8S Mountains in New York, 



r 



which sustains the column of mercury, arising from fluctuations, 

 that are independent of temperature, and for which no provision 

 is made in most formulas, and the discrepancy in the resiiUs as 

 given by different formulas, all claiming to be equally correct. 



Errors from these sonrces when they occur so as to affect the 

 result differently^ may neutralize each other, but when they ope- 

 rate the same ivay^ may produce a very considerable deviation 

 from the truth. In the observations of Mr. Emmons, the barome- 

 ter at Whiteface was compared with the barometer at Burlington 

 and Albany, and if I rightly understand him, the mean of the two 

 was taken, the difference being about 100 feet less at the former 

 than at the latter. The time of making the observations was 6, 

 A. M. of the same day, Sept. 21. In the record which he gives 

 of the state of the barometer at the two latter places at noon of 

 the same day, the fact is made known that while the baromet- 

 ric column fell at the one place it rose at the other, causing a 

 diAerence equivalent to upwards of 100 feet of elevation. Com- 

 pntiiig the elevation of the place of observation at Burlington at 

 6, A, M. above tide from the observation at Albany at the same 

 time, and it gives 500 feet, nearly. Taking the observations 

 made at the same places at 12, M. of the same day, and the re- 

 sult is 390 feet, nearly. Which of these is correct, or whether 

 either is only known from the fact that the elevation in question 

 has been ascertained by the common mode of levelling to be 373 

 feet, nearly, giving a maximum deviation from the truth in two 

 observations only, of 128 feet, nearly. In the case of the obser- 

 vation on the summit of Whiteface, there exist no data by which 

 the relative conditions of the atmospheric column as compared 

 with the same column at Burlington and Albany can be ascer- 

 tained. 



Whiteface is about 35 miles west of Burlington, the nearest of 

 the points mentioned, but far enough, it is believed, for consider- 

 able difference to exist. But one observation is recorded as hav- 

 mg been made on its summit and that not under the most favor- 

 able circumstances, since it is stated that the ''wind was strong 

 from the northeast and cloudy." In the case of Mt. Marcy, the 

 comparison was made with the barometer at Albany. In conse- 



quence of the greater distance of the places of observation, a much 



greater error might result than in the case of the observatior]S-at 

 Whiteface and Burlington. That the greater discrepancy be- 

 tween the barometric and trigonometric elevations of Mt. Marcy 



