fi Of the Cauje of a Pe/Mence, fdn and Experience j and after I have" enu- merated the Conditions of a contagious Exertion, I doubt not but to make this Matter clear to every one. FOUR Things chiefly are neceffary to a Contagion: FIRST, That there ii an Efflux of the contagious Seminium, SECONDLY, That there is a conve- nient Medium for the contagious Particles to move through, and be conveyed by. THIRDLY, A Fitnefs in the Sub/eft to receive and cherifh. the contagious Efflu- via, And, EOVRTHLY, A due Stay of this Se- minium j of all which diftinftly. THE Quantity of NecefTaries daily taken in for Refreshment does evidently demonftrate, that infenfible Perfpiration is much larger than all other Evacuations together : But where a Peftilence invades, a yet much greater Waft, is made that Way than in a Time of Health, by the interline
