170 



GEODESY. 



"B," thus laying off a radius of twenty miles. At the extremity of this line, a perpendicular 

 was erected, or, in other words, a tangent was drawn to the circumference of a circle with 

 that radius and the junction as a centre, and, by means of the following table, the circle was 



described. 



Co-ordinates of points of the circle. 



Abscigsas in feet. Corresponding ordinates. 



I 



Abscissas in feet,, 



1 



Corresponding ordinates, 



M J^ 1 _._ 



measured along 



in feetj measured on 



measured along 



in feet, measured on 



the tangent. 



perpendiculars to the 



the tangent. 



perpendiculars to the 





tangent. 



1 





tangent. 



Fed. 





Fed. 



1 



— 



0-00 



1,300 — 



8.29 



1 



100 



0. 04745 



1,400 



9.30 



200 — 



0. 19 



1,500 — 



10.67 



300 — 



0. 427 



1,600 — 



12. 148 



400 — 



0.759 



1,800 — 



15.37 



500 — 



1.186 



2,000 — 



18.90 



600 — 



1.708 



: 2.200 — 



22.96 



700 — 



2.325 



2,400 — 



27.33 



800 — 



3.037 



2,600 — 



33.00 



900 — 



3.843 



3,000 — 



42.66 



1,000 — 



4.74 



5,000 — 



118.10 



1,100 — 



5.74 



10,000 — 



472.2 



1,200 — 



6.83 







of the circumference of 

 miles. 



from the moutli 



the line joining this point and the mouth of the Gila, protract a straight line, mating an angle 



1478 



with the tangent to the circle at the point; then run 5,280 feet on this line, and this will give 

 you a second point on the circle ; then place your instrument alternately at the second and first 

 ■,^r.,-r,+o OT.^ 1ai- r,ff +TiP fnllovvi'Tio- a.fio-lfis With this chord of a mile lonsc, and their intersections 



n the 



circumference of 



' the Circle. 







First point. 



Second point. 



Intermediate 

 points of cir- 

 cumference. 



1 

 1 



r 

 1 



1 



2 

 3 

 4 



1 



5 

 6 



O / " 



06 3G. 70 

 13 13.41 

 19 50.11 

 26 26.81 

 33 3.52 

 39 40. 22 



1 19 20.44 

 1 12 43.74 

 1 6 7.03 

 59 30.33 

 52 53. 63 

 40 16.92 



1st, 



2d. 

 3d. 

 4th. 

 5th. 

 6 th. 



Having come to a point more than half way, reverse the readings, and they will give you 



other points commencing near the second point. 

 this chord is ahout thirty- three feet. 



from 



