C 5 ” J 
One of thofe Pellets alfo that Boys play with, and 
which they commonly call Marbles, broke a Glafs into 
which it was dropped ; but not till four Minutes after 
its Fall. 
Being defirous to know if the Bodies upon which? 
I relied my Glalfes contributed any thing to the Eafe 
of their breaking, I repeated the fame Experiments,, 
holding the Glalfes in my Hand, fetting them upright 
in Clay, placing them on a Down Pillow, and put- 
ting them in Water ; in ail which Cafes they broke 
in the very fame Manner. I then half filled one of 
them with Water, and a Piece of Flint, about the 
Size of a Pea, broke it. 
All the Bodies with which I had yet broken Glalfes 
having been elaftic without being dudile, I was willing 
to inquire, if thofe Qualities were elfentially necelfary,. 
tho’ I was already fatisficd, that all the Bodies that 
had thofe Qualities, fuch as Ivory, for Example, 
would not produce the Effed. After many Trials, 
none of which fucceeded, I thought of {lightly 
rubbing the Bottoms of fome of the Glalfes with my 
Finger, and all thofe upon which I made that Expe- 
riment broke; tho' fome of them did not fly till 
above half an Hour after they had been fo rubbed. 
Thinking, that perhaps the Heat I communicated 
to them with my Hand might occafion their 
breaking, to examine whether it was fo or not, I 
poured into feveral fome almoll boiling Water,, 
which certainly gave them a much greater Heat than 
I could have given them with my Hand ; but none 
of thofe Glalfes broke. 
I have found in the Animal Kingdom but one 
fort of Bodies capable of breaking thefe Glalfes,, 
4. which* 
