Mountains in New York. 87 
tioned. It is granted that it is possible he may be after all nearest 
the truth, but so long as the evidence in the case is more against — 
than for such a conclusion, his claim to superior accuracy cannot 
be allowed. Capt. Partridge has had perhaps more experience 
than any other individual in the United States in measuring 
mountain elevations with the barometer. In two measurements 
made by him of Mt. Washington in New Hampshire, the first 
gave 6,103 feet and the second 6,234 feet. The measurement 
of the same mountains by Prof. Bigelow, as computed by Prof. 
Farrar of Cambridge, gave as the height above tide 6,225 feet, 
a coincidence somewhat remarkable, considering the very great 
elevation of Mt. Washington. 
'. Emmons states that the distance from Mt. Marcy to White- 
face is about 16 miles, and that the depression of the latter from 
the former is 15 minutes of a degree. If the instrument used by 
Mr. Emmons in taking this angular depression was a suitable one 
and in a proper state of adjustment, and if he is correct as to the 
distance, the difference in elevation of those two summits would 
have been obtained therefrom with more accuracy than from the 
barometrical measurements. No one capable of appreciating all 
the causes of error in the two modes of measurement would prob: 
ably deny this. Assuming, therefore, the data above given as 
Correct, of which I cannot but express some doubt, it gives a dif- 
ference in elevation of the two peaks of 578 feet, nearly, whereas 
the difference shown by Mr. Emmons’s barometrical measure- 
Ments is 739 feet, or nearly 30 per cent. greater, being nearly as 
Much greater as the result by my measurement is /ess, showing 
that, if the 578 feet is taken as the standard, there is about as near 
‘1 approximation to the truth in the one case as in the other. 
The barometer I consider a very valuable instrument, and have 
made much use of it, as being a cheap and expeditious mode of 
ativing at an approximate knowledge of the generak features of a 
Country ; but that it will afford, by a single observation, in the 
of practiced or unpracticed observers, and under all cireum- 
Stances, resnits as much to be depended on for their accuracy as 
a be inferred from Mr. Emmons’s statement, cannot be con- 
: The principal sources of error in the use of this instrument are 
MS great liability, particularly the mountain barometer to get out 
pe i. The difficulty also of arriving at a correct knowledge 
oy change of pressure, or condition of the atmospheric column 
