From Chapter 1:
Every one knows the legend of the water (or beer) thrown over Sir Walter by his servant when he first saw his master smoking, and imagined he was on fire. The story was first associated with Raleigh by a writer in 1708 in a magazine called the British Apollo. According to this yarn Sir Walter usually "indulged himself in Smoaking secretly, two pipes a Day; at which time, he order'd a Simple Fellow, who waited, to bring him up a Tankard of old Ale and Nutmeg, always laying aside the Pipe, when he heard his servant coming." On this particular occasion, however, the pipe was not laid aside in time, and the "Simple Fellow," imagining his master was on fire, as he saw the smoke issuing from his mouth, promptly put the fire out by sousing him with the contents of the tankard. One difficulty about this story is the alleged secrecy of Raleigh's indulgence in tobacco. There seems to be no imaginable reason why he should not have smoked openly. Later versions turn the ale into water and otherwise vary the story.

From Chapter Chapter 8:
He describes the box and its contents in lines which show not only tolerance but appreciation of tobacco, from which it is not unreasonable to infer that Cowper's first view of his friend's smoking-habit as a drawback—as shown in his letter to Unwin, quoted above—had been modified by neighbourhood and custom. It might have been well for the poet himself if he had learned to smoke a social pipe with his friend Bull. The appreciative lines run thus:

This oval box well filled
With best tobacco, finely milled,
Beats all Anticyra's pretences
To disengage the encumbered senses.
O Nymph of transatlantic fame,
Where'er thine haunt, whate'er thy name,
Whether reposing on the side
Of Oronoco's spacious tide,
Or listening with delight not small
To Niagara's distant fall,
'Tis thine to cherish and to feed
The pungent nose-refreshing weed,
Which, whether pulverized it gain
A speedy passage to the brain,
Or whether, touched with fire, it rise
In circling eddies to the skies,
Does thought more quicken and refine
Than all the breath of all the Nine—
Forgive the bard, if bard he be,
Who once too wantonly made free,
To touch with a satiric wipe
That symbol of thy power, the pipe;
        *     *     *     *     *     *     *
And so may smoke-inhaling Bull
Be always filling, never full.