was also to be sent. The molasses upon reaching Newport was expected to
bring twice as much as it had cost in the tropics. After deducting factor's
commissions of from 2-1/2 to 5 per cent. on all sales and purchases, and of
"4 in 104" on the slave sales as the captain's allowance, after providing
for insurance at four per cent. on ship and cargo for each leg of the
voyage, and for leakage of ten per cent. of the rum and five per cent. of
the molasses, and after charging off the whole cost of the ship's outfit
and one-third of her original value, there remained the sum of £357, 8s.
2d. as the expected profits of the voyage.

[Footnote 41: "An estimate of a voyage from Rhode Island to the Coast of
Guinea and from thence to Jamaica and so back to Rhode Island for a sloop
of 60 Tons." The authorities of Yale University, which possesses the
manuscript, have kindly permitted the publication of these data. The
estimates in Rhode Island and Jamaica currencies, which were then
depreciated, as stated in the document, to twelve for one and seven for
five sterling respectively, are here changed into their approximate
sterling equivalents.]

As to the gross volume of the trade, there are few statistics. As early as
1734 one of the captains engaged in it estimated that a maximum of seventy
thousand slaves a year had already been attained.[42] For the next half
century and more each passing year probably saw between fifty thousand and
a hundred thousand shipped. The total transportation from first to last may
well have numbered more than five million souls. Prior to the nineteenth
century far more negro than white colonists crossed the seas, though less
than one tenth of all the blacks brought to the western world appear to
have been landed on the North American continent. Indeed, a statistician
has reckoned, though not convincingly, that in the whole period before 1810
these did not exceed 385,500[43]