« ForrigeFortsett »
And likewise through c, and d, and where these Lines Interfečt gives you the very corner at x: Next from the point C, prick off 20.50 l. and at right Angles to the point al 26. 50l.prick off I 6. 20 1. to the Hedge at g, and draw the black Linegf: Next from the point C: prick off 3.c. 90. l. and at that distance prick off I c 401 at right Argles, to the Hedge at h, and draw ihe Black-line h g,then from the point C prick off 6 0..301. to the Station at D; at this S:a. tion D prick off 80 Links to the Hedge at c, and 50 Links to k, both at right Angles: At the Station D prick the Quantity of the Angle CDE with your protractor, which contains 75° 304 then from the point D, with your Scale prick off 36. 501. and at right Angles to this Mark last set off, prick. off 1c5° 1, to the Angle at C, and draw the Lines 1 k and hi, till they interfect. each other, which will give you the corner at z. At the Station D. Prick off 8 c. 151. from your Scale of equal parts, and at right Angles to this last Mark prick oft 16. solo to the Angle at m; and draw the Blackline ml. At the Station D, prick off' vpon the Line DE 13.6. 201. to the Station at E; from this Sation prick off 30 Links at right Angles to the Hedge at n,and 30 Lin. to the Hedge at o; at the point E protract the Quantity of the Angle DEF with your protractor, which contains 99° : Oihen
from the point E prick off 40 10 l. where it touches the Hedge at p, then prick off 8 c. 30 l. to your Station at F. prick off at the point F 50 Links at right Angles to the corner at g, then draw the Black lines p9 pc. Likewise draw the Black-lines m n; where the two Lines m n and p o Interfect gives you the very corner of the Field at y: at the point F, protract the Quantity of the Angle EF A with your protractor, which contains 10 8° 3'o, and if the Lige FA falls in the point A; your work is right fo far: From the point F prick off 2c, 701. froin which point prick off at right Angles 85 Links to the Angle at s; then from the poin: F prick off 6c. 651. and if 6 0.651. reachis just to the poin: A, you may be allu:ed your Survey was taken truly. To enclose your Field draw the Black-line from a to s, and from s to a, ihe line cb and fabeing continued, will intersect at w, the very corner which encloses your Field.
N. B. As I have recommended in this Example the thin Ruler with qual parts, upon ihe very Edge to protract with, be.
better than Compasses on many Accounts, as every Surveyor will find. So I wou'd adı ise every Surveyor, that is curious, to make use of Mr Words Protractor improved : The Semi-Circle is made near as usual ; upon this Semi-Circle is moveable Index of 7 Inches lorg, the upper
part being 5 degrees from the Center, and the lower part next the Liinb; 4 Degrees, so that each Edge will be Diagonal of one deg. upon this Edge is un qual Divisions Calculated to every Minute. This Description is accordirg to Mr Wards, instead of having the Index thus made, I think it much better to have that part of the Index above the Dimb to be part of an Arch of two degrees, and the other part supposed to pass thro the Centre: Now upon this Index the Divisions will be equal, and will be considerably larger at the beginning of the Divisions than in the other. The Demonstration of this depends upon Theo. 13 where 'tis proved that the Argle at the Center is double to that at the Circuinference. The use of this Instrument is very easy ; for you have no more to do but to set the Index to the whole degrees observed, and upon the Index graduated, prick off the Minutes: This Protractor with Scales, as before mentioned, with all forts of Mathematical Instruments, are inade and fold by Benjamin Scot ( who served his time with Mr Rowley,) he keeps a Shop at the Mariner and Globe over against Exeter Change in the Strand.
Having now recommended proper Inftruments for protracting your Observations, I cannot avoid acquanting the Reader, that the best Inftrument to take Angles, is the