Daguerreotype of Herman Melville by S. L. Walker?

Melville truculently refused to be daguerreotyped in February 1851. The following year his fictional hero Pierre showed the same defiance: "To the devil with you and your Daguerreotype!"
Nonetheless, in August 1847 (the month and year of Melville's marriage to Elizabeth Shaw) we find Albany photographer S. L. Walker (formerly of Troy) in Kingston showing off a daguerreotype of Herman Melville. Was this taken from the life, or did Walker cleverly make his picture somehow from the Twitchell painting?

Well, that might explain why his pictures boasted "the transparency, and softness of the best painted portraits."  For his part, Twitchell in some works is said to have been

''inspired by the detail possible in daguerreotypes.'' 
(Mary-Kate O'Hare, quoted by William Zimmer in a 1997 New York Times article)

From the Rondout [New York] Freeman, Saturday, August 21, 1847:

DAGUERREOTYPES WORTH HAVING. Mr. Walker, whose card is in to-days paper is one of the few daguerreotypists who thoroughly understand his beautiful art. That the blessed sun himself can be a very bad painter when maltreated by bunglers is very apparent in the swarms of specters of dismal countenance clad in very blue linen, called by courtesy daguerrean likenesses. Mr. W’s productions are of a very different stamp; remarkable for distinctness, for the absence of the ghastly tints, startling lights and shades, and painful distortions so common; and possessing the transparency, and softness of the best painted portraits. His daguerreotypes of Martin Van Buren, Silas Wright, W. H. Seward, Gov. Bouck and other men of note, have commanded the admiration of the best critics in art. To give the people of Rondout an opportunity of judging of his quality, Mr. W has left some specimens at the Mansion House, embracing Herman Melville, author of “Omoo” &c, Dr. McNaughton of Albany, and other widely known personages.

The advertisement or "card" referred to, again from the Rondout Freeman:

PREMIUM DAGUERREOTYPES. S. L. WALKER, of ALBANY, will be found at his rooms in Kingston for a few weeks. He is prepared to furnish Daguerreotypes of surpassing excellence, in either fair or cloudy weather, warranted to give satisfaction. Mr. W. received the first premium medal at the State Agricultural Fair in 1843, and also the silver medal at the American Institute, New York. Citizens generally are invited to call and examine specimens of skill, at his rooms, in North Front street Kingston, formerly Culley’s Printing Office.

And what's up with the middle name?  Is it Samuel Lear or Samuel Leon Walker?  Are they one and the same, or different men? Walker relocated from Albany to Poughkeepsie, apparently in June 1847 though he may have returned to the Albany area for a few years, before settling down in Poughkeepsie for good.  According to Michael Pritchard, writing of Samuel Leon Walker, the

“only known collection of Walker’s work is held by George Eastman House,in Rochester, New York.”  (Encyclopedia of Nineteenth-Century Photography, 1465)

But you can still find stray images of daguerreotypes by S. L. Walker online at places like ebay and Google Images.  Hey how cool would it be, to spot young Herman Melville's mug in on some dusty unidentified daguerreotype by say "S L Walker, Albany" or "Walker & Gavit" or even "Walker, Troy."

Update: The "painter-like" quality of Walker's work was noted by the Albany Argus of September 9, 1845, specifically with reference to the daguerreotype portrait of Silas Wright by Walker & Gavit.

DAGUERREOTYPE PORTRAITS.—We were shown yesterday, a remarkably fine specimen of the perfection to which the art of Daguerreotyping has attained in the hands of Messrs. WALKER & GAVIT, of this city. It was a portrait of GOV. WRIGHT. The expression and features were of course to the life; but the exquisite gradations of light and shadow, and the painter-like effect, could scarce be surpassed.