William Collins's Superstitions Ode was first printed with the famous gap filled by interpolated lines by Henry Mackenzie and Alexander Carlyle. These lines were reprinted in a footnote in the editions of the Ode published by J. Bell in 1788 and 1789 with the supposedly "original" text.
Henry Mackenzie: "The beautiful Ode on the Superstitions in the Highlands lay long among Mr. Home's papers unknown to him till Dr. Carlyle found it and gave it to the Royal Society of Edinburgh. I filled up at the desire of Mr. Tytler a chasm that had somehow been made in it, which obtained the Society's approbation; it was an almost extempore production, written the same evening in which Mr. Tytler asked me to write it" Anecdotes and Egotisms, ed. Harold W. Thompson (1927) 166.
Nathan Drake: The imagery in this last simile [in Macpherson's Ossian: 'Like the shrill spirit of a storm that sits dim on the clouds of Gormal, and enjoys the death of the mariner'] has furnished Mr. Mackenzie with the groundwork of an admirable description in the supplemental stanza he has in Collins's Ode on the Popular Superstitions of the Highlands of Scotland; alluded to the gifted Wizard, he observers, they 'list the nightly yell | Of that dread spirit, whose gigantic form | The seer's entranced eye can well survey, | Through the dim air who guides the driving storm, | And points the wretched bark its destin'd prey'" "On the Superstitions of the Highlands" Literary Hours (1800) 2:232.
Peter Cunningham: "Other verses were written by the late Lord Kinnedder, which Sir Walter Scott, in all the partiality of friendship, thought equal to the original. To add to an unfinished poem one must write with the same genius which the author wrote: and Collins, as Pope said of Akenside, was no every-day writer" in Thomas Campbell, Specimens of the British Poets (1845) 431n.
Or on some bellying rock that shades the deep,
They view the lurid signs that cross the sky,
Where, in the west, the brooding tempests lie,
And hear their first, faint, rustling pennons sweep.
Or in the arched cave, where deep and dark
The broad, unbroken billows heave and swell,
In horrid musings rapt, they sit to mark
The labouring moon; or list the nightly yell
Of that dread spirit, whose gigantic form
The seer's entranced eye can well survey,
Through the dim air who guides the driving storm,
And points the wretched bark its destin'd prey.
Or him who hovers, on his flagging wing,
O'er the dire whirlpool, that, in ocean's waste,
Draws instant down whate'er devoted thing
The failing breeze within its reach hath plac'd—
The distant seaman hears, and flies with trembling haste.
Or, if on land the fiend exerts his sway,
Silent he broods o'er quicksand, bog, or fen,
Far from the shelt'ring roof and haunts of men,
When witched darkness shuts the eye of day,
And shrouds each star that wont to cheer the night;
Or, if the drifted snow perplex the way,
With treach'rous gleam he lures the fated wight,
And leads him flound'ring on, and quite astray. . . .
[European Magazine 13 (April 1788) 242-43]