16G 



GEODESY. 



Next we compute the correction d P, to I>e applied to the spheroidal difference of longitude 



P, by the formula 

 ' ^ dP = -a{i,e-^e^) cos. I = + 21". 12 



And wp get P + ^ P z=: 2° 32' 4G".62 



Substituting this into the former computation, we obtain 



Z' = 85° 34' 14". 41 <T = 1758". 10 



Z" _ 180° = 84° 12' 02". 89 I = 32° 54' 16".n 



And by a second substitution of the latter values we obtain, finally. 



Z' = 85° 34' 14". 49 d P =: -^ 21" .11 



7" _ 180° = 84° 12' 02". 95 ^ = 1158" Ab 



W 



;" to the foot of the perpendicular I, viz : 



</ = 6° 52' 31".5 ; </' = 9° 01' 49". Y 



s 

 h 



^ (1 -f i e sin.2 Z — /^ e^ sin.* I) -\- (sin. 2 a" — sin. 2 </) (^ e sin.^ Z — ^ e^ sin." I) 



1st term = + 239187.0 



2d term =+ HS-^ 



3d term 



0.0 



Distance s = 239300.8 metres = 261692.0 yards = 148.689 miles. 



Azimuth at initial point on Pacific coast = 84° 12' 02". 95 



Azimuth at junction of Gila and Colorado =85° 34' 14''.49 



Length of line of boundary connecting above points = 148.689 miles 



B. 



Detei-minations of houndarij line from tlie Fdo Colorado of the ivest, to the intersection of 

 meridian of longitude, west of Greemvich, and parallel 31° 20' north latitude : By I 

 N. Michler, Topographical Engineers U. S. A. 



I. — Azimuth line — astronomical positions. 



The longitude of the initial point on the Eio Colorado, twenty English miles below its junc- 

 tion with the Gila, as agreed upon by Lieutenant N. Michler, Topographical Engineers United 

 States Army, on the part of the United States, and Francisco Jimenez, first engineer of the 

 Mexican commission, 'on the part of Mexico, was determined to be 114° 48' 44.53" west ot 

 Greenwich. 



This result was obtained by transferring the longitude of the monument near the junction to 

 the initial point, by Lieutenant Michler's triangulation of the 'twenty English miles," the 

 longitude of said monument having been previously obtained from observations by Lieutenant 

 A. W. Whipple, Topographical Engineers, Assistant United States Boundary Survey, deduced 



from corresponding observations at Greenwich. 



o r If 



Longitude of the monument 114 36 22.20 W. of Greenwich. 



Difference of longitude between monument and initial point + 1^ 22.33 



Longitude of initial point 114 48 44.53 



The latitude of the initial point on the Kio Colorado was ° ' " 



found to be 32 29 44.45 North. 



