184 Mayow 



Others a^ain suppose that the air about the chest, 

 pushed forward by its expansion, propels that which is 

 next it, and this again the next ; and that so the pro- 

 pulsion goes on, and thus at last the air near the 

 mouth is driven into the lungs. 



But indeed this view assumes that every place is 

 full and that this immense space cannot admit any 

 additional air, however little. But there is no reason 

 for having recourse to this fulness when the thing can 

 be and ought to be explained otherwise ; for we may 

 believe that propulsion of that kind cannot take place 

 in air, as it is a fluid and easily moved. But this will 

 be made clearer by the fullowing experiment. For 

 let us suppose that the narrow neck of a large enough 

 glass vessel is put into pne's mouth ; then, the nostrils 

 being firmly closed, let the air be sucked from the 

 glass and drawn into the lungs, which will certainly 

 happen if inspiration begins, the chest being dilated. 

 But certainly in this case, such a propulsion of the 

 air from the thorax to the lungs cannot be propa- 

 gated, because of the interposition of the glass. 

 But perhaps you will say that some more subtle 

 matter passes through the glass and is pushed into 

 the thorax, and that this serves as material for respira- 

 tion. But indeed if the case were so, how could it be 

 explained that a small animal shut up in a completely 

 closed glass will soon die, if particles suitable for 

 respiration still pass through the glass ? 



With respect, then, to the entrance of the air into 

 the lungs, I think it is to be maintained that it is 

 caused in the following manner by the pressure of the 

 atmosphere. For as the air, on account of the weight 

 of the superincumbent atmosphere, not only rushes 

 into all empty places, but also presses forcibly upon 

 whatever is next it (as Boyle's experiments have put 



