F. GEOGRAPHY. 303 



more than a hundred feet too low. Omaha is raised about 

 thirty-one feet, and Indianapolis about one hundred. The 

 range between the determinations of the elevations of vari- 

 ous points is as follows : Lake Ontario, two determinations, 

 a range of 3j feet ; Lake Erie, five determinations, a range 

 of 2^ feet ; Lakes Michigan and Huron, nine determina- 

 tions, a range of 5 feet ; St. Louis, five determinations, a 

 range of 7 feet; Omaha, five determinations, a range of 23 

 feet; Kansas City, four determinations, a range of 10 feet; 

 Denver, three determinations, a range of 6 feet. Hayderts 

 Annual Report for 1873, p. 638. 



HYPSOMETKY IN CALIFOENIA. 



The use of the barometer in measuring altitudes in the 

 interior of this continent has received excellent aid from the 

 tables and investigations of Mr. Pettee, of Cambridge, Mas- 

 sachusetts, under the charge of Professor Whitney, state 

 geologist of California. The work of Professor Whitney, 

 besides containing an abstract of all the important publica- 

 tions relating to this subject, gives in detail the steps by 

 which he has been able to compile an empirical table which, 

 he says, may be used with advantage for California, and 

 possibly for the whole of the Rocky Mountain region. The 

 first requisite in the investigation being the accumulation 

 of trustworthy observations, Professor Whitney found it 

 necessary to establish stations in care of the telegraph op- 

 erators on the line of the Central Pacific Railroad, supply- 

 ing them with all auxiliary apparatus. These stations were 

 maintained for three years, although with considerable 

 breaks in the continuity of their record. The elevation of 

 the highest point was seven thousand feet above the sea, 

 and that of the lowest point only twenty or thirty. Among 

 the conclusions that Professor Whitney draws from his ob- 

 servations, we mention that the resulting altitudes are al- 

 ways lower as computed from morning and night observa- 

 tions than at mid-day. They are also lower in winter than 

 in summer, when the lines are based upon the mean of all 

 the observations of any day. The results are found at some 

 stations to approximate most closely to the truth in Febru- 

 ary, September, and October; at other stations in March, 

 April, and September. The 7 A.M. and 9 P.M. observations 



