F. GEOGRAPHY. 241 



present to us a specimen of the whole, the stations in question 

 being chosen as typical stations, and " not selected because 

 of probable errors that are a minimum." Without at present 

 critically discussing the accuracy of the observations, or the 

 propriety of certain arithmetical operations, we must conclude 

 by congratulating Lieutenant Wheeler upon the thorough 

 method and the evident desire for the highest attainable ac- 

 curacy that are manifest in every page of the report; and must 

 express our conviction that if the work undertaken by him 

 be carried on in the spirit in which it appears to have been 

 begun (with only a little less striving after meaningless prob- 

 able errors of unattainable smallness), he will have earned the 

 lasting gratitude of future generations, who will surely ap- 

 preciate better than we can, and better than we can foresee, 

 the value to a civilized nation of an accurate map and a re- 

 liable census of the contents of all its landed possessions. 



MEASUREMENT OF ALTITUDES BY THE BAROMETER. 



The employment of the barometer to the measurement of 

 altitudes has I0112: been recognized as one of the most valua- 

 ble aids to geographical surveys that the physical sciences 

 have as yet afforded ; and although for works in which the 

 highest accuracy is desired the barometer must, as has been 

 shown by Iviihlmann and many others, be replaced by the en- 

 gineer's level, yet for common approximate purposes this in- 

 strument, in one form or another, must always continue to be 

 employed. Its general usefulness, therefore, increases our in- 

 terest in the history of its application to hypsometry; and 

 while Ruhlmann and others have dealt with this question 

 very extensively, and from a purely physical point of view, 

 it is particularly interesting to notice a memoir, historical 

 rather than mathematical in its nature, that has been present- 

 ed to the Academy of Turin by no less a person than Pro- 

 fessor Govi, who has endeavored to secure for Italy the credit 

 of both the invention and the application of the barometer, 

 since it seems that, while Mariotte did not publish his essay 

 on this subject until 1679, the Torricellian tube had been ap- 

 plied still earlier to hypsometric measures by Montanari. 

 Montanari, a name new to American students, was born at 

 Modena in 1033, and died in 1687 at Padua. Govi claims for 

 him the invention of that most beautiful astronomical instru- 



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