The purifying action of tobacco-smoke on unwholesome air was fully recognised in Pepys’ time, when during the Great Plague of 1665-6 the pipe was to be seen in almost every mouth. Pepys like others sought protection in the weed, and purchased roll-tobacco to ‘chaw.’ Alas, poor man, it took away his apprehension! In his immortal diary is a note under date, June 7th. 1665: This is the hottest day that I ever felt in my life. This day, much against my will, I did in Drury Lane, see two or three houses marked with a red cross upon the doors, and, ‘Lord, have mercy upon us,’ writ there, which was a sad sight to me, being the first of the kind that to my remembrance I ever saw. It put me in an ill-conception of myself and my smell, so that I was forced to buy some roll-tobacco to smell and chaw, which took away my apprehension. Clearly Pepys was not a ‘tobacconist,’ but surely he should have known better than to have ‘chawed’ the black twist. Dr. Willis, physician in ordinary to Charles the Second, speaks highly of the valuable antiseptic properties of tobacco. In his work entitled, _A Plain and Easy Method of Preserving (by God’s Blessing) Those That are Well From the Infection of the Plague_ (1666) he remarks upon the exemption from the pestilence of houses where tobacco was stored for manufacture or sale. Nor indeed were those persons affected who smoked tobacco, especially if they smoked in the morning, a time when the body is more susceptible to outer influences than it is later in the day. For the smoke of the plant secures those parts which lie most open, namely, the mouth, nostrils, etc., and at once intercepts and keeps the contagion that floats in the air from the brain, lungs, and stomach. It also stirs the blood and spirits all over, and makes them throw off any contagion that may adhere to them. In another treatise on the subject Dr. Willis makes equally shrewd remarks on the use of tobacco among soldiers and sailors. He says, ‘Tobacco taken in the vulgar way at the mouth through a pipe has effects not only manifold but diverse,’ and he explains that its use, when it may be had, seems not only necessary but profitable for soldiers and mariners, for that it renders them both fearless of any danger, and patient of hunger, cold, and labour.’ Army experiences of recent years bear testimony to the beneficial use of tobacco in almost the same words.