-46 16-68 91 83-13 37-01 41 37-16 17-33 91 82-47 38-46 42 38-37 17-08 92 84-05 37-42 42 38-06 17-75 92 83-38 38-88 43 39-28 17-49 93 84-96 37-82 43 38-97 18-17 93 84-29 39-30 44 40-20 17-90 94 85-87 38-23 44 39-88 18-60 91 85-19 39-73 45 41-11 18-30 95 86-79 38-64 45 40-78 19-02 95 86-10 40-15 46 42-02 18-71 96 87 70 39-04 46 41-69 19-44 96 87-01 40-57 47 42-Q4 19-12 97 88-61 39-45 47 42-60 19-86 97 87-91 40-99 48 43-85 19-52 98 89-53 39-86 48 43-50 20-29 98 88-82 41-42 49 44-76 19-93 99 90-44 40-26 49 44-41 20-71 99 89-72 41-84 50 45-68 20-34 100 91-35 40-67 50 45-32 21-13 100 90-63 42-26 E.orW. N. or S. E.orW. N. or S. E.orW N.or S. E. or W. N. or S. 66 65 148 TEAVEESE TABLES. 26 27 If "1 isf It ti l*| *C "M dj is| *' ii ?1 i "to ^ tfl 4 a "M ^ 03 3 s tc ^ "02 5 C o ~ C " MJ fc'S WQ MJ Q HQ MJ SZJQ HQ fflvJ Q HQ i 0-90 0-44 51 45-84 22-36 1 0-89 0-45 51 45-44 23-15 2 1-80 0-88 52 46-74 22-80 2 1-78 0-91 52 46-33 23-61 3 2-70 1-32 53 47-64 23-23 3 2-67 1-36 53 47"22 24-06 4 3-60 1-75 54 48-53 23-67 4 3-56 1-82 54 48'U 24-52 5 4-49 2-19 55 49-43 24-11 5 4-46 ' 2"27 55 49-01 24-97 6 5-39 2-63 56 50-33 24-55 6 5-35 2-72 56 49-90 25-42 7 6-29 3'07 57 51-23 24-99 7 6-24 3-18 57 50-79 25-88 8 7-19 3-50 58 52-13 25-43 8 7-13 3-63 58 51-68 26-33 9 8-09 3-95 59 53-03 25-86 9 8-02 4-09 59 52-57 2679 10 8-99 4-38 60 5393 26-30 10 8-91 I 4-54 60 53-46 27-24 11 9-89 4-82 61 54-83 26-74 11 9-80 4-99 61 54-35 27-69 12 10-79 5-26 62 55-73 27-18 12 10-69 545 62 55-24 28-15 13 11-68 5-70 63 56-62 27-62 13 11-58 5-90 63 56-13 28-60 14 12-58 6-14 64 57-52 28-06 14 12-47 6-36 64 57-02 29-06 15 13-48 6-58 65 58-42 28-49 15 13-37 6-81 65 57-92 29-51 16 14-38 7-01 66 59-32 28-93 16 14-26 7-23 66 58-81 29-96 17 15-28 7-45 67 60-22 29-37 17 15-15 7-72 67 59-70 30-42 18 16-18 7-89 68 61-12 29-81 18 16-04 8-17 68 60-59 30-87 19 17-08 8-33 69 62-02 30-25 19 16-93 8-63 69 61-48 31-33 20 17-98 8-77 70 62-92 30-69 20 17-82 9-08 70 62-37 31-78 21 18-87 9-21 71 63-81 31-12 21 18-71 9-53 71 63-26 32-23 22 19-77 9-64 72 64-71 31-56 22 19-60 9-99 72 64-15 32-69 23 20-67 10-08 73 65-61 32-00 23 20'49 10-44 73 65-04 33-14 24 21-57 10-52 74 66-51 32-44 24 21-38 10-90 74 65-93 33-60 25 22-47 10-96 75 67-41 32-88 25 22-28 11-35 75 66-83 34-05 23-37 11-40 76 68-31 33-32 26 23-17 11-80 76 67-72 34-50 27 24-27 11-84 77 69-21 33-75 27 24-06 12-26 77 68-61 34-96 28 25-17 12-27 78 70-11 34-19 28 24-95 12-71 78 69-50 35-41 29 26-06 12-71 79 71-00 34-63 29 25'84 13-17 79 70-39 35-87 30 26-96 13-15 80 71-90 35-07 30 26-73 13-62 80 71-28 36-32 31 27-86 13-59 81 72-80 35-51 31 27-63 14-07 81 72-17 36-77 32 28-76 14-03 82 73-70 35-95 32 28-51 14-53 82 73-06 37-23 33 29-66 14-47 83 74-60 36-38 33 29-40 14-98 83 73-95 37-68 34 30-56 14-90 84 75-50 36-82 34 30-29 15-44 84 74-84 38-14 35 31-46 1634 85 76-40 37-26 35 31-19 15-89 85 75-74 38-59 36 32-36 15-78 86 77-30 37-70 36 32-03 16-34 86 7663 39-04 37 33-26 1622 87 78-19 38-14 37 3297 16-80 87 77-52 39-50 38 34-15 16-66 88 79-09 38-58 38 33-86 17-25 88 78-41 39-95 39 35-05 1710 89 79-99 39-02 39 3475 17-71 89 79-30 40-41 40 3595 17-53 90 80-89 39-45 40 35-64 18-16 90 80-19 40-86 41 36-85 17-97 91 81-79 39-89 41 36-53 18-61 91 81-08 41-31 42 37-75 18-41 92 82-69 40-33 42 37-42 19-07 92 81-97 41-77 43 38-65 18-85 93 63-59 40-77 43 38-31 19-52 93 82-86 42-22 44 3y-55 19-29 94 84-49 41-21 44 39-20 1998 94 83-75 42-68 45 40-45 19-73 95 85-39 41-65 45 40-10 2043 95 84-65 43-13 46 41-34 20-17 96 86-28 42-08 46 40-99 20-88 93 85-54 43-58 47 42-24 20-60 97 87-18 42-52 47 41-88 21-34 97 86-43 44-04 48 43-14 21-04 98 88-08 42-96 48 42-77 21-79 98 87-32 44-49 49 44-04 21-48 99 88-98 43-40 49 43-66 22-25 99 88-21 44-95 50 44-94 21-92 100 89-88 43-84 50 44-55 22-70 100 89-10 45-40 IE.OVW. N. orS. E.orW. N.orS. E.orW. N. or S. E.orW. N. or S. 64 63 TRAYERSE TABLES. 149 28 | 29 9 g>i i *| aJ 02 | ft be? c ~~ 0*1 ft iC X rfl ft fH ci B B] f If fe-3 "5 *l P o *J "^ br, ji s ~ a ts *| 3 E'Q w5 3 KiS H*S 35^ fc5 w"3 ^ * a HQ 1 0-88 0-47 51 45-03 23-94 1 0-87 0-48 51 44-G 1 24-73 2 1-77 0-94 52 45-91 24-41 2 1-75 0-97 52 45-48 25-21 3 2-65 1-41 53 46-80 24-88 3 2-62 1-45 53 46-35 25-69 4 3-53 1-88 54 47-68 2535 4 3-50 1-94 54 47-23 28-18 5 4-41 2-35 55 48-56 25-82 5 4-37 2-42 rt 48-10 26-66 6 5-30 2-82 56 49-45 28-29 6 5-25 291 56 48-98 27-15 7 6-18 3-29 57 50-33 26-76 7 6-12 3-39 57 49-85 27-63 8 7-06 3-76 58 51-21 27-23 8 7-00 3-88 58 50-73 28-12 9 7-95 4-23 59 52-09 27-70 9 7-87 4-36 59 51-60 28-60 10 8-83 4-69 60 52-98 28-17 10 8-75 485 60 52-48 29-09 11 9-71 5-16 61 53-86 28-64 11 9-62 5-33 61 53-35 29-57 12 1060 563 62 54-76 29-11 12 10-50 5-82 62 54-23 30-06 13 11-43 6-10 63 55-63 29-58 13 11-37 6-30 63 55-10 30-54 14 12-86 6-57 64 56-51 30-05 14 12-24 679 64 55-93 31-03 15 13-24 7 '04 65 57-39 30-52 15 13-12 7-27 65 56-85 31-51 16 14-13 7-51 66 58-27 30-99 16 13-99 7-76 6 ( 3 57-72 32-00 17 15-01 7-98 67 59-16 31 45 17 14-87 8-24 67 5860 32-48 18 15-89 8--15 68 60-04 31-92 18 15-74 873 68 59-47 32-97 19 16-78 8-92 69 60-92 3239 19 16-62 921 69 60-35 33-45 20 17-66 9-39 70 61-81 32-86 20 17'49 970 70 6122 3394 21 18-54 9-86 71 62-69 3333 21 18-37 10-13 71 62-10 34-42 22 19-42 10-33 72 63-57 33-80 22 19-24 10-67 72 62-97 34-91 23 20-31 10-80 73 6446 34-27 23 212 11-15 73 63-85 3539 24 21-19 11-27 74 65-34 34-74 24 20-99 11-64 74 6472 35-88 25 22-07 11-74 75 66-22 35-21 25 21-87 12-12 75 6560 36-36 2G 22-96 12-21 76 67-10 3568 26 22-74 12-61 76 66-47 36-85 27 23-84 12-68 77 67-93 36-15 27 23-61 13-09 77 67-35 37-33 28 24-72 1315 78 6887 3662 28 2449 13-57 78 68-22 37-82 29 25-61 1361 79 6975 37d9 29 25-36 14-06 79 69-09 38-30 30 26-49 14-08 80 70-64 37-56 30 26-^4 14-54 80 69-97 38-78 31 27-37 14-55 81 71-52 38-03 31 27-11 15-03 81 70-84 39-27 32 28-25 15-02 82 72-40 38-50 32 27-99 15-51 82 7172 39-75 33 29-14 15-49 83 73-28 38-97 33 28-86 1600 83 72-59 40-24 34 30-02 15-96 84 74-17 39-44 34 29-74 16-48 84 73-47 40-72 35 30-90 16-43 85 75-05 39-91 35 30-61 16-97 85 74-34 41-21 36 31-79 1690 86 75-93 4037 36 31-49 17-45 86 75-22 41-69 37 32-67 17-37 87 76-82 40-84 37 32-36 1794 87 76-09 42-18 38 33-55 17-84 88 77-70 41-31 38 33-23 18-42 88 76-97 4266 39 34-43 1831 89 78-58 41-78 39 34-11 1891 89 77-84 43-15 40 35-32 18-78 90 79-47 42-25 40 3498 19-39 90 . 78-72 43-63 41 36-20 19-25 91 RO-35 42-72 41 3586 19-88 91 79-59 44-12 42 37-08 1972 H2 81-23 4319 42 36-T3 20-36 92 80-47 44-60 43 3797 20-19 93 82-11 43-66 43 37-61 2085 93 81-34 45-02 44 3885 2o-66 91 83 CO 44-13 44 3S-48 21-33 94 82-21 45-57 45 3973 2113 95 83-88 44-60 45 39-36 21-82 95 83-09 46-06 46 40-62 21-60 96 84-76 45-07 46 40-24 22-30 9*5 83-96 46-54 47 41-50 22-i7 97 85-65 45-54 47 4111 2279 97 84-84 47-03 48 42-38 2253 98 8653 46-01 48 41-98 23-27 98 85-71 47-51 49 43-26 2:Kn 99 87-41 46-48 49 42-86 23-76 99 86-59 48-00 60 44-15 23-47 100 88-29 4695 50 43-73 2424 ICO 87-46 48-48 E.orW. N.orS. E.orW. N. or S. E. or W. N. or S. E. or W.j N.orS. 62 61 150 TEAVEESE TABLES, 30 31 CM y 1 '1 c -5 fcQ E. or W. Distance. gf S3 ** .S WQ 11 fcQ WQ ! 0-87 0-50 51 44-17 25-60 1 0-86 0-52 51 43-72 26-27 2 1-73 1-00 52 45-03 26-00 2 1-71 1-03 52 44-57 26-78 3 2-60 1'50 53 45-90 26-50 3 2-57 1-55 53 45-43 27-30 4 3-46 2-00 54 46-77 27-00 4 3-43 2-06 54 46-29 27-81 5 4-33 2-50 55 47-63 27-50 5 4-29 2-58 55 47-14 28-33 6 5-20 3-00 56 48-50 28-00 6 5-14 3-09 56 48-00 28-84 7 6-06 3-50 57 49-36 28-50 7 6-00 3-61 57 48-86 29-36 8 6-93 4-00 58 50-23 29-00 8 6-88 4-12 58 49-72 29-87 9 7-79 4-50 59 51-10 29-50 9 7-71 4-64 59 50-57 30-39 10 8-66 5-00 60 51-96 30-00 10 8-57 5-15 60 51-43 30-90 11 9-53 5-50 61 52-83 30-50 11 9-43 5-67 61 52-29 31-42 12 10-39 6-00 62 53-69 Sl'OO 12 10-29 6-18 62 53-14 31-93 13 11-26 6-50 63 54-56 31-50 13 11-14 6-70 63 54'CO 32-45 14 12-12 7-00 64 55-43 32-00 14 12-00 7-21 64 54-86 32-96 15 12-99 7-50 65 56-29 32-50 15 12-86 7-73 65 55-72 33-48 16 13-86 8-00 66 57-16 33-00 16 13-71 8-24 66 56-57 33-99 17 14-72 8-50 67 58-02 33-50 17 14-57 8-76 67 57-43 34-51 18 15-59 9-00 68 58-89 34-00 18 15-43 9-27 68 58-29 35-02 19 16-45 9-50 69 59-76 34-50 19 16-29 9-79 69 59-14 35-54 20 17-32 10-00 70 60-62 35-00 20 17-14 10-30 70 60-00 36-05 21 18-19 10-50 71 61-49 35-50 21 18-00 10-82 71 60-86 - 36-57 22 19-05 11-00 72 62-35 36-00 22 18-86 11-33 72 61-72 37-08 23 19-92 11-50 73 63-22 36-50 23 19-71 11-85 73 62-57 37-60 24 20-78 12-00 74 64-09 37-00 24 20-58 12-36 74 63-43 38-11 25 21-65 12-50 75 64-95 37-50 25 21-43 12-88 75 64-29 38-63 26 22-52 13-00 76 65-82 38-00 26 22-29 13-39 76 65-14 39-14 27 23-38 13-50 77 66-68 38-50 27 23-14 13-91 77 66-00 39-66 28 24-25 14-00 78 67-55 39-00 28 24-00 14-42 78 66-86 40-17 29 25-11 14-50 79 68-42 39-50 29 24-86 14-94 79 67-72 40-69 30 25-98 15-00 80 69-28 40-00 30 25-72 15-45 80 68-57 41-20 31 26-85 15-50 81 70-15 40-50 31 26-57 15-97 81 69-43 41-72 32 27-71 16-00 82 71-01 41-00 32 27-43 16-48 82 70-29 42-23 33 28-58 16-50 83 71-88 41-50 33 28-29 17-00 83 71-15 42-75 34 29-44 17-00 84 72-75 42-00 34 29-14 17-51 84 72-00 43-26 35 30-31 17-50 85 73-61 42-50 35 30-00 18-03 85 72-86 43-78 36 31-18 18-00 86 74-43 43-00 36 30-86 18-54 86 73-72 44-29 37 32-04 18-50 87 75-35 43-50 37 31-72 19-06 87 74*57 44-81 38 32-91 19-00 88 76-21 44-00 38 32-57 19-57 88 7543 45-32 39 33-78 19-50 89 77-08 44-50 39 33-43 20-09 89 76-29 45-84 40 34-61 20-00 90 77-94 45-00 40 34-29 20-60 90 77-15 46-35 41 35-51 20-50 91 78-81 45-50 41 35-14 21-12 91 78-00 46-87 42 36'37 21-00 92 79-68 46-00 42 36-00 2163 92 78-86 47-38 43 37-24 21-50 93 80-54 46-50 43 36-86 22-15 93 7972 47-90 44 38-11 22-00 94 81-41 47-00 44 37-72 2266 94 80-57 48-41 45 38-97 22-50 95 82-27 47-50 45 38-57 23-18 95 81-43 48-93 48 39-84 23-00 96 83-14 48-00 46 39-43 23-69 96 82-29 49-44 47 40-70 23-50 97 84-00 48-50 47 40-29 24-21 97 83-15 49-96 48 41-57 24-00 98 84-87 49-00 48 41 14 24-72 98 84-00 50-47 49 42-44 24-50 99 85-74 49-50 49 42-00 25-24 99 84-86 50-99 50 43-30 25-00 100 86-60 60-00 50 42-86 25-75 00 86-72 51-50 E.orW. N.orS. E.orW. N. or S. E.or W.I N.or S. iE.orW. N. or S. 60 59 TBAYEKSE TABLES. 151 32 33 ri 02 | *f = J2 ail *i 11 *l *i i?! n| f i= r - - 93 o -*- 1 si Z t>D ss a sl s| s| sf C be * c g| o| 33 fcS piS 3 fcS w*5 IJ &3 W"Q ?-i 3 P * """ ^ic t-f flS c3 3 P o S O 02 i 30 O "^ 5 s O * O "^ g = .2 O "g^ sj WQ 3 S5Q a 5 O; i, zo s 11 1 f4 M F3Q 1 0-81 0'59 51 4T26 29-98 1 0-80 0-60 61 40-73 30-69 2 1-62 1-18 52 42-07 30-57 2 1-60 1-20 52 41-53 31-29 3 2-43 1-76 53 42-88 31-15 3 2-40 1-81 53 42-33 31-90 4 3-24 2-35 54 43-69 31-74 4 3-19 2-41 54 43-13 32-50 5 4-05 2-94 55 44-50 3-2-33 5 3-99 3-01 55 43-93 33-10 6 4-85 3-53 56 45-31 32-92 6 4-79 3-61 56 44-72 33-70 7 5-66 4-12 57 46-11 33-50 7 5-59 4-21 57 45-52 34-30 8 6-47 4-70 58 46-92 34-09 8 6-39 4-81 58 46-32 34-90 9 7-28 5"29 59 47-73 34-68 9 7-19 5-42 59 47-12 35-51 10 8-09 5-88 60 48-54 35-27 10 7-99 6-02 60 47-92 36-11 11 8-90 6-47 61 49-35 35-86 11 8-79 6-62 61 48-72 36-71 12 9-71 7-05 62 50-16 36-44 12 9-58 7-22 62 49-52 37-31 13 10-52 7-64 63 50-97 37-03 13 10-38 7-82 63 50-31 37-91 14 11-33 8-23 64 51-78 37-62 14 11-18 8-43 64 51-11 38-52 15 12-14 8-82 65 52-59 38-21 15 11-98 9-03 65 51-91 39-12 16 12-94 9-40 66 53-40 38-79 16 12-78 9-63 66 52-71 39-72 17 13-75 9-99 67 54-20 39-38 17 13-58 10-23 67 53-51 40-32" 18 14-56 10-58 68 55-01 39-97 18 14-38 10-83 68 54-31 40-92 19 15-37 11-17 69 55-82 40-56 19 15-17 11-43 69 55-11 4r52 20 16-18 11-76 70 5ti-63 41-14 20 15-97 12-04 70 55-90 42-13 21 16-99 12-34 71 57-44 41-73 21 16-77 12-64 71 56-70 42-73 22 17-80 12-93 72 58-25 42-32 22 17-57 13-24 72 57-50 43-33 23 18-61 13-62 73 59-06 42-91 23 18-37 13-84 73 58-30 43-93 24 19-42 14-11 74 59-87 43-50 24 19-17 14-44 74 69-10 44-53 25 20-23 14-69 75 44-08 25 19-97 15-05 75 59-90 45-14 26 21-03 15-28 76 61-49 44-67 26 20-76 15-65 76 60-70 45-74 27 21-84 15-87 77 62"29 45-26 27 21-56 16-25 77 61-50 46-34 28 22-65 16-46 78 63-10 45-85 28 22-36 16-85 78 62-29 46-94 29 23-4(3 17-05 79 63-91 46-44 29 23-16 17-45 79 63-09 47-54 30 24-27 17-63 80 64-72 47-02 30 23-96 18-05 80 63-89 48-14 31 25-08 18-22 81 65-53 47-61 31 24-76 18-66 81 64-69 48-75 32 25-89 18-81 82 66-34 48-20 32 25-56 19-26 82 65-49 49-35 33 26-70 19-40 83 67-15 48-79 33 26-36 19-86 83 66-29 49-95 34 27-51 19-98 84 67-96 49-37 34 27-15 20-46 81 67-09 60-55 35 28-32 20-57 85 68-77 49-96 35 27-95 21-06 85 67-83 51-15 36 29-12 21-16 86 69-58 50-55 36 28-75 21-67 86 68-68 51-76 37 29-93 21-75 87 70-38 51-14 37 29-55 22-27 87 69-48 52-36 38 30-74 22-34 88 71-19 51-73 38 30-35 22-87 88 70-28 52-96 89 31-55 22 -9 i 89 72-00 52-31 39 31-15 23-47 89 71-08 53-56 40 32-36 23-51 90 72-81 52-90 40 31-95 24-07 90 71-88 54-16 41 33-17 24-10 91 73-62 53-49 41 32-74 24-67 91 72-68 54-76 42 33-98 24-69 92 74-43 54-08 42 33-54 25-28 92 73-47 55-37 43 34-79 25-VJ7 93 75-24 64-66 43 34-34 25-88 93 74-27 55-97 44 35-HO 25-86 94 76-05 65-25 44 35-14 26-48 94 75-07 56-57 45 36-41 26-45 95 76-36 55-84 45 35-94 27-08 95 75-87 57-17 40 37-21 27-04 96 77-67 56-43 46 36-74 27-68 96 76-67 57-77 47 38-02 27-63 97 78-47 57-02 47 37-54 28-29 97 77-47 58-38 48 38-83 28-21 98 79"28 57-60 48 38-33 28-89 98 78-27 58-98 49 39-64 28-80 99 80M.9 58-19 49 39-13 29-49 99 79-07 59-58 60 40-45 29-39 100 80-90 68-78 50 39-93 30-09 100 79-86 60-18 E.or W N.orS E.or W N.orS E.or W N.orS E.orW N. or S 54 53 H 3 154 TBAYERSE TABLES. 38 39 hn c ^ 02 H ij "I 1 il 05 f rj 02 *l * 5' o *j g S| H Z 60 3! 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SJC ~ s| J fcS wa ^ fc"3 wS S Q HQ j 5 mo 1 0-79 0-62 51 40-19 31-40 i 0-78 0-63 51 39-63 32-09 2 1-58 1-23 52 40-98 32-01 2 1-55 1-26 52 40-41 32-72 3 2-36 1-85 53 41-76 3263 3 2-33 1-89 53 41-19 33-35 4 3-15 2-46 54 42-55 S3 25 4 3-11 2-52 54 41-97 3398 5 394 3-08 55 43-34 33-86 5 3-89 3-15 55 42-74 34-61 6 4-73 3-69 56 44-13 34-48 6 4-66 3-78 56 43-52 35-24 7 5-52 4-31 57 44-92 35-09 7 5-44 4-41 67 44-30 35-87 8 6-30 4-93 58 4570 35-71 8 6-22 5-03 58 45-07 36-50 9 7-09 5-54 59 46-49 36-32 9 6-99 5-66 59 45-85 3713 10 7-88 6-16 60 47-28 36-94 10 7-77 629 60 46-63 37-76 11 8-67 6-77 61 48-07 37-56 11 8-55 6-92 61 47-41 38-39 12 9-46 7-39 62 48-86 38-17 12 9-33 7-55 62 48-18 39-02 13 10-24 8-00 63 49-64 38-79 13 10-10 8-18 63 48-96 3965 14 11-03 8-62 64 50-43 39-40 14 10-88 8-81 64 49-74 40-28 15 11-82 9-23 65 51-22 40-02 15 11-66 9-44 65 50-51 40-91 16 12-61 9-85 66 52-01 4063 16 12-43 1007 66 51-29 41-53 17 13-40 10-47 67 52-80 4125 17 13-21 10-70 67 5207 4216 18 14-18 11-08 68 53-68 41-86 18 13-99 1133 68 52-85 42-79 19 14-97 11-70 69 54-37 42-48 19 14-77 1196 69 53-62 43-42 20 15-76 12-31 70 5516 43-10 20 15-54 12-59 70 54-40 44-05 21 16-55 12-93 71 55-95 4371 21 16-32 13-22 71 55-18 44-68 22 17-34 1354 72 56-74 4433 22 17-10 13-84 72 55-95 45-31 23 18-12 14-16 73 57-52 44-94 23 1787 14-47 73 56-73 45-94 24 18-91 14-78 74 58-31 45-56 24 18-65 15-10 74 57-51 4657 25 1970 15-39 75 59-10 46-17 25 19-43 15-73 75 58 29 47-20 26 20-49 16-01 76 59-89 46-79 26 20-21 16-36 76 5906 47-83 27 21-28 16-62 77 60-68 47-41 27 20-98 1699 77 5984 48-46 28 22-06 1724 78 61-46 48-02 28 2176 17-62 78 60-62 49-09 29 22-85 17-85 79 62-25 48-64 29 22-54 18-25 79 61-39 49-72 30 23-64 18-47 80 63-04 49-25 30 23-31 18-88 80 62-17 50-34 31 24-43 19-09 81 63-83 49-87 31 24-09 19-51 81 62-95 50-97 32 2522 19-70 82 64-62 50-48 32 24-87 20-14 82 63-73 51-60 33 2600 20-32 83 65-40 51-10 33 25-65 20-77 83 64-50 52-23 34 26-79 20-93 84 66-19 51-72 34 2642 21-40 84 65-28 52-86 35 27-58 21-55 85 66-98 52-33 35 27-20 22-03 85 66-06 5349 36 28-37 2216 86 67-77 52-95 36 27-93 22-66 86 66-83 54-12 37 29-13 22-78 87 6856 53-56 37 28-75 23-28 87 67-61 54-75 38 29-94 23-40 88 6934 54-18 38 29-53 23-91 88 68-39 55-38 39 30-73 2401 89 70-13 54-79 39 30-31 24-54 89 69-17 56-01 40 31-52 24-63 90 70-92 5541 40 31-09 25-17 90 69-94 56-64 41 32-31 25-24 91 71-71 56-03 41 3186 25-80 91 70-72 57-27 42 33-10 25-86 92 72-50 56-64 42 32-64 26-43 92 71'50 57-90 43 33-88 26-47 93 73-28 57-26 43 33-42 2706 93 72-27 58-53 44 34-67 27-09 94 74-07 57-87 44 34-19 27-69 94 73-05 5916 45 35-46 2770 95 74-86 58-49 45 34-97 28-32 95 73-83 59-78 46 36-25 28-32 96 75-65 59-10 46 35-75 28-95 96 74-61 60-41 47 37-04 28-94 97 76-44 59-72 47 3653 2958 97 75-38 61-04 48 3782 29-55 98 77-22 60-33 48 37-30 30-21 98 76-16 61-67 49 3861 30-17 99 78-01 60-95 49 33-08 30-84 99 76-94 62-30 50 39-40 30-78 100 78-80 61-57 50 38-86 31-47 ICO 77-72 62-93 E.orW N.orS E.orW N. or S E.orW N.orS |E. or W.j N.orS. 52 51 TEAVEESE TABLES. 155 40 41 . iJC ' s ft rd "I ft r| oil ft d ?i ft ' tc Ti C k, cs o ** 3* it 1 It S* 8j C M o c ij i St-S aS wa | Q si 5 Z3 *3 w"5 z$ fcS s'S 1 0-77 0-64 51 39-07 32-78 i 0-75 0-66 51 38-49 33-46 2 1-33 1-29 52 39-83 33-43 2 1-51 1-31 52 39-24 34-12 3 2-30 1-93 53 40-60 34-07 3 2-26 1-97 53 40-00 34-77 4 3-06 2-57^ 54 41-37 34-71 4 3-02 2-62 54 40-75 35-43 5 3-81 3-21 55 42-13 35-35 5 3-77 3-28 55 41-51 36-08 6 4-60 3-86 56 42-90 36-00 6 4-53 3-94 56 42-26 36-74 7 5-36 4-50 57 43-66 36-64 7 5-28 4-59 57 43-02 37-40 8 6-13 5-14 58 44-43 37-28 8 6-04 5-25 58 43-77 38-05 9 6-89 5-79 59 45-20 37-93 9 6-79 5-90 59 44-53 38-71 10 7-66 6-43 60 45-96 38-57 10 7-55 6-56 60 45-28 39-36 11 8-43 7-07 61 46-73 39-21 11 8-30 7-22 61 46-04 40'02 12 9-19 7-71 62 47-49 39-85 12 9-06 7-37 62 46-79 40-68 13 9-96 8-36 63 48-26 40-50 13 9-81 8-53 63 47-55 41-33 14 10-72 9-00 64 49-03 41-14 14 10-57 9-18 64 48-30 41-99 15 11-49 9-64 65 49-79 41-78 15 11-32 9-84 65 49-06 42-64 16 12-26 10-28 66 50-56 42-43 16 12-08 10-50 66 49-81 43-30 17 13-02 10-93 67 51-32 43-07 17 12-83 11-15 67 50-57 43-96 18 13-79 11-57 63 52-09 43-71 18 13-58 11-81 68 51-32 44-61 19 14-55 12-21 69 52-86 44-35 19 ! 14-34 12-47 69 52-07 45-27 20 15-32 12-86 70 53-62 45-00 20 15-09 13-12 70 52-83 45-92 21 16-09 13-50 71 54-39 45-64 21 15-85 13-78 71 53-58 46-58 22 16-85 14-14 72 55'15 46"28 22 16-60 14-43 72 54-34 47-24 23 17-62 14-78 73 55-92 46-92 23 17-36 15-09 73 55-09 47-89 24 18-38 15-43 74 58-69 47-57 24 18-11 15-75 74 55-85 48-55 25 19-15 16-07 75 57-45 48-21 25 18-37 16-40 75 56-60 49-20 26 19-92 16-71 76 58-22 48-85 26 19-62 17-06 76 57-36 49-86 27 20-68 17-36 77 58-99 49-49 27 20-38 17-71 77 58-11 50-52 28 21-45 18-00 78 59-75 50-14 28 21-13 18-37 78 58-87 51-17 29 22-21 18-64 79 60-52 50-78 29 21-89 19-03 79 59-62 51-83 30 22-98 19-28 80 61-30 ,31-42 30 22-64 19-68 80 60-38 52-48 31 23-75 19-93 61 62-05 52-07 31 23-40 20-34 81 61-13 53-14 82 24-51 20-57 82 62-82 52-71 32 24-15 20-99 82 61-89 53-80 83 25-28 21-21 83 62-56 53-35 33 24-91 21-65 83 62-64 54-45 34 26-05 21-85 84 64 -35 53-99 34 25-66 22-31 84 63-40 55-11 35 26-81 22-50 85 65-11 51-64 35 26-41 22-96 85 64-15 56-77 36 27-58 23-14 86 65-88 55-28 36 27-17 23-62 86 64-91 56-42 37 28-34 23-78 87 66-65 55-92 37 27-92 24-27 87 65-66 57-08 38 29-11 24-43 88 67-41 56-57 38 28-68 24-93 88 66-41 57-73 39 29-88 25-07 89 68-18 57-21 39 29-43 25-59 89 67-17 56-39 40 30-64 25-71 90 68-94 57-85 40 30-19 26-24 90 67-92 59-05 41 31-41 26-35 91 69-71 58-49 41 30-94 26-90 91 68-66 59-70 42 32-17 27-00 92 70-48 59-14 42 31-70 27-55 92 69-43 60-36 43 32-94 27-64 93 71-24 59-78 43 32-45 28-21 93 70-19 61-01 44 33-71 28-28 94 72-01 60-42 44 33-21 28-87 94 70-94 61-67 45 34-47 28-93 95 72-77 61-07 45 33-96 29-52 93 71-70 62-33 4-; 35-24 29-57 96 73-54 61-71 46 34-72 30-18 96 i 72-45 62-98 47 36'CO 30-21 97 74-31 62-35 47 35-47 30-83 97 73-21 63-64 48 36-77 30-85 98 75-07 62-99 48 36-23 31-49 98 73-96 64-29 49 37-54 31-50 99 75-81 63-64 49 36-98 32-15 99 74-72 64-95 50 38-18 32-14 100 76-60 64-28 37-74 32-80 100 ! 75-47 65-61 E. or W N.orS. E.or W. N. or S. E.or W. N.orS. E.orW N. or S. 50 1 156 TKA.YEKSE TABLES. 42 43 M ri| *'! 5PJ CO g | gJ rf| 'I spj rf| M if ol o -g i C i* a O '*-' o| It s| l 5 c o +* fcJ 33 fc5 wS &5 HQ 33 fc w3 SB a w'S j 0-74 0-67 51 37-90 34-13 i 0-73 0-68 51 37-30 34-78 2 1-49 1-34 52 38-64 34-79 2 1-46 1-36 52 38-03 3 2-23 2-01 53 39-39 35-46 3 2-19 2-05 53 38-76 36-15 4 2-97 2-68 54 40-13 36-13 4 2-93 2-73 54 39-49 36-83 5 372 3-35 55 40-87 3680 5 3-66 3-41 55 40-22 37-51 6 4-46 4-01 56 41-62 37-47 6 4-39 4-09 56 40-96 38-19 7 5-20 5-68 57 42-36 38-14 7 5-12 4-77 57 41-69 38-87 8 5-95 5-35 58 43-10 38-81 8 5-85 5-46 58 4242 39-56 9 6-69 6-02 59 43-85 39-48 9 658 6-14 59 43-15 40-24 10 7-43 6-69 60 44-59 40-15 10 7-31 6-82 60 43-88 40-92 11 8-17 7-36 61 45-33 40-82 11 804 7-50 61 44-61 41-60 12 9-92 8-03 62 46-07 41-49 12 8-78 8-18 62 45-34 42-28 13 9-66 8-70 63 46-82 42-16 13 9-51 8-87 63 46-08 42-97 14 10-40 9-37 64 47-56 42-82 14 10-24 9-55 64 46-81 43-65 15 11-15 10-04 65 48-30 43-49 15 10-97 10-23 65 47-54 44-33 16 11-89 10-71 66 49-05 44-16 16 11-70 10-91 66 48-27 45-01 17 12-63 11-38 67 49-79 4483 17 12-43 11-59 67 49-00 45-69 18 13-38 12-04 68 50-53 45-50 18 13-16 12-28 68 49-73 46-38 19 14-12 12-71 69 51-28 46-17 19 13-90 1296 69 50-46 47-06 20 14-86 13-38 70 52-02 46-84 20 14-63 1364 70 51-19 47-74 21 15-61 14-05 71 5276 47-51 21 15-36 14-32 71 51-93 48-42 22 16-35 14-72 72 53-51 48-18 22 16-09 15-00 72 52-66 49-10 23 17-09 15-39 73 54-25 48-85 23 1682 1569 73 53-39 49-79 24 17-84 16-06 74 54-99 49-52 24 17-55 16-37 74 54'12 50-47 25 18-58 16-73 75 55-59 49-79 25 18-28 17-05 75 5485 51-15 26 19-32 17-40 76 56-48 50-85 26 19-02 17-73 76 55-58 51-83 27 20-06 18-07 77 57-22 51-52 27 19-75 18-41 77 56-31 52-51 28 20-81 18-74 78 57-96 52-19 28 20-48 19-10 78 57-05 53-20 29 21-55 19-40 79 58-71 5286 29 21-21 19-78 79 57-78 53-88 30 22-29 20-07 80 59-45 53-53 30 21-94 20-46 80 58-51 54-56 31 23-04 20-74 81 60-19 54-20 31 22-67 21-14 81 59-24 55-24 32 23-78 21-41 82 60-94 51-87 32 23-40 21-82 82 59-97 56-92 33 24-52 22-08 83 61-68 55-54 33 24-13 2251 83 60-70 56-61 34 25-27 22-75 84 62-42 56-21 34 24-87 23-19 84 61-43 57-29 35 26-01 23-42 85 63-17 56-88 35 25-60 23-87 85 62-16 57-97 36 26-75 24-09 86 63-91 57-55 36 26-33 24-55 86 62-90 58-65 37 27-50 24-76 87 64-65 58-21 37 27-06 25-23 87 63-63 59-33 38 28-24 25-43 88 65-40 58-88 38 27-79 25-92 88 64-36 60-02 39 28-98 26-10 89 66-14 59-55 39 28-52 26-60 89 65-09 60-70 40 29-73 26-80 90 66-88 60-22 40 2925 27-28 90 65-82 61-38 41 30-47 27-43 91 67-63 60-89 41 2999 27-96 91 66-55 61-06 42 31-21 28-10 92 68-37 61-56 42 30-72 28-64 92 67-28 62-74 43 31-96 28-77 93 69-11 62-23 43 31-45 29-33 93 68-02 63-43 44 32-70 29-44 94 69-86 62-90 44 32-18 30-01 94 68-75 6411 45 33-44 30-11 95 70-60 63-57 45 32-91 30-69 95 69-48 64-79 46 34-18 30-78 96 71-34 64-24 46 33-64 31-37 96 70-21 65-47 47 34-93 31-45 97 72-08 64-91 47 34-37 32-05 97 70-94 66-15 48 35-67 32-12 98 72-83 65-57 48 35-10 32-74 98 71-67 66-84 49 36-41 3279 99 73-57 66-24 49 35-84 33-42 99 72-40 67-52 50 37-20 33-50 100 74-31 66-91 50 36-57 34-10 ICO 73-14 68-20 E.orW. N. or S. E.orW. N.orS. E.orW. N. or S. E.orW. N.or S. 48 47 TRAVERSE TABLES. 157 44 45 . I " ' . 2fjc! rh * M SfjS *J 60 JS to | fe S ifi^- to * fe S 5 z l it si 11 g| c| gte c C c *; o| ft A H'S .5 . .s fcQ SO (33 fc5 w5 83 fc'S WQ 1 0-72 0-69 51 36-69 35-43 1 0-71 0-71 51 36-06 36-06 2 1-44 1-39 52 37-41 36-12 2 1-41 1-41 52 36-77 36-77 3 2-16 2-08 53 38-13 36-82 3 2-12 2-12 53 37-48 37-48 4 2-88 2-78 54 38-84 37-51 4 2-83 2-83 54 38-18 38-18 5 3-60 3-47 55 39-56 38-21 5 3-54 3-54 55 38-89 38-89 6 4-32 4-17 56 40-28 38-90 6 4-24 4-24 56 39-60 39-60 7 5-04 4-86 57 41-00 39-60 7 4-95 4-95 57 40-31 40-31 8 5-75 5-55 58 41-72 40-29 8 5-66 5-66 58 41-01 41-01 9 6'47 6-25 59 42-44 49-98 9 6-36 6-36 59 41-72 41-72 10 7-19 6-95 60 43-16 41-68 10 7-07 7-07 60 42-43 42-43 11 7-91 7-64 61 43-88 42-37 11 7-78 7-78 61 43-13 43-13 12 8-63 8-34 62 44-60 42-07 12 8-49 8-49 62 43-84 43-84 13 9-35 9-03 63 45-32 43-76 13 9-19 9-19 63 44-55 44-55 14 10-07 9-73 64 46-04 44-46 14 990 9-90 64 45-26 45-26 15 10-79 10-42 65 46-76 45-15 15 10-61 10-61 65 45-96 45-96 16 11-11 66 47-48 45-85 16 11-31 11-31 66 46-67 46-67 17 12-23 11-81 67 48-20 46-54 17 12-02 12-02 67 47-38 47-38 18 12-95 12-50 68 48-92 47-24 18 12-73 12-73 68 48-08 48-08 19 13-67 13-20 69 49-63 47-93 19 13-44 13-44 69 48-79 48-79 20 14-39 13-89 70 50-35 48-63 20 14-14 14-14 70 49-50 49-50 21 15-11 14-59 71 51-07 49-32 21 14-85 14-85 71 50-20 50-20 22 15-83 15-28 72 51-79 50-02 22 15-56 15-56 72 50-91 50-91 23 16-54 15-98 73 52-51 50-71 23 16-26 16-26 73 51-62 51-62 24 17-26 16-67 74 53-23 51-40 24 16-97 16-97 74 52-33 52-33 25 17-98 17-37 75 53-95 52-10 25 17-68 17-68 75 53-03 53-03 26 18-70 18-06 76 54-67 52-79 26 18-38 18-38 76 53-74 53-74 '27 19-42 18-76 77 55-39 53-49 27 19-09 19-09 77 54-45 54-45 28 20-14 19-45 78 56-11 54-18 28 19-80 19-80 78 55-15 55-15 29 20-86 20-15 79 56-83 54-88 29 20-51 20-51 79 55-86 55-86 30 21-58 20-84 80 57-55 55-57 30 21-21 21-21 80 56-57 56-57 31 22-30 21-53 81 58-27 56-27 31 21-92 21-92 81 57-28 57-28 32 23-02 22-23 82 58-99 56-96 82 22-63 22-63 82 57-98 57-98 33 23-74 22-92 83 59-71 57-66 33 23-33 23-33 83 58-69 58-69 34 24-46 23-62 84 60-42 58-35 34 24-04 24-04 84 59-40 59-40 35 25-18 24-31 85 61-14 59-05 35 24-75 24-75 85 60-10 60-10 36 25-90 25-01 86 61-86 59-74 36 25-46 25-46 86 60-81 60-81 37 26-62 87 62-58 60-44 37 26-16 26-16 87 61-52 61-52 38 27-33 26-40 88 63-30 61-13 38 26-87 26-87 88 62-23 62-23 39 28-05 27-09 89 64-02 01-82 39 27-58 27-58 89 62-93 62-93 40 28-77 27-79 90 64-74 62-52 40 28-28 28-28 90 63-64 63-64 j 41 29-49 28-48 91 65-46 63-21 41 28-99 28-99 91 64-33 64-33 42 30-21 29-18 92 66-18 63-91 42 29-70 29-70 92 65-05 65-05 43 30-93 29-87 93 66-90 64-60 43 30-41 30-41 93 65-76 65-76 44 31'fi5 30-57 94 67-62 65-30 44 31-11 31-11 94 66-47 66-47 45 32-37 31-26 95 68-34 65-99 45 31-82 31-82 95 67-18 67-18 46 33-09 31-95 96 69-06 66-69 46 32-53 32-53 96 67 -88 67-88 47 33-81 32-65 97 69-78 67-38 47 33-23 33-23 97 68-59 68-59 48 34-53 33-34 98 70-50 68-08 48 33-94 33-94 98 69-30 69-30 49 35-25 34-04 99 71-21 68-77 49 34-65 34-65 99 70-00 70-CO 50 35-97 34-73 100 71-93 69-47 50 35-35 35-35 100 70-71 70-71 IE. orW. N. or S. E. or W N. or S. E. or W. N.or S. E. or W N. or S. 46 45 158 OF THE PEODUCE OF SEAMS OF COAL. (61.) From the various experiments which have been made on the produce of tracts of coal mines, in the neigh- bourhood of Newcastle-upon-Tyne, it has been found that a cubic yard of coal weighs -936 of a ton ; therefore, an acre of that stratum, 1 foot thick, will produce (if all wrought out) 1510 tons; consequently an equal area of stratum, 2, 3, 4, &c., feet in thickness, will produce 2, 3, 4, &c., times the quantity of tons of coal that a seam of 1 foot thick will produce. From this datum easy rules may be constructed for the use of the practical miner, which with facility may be retained for application in calculating the produce of seams of any given thickness in tons. To find the number of tons of coal contained per acre by a seam of any given thickness. EULE I. Multiply 1510 by the thickness or height of the seam in feet, and the product will be the number of tons of coal contained in an acre of that seam. To find the number of tons of coal produced per acre by a seam, where part thereof is only worlced or taken away, the other part being left as a support to the roof. EULE II. As the sum of the two parts, i.e., that left and that taken away, is to the part excavated or taken away, so is the whole number of tons contained in an acre of the seam to the number of tons produced per acre by the ex- cavated part. s EXAMPLE I. What number of tons of coal is contained in an acre of coal stratum 6 feet thick ? From rule 1st, 1510 x 6 = 9060 tons, the content. EXAMPLE IT. What number of tons of coal is contained in an area of coal stratum of 100 acres, 5 feet thick ? ON THE PRODUCE OF SEAMS OF COAL. 159 1510 x 5 = 7550 tons contained in one acre. Then 7550 x 100 = 755,000 tons contained in 100 acres. EXAMPLE III. What number of tons of coal is con- tained in 400 acres of coal stratum 5 feet 3 inches thick ? First 5 ft. 3 in. = ft. 4 And 151 X21 X 4<30 = ^^ ^ EXAMPLE IV. What number of tons of coal is contained in 400 acres of coal stratum 8 feet 4 inches thick ? OK First 8 ft. 4 in. =~ft. 3 , 1510 x 25 x 400 r nyq r And = 5,033,333 tons. 3 EXAMPLE V. What number of tons of coal is contained in 500 acres of coal stratum 4 feet 9 inches thick, exclud- ing a band of stone which lies therein 6 -inches thick ? 4-75 __ -50 = 4*25 feet, the thickness of the coal stratum, exclusive of the band of stone. Then 1510 x 4'25 x 500 = 3,208,750 tons contained in 500 acres. EXAMPLE VI. In a seam of coal which is 7 feet 3 inches thick ; that is to say, 6 feet of its thickness is marketable, and 1 foot 3 inches inferior ; I wish to know the produce in tons per acre, both of the marketable and the inferior parts of the seam ? 1510 x 6 = 9060 tons per acre, the marketable produce of the seam First 1 ft. 3 in. = I ft, 1510 x 5 . . And = 1887J tons of the inferior parts. EXAMPLE VII. In a seam of coal 6 feet thick, I wish to know what number of tons it produces per acre, when 1 part is taken away, and 2 left for pillars or supports ? 1510 x 6 = 9060 tons, the whole content per acre. 160 ON THE PBODUCE OF SEAMS OF COAL. Prom rale 2nd, as 2 + 1 =3:1:: 9060 : 3020 tons, the produce per acre of the part taken away. EXAMPLE VIII. In a seam of coal 3 feet 6 inches thick, 1 wish to know what number of tons it will produce per acre, when two parts are taken away and 1 left ? 1510 x 3-5 = 5285 tons, the content per acre. As 2 + 1 = 3 : 2 : : 5285 : 3523'33 tons, the produce per acre of the part taken away. EXAMPLE IX. In 1000 acres of co'al5feetthick ; whereof 2 parts are worked and 1 left, I wish to know how many years this stratum of coal will produce an annual quantity of 50,000 tons ? 1510 x 5 = 7550 tons, the whole produce of the seam per acre. Then as 3 : 2 : : 7550 : 5033, the quantity got per acre. EXAMPLE X. I have a tract of 600 acres of coal stratum, containing 2 seams, the first 5 feet 3 inches thick, and the second 3 feet 6 inches thick : Out of the first seam 3 parts are got and 1 left ; and out of the second 4 parts are got and 1 left. JSTow, if the annual vend of the two seams together is 75,000 tons, what number must be wrought out of each seam yearly, so that they may terminate together ; and how many years will the colliery last ? - = 7927J tons, the whole produce per acre of the first seam. And 4:3:: 7927 J : 5945 tons, the quantity wrought per acre out of the first seam. Then 5945 x 600 = 3,567,000 tons, total produce of the first seam. Again, - - 5285 tons, the whole produce per acre of the second seam. ON THE PllODUCE OE SEAMS OF COAL. 161 Aiid 5:4:: 5285 : 4228 tons, the quantity wrought per acre out of the second seam. Then 4228 x 600 = 2,536,800 tons, total produce of the second seam. Now, to make the two seams terminate together, the quantity wrought out of each seam annually must bear the same proportion to each other as the quantity wrought out of each acre of each seam. Therefore 5945 + 4228 = 10,173 : 5945 : : 75,000 : 43,829 tons, the quantity to be wrought out of the first seam annually. And 75000 43829 ^ 31,171 tons, the quantity to be wrought out of the second seam annually. 3567000 + 2536800 Whence = 80 years 18 days, YoOOu the duration of the colliery. Note. Elaborate statistics and details of the extent, the probable pro- duce and duration of all the coal-fields in the United Kingdom, also the extent and thickness of the strata of those of the United States and the British colonies, as far as they are known ; as well as those of Belgium, France, Germany, and other foreign countries, are given in the Reports of the Institution of Mining Engineers of Neivcastle-upon-Tyne, to which the student is referred, who may be desirous to be acquainted with these -subjects. Questions in Mine Surveying. Note. The solutions to the two following Questions in Mine Surveying will require a knowledge of the application of Algebra to Geometry, and the latter of the two will require a further knowledge of the application of Spherical Trigonometry to Astronomy. See Question- XVII, page 211, Baker's Land and Engineering Surveying. Wealds Series. The student will have no difficulty in sketching the figures and assigning the dimensions to the given parts in the two Questions. Question 1. There are four drifts in a coal mine formiug a trapezium, the given lengths of which are a, b, c, d, and the sums of the opposite angles of the trapezium are known to be equal to two right angles, none of the angles being separately given. It is required to plot this subterraneous survey by the help of the following formula. 162 ON THE PRODUCE OF SEAMS OF COAL. Let S - half the sum of the lengths of the four drifts -J (a + b + c + d), and D the diameter of circle, which will circumscribe the trapezium ; then T) _ / ( (ac + ld) (al + cd) (ad+ Ic) = V \ (S-o) (-&) (S-,) (S-dj Note. This formula will divest the preceding Question of its chief diffi- culty, while it will accustom the student to the application of this species of mathematical analysis. Question 2. There are five straight drifts, AB, EC, CD, DE, EA, in a coal-mine, forming an irregular polygon ; now, the several lengths of each of the five drifts are given, and the angles at B, C, and D are known to be equal to one another, but are not given : also at each of the angles B and D is a shaft, and the tops of these two shafts range with the sun at 3 h. 35' P.M. on the 22d of October, 1860. It is required from these data to plot this subterraneous survey in its true position with respect to the cardinal points. NOTE. This question was proposed by B. Gksmpertz, Esq., F.R.S., in the Gentleman's Mathematical Companion ; to which he gave a solution in a concise, novel, and ingenious manner by his Principles of Imaginary Quantities : other solutions by the ordinary methods were also given to the same problem. THE END. BRADBTJET AND EVANS, PRINTERS, WHITE FRIARS. 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