In 1860, Melville was unemployed, once he had given his last lecture, and he remained unemployed till near the end of 1866, when he gained his appointment in the New York Custom House. For several years now, thanks to databases of newspapers, Scott Norsworthy, Dennis Marnon, and George Monteiro have pointed out that Melville’s nineteen years of uninterrupted employment were achieved only through the intervention of an angel in the Custom House, a man with a Lansingburgh connection, Chester A. Arthur.
Parker, Hershel. “The Unemployable Herman Melville.” Historic Nantucket 62(2). Spring 2012. 10. https://issuu.com/novationmedia/docs/historicnantucketthemelvilleissue

Harper & Bros. announce […] “Battle Pieces and Aspects of the War,” by Herman Melville, (for ten years the public has wondered what had become of Melville)
“The Book World.” New York Daily Herald. August 12, 1866: 5 col 3.

AMONG THE LITERARY GENTLEMEN having positions in the New York Custom House are Mr. R. H. Stoddard, Mr. Barry Gray, Mr. Charles F. Briggs, Mr. Gaylord Clarke [sic – Lewis Gaylord Clark], Mr. John Savage, and Mr. Herman Melville.
“Personal and Political.” Buffalo Commercial. January 2, 1867: 2 col 3.

GATH.
—

Summer Speculation in New York—Mines in New England—Sectional Interviews.
Special Correspondence of the Enquirer.
SARATOGA, June 30, 1879.
I suppose people are most of all engaged in money-making this summer. […]
LITERATURE IN THE CUSTOM-HOUSE

I asked General Chester A. Arthur, late Collector of the Port of New York, whom the Republicans would have to support for Governor. He said there were plenty of good men and a fair field this year. Speaking of some who had lately behaved very well, Mr. Arthur said:
“The shark is only an angel well governed.” Not being quite understood, he added:
“Did you ever hear of Herman Melville, one of our novelists? He wrote ‘Typee.’ When I went into the Custom-house first, as an associate officer, I saw a list of men doomed to be decapitated. Among them was the name ‘Herman Melville.’ It struck me as singular, and I inquired whether he was any relation of the author. They told me he was the same man. I had read ‘Typee’ and ‘Omoo’ and ‘Moby Dick’ with a good deal of interest, and I said: “It is certainly a shame to turn out a man like that from a mere clerkship.” I had him saved. Then when I became Collector of the Port I kept him in my eye and protection again, though I never spoke to him. It was Melville, in his novel of ‘Moby Dick,’ who depicted a sermon by a negro who told of an escape from a shark, and after describing the shark in horrible language as a monster of iniquity and vice, he ended by saying: ‘But, my breddren, we mustn’t tink we is much better dan de shark. De angels is only sharks well governed.’”
Herman Melville is said to be still in the Custom-house, aged 60 years. He was born in New York city and brought up near Troy, when he concluded to go to sea. He deserted in the Marquesas Islands, and was directed by the savages and went from group to group of the islands until in 1843 he shipped about one of our frigates and came home. He published ‘Typee’ in 1846. The next year he married a daughter of Chief Justice Shaw, and then went into tale-writing as a business in Massachusetts. As late as 1860 he went around the world again. After such a life of adventure and literary prominence, it is strange to see Melville doomed by politicians to lose his clerkship, and only saved by the youthful remembrance of General Arthur. […]
GATH [George Alfred Townsend].
Cincinnati Enquirer. July 4, 1879: 5 cols 1-2.
“A Forgotten Author.” Indianapolis News. July 5, 1879: 2 col 3.
“A Forgotten Author.” Chicago Daily News. July 16, 1879: 4 col 3.
“A Novelist in the Custom House.” Evening Bulletin [San Francisco, CA]. July 17, 1879: 3 col 8.
“A Forgotten Author.” Greensburg Standard [IN]. August 22, 1879: 2 col 6.
“A Forgotten Author.” National Democrat [Jeffersonville, IN]. August 22, 1879: 7 col 4.
[The 1879 Cincinnati Enquirer and San Francisco Evening Bulletin appearances were both noted, and the text of the former reprinted, in:
Parker, Hershel, ed. “Belated Praise and the Melville Revival: 1879-1927.” Norton Critical Edition of Herman Melville’s Moby-Dick. 3rd Ed. NY: W. W. Norton, 2017.

VENOM
—
Emitted By the Fallen Chief.
—
Cowardly and Cruel Warfare Upon Great Names.
—
The Scandal Concerning Mrs. Sprague and Senator Conkling.
—
Gould’s Contemplated Capture of the Newspapers.
—
Tragedies in Daily Life—The Stealing of Stewart’s Bones.
—
American Manufactures of Silk and Kid Gloves.
—
The Miasma of Washington—General Grant’s Severe Strictures Upon Porter.
—
Evils of Unrestricted Immigration—The Conkling-Bayard Quarrel—And Many Other Matters Too Numerous to Specify.
—

SPECIAL DISPATCH TO THE ENQUIRER.
NEW YORK, December 17.— […]
The newspapers do not mention in New York, in their obituary of Charles P. Clinch, brother-in-law of the late A. T. Stewart, an imputation which grew out of the jealousy and back-biting of Stewart’s rivals, asserting that Mr. Clinch was kept in the New York Custom-house to give Stewart an advantage in his importations. I suppose that I have had this yard told to me one hundred times when Stewart was in the height of his business and a candidate for Secretary of the Treasury. When Grant selected him for the Treasury, the choice was abhorrent to every loafer and ring politician, because Stewart’s way of dealing with his clerks was a forecast of how he would manage the Custom-house and the Treasury Department, so they hit upon the coincidence of Stewart having a brother-in-law prominent in the Custom-house as a necessary reason why Stewart should be getting the advantage. The fact is that poor Clinch went in the Custom-house under Martin Van Buren, about 1838, when A. T. Stewart was hardly a quantity in New York. Mrs. Stewart, like her brother Clinch, belonged to a very good family, and in the old days it was the habit to put in the Custom-house literary men. I heard Collector Arthur once say that among his clerks was Herman Melville, the novelist. Richard Grant White and the poet Stoddard have been recently in the Custom-house, and so was Hawthorne in his best days, when he wrote “The Scarlet Letter.” What a magnificent return to the people was that one little book, ground out during dull office hours—perhaps on a salary of $2,000 a year! In England Anthony Trollope has been in the Post-office Department since he was a young man. Dickens was the son of a Custom-house officer, [Robert] Burns was a Whisky Inspector and Sir Walter Scott was a Sheriff. […]
GATH.
Cincinnati Enquirer. December 18, 1880: 1 cols 1-4.
“Literary Office Holders.” Detroit Free Press. December 21, 1880: 5 col 2.
 

GATH
—
Gives Free Rein to His Lively Imagination.
—
Cabinet Rumors—Conkling’s Hold upon Arthur.
—
The Field Fund and the Garfield Family.
—
The Political Career of President Chester A. Arthur.
—
Points Suggested by the National Afflication.
—

NEW YORK, Sept. 23.—The business men have a rumor that Arthur is going to make Conkling Secretary of the Treasury […]
Everything about Gen. Arthur is now of interest, and I will relate the little I have personally seen of him. About 1874 I was introduced to him in the Custom-House, when he was collector. I was at once charmed with his address and a certain sweet gentility of countenance. He has a great faculty for making every body at home whom he wishes to. He said to me that he had taken pleasure on several occasions in giving Custom-House positions to literary men who had not accumulated anything; and he mentioned the author of “Typee,” Herman Melville, whose novels Gen. Arthur said he had much delight in, and he was glad to keep him in a comfortable clerkship. […]
GATH.
Cincinnati Enquirer. September 23, 1881: 4 cols 6-8.
Chicago Tribune. September 25, 1881: 18 cols 3-4.
“President Arthur: What George Alfred Townsend Thinks of Him.” Helena Independent [MT]. October 7, 1881: 1 col 6.\
[The 1881 Cincinnati Enquirer and Helena Independent appearances were both noted in: Parker, Hershel, ed. “Belated Praise and the Melville Revival: 1879-1927.” Norton Critical Edition of Herman Melville’s Moby-Dick. 3rd Ed. NY: W. W. Norton, 2017.]

One of the good actions of President Arthur’s life was the appointment, when he was Collector of New York, of Herman Melville, the author of “Typee,” and other good stories, to a place in the Custom House. Melville’s “White Jacket” is one of the best pictures extant of life on board an old-fashioned man-of-war.
Atchison Daily Champion [KS]. September 27, 1881: 2 col 1.
Topeka Weekly Times [KS]. October 7, 1881: 2 col 1.

“PRESIDENT ARTHUR’S father was a minister in the Baptist Church, a teacher fond of his labors, and an author. One of his books, ‘Arthur on Names,’ is said to be a work of permanent value. Still it is not thought the President will take kindly to the ‘damned literary fellows’ in politics.”—[Courier Journal.
You are in a state of mistakenness. ARTHUR is a man of strong literary sympathies, and when he had the Custom-house in hand he violated the “rules of civil service reform” in behalf of literary men. Two of his closest personal friends were MILES O’REILLEY [“Miles O’Reilly” i.e. Charles Graham Halpine] and HERMAN MELVILLE.
Cincinnati Commercial [OH]. September 28, 1881: 4 col 5. [The Courier Journal‘s comment harkens back to 1876 when President Ulysses S. Grant had nominated Richard Henry Dana, author of Two Years Before the Mast, to be Minister to Great Britain. For various reasons the appointment was opposed. Senator Simon Cameron (PA) reportedly spoke of Dana as “one of those damned literary fellows.”]

President Arthur has always liked “literary fellers,” and violated the “rules of civil service reform” to make places for Miles O’Reilly and Herman Melville.
“Notes and Comments.” St. Albans Daily Messenger [VT]. October 7, 1881: 2.

New York Custom House Records 1792-1896 [bulk 1802-1854] http://archives.nypl.org/mss/3092

In 1834, Samuel Thomson, a prominent New York builder, was hired as Superintendent of construction, and excavation on the site began. However, in August of 1834, the Commissioners for the Building of the New Custom House (Samuel Swartwout, Elisha Tibbits, and Walter Bowne) wrote to Sec. Woodbury to propose last minute changes to the Town and Davis plan. They argued that the excessive expense required to complete the design as planned compounded by its inappropriateness to the function of a custom house merited revision. Thomson was charged with making changes to the design’s interior. Alexander Davis vehemently criticized the Commissioners for the failure to carry out the design as it had been accepted by Congress in legislation. Superintendent Thomson was himself engaged in a lengthy dispute with the Commissioners and successive Secretaries Taney and Woodbury, most essentially concerning his pay and duties as Superintendent. These bitter disagreements led to Thomson’s resignation in late spring of 1835 and his repossession of all architectural plans to which he had contributed. John Frazee, the popular sculptor of portrait busts was appointed Superintendent in July 1835. Without Thomson’s plans for the revised interior, Frazee had no choice but to start over, beginning the arduous task of drawing new plans from the foundation that had been laid previous to his appointment. Despite the enormous difficulty of the task, Frazee saw the project through almost to completion only to be fired by Commissioner Bowne in the very last stages of work after years of infighting.
At the time of its completion in 1842, the construction of the Custom House had cost above one million
dollars and spanned eight years.
For twenty years, the Custom House managed New York’s growing import and export customs revenue until 1862 when it was moved to the New York Merchant’s Exchange at 55 Wall Street.
National Park Service U.S. Department of the Interior. Federal Hall National Memorial Cataloged Archival Items, 1733-1989 Finding Aid. http://www.mhsarchive.org/FullImages/FEHACataloged-Finding-Aid.pdf [Elisha Tibbits of Troy died in 1835; his grave was reinterred in Oakwood Cemetery in the Town of Lansingburgh.]