66 Mayow 



must be bent before it is broken ; whence it follows 

 that the matter contained in the beak undergoes com- 

 pression anew, as was shown above to happen when 

 rigid bodies are bent. Hence the subtle matter, com- 

 pressed by the bending of the beak, strikes against all 

 the adjoining particles of the glass ; but since the 

 external surface of the glass is more compact and solid 

 than its interior parts (for when these globules are 

 formed, the heated and melted glass is dropped into 

 cold water, so that the external surface is cooled 

 quickly by the water while the internal parts cool 

 more slowly), it comes to pass that the compressed 

 subtle matter can more easily make a way for itself 

 into the globular part of the glass, as being less com- 

 pact, than break through the more solid surface of the 

 glass. And this may 'also be inferred from the fact 

 that the glass beak can be bent much more and is 

 broken with greater difficulty than glass under other 

 conditions. And the reason of this seems to be that 

 the subtle matter which, when compressed under other 

 conditions and about to make its escape, bursts through 

 the particles of the bent glass and drives them out 

 with violence, now takes its way into the globular part 

 of the glass (the pyramidal shape of the glass con- 

 tributing not a little to this) : but the particles of the 

 subtle matter when pushed from the beak into the 

 globular part of the glass, effect a greater compression 

 there, and in consequence the whole glass is violently 

 and most minutely fractured. For as under other 

 conditions, if glass or any rigid body is broken, the 

 parts about the middle, where the matter is most 

 compressed, are broken into small pieces and fly 

 asunder, so the matter in the glasses here discussed, 

 being everywhere compressed, bursts all over. 



