added profit. From careful study and observation he had deduced
a specific formulary by which he measured the rate of gain. With
a well-selected force, two thirds of which should be females, he
calculated that with proper care such plantations could be made to
pay, year by year, an interest of five per cent on the first cost,
and, in addition, double the value of the working force every eight
years. This conclusion he had arrived at from scientific study of
the rates of mortality and increase, and in settling upon it he
had cautiously left a large margin for contingencies. He was not
accustomed to talk about his business, but when questioned as to
his uniform success and remarkable prosperity, always attributed it
to a system which he had inexorably followed, and which had never
failed to return to him at least twenty per cent. per annum upon
every dollar he had invested.

So confident was he in regard to the success of this plan that he
became a large but systematic borrower of money at the legal rate
of six per cent, taking care that his maturing liabilities should,
at no time, exceed a certain proportion of his available estate.
By this means his wealth increased with marvelous rapidity.

The success of his system depended, however, entirely upon the care
bestowed upon his slaves. They were never neglected. Though he had
so many that of hundreds of them he did not know even the faces, he
gave the closest attention to their hygienic condition, especially
that of the women, who were encouraged by every means to bear children.
It was a sure passport to favor with the master and the overseer:
tasks were lightened; more abundant food provided; greater liberty
enjoyed; and on the birth of a child a present of some sort was
certain to be given the mother.