112 



Before, however, this conclusion can be considered as 

 fully established, and before we can judge correctly of the 

 amount of the errors by which his table is affected, it will be 

 necessary to inquire Avhether the thermometer I have em- 

 ployed be a true one. This essential inquiry I have been 

 enabled to institute by my friend. Professor Lloyd, who has 

 put into my possession, for the purpose, a thermometer given 

 him by Professor John Phillips, together with a table of 

 differences between it and the standard thermometer belong- 

 ing to the Royal Society. Upon a comparison of the two 

 instruments, I find, that at and about 60°, the thermometer 

 I have employed stands '6 of a degree higher than that lent 

 me by Professor Lloyd, while the latter stands -3 of a 

 degree higher than the standard in possession of the Royal 

 Society ; so that the indications of my instrument are at G0°' 

 9-lOths of a degree higher than the truth. If such be the 

 case, •5457, instead of being the force of vapour at 61°.63, is 

 the force at 6r6.3 — 0*9 = 60°-73 ; and to compare the result 

 of my experiments with the tables of Dalton and Kamtz, it 

 is only necessary to extract from these the values of the force 

 of vapour corresponding to the temperature 60°*73. 



My Experiments. Dalton. Kamtz. 



60°-73 . . -5457 . . . -5361. . . -5157 



Difference between Dalton's number and mine — '0096. 



Difference between Dalton's number and that of Kamtz 

 + •0184. 



The consideration, therefore, of the error of my thermo- 

 meter, and the allowance made for it, only strengthens the 

 conclusion already arrived at ; and I do not now feel any dif- 

 ficulty in giving it as my deliberate opinion, that the table 

 of the force of vapour given by Kamtz is, within the atmos- 

 pheric range of temperature, erroneous, his values being all 

 too low. 



