HENCE moreover it appears, of what a diffused Nature this Contagion may be of, by the great Plenty that transpires from an infected Person; and which Steam alone, as it is sufficient to communicate the Infection, so it is also capable of vast Dilatation and Diffusion; not much unlike the Snuff of a Candle, which not only emits a great deal of Smoak, but carries a considerable Stench along with it into very distant Parts. _SECONDLY_, A fit _Medium_ is very conducive to the Propagation of the Plague; for according to the Disposition of that, in being more or less open or confined, is the Infection sooner or slower communicated: Nor is there any Doubt, but that the Air is this fit _Medium_, and whose Pores, altho’ very minute, are readily filled with it; and therein the noxious _Effluvia_ lodge securely, unless expelled by any external Force. THE Air is moreover the more convenient Recepticle and Conveyance of this pestilential Poyson, on account of that nitrous Spirit with which it abounds; hence it more easily receives the poisonous _Aura_, and faithfully preserves it as in a proper Conservatory, and on this Account the pernicious Qualities, (unless first destroyed by some uncommon Power) sooner reach any Subject to act upon, and float about in Readiness for Destruction: Sometimes also the pestilential _Miasmata_ may be broke and destroyed by the Occursion of others, without any Perception of either having been in this _Medium_. HENCE it comes strongly to be conjectured, how the pestilential _Seminium_ comes to be hid so secretly in the Porosities of the Air, so as to be conveyed from one Country to another, and to travel unperceived into very distant Regions. Further, as this _Medium_ is more still, it is so much the more capable to receive the pestilential Infection; whereupon Places that are close, confined, and dark, as Prisons, and Houses in Vallies, are much more liable to Contagion, than Situations upon Eminencies, where the Air is frequently agitated by Winds; for the malignant _Effluvia_ cannot so well fix in an Air so tumultuously hurried about; and they are likewise rendred less hurtful by a continual Mixture of fresh Air with them. _THIRDLY_, A suitable Disposition of the Subject is very necessary for the Reception of the pestilential Taint; and this Disposition respects either some Fitness in the Pores of the Body, or a long Accumulation of distempered Humours. The more open the Pores are, and the wider, by so much the more easily will the Infection penetrate into the Body; and the more constringed they are, the better Security is there against it, insomuch that hardly by any other Means can it enter.