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 8:
Notwithstanding the unfashionableness of tobacco, there were still some noteworthy smokers to be found among the clergy. Dr. Sumner, head master of Harrow, who died in 1771, was devoted to his pipe. The greatest of clerical "tobacconists" of late eighteenth century and early nineteenth century date was the once famous Dr. Parr. It was from him that Dr. Sumner learned to smoke. When he and Parr got together Sumner was in the habit of refilling his pipe again and again in such a way as to be unobserved, at the same time begging Parr not to depart till he had finished his pipe, in order that he might detain him, we are told, in the evening as long as possible.