The Senfation of Sound is frequently felt at amuch greater diftance from the founding, thanthat of Smell ever is from the odoriferous body.The vibrations of the founding body, however,are fuppofed to produce certain correfpondent vi-brations and pulfes in the furrounding atmofphere,which being propagated in all directions, reachour organ of Hearing, and produce there theSenfation of Sound. There are not many philofo-phical doClrines, perhaps, eftablifhed upon a moreprobable foundation, than that of the propaga-tion of Sound by means of the pulfes or vibra-tions of the air. The experiment of the bell, which,in an exhaufted receiver, produces no fenfibleSound, would alone render this doChine fome-what more than probable. But this great proba-bility is ftill further confirmed by the computa-tions of Sir Ifaac Newton, who has fhown that,what is called the velocity of Sound, or the timewhich paffes between the commencement of theaction of the founding body, and that of the Sen-fation in our ear, is perfe&ly fuitable to the ve-locity with which the pulfes and vibrations ofan elaftic fluid of the fame denfity with the air, arenaturally propagated. Dr. Franklin has made ob-jections to this doflrine, but, I think, withoutfuccefs.

Such are the intermediate caufes by whichphilofophers have endeavoured to connect theSenfations in our organs, with the diftant bodieswhich excite them. How thofe intermediate cau-fes, by the different motions and vibrations which