236 Mr Anderson’s Corrections for the Effects of Humidity 
below the temperature of the air. We thus obtain f— -704 and 
f' — ’528 ; and the several co-efficients determined, as before, 
are, in their order, 10,000, 1*07614, 1*02331, and *042980. 
The height, from these data, is 2839*8 feet, differing only 3f 
feet from the former result, and 8J feet from the geometrical 
height. The height deduced by De Luc’s rules is 68 feet in 
defect, being 12 feet less than before, on account of the greater 
dampness of the atmosphere. By a compensation of errors, the 
height computed by the common formula is 2828 feet, which 
is only 3/^ feet in defect. 
With regard to the degree of accuracy that can be supposed 
to belong to the geometrical measurements of Mount Saleve, as 
given by Sir G. Shuckburgh, it may be proper to state, that all 
the requisite data seem to have been determined with the most 
scrupulous care ; and, though the results do not accord exactly 
with each other, the height being 2828*45 feet, by one series of 
observations, and 2835*07 feet by another, it is probable that 
the mean of the two, 2831*3 feet, is within 4 feet of the truth. 
Of these results, however, the latter, having been deduced in a 
more direct manner, is perhaps more entitled to confidence. 
The error in the data furnished by the barometers, could not, 
according to the estimate of Sir G. Shuckburgh, exceed *008 of 
an inch, though all the errors were on one side ; but, as this 
might have produced a difference of upwards of 8 feet in the 
computed height, it cannot, under all these circumstances, be 
expected that the altitude deduced from the barometrical obser- 
vations, should coincide within less than 10 or 12 feet of the as- 
signed geometrical height. 
Having thus shewn that the formula, when applied to the 
observations of Sir G. Shuckburgh, affords results which agree 
as closely as the nature of the data permits, with the heights 
computed by the geometrical method, I shall now apply it to 
some of the barometrical observations of General Roy, selecting 
only such examples as are distinguished by some peculiarity in 
the hygrometric condition of the atmosphere, or such as afford 
results, when solved by the common formula, that differ consi- 
derably from the true height. 
The first example I shall take is contained in the 67th vo- 
lume of the Phil. Trans., entitled, “ No. IV. Computations of 
