No. 50.J 
329 
correction produced much more uniformity in the results of observa- 
tions made at any one point than appeared without it. This correc- 
tion hkewise provides, to some extent at least, for any error which pos- 
sibly may exist in the ordinary valuation of the effect of the tempera- 
ture of the air upon the calculated elevation, or of its hydrometrical 
state so far as it may be indicated by this temperature, which at the su- 
perior station differs but little from T. The formula therefore used is 
h — p -\- (451 — a) X 0,021 x (16 — T), in which h represents 
the true difference of level between the stations in metres, p this diffe- 
rence, according to the tables of Oltmanns, a the upper reading of the 
superior barometer, and T the temperature indicated by its attached 
thermometer. 
The additional correction which I applied to the elevations of Lake 
Golden and Mt. Marcy is 12 ( — m + + n — n^), in which wz, m/, 
are the first members of the conditions (1), (2) ; and n, n\ the second. 
A slight correction for capillarity, of about three-tenths of a millime- 
tre, I deducted from the correction 2 . 50 in the 7 observations made 
during my first visit. 
Oltmanns' tables have been employed in these calculations, which 
have furnished, in the cases in which I have compared them, the same 
results as those derived from La Place's theorem. An example of 
this agreement appears in the calculation of the height of Mt. Marcy. 
I have not seen the construction of these tables, but conjecture from 
this agreement, that La Place's theorem was made their base. Hum- 
boldt, who made his calculations according to the theorem, mentions 
the harmony of his results with those of the same heights by Prof. 
Oltmanns, and pronounces the tables of the latter to be of the utmost 
precision." 
[Assembly, No. 50.] 42 
