VOL. VII.3 PHILOSOPHICAL TRANSACTIONS. S 



The second experiment is, that whereas the effect of a syphon of unequal legs, 

 by which you make the water of a vessel run over, is no longer ascrihed to a 

 fuga vacui, but to the weight of the air, which pressing upon the water of the 

 vessel makes it rise in the syphon, whilst on the other side it descends by its 

 \veight; M. Huy gens found a means to make the water of the syphon run, 

 after the recipient was exhausted of air, and he saw, that with water purged of 

 air* it did the effect as well as without the recipient. The shortest of the leg* 

 of the syphon was 8 inches long, and its aperture, of two lines. And he will not 

 have us doubt, whether the recipient was well exhausted of air; for he did assure 

 himself of that, as well by finding that there came out no more air through the 

 pump, as by other more certain marks. 



And this he takes for a further confirmation of his supposition of a pressing 

 matter more subtle than the air. To which he adds, that if you take the pains of 

 searching, to what degree the force of this pressure reaches, (which he says 

 cannot be better made than by pursuing the experiment with tubes full of mer- 

 cury, yet longer than those employed by M. Boyle,) it will perhaps be found, 

 that this force is great enough to cause the union of the parts of glass and of 

 other sorts of bodies, which hold too well together to be conjoined only by their 

 contiguity and rest, as M. Descartes would have it.-f- 



Extract from Mr. John Templers Letter of March 30, 1672, to Dr. Walter 

 Needham, concerning the Structure of the Lungs. N° 86, p. 5031. 



In answer to the request of an ingenious physician, I was lately engaged to 

 give my thoughts on the structure of the lungs, as follows : — 



I formerly conceived the lungs to be composed of a multitude of vesicles; into 

 "which opinion I was persuaded by inflation in the aspera arteria of fowls ; and 

 observing the continuation of many vesicles extended from the bronchia through 



* M. Huygens has made this experiment, as well with water as with mercury. 



f M, Huygens, though a very great mathematician, in tliis memoir, very unphilosophically, in 

 order to explain the cause of the adherence of certain bodies together, when in close contact, has 

 recourse to the action of a matter, of whose existence there has never been any kind of evidence. 

 The effects in such instances as above-mentioned, have since that time been more rationally ascribed 

 to the attraction of cohesion j a principle which manifests itself whenever bodies are brought into close 

 contact. Hence arises tlie considerable adhesion of two perfect planes: hence the compact and firm 

 adherence of masses of matter : hence the ascent of fluids up the sides of their containing vessels : 

 hence their ascent even in open tubes, to considerable heights, so much the higher as the tubes are 

 smaller: hence the necessity of giving a considerable width to the barometer tubes: hence even a 

 drop of water falls not from a mass without a visible reluctance, &:c. 



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