From Chapter 1:
It may further be added that though the use of tobacco was known and practised on the continent of Europe for some time before smoking became common in England—it was taken to Spain from Mexico by a physician about 1560, and Jean Nicot about the same time sent tobacco seeds to France—yet such use was exclusively for medicinal purposes. The smoking of tobacco in England seems from the first to have been much more a matter of pleasure than of hygiene.

From Chapter 5:
When plague was abroad even children were compelled to smoke. At the time of the dreadful visitation of 1665 all the boys at Eton were obliged to smoke in school every morning. One of these juvenile smokers, a certain Tom Rogers, years afterwards declared to Hearne, the Oxford antiquary, that he never was whipped so much in his life as he was one morning for not smoking. Times have changed at Eton since this anti-tobacconist martyr received his whipping. It is sometimes stated that at this time smoking was generally practised in schools, and that at a stated hour each morning lessons were laid aside, and masters and scholars alike produced their pipes and proceeded to smoke tobacco. But I know of no authority for this wider statement; it seems to have grown out of Hearne's record of the practice at Eton.