meafuring Heights with the Barometer. 695: 
expected, nor any way fo great as to render the refearch 
fruitlefs : for a few of that kind being thrown out of the 
total number, the mean of the others, which were very 
confiftent among themfelves, ferved to prove beyond the 
poffibility of doubt, that the expanfions of common air 
did not keep pace with the dilatations of quickfilver., 
The manometrical fpace, anl'wering to the 20° of the 
thermometer between 5 2 0 and 7 2 0 , was always found to 
be greater than any other 20° of the fcale. Here it is to- 
be underftood, that I do not pretend to have afcertained 
the exaft point in that fpace where the maximum falls : 
the mean correfponds to the 6 ad degree, and yet I am 
inclined to think that it is fomewhat lower, perhaps it 
may be about the 57th: from this point, the condenfa- 
tions of air downwards, and its expanfions upwards, fol- 
low a diminilhing progreflion, compared with the con- 
denfations and dilatations of quickfilver. The mano- 
metrical are equal to the thermometrical fpaces, in two 
points of the fcale; namely, at or near the freezing tem- 
perature on one fide, and between the ua° and 13 ad 
degrees of the fcale on the other. At the zero and boil- 
ing point they are lefs than the thermometrical fpaces. 
Whether this maximum of expanfion of air, compared , 
with that of quickfilver, be owing to moifture, or any 
thing 
