fhe “~ : Pi — d * } a “ : “4 
364 ! Litionmieont $ Method. of connetting — a A 
fome time in er water, of the ccc 50° of Fan 
RENHEIT: the point which the piece went to in this cold ftate 
is that marked o near the narrow end of the gage. The ad-_ 
juftment is re-examined at the beginning and end of every fuc- 
ceeding experiment, left the repeated attrition, in fliding the 
eer backwards and forwards, fhould wear off fo much, from 
the furface of this foft metal as to occafion an error in the mim. 

o% eg 
nute’ quantities here meafured. 
The apparatus is then expoied fucceflively to different acre 
of heat, with the piece lying always in a part of the canal at” 
leaft as wide as it is expected to fll when expanded, otherwife 
the fides of the gage would be burft afunder by its. .expanfion, ’ 
as 1 experienced in fome of my firft trials. When the whole: 
has received any particular degree of heat defired, the piece is: 
cautioufly and equably pufhed along, tll it is ftopped by the 
convergency of the fides, of which L always find notice given 
me by the gage itfelf (which is {mall and light) beginning to 
move upon the continuance of theimpulfe. A flat flip of iron, 
a little narrower than the piece, bent down to a right-angle at’ 
one end, and fixed in a long handle at the other, makes, a con- 
venient inftrument for pufhing the piece forward, or drawing it) 
back again, whilft red-hot: this inftrument, at every time of 
ufing, is heated to the:fame degree as the piece itfelf. 
The heat of boiling water is taken without difficulty, by. 
keeping the apparatus in boiling water itfelf during a fufficient’ 
{pace of time for the full heat to becommunicated to it. The,” 
water I made ule of was a very fine {pring water, which on) 
chemical trials appeared very nearly equal in purity te that of 
rain or fnow; and Lhad previoufly fatisfied myfelfy by trials in) 
the cold, that the gage and piece being wet, or under water, 
made no difference in the meafurement. The expanfion of the 
3 filver 
