From Chapter 4:
In this "Diary," covering the years 1631-43, there are some forty entries concerning the purchase of what is always, save in one case, called "tobacka." These entries give valuable information as to the prices of the two chief kinds of tobacco. One was imported from Spanish America, which up to 1639 Hayne calls "Varinaes," and after that date "Spanish"; the other was imported from English colonies—chiefly from Virginia. The "Varinaes" kind, Dr. Brushfield suggests, was obtained from Varina, near the foot of the range of mountains forming the west boundary of Venezuela, and watered by a branch of the Orinoco River. Hayne also notes the purchase of "Tertudoes" tobacco, but what that may have been I cannot say. From the various entries relating respectively to Varinaes or Spanish tobacco, and to Virginia tobacco, it is clear that the former ranged in price from 8s. to 13s. per lb., while the latter was from 1s. 6d. to 4s. per lb. There is one entry of "perfumed Tobacka," 10 oz. of which were bought at the very high price of 15s. 6d.

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.