From Chapter 2:
A curious feature of tobacco-manners among fashionable smokers of the period was the practice of passing a pipe from one to another, after the fashion of the "loving cup." There is a scene in "Greene's Tu Quoque," 1614, laid in a fashionable ordinary, where the London gallants meet as usual, and one says to a companion who is smoking: "Please you to impart your smoke?" "Very willingly, sir," says the smoker. Number two takes a whiff or two and courteously says: "In good faith, a pipe of excellent vapour!" The owner of the pipe then explains that it is "the best the house yields," whereupon the other immediately depreciates it, saying affectedly: "Had you it in the house? I thought it had been your own: 'tis not so good now as I took it for!" Another writer of this time speaks of one pipe of tobacco sufficing "three or four men at once."

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.