228 MEASUREMENT OF HIGH TEMPERATURES. | bull. 54 
^^TOOO {l + aT) 2= ~ 6M 
(l+atf T __ (l+aty 
0l ~ 1000 (1 + aT) 2 a 0M 
*m_ (l+^i) 2 T v^ + aTtfdM 
«""iooo [/(To— /(*')] (i+.«T) 2 --[/(ro- /(*')f j¥ 
ai; 2 T v 2 SM 
6v 
lOWfiTJViil+aT)*-- l "/(T 1 ) F, 
tfa= 
1000 
*/) 
10001+ a '/' 
V/^~1000/(f) /(*) 2 - iooo V i> fit) J 1 ) 
These forms have a more general importance, inasmuch as they sho^ 
what correction is to be applied to T to compensate for unavoidable o 
current errors of any of the special quantities to which the formulae r* 
fer. Such errors, for instance, are the permanent changes of volum 
of the porcelain bulb in successive heatings, and due to the vitrificatil 
of porcelain. The correction to be applied is 
6T= _fAI^ YAl+aTfdv. 
av 2 v ' 
Y\ 
It is well to remark that — in the above equations has approxi 
mately the value 
v~ /(T 1 )(l+a:T) , 
since for the present purposes t and T x may be supposed identical 
(882) 
