PHILOSOPHICAL 
TRANSACTIONS. 
XIII. Description of a thermometric al barometer for measuring 
altitudes. By the Rev . Francis John Hyde Wollaston, B. D, 
F. R. S. 
Read March 6 , 1817. 
Having had my attention drawn, some years ago, when 
engaged in experimental Lectures at Cambridge, to the vari- 
ations in the heat of boiling water as corresponding with the 
changes in atmospherical pressure and the height of the 
barometer, I constructed several very sensible thermometers, 
for the purpose of ascertaining these variations with minute- 
ness, and have been led on by my observations into making 
an instrument, which I believe may be useful in measuring 
heights with greater accuracy and convenience than the com- 
mon barometer. This is not proposed as a new idea, for I 
find that Fahrenheit has suggested it- in his “ Barometri 
novi description Phil. Trans. Vol. 33, p. 179, and also Mr. 
Cavallo, Phil. Trans. Vol. 71, p. 524. But the instrument is 
carried farther than had been done by them. 
At first my thermometers were made with different scales 
MDCCCXVII. B b 
