under the lights of the Instrument to the mark at F, is (as it were) the prime Dia. meter whence the D-grees of the Argles are to be numbred, and accordingly I mark: the Angle A, in my Table hereafter lo be exemplified with 360 Degrees. But to proceed, turnirg the Index with the fiducial Edge upon the Center, till I see that Thread cutting the Mark at at B, the faid Edge cuts upon the Frame at 76 Degrees 15 Minutes : I note down for that Angle : The like' work I do, turning the fights to C,D and E, (but not 10 F, for there is no Angle but only a Mark in the Boundary) and I find mine Index to cut for every Angle as I have Marked them within the pricked Circle of the laft Figure, viz. 157 deg.. 35. Minutes for C, 225 degrees 20 Minutes for D, and 278 Degrees and 50 Minutes for E. Then I meafure (or cause to be frictly meam [ured by others) the distances betwixt the place where the Field Book. Instrument stands, and eveo D MIDL ry Angle, and find them to A 360004 to be as I have set them upon c115735384 B1 76/15/4/03 the pricked Lines in the little 02251205135 Circle, viz. A 4 Chains 20 E2781 có lo Links, B.4 Chains 3 Links, C 3 Chains 84 L nks, Ds. Chains 35 Links, E 6 Chains 6 Links. And now my Table bath for Lines and Angles is thus perfect ed, ed, and the work is ready for Protraction within Doors. Now to protract our Observations : I draw tipon Paper a Line A Fat Adventure, so it be long enough, and stick a pin in it at plealure for the Center O, upon which I place the Center of the Protractor, fo that the streight side of the Protractor may lye upon the Line AP; the Limb or Arched fide being upwards towards B, by the help whereof I make a prick on the Paper at 76 dtg. 15 Min. for B, and at 157 deg. 35 de Min. for C, according to the numbers in my Field-Book.. Then turning the Protractor about the pin, with the Limb down towards I) and E, till the Diameter lye again juft upon the Line AF, I number downwards from the Righthand towards the Left, beginning 190, 200, Esc. And ove-ragainst the place where 225 digrees 20 Minutes and 278 degrees só Minutes fall, I prick the Paper at the side of the Limb, and through those four points. I draw so many several Lines, upon which and also upon the Line A O, I'mark: out by points the true measure of every Line by a Scale trom the Center, and from those points drawing the Lines AB, BC, CD, DE, and Eg I have the true Plot of the Field. How to take the plot of ar Irregular Field by the Theodolite or by the Degrees on the plain Table by going round the same, being the best M thod in Practice. Fig. 101 First cause marks to be set up at every Station, as A, B, C, D, E, F; then making Choice of a Station at A to begin at : Measure from A, to the Hedge at a, which you'll find to be 35 Links, which pote down in your Eye Draught or Field Book, likewise measure from A, to the Hedge at b,and you'll find it to be 20 Links, which Note down; then measure from your Sation A, towards B your second Station. and at 66. 40 l. you have an off-set of 30 Links to the right at the corner c, and at 6c.go? you have measured to your second Station at B, where you are to fix your In . ftrument and take the Argle ABC, which is found to be 1 26° 30' which note down, then measure from your Station B to your Station C: which contains 30. 2; l. at Station C, measure to the Hedge at right Angles to d; which let be 35 Links and from C to the Hedge at e, is 20 Links, fixing your e Ioftrument at take the Angle: BCD, which contains: 104 o'; then measure in a ftreight Line from C: towards D, and at I c. 70 1. you have an off-set to the Corner at f, which contains 25 Links; at 2 c. sol. you have an off-set to the Corner g: which is 50 I c. 20 l. at 3c. gol. you have another, at h, of 1 c 401. then measuring on 6 c. 30 l. yoi are come to your Station D. ineafure from D to the Hedge at right Argles to i, which is 80 Links, and from D to k: which is go Links: Then fix your Instrument at Đi and take the Angle ČDE: which is 75° 30': Measuring along the Line DE, you'll find that at 3 č. 60 l. you have an off fet of 1 c.50 1. to the Angle at 1: and at 8 6.151. you have an off-set of 1 c. šol. to:he Argle at m : and at 13 c. 20 l. you have measured to your Station at E: from E to the Hedge at right Angles measure to n : which is 30 Links and fromE to o, which is o Links alfo: Then fix your Inftrument faflat E, and take the Angle D EF, which is 999 then measuring in a streight line from E towards F: you'll find that at 40. 10l. you touch the Hedge, and at 8 c. 30.1. you have imeasured to your Station at F: From F to the Cerner q, at right Angles contains 53 Links; because you have measured to the very Corner, you have no occafion to measure from the Station F, to the Hedge at r: Having fixt your Inftrument at F: take the Angle E FĂ which contains 10 8° 300 then measuring from F: towards A you'll find that at 20, 70 1. you have an offset of 85 Links to the bend at' S: and at 60.651. you have measured to your first S'ation at A : where you began. How to protra&t these Observations.. First draw an obfcure line at pleasure, as AB,then with your thin Ruler, having 27€ qual parts in an Inch placed upon the very Edge ( being the number that this Draught was protracted by ) apply the Edge of this Ruler to the Line AB, and with your protracting pin make a mark at 35 Links, from A to a, then place the Edge of your Ruler at right Angles to the line AB, and prick off 20 Links from A to b: then place the be. ginning of your Scale at the point A: the Edge being laid along the Line AB, by your Field Book or Eye Dragght you'll find that at 6 0.401. you have an off-fer to the Corner c: which accordingly prick off, and draw the Black-line b c, then at 60.50! prick off the length of the Line AB; at the point B, with your protractor lay down the quantity of the Angle ABC-1268:30, and with your thin Ruler prick off upon the Line BC 30, 25 from B to C, at the Station C: prick off 25. Links to d, and 20 Links to c: both being at right Angles ; at the point C: Protract the quantity of the Angle BCD 104° ', then with your Scale prick off upon the line CD 16.70 1. and at right Angles to this point prick off 25. Links to the Hedge at f: Then draw your boundary Line through the point f and e: and . |