1;I4 Mayow 



the glass first described has been placed. And let the- 

 orifice of the glass in which the air is, be placed in 

 the orifice of the other glass filled with water, as is 

 seen in Plate V., Fig. 5 (care being taken that the 

 mouth of neither of the glasses is raised above the 

 surface of the water), and let the glass be inclined 

 until the air contained in it escapes and ascends into 

 the other glass, which can in this way be filled with 

 that air, although it is enough that a little of the air 

 be introduced into it. 



And now the glass into which the air is transferred 

 in this manner, is to be enclosed in another glass from 

 which the air may afterwards be pumped by Boyle's, 

 air-pump, which may be done in this way. Let a 

 vessel, not too large, but capable of admitting the 

 orifice of the glass in which the air has now been 

 collected, be put under it, and then let this vessel 

 filled with water be removed, with the other glass 

 inverted and resting upon it, and be put inside the glass, 

 from which the air is to be pumped out. After the 

 air has been partly exhausted, the air enclosed in the 

 said glass will expand beyond the cavity of the glass, 

 and most of it will escape through the underlying 

 water. When the air has been removed as far as 

 possible by the pump, let it be permitted to enter 

 anew. When this is done the water in contact with 

 the glass in which the aforesaid air is, will be driven 

 up into it on account of the pressure of the atmo- 

 sphere and will almost entirely fill it. For the air 

 which was left in that glass will occupy only a part 

 of the narrower glass ; and yet that small portion of 

 air, a moment ago, when the pressure of the sur- 

 rounding air was almost withdrawn, occupied the 

 whole glass, and was able to resist the pressure of the 

 surrounding water, and also of the air which could 



