CHAP. IX.
To take, or draw the Plot of a great Champain Plain, by the help of the Degrees on the Frame of the Table.
LEt A, B, C, D, be the Champain Plain; then first place your Instrument at A, laying the Index on the Diameter of the Table, and turning the whole Instrument about until through the Sights you see the Angle at B; where fix the In∣strument, and turn the Index about until through the Sights you see the Angle on the other side of your Station at D, ob∣serving the Degrees cut by the Index, which sup∣pose 71, which is the quantity of the Angle B, A, D. Then measure with
Secondly, Remove your Instrument to the next Angle at D, and laying the Index on the Diame∣ter thereof, direct your Sights to the last Station at A, and there fix the Instrument; then turn the Index about until you see the next Angle at C, [ 10] observing the Degrees there cut, which suppose 86, which is the quantity of Degrees of the Ang∣le A, D, C; then measure the distance. D C, 31 Perches in the third Colum of your Field-Book.
Thirdly, Remove your Instrument to G, and laying the Index on the Diameter thereof, direct your Sights to D, and then fasten the Instrument. Then turn the Index about until through the Sights you see the next Angle at B, observing the [ 20] Degrees cut, which suppose 73, and 30 Minutes; and measure the Distance C B, 22 Perches, 3 Primes, the 73 Degrees, 30 Minutes must be pla∣ced in the first and second Colums of your Field-Book, and the 22 Perches, 3 Primes in the third and fourth Colums.
Lastly, Remove your Instrument to B, and laying the Index on the Diameter thereof, direct your Sights to C, and then fix the Instrument; then move the Index about until through the [ 30] the Sights you see the Angle at A, where you be∣gan, noteing the Degrees there cut, which are 129, and 30 Minutes, which is the quantity of the Angle C, B, A; then with your Chain the distance from B, to A, 25 Perches, 5 Primes, these 129 Degrees, 30 Minutes, and the 25 Perches, 5 Primes must be noted in your Field-Book, as a∣foresaid, and then will they stand thus.
Degrees. | Minutes. | Perches. | Primes. | |
A | 71 | 00 | 32 | 2 |
D | 86 | 00 | 31 | 0 |
C | 73 | 30 | 22 | 3 |
B | 129 | 30 | 25 | 5 |
The work of this Chapter may be performed upon your Plain-Table, the operation differing nothing from what is here delivered, except only, that here you have the Angles by the Degrees on the Frame of your Table, and you must by the [ 50] other attain them by drawing of Lines upon the Table. [ 60]