I assure you

I. F.— That's right! pepper them well; a lucky shot! that fellow will pay us for our fright. I assure you I did not breathe! --Scenes Beyond the Western Border, September 1851; and Scenes and Adventures in the Army

***

I. F. "A forfeit! Mathematics are infernal.'"

"— I assure you (it is a secret of mine) that nothing else known among men can cope with feminine logic; but that is magical; the d—l can as well resist holy water."  --Scenes Beyond the Western Border, December 1851; and, revised, in Scenes and Adventures in the Army

* * *

My romance I assure you is no dish water nor its model borrowed from the Circulating Library. It is something new I assure you, & original if nothing more. But I can give you no adequate idea, of it. You must see it for yourself. -- Only forbear to prejudge it. -- It opens like a true narrative -- like Omoo for example, on ship board -- & the romance & poetry of the thing thence grow continually, till it becomes a story wild enough I assure you & with a meaning too. --Letter to John Murray, March 25 1848 - Melville's Correspondence.

The transition is a keen one, I assure you, from a schoolmaster to a sailor, and requires a strong decoction of Seneca and the Stoics to enable you to grin and bear it.  -- Moby-Dick

—so one may wake up wise, and slow of assent, very wise and very slow, I assure you, and for all that, before night, by like trick in the atmosphere, be left in the lurch a ninny. --The Confidence-Man

how to make literary use of grass and frost

Here's a cool little case study in creative revision or ghostwriting.  See how the plain matter-of-fact journal entry of Philip St George Cooke has been used to jump start one of the numerous prairie dialogues between the narrating Captain of U.S. Dragoons and his Imaginary Friend (I. F. for short).  In his original 1843 report, Cooke mentioned "black frosts" and routinely noted the availability and condition of grass:

"October 5th.   I marched Eastward.  We began now to be exposed to black frosts and the grass rather suddenly failed us.....

October 18....I found grass in a timbered creek bottom  Page 9

The rewrite makes a dramatic scene out of Cooke's straightforward narrative.  The dialogue is invented, but key factual details have been lifted from the 1843 army journal:

I. F.—"Very interesting, this dry grass and frost! Has the idea of home banished me from your thoughts?"

— "Ah, no! I am a bit of a philosopher; and take this October marching very kindly— particularly after thawing of a morning; and riding ahead, I kill a grouse occasionally with my pistol."  (Scenes Beyond the Western Border, January 1852)

A bit of a philosopher!

white stone added in revision of Cooke's 1843 Journal

Hey look! That Melvillean reference to marking fortunate days with a white stone was added in revision of Philip St George Cooke's 1843 Journal of the Santa Fe Trail.

Original:

"October 5th.   I marched Eastward.  We began now to be exposed to black frosts and the grass rather suddenly failed us.  In order to encamp every night in a river bottom where it was best, and where some drift wood could be obtained, I left the road near Jackson Grove, and guided my command three days and a half, and finally struck the road again at the point I wished, and within a mile of the distance I expected; although in places ten or twelve miles from the road, I had not lost a mile in the distance."

William E. Connelley, ed., A Journal of the Santa Fe Trail. Quoted passage above is from Cooke's account of the return trip.  His account of the march home (a copy, not in Cooke's handwriting) in fall 1843 is in the National Archives and available now at Fold3, Letters Received by the Adjutant General, 1843 C307.  Cooke's longer chronicle of the summer escort is also in the 1843 Letters Received by the Adjutant General, C252.

1851-2 rewrite:

Oct. 7.—Mark this day with a white stone! After travelling 60 or 70 miles off the road—encamping each night on the river in comparatively good grass, and with drift-wood fuel too, I this morning, as guide, took a course for the crossing of the Pawnee Fork, and struck it to a degree!

Scenes Beyond the Western Border, January 1852  and

 Scenes and Adventures in the Army

days marked with a white stone

"...whiteness has been even made significant of gladness, for among the Romans a white stone marked a joyful day..." Moby-Dick (1851)

Oct. 7.—Mark this day with a white stone! After travelling sixty or seventy miles off the road—encamping each night on the river in comparatively good grass, and with driftwood fuel too, I this morning, as guide, took a course for the crossing of the Pawnee Fork, and struck it to a degree! ....This has been a true October day—delightful and magnificent October!

 Scenes Beyond the Western Border, January 1852

Scenes and Adventures in the Army

"... you desire to hear of Colonel John Moredock. Well, a day in my boyhood is marked with a white stone—the day I saw the colonel's rifle, powder-horn attached, hanging in a cabin on the West bank of the Wabash river."  The Confidence-Man (1857)

not for the worldling

"View not the world with worldling's eyes...."  Lone Founts from Timoleon 

I address not then, the shallow or hurried worldling; but the friendly one, who in the calm intervals from worldly cares, grants me the aid of a quiet and thoughtful,—and if it may be,—a poetic mood!

Scenes Beyond the Western Border, July 1852;
 and
Scenes and Adventures in the Army

philosophical pretensions

"... in this sheet, he seems to have directly plagiarized from his own experiences, to fill out the mood of his apparent author-hero, Vivia, who thus soliloquizes: "A deep-down, unutterable mournfulness is in me. Now I drop all humorous or indifferent disguises, and all philosophical pretensions."  -- Pierre; Or, The Ambiguities (1852)

I. F. "And how do you like 'A Glimmering Light on Mesmerism,' which I perceive you have been reading?"

C. "It shows a research quite extraordinary for a soldier—generally exposed to much literary privation; his enquiring and sceptical mind has been excited and puzzled by the strange developments, or pretensions of this magical philosophy."   

-- Scenes Beyond the Western Border, June 1852; and
Scenes and Adventures in the Army

that extraordinary leg of Mynheer von Clam

Update:
See the famous first chapter of Moby-Dick for a good verbal parallel in the similar use of "a-going":  

Let the most absent-minded of men be plunged in his deepest reveries—stand that man on his legs, set his feet a-going, and he will infallibly lead you to water... 

Melville's narrator Ishmael writes of feet set a-going; our wandering dragoon captain has a jingle set a-going, punning on different senses of "feet."



For the longest time I never got the allusion to "an extraordinary leg" in the May 1853 installment of Scenes Beyond the Western Border. 

Yet unstained, bright and cheerful, gayly pattering o'er [1857: splashing 'mong] the rocks,—merry river, knowest thou surely where thou rushest in such haste?

Art careless now, in thy morning, of these pleasant green trees' shade?

Well, [1857: Ah!] be happy while thou mayst, round thy mountain parents' feet; smiling thou, and reflecting every hopeful smile of theirs!

Yes, whilst they shelter, dance in sunshine, now thou mayst—

F.—"Hillo! what are you about? Writing in tune with the merry cotton wood leaves? You will have to frankly confess you have invented a new style." 

C. —"Upon my word I was becoming as curious as yourself; a first unfortunate line set the jingle a-going, and I could not stop it; my "feet" got into such a measure, that they were running off with me, —and my discretion, (somewhat like an extraordinary leg of which I once heard a clown sing.) Shall it stand?—to be laughed at one of these days?"

F.—"You are wonderfully given to personification; particularly of rivers..."

(Scenes Beyond the Western Border, May 1853; and
Scenes and Adventures in the Army)

But yesterday I stumbled on the source while reading the London Atlas review of Moby-Dick (First Notice, as transcribed in Contemporary Reviews, edited by Brian Higgins and Hershel Parker).  Complaining about Melville's "extravagance," the London reviewer refers to the comic song of Mynheer von Clam:

Mr. Melville is endowed with a fatal facility for the writing of rhapsodies.  Once embarked on a flourishing topic, he knows not when or how to stop. He flies over the pages as Mynheer Von Clam flew over Holland on his steam leg, perfectly powerless to control the impulse which has run away with him, and leaving the dismayed and confounded reader panting far behind. (Contemporary Reviews)

So there we have it.

The context in Scenes Beyond the Western Border is yet another scene of writing.  The narrating Captain of U. S. Dragoons presents himself in the act of experimental writing, trying out a "new style" (mimicking Disraeli's claim in Alroy) of metrical prose.  In the act of writing, our narrator is interrupted by his imaginary traveling companion and critic, Frank.  Explaining his lapse into poetry, the narrator claims he could not help himself:  the urge to write verse took control and started "running off," like the "extraordinary leg" of a popular comic song. 

Besides the obvious pun on "feet" as both parts of the body and metrical units, the dialogue here alludes parenthetically to the comic song of the steam-powered "Cork Leg."  Melville's critic in the London Atlas charged that in Moby-Dick, Melville's penchant for rhapsody ran amuck, like Mynheer von Clam "on his steam leg." Now, in reply to criticism of his writing style, the Captain admits his poetic urge took control over his will and ran off "like an extraordinary leg of which I once heard a clown sing."

He walk'd thro' squares and pass'd each shop,
Of speed he went at the very top ;
Each step he took with a bound and a hop,
And he found his leg he could not stop.  (English ballads)  

In March 1834 the Baltimore Gazette advertised a performance at the Baltimore Museum that included the "Cork Leg" routine: "Comic song, Mr. Foster, "The cork leg" (founded upon a celebrated Dutch legend)."

In November 1859, the English comedian Sam Cowell was performing three nights a week at the French Theater in New York,  The NY Herald advertisement promised that, among other routines, Cowell would 

"illustrate the disastrous results obtained by the application of modern machinery to an offending member of the civic fraternity as developed by the adventures of Mynheer Von Clam, while aided by a CORK LEG."

As a child, Cowell had performed in Boston and Philadelphia.  In 1839 Cowell was doing shows in New Orleans.

For the entire ballad of the Cork Leg, check out the 1844 Quaver; or, Songster's Pocket Companion and the online collection of Music Hall Lyrics.

Samuel Houghton Cowell (1820-1864)