for ttieafuring the higher Degrees of Deat^ &c. j r ^ 
IV. The thermometric pieces may be formed much more 
expeditioufly than in the fingle mould, by means of an indru- 
ment uled for fimilar purpofes by the potters. It confids of a 
cylindrical iron veffcl, with holes, in the bottom, of the form 
and dimenlions required. The loft clay, put in the veflel, is 
forced by a prefs down through thefe apertures, in long rods, 
which may be cut while mold, or broken when dry, into 
pieces of convenient lengths. It was hoped, that this method 
would of itfelf have been diffident, without the addition of 
the paring gage, making proper allowance, in the lize of the 
holes, for the fhrinking of the clay in drying. But it was 
found, that a variety of little accidents might happen to alter 
the fhape and dimenlions of the pieces, in a fenfible degree, 
while in their foft date ; fo that it will be always fated to have 
recourfe to the paring gage, for aftertaining and adjuding their 
breadth when perfectly dry, this being the period at which the 
pieces are exactly alike with regard to their future diminithing ; 
fo that if they are now reduced to the fame breadth, we may 
be fure that they will differ equal contractions from equal de- 
grees of heat afterwards, whether they have been made in a 
mould, or by a prefs, or in any other way ; neither is any varia- 
tion in the length or thicknefs of thefe pieces of the lead con- 
fequence, provided one of the dimenlions, that by which they 
are afterwards to be meafured, is made accurate to the gage. 
V. It will be proper to bake the pieces, when dry, with a 
low red-heat, in order to give them fome hrmnefs or hardnefs, 
that they may, if neceflary, be able to bear package and car- 
riage ; but more efpecially to prepare them for being put into 
an immediate heat, along with the matters they are to ferve as 
meafures to, without burdingor flying, as vmburnt clay would 
Vol. LXXII. T t 'do. 
