190 PRIMARY TRIANGULATION AND PRIMARY TRAVERSE. [bull. 216. 
water's edge at this point of the river. Station is about 35 miles by 
the river below Ehrenberg and 30 miles up the river from Picacho. 
Station mark: A bronze triangulation tablet cemented in solid rock. 
[Latitude 33° 20' 19.96". Longitude 114 43' 10.82".] 
To station- 
Azimuth. 
Back azimuth. 
Log. distance. 
Fort Grass . . _ - 
78 36 56.30 
294 22 48.62 
258 35 03.20 
114 27 58.44 
Meters. 
3. 73479 
Chocolate - 
Mulewash ... - - - . 
4. 20491 
4.27211 
Hodges -. -.- 
4. 22373 
No. 17 
3. 55739 
No. 16 
4. 13086 
No. 19 
3. 98436 
NO. ID, SAN DIEGO COUNTY. 
(Not occupied.) 
On the edge of mesa where it bluffs to the Colorado River bottom, 
and is about one-half mile from the river at the nearest point. At the 
lower end of Apache Island the river makes a horseshoe bend to the 
east-northeast; about the middle of this bend the slough forming this 
island rejoins the river. No. 10 is about the middle of the heel of this 
horseshoe. 
Station mark 
placed in ground level with surface 
A bronze triangulation tablet cemented in rock and 
Latitude 33° 15' 13.52". Longitude 114 41' 54.39". 
To station- 
Azimuth. 
Back azimuth. 
Log. distance. 
o 

Meters. 
Fort Gass 
138 54 31.93 
318 51 57.01 
4. 04557 
Chocolate ... 
257 23 58.78 
77 28 26.34 
4.11172 
Lava . ... 
4.17314 
No. 18 
3. 98436 
Quartz 
4. 33563 
NO. 20, SAN DIEGO COUNTY. 
(Not occupied.) 
On summit of a sharp rocky peak about a mile from the Colorado 
River and about the same distance from Draper's ranch at Light- 
house Rock, and bears north 39° west from Mr. Draper's, about 18 
miles up the river from Picacho. 
