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XXII. Additional Obfervations on making a Thermometer for 
meafuring the higher Degrees of Heat . By Mr e Jofiah 
Wedgwood, P . R, S. and Potter to Her Majejly, 
Read June 22, 1 7 86 . 
M Y thermometer for meafuring the higher degrees of heat 
having been honoured with the notice of this illuf- 
trious Society, I now requeft a further indulgence for a few 
more obfervations on the fame fubje&v 
In my firft Paper * I communicated every thing that expe- 
rience had then taught me, refpedting both the conftruCtion and 
life of this thermometer ; but more extenfive practice has finco 
convinced me, that other managements and precautions are 
neceflary, in order to bring it to the perfection it is capable of 
receiving : for pieces made of the fame clay, and exactly of 
the feme dimenfions, have been found to differ in the degree of 
their diminution by fire, in confequence of feme circumftances 
in the mode of their formation, at that time unheeded, and; 
very difficult to be developed. 
Of the two ways propofed for forming them, the mould 
and the prefs, the former was made choice of, as being, for 
general ufe, the moil commodious. The foft clay was prefled 
into a fquare mould with the fingers ; and the pieces* when 
dry, were pared down on two oppofite fides, by means of a 
* Ehilofophical Tranfa&ions, Vol, LXXIL 
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