[ 2 7 8 ] 
reafon, concludes, that between thefe two fta- 
tions, where the preffure was changing, at the fame 
time, contrary ways, there mull; have been an inter- 
mediate one, which I call the height of ftationary 
prelfure, where no change, in either fenfe, could 
take place. 
I lhall hereafter Ihew, at what height the place 
of unaltered preffure fhould fall, by theory, for 
every change of temperature. It feems a problem 
worthy of a naturalill:, to enquire how far theory 
doth, in this circumftance, agree with the real ope- 
rations of nature. 
6. It may feem, perhaps, hill more furprizing, 
but it is no lei's true, that there will generally be a 
particular height in the atmojphere where the derifity 
will remain unchanged, by a given change of tempera- 
ture. To determine in what changes this will hap- 
pen, and at what height the place of unaltered 
denfity, for given changes of temperature, Ihould 
fall, requires only the folution of the following 
problem. 
PROBLEM FIRST. 
To find the interfeBion of two logarithm cs , which 
; have a right line given in pofition for their common 
ajpnptote, and their jubtangents given in magnitude ; 
an ordinate in each curve , drawn at right angles 
with the common afymptote, through a given point in it, 
being c iljo given in magnitude. 
IMA- 
