INTRODUCTION.

XV

The motion and circulation of the blood is mani-festly connected with our breathing. For everybreath extends and contracts our lungs ; and by thismotion I conceive the valves of the heart are keptin operation; and every spring of the arteries andbeating of the pulse are exactly in proportion to theoperation ot the lungs. When the breath is let out,

the breath into the lungs, and there it either poisons, orpropagates its kind, so as to produce that dreadful dis-ease. This, he was confirmed, was likely to be thetruth, from the experiments frequently made at Gibral-tar. For there, said he, they of the garrison, whenthey fear the plague, have a way to elevate a piece offresh meat, pretty high in the air ; they put it up atnight, and if it comes down sound and sweet in the morn-ing, they conclude there is no danger of the plague.But if the plague is in the air, the meat will be taintedand spoiled, and sometimes almost rotten.

" He was farther confirmed in his opinion of the insect,because in and about tobacco ware houses, the plaguehas never been known." I will remark. Now it is wellknown that tobacco will prevent moths from eating ourwoolen clothes, if we pack but a little of it with them,that is, the moth cannot breed nor exist, where there is asufficient scent of the tobacco—this scent may be deathto the invisible insect even after they are drawn in withthe breath and fastened upon the lungs. This may ac-count for tobacco being burned (as I have heard it is) inmany old countries, on a chaffing dish in a room, that thepeople of the house may take in the smoke plentifullywith their breath, to preserve their health and preventpestilential disorders.

Agreeable to this view, we may conclude that alltainted air may bring disease and death to us. And thothe plague has never been (properly speaking) in Ame-rica, as we know of. Yet other effluvia taken in withthe breath may have occasioned other fearful diseases :such as the yellow*fever, and other bilious and contagi-ous complaints.