From Chapter 4:
From the various entries in the "Diary" relating to the purchase of tobacco, it seems clear that there was no shop in Exeter devoted specially or exclusively to the sale of the weed. Hayne bought his supplies from four of the leading goldsmiths of the city, who can be identified by the fact that he had dealings with them in their own special wares, also from two drapers, one grocer, and four other tradesmen (on a single occasion each) whose particular occupations are unknown.

From Chapter 8:
The allusion in these verses to a "satiric wipe" refers to a passage in the poem entitled "Conversation," which Cowper had written in the previous year, 1781. In this passage tobacco is abused in terms which Cowper clearly felt to need modification after his personal intercourse with such a smoker as his friend Bull. In describing, in "Conversation," the manner in which a story is sometimes told, the poet says:

The pipe, with solemn interposing puff,
Makes half a sentence at a time enough;
The dozing sages drop the drowsy strain,
Then pause and puff—and speak, and pause again.
Such often, like the tube they so admire,
Important triflers! have more smoke than fire.