REPORT ON ASTRONOMY AND HYPSOMETRY. 



By Henry Gannett, M. E. 



Washington, D. C, April 11, 1873. 



SiE : I have the honor to submit to you the following report on the 

 astronomical, hypsometrical, and meteorological work of the United 

 States Geological Survey of the Territories during the season of 1872. 



The field-work of the Yellowstone division was conducted by myself, 

 assisted bv Professor B. B. Wakefield, of Hiram College ; Mr. A. E. 

 Brown, and Mr. T. O'C. Sloan e. 



The field-work of the Snake Eiver division was conducted by Mr. 

 Eudolph Hering, assisted b^^ Messrs. Thomas W. Jaycox and W. A. 

 West. Mr, William iSTicholsou was stationed at Fort Hall through the 

 summer taking barometric observations. During the winter he has as- 

 sisted me in the office-work. 



Mr. Hering left the survey early in the spring, shortly before his re- 

 port was completed. I have finished it, and present it in as complete a 

 form as possible. 



The meteorological observations at Fort Hall, and at the camps of the 

 two divisions, I have thought best to print in a volume separate from 

 the report, putting in the report only a few deductions from them. 



I would express my thanks for assistance received from the United 



States Coast Survey, the Navy Department, the Signal Service of the 



United States Army, Captain J. B. Putnam, at that^ time in command 



at Fort Hall, and to General J. E. Blaine, surveyor-general of Montana. 



I am, sir, very respectfully, yours, 



HENRY GANNETT. 



Dr. F. Y. Hayden, 



United States Geologist. 



The astronomical instruments placed at my disposal were: an astro- 

 nomical transit, belonging to the United States Coast Survey, of one 

 and a half inches aperture and sixteen inches focal lengthy a zenith 

 telescope belonging to the United States Coast Survey ; two sextants 

 and artificial horizons j a box-chronometer rated on sidereal time; two 

 pocket-chronometers, the property of the United States Navy, rated on 

 mean time. 



Of these, a sextant and horizon and one of the pocket-chronometers 

 were put in charge of Mr. Hering for use in the Snake Eiver division. 

 The chronometer ran very badly, stopping on several occasions, of 

 course making longitude determinations by it worthless. I append the 

 list of latitudes. 



The pocket- chronometer taken by me got out of order while at Fort 

 Ellis, and was of no use on the trip. 



The latitude of Fort Hall was determined with the zenith telescope 

 by observations on five pairs of stars on three nights. The result, with 

 a probable error of 0".80, is given below. 



Having been disappointed in my plans for determining longitude by 

 telegTaph, where the telegraph was available, I was compelled to resort 

 to moon culminations, whenever the time permitted. 



