C 59 s 1 
the fame difappointment, even in recent wounds, that 
are made upon difeaied parts So that I think it may 
be reafonably quedioned, whether I fhould not have 
met with the like difficulty in this fubjed, had I at- 
tempted to fecure the veffels by ligatures. 
Hatton-Garden, Thurfday 
May 23, 1754. 
LXXIX. Defcription of a new Pyrometer , 
with a Table of Experiments made there- 
with. By Mr. J. Smeaton, F. R. S. 
Read May 23, A S it may tend to illudrate the fol- 
1/54 t \ lowing account, it may not be im- 
proper to make mention of the properties, that a com- 
plete indrument, for meafuring the expanfions, that 
metalline bodies are fubjed to by heat and cold, ought 
to be endowed with. 
And, fird, fince the quantities of thofe expan- 
fions muft be proportionable to the length of the bar 
to be meafured ; the longer the bar, the more fen- 
fible the expan fion : And therefore fuch a condrudion 
is befl, as (cceteris paribus) will admit of the longed 
bar. 
Secondly, That the fcale, whereupon thofe minute 
alterations are to be meafured, ought to be, at lead, fo 
large, that the fmalled change in the length of the 
bar, which the indrument is capable of being with 
certainty affeded with, ought to be perceiveable 
thereon. 
Thirdly, 
