[ S°6 ] 
vifed; whereby, parting very gradually, in the Space 
of Tome Hours, through what is called the Leer, 
from a very intenfe Degree of Heat to the Tempe- 
rature of the common Air, they were found to acquire 
fuch a Toughnefs or Tenacity, as fitted them for the 
feveral Ufes for which they were refpe&ively de- 
signed. 
But Some of the ‘Phenomena depending upon their 
firft Brittlenefs, or at leaft very nearly connedted 
with it, have been often judged to deferve the At- 
tention of the Curious. One of the firft very worthy 
Founders of the Royal Society , the Right Honourable 
Sir Rob. Moray , very early gave in his Experiments, 
which appear in the Regifter, upon thofe Drops or 
Lachrymre of darts, which, inftead of being nealed, 
had been immediately quenched in Water, or fome 
other Fluid. And the fame learned Perfon further 
obferved, that hollow Balls, made of unnealed Glafs 
with a Small Hole in them, would flie in Pieces with 
the Heat of the Hand only, if the Small Hole, by 
which the internal and external Air communicated, 
was but flopped with the Finger. 
The Glafi.es which the following Paper concerns, 
have been already mention’d to the Society by Mr. 
Baker i who, on the 3 1 ft Day of January laft, com- 
municated the Extradf of a Letter he had then newly 
received from Dr. Laur entiles Bruni of Turing taking 
notice of the fame ; and relating their remarkable 
Property of refilling very hard Strokes that were given 
them from without, notwithftanding they at the fame 
time fhivered to Pieces, upon the Shocks they received 
by 
* See thefc Tranjaffions) N°. 475, p. 272. 
