Calhoun's February 9, 1825 report to the Senate  https://books.google.com/books/reader?id=Y5YbAQAAMAAJ&printsec=frontcover&output=reader&pg=GBS.PA826

FROM COMMISSIONER SWANN'S 1825 REPORT:
The testimony unites in proving that, at the time of the abandonment of the contract, on the part of the Government, every thing was in complete preparation for the successful prosecution of the work; in the language of one of the witnesses, " a very sufficient outfit of tools, implements, laborers, and mechanics, to have completed the work within the stipulated time, with a large stock of provisions and materials of all kinds, including materials of bricks, lime, timber, iron, &c, &c, and a sufficient number of vessels to transport the same to Dauphin Island." Upon this state of things several of the witnesses have expressed their opinions, and have declared that the course pursued by the contractors, of substituting slaves for hired white men, was judicious; and that with the slaves which they had purchased, and had engaged for the prosecution of the work, they would not only have been able to have performed it within the period prescribed by the contract, but with very great profit to themselves.

THOMAS SWANN D.A. OF D.C. BEFORE F.S. KEY  http://jay.typepad.com/william_jay/2014/08/the-swann-stop.html

SWANN AND F.S. KEY COMMISSIONERS ON YAZOO FRAUD  https://books.google.com/books?id=NWi6x3HPpkkC&pg=PA168&lpg=PA168&dq=%22THOMAS+SWANN%22+%22FRANCIS+SCOTT+KEY%22&source=bl&ots=RGP48nJ_iJ&sig=YSIvCbdjise2LeutUhrgJ4_ehLI&hl=en&sa=X&ved=0ahUKEwjg3fD-1e7OAhUF6SYKHY6SA_0Q6AEILTAD#v=onepage&q=%22THOMAS%20SWANN%22%20%22FRANCIS%20SCOTT%20KEY%22&f=false

COST OF SLAVE LABOR ON D.I.  (B.) As the item of labor had a material bearing upon every part of the contract, the commissioner found it necessary to obtain all the information touching its value which the witnesses could furnish. In referring to the testimony, he found that its value had been variously rated. Colonel Fisher, in his last deposition, in his estimate of the value of lime, raTes the value of a laboring man at forty cents a day; and yet, in the same deposition, he states that a laboring slave would hire for from $10 to $12 a month; that the expense of a white laborer for one year would be $300 to $350, while that of a slave would not be more than from $150 to $175. If this would have been the price of a hired slave by the year, the commissioner cannot perceive how he could be hired by the day for forty cents. Colonel Russell, in his last deposition, states, since the year 1818, and since the fall in the price of cotton, a field negro in Alabama would not be worth more than $100 a year, and consequently not worth a dollar a day. Perhaps Colonel Fisher rated the labor at forty cents a day in consequence of the fall in the price of cotton. But both these gentlemen agree that a good male laboring slave in 1821 would have been worth in that country $600. Russell thinks $650. If this be true, could the owner have afforded to hire him for less than $150 a year? If the duration of his life is estimated at seven years, which, in that climate, it is believed would be a full allowance, the owner would hardly afford to hire him for less than this sum; and if so, it may well be questioned whether it would not have been more profitable to the contractors to have hired by the day at eighty-four cents, or even a dollar, than by the year at $150. Taking into consideration the lassitude and sickness which attend the climate of that country, with the losses which might arise from bad weather and other causes, the commissioner is inclined to prefer the daily hiring, and he believes that he has done full justice to the contractors in deducting one-third from the estimate of the board of engineers.