From Chapter 1:
In the Wallace Collection at Hertford House is a pouch or case labelled as having belonged to and been used by Sir Walter Raleigh. This pouch contains several clay pipes. It was perhaps this same pouch or case which once upon a time figured in Ralph Thoresby's museum at Leeds, and is described by Thoresby himself in his "Ducatus Leodiensis," 1715. Curiously enough, a few years ago when excavations were being made around the foundations of Raleigh's house at Youghal a clay pipe-bowl was dug up which in size, shape, &c., was exactly like the pipes in the Wallace exhibit. Raleigh lived and no doubt smoked in the Youghal house, so it is quite possible that the bowl found belonged to one of the pipes actually smoked by him. In the garden of the Youghal house, by the way, they used to show the tree—perhaps still do so—under which Raleigh was sitting, smoking his pipe, when his servant drenched him. Thus the tradition, which, as we have seen, dates from 1708 only, has obtained two local habitations—Youghal and Durham House on the Adelphi site.

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.