Journal 26 McBoll Ojo Sajuna, Chihuahua, 5000 ft. el. Mexico. March 16. Returned from Chihuahua at 4 p.m. - did not go to the field Elevation - Jon Christman told me that there was some uncertainty regarding the elevation of this camp. I checked my altimeter on leaving camp and on reaching Chihuahua 1/2 hrs. later. And again on our return, when we left Chihuahua and when we reached camp. Going to Chihuahua our altimeter registered a drop of about 350 feet and on the return a gain of about the same amount. Our A&P basket gives the altitude of Chihuahua as 4593. If we add 350 feet to that we get Ojo Sajuna (altitude) of a prop. 5000 ft. My altimeter seems to be somewhat too much but difficult to read closer than estimated 100 feet. Later notions lead - I believe my altimeter is too much but difficult 16. A, B, Trees in leaf and bird singy in Chihuahua. Makes it appear that Chihuahua is considerably lower than Ojo Sajuna but that one may be due to the fact.