60 Joseph E. Inikoridemand for insurance cover was important in the development of marine
insurance in Great Britain. The trade required the extension of credit^12 at
various stages—credit to slave-dealers on the African coast, and more import-
ant, credit to the employers of slave labour in the Americas. In addition, a
long space of time, usually over a year, elapsed between the time a merchant in
Great Britain invested in goods and shipping and the time the slaves were
finally sold in the Americas. In consequence, the financial resources of the
slave merchants were more than ordinarily stretched. In fact, the commercial
capital required by the slave trade—in shipping, in stock of goods, and in trade
credits—was far in excess of the annual volume of the trade. Rather than sink
the whole of their fortunes in the trade, the slave-merchants always preferred
to obtain credit in various forms. They obtained export credit from the pro-
ducers of goods for the trade, a requirement which in turn compelled the latter
to look for sources of credit for their operation. More important, the slave-
merchants obtained credit through the discounting to the voluminous bills of
exchange they obtained from the sale of slaves in the Americas.
The favourable demand conditions created in this way were important
for the development of banking and the discount market in Great Britain. In
fact, some of the provincial banks that sprang up at this time, especially in
Lancashire, were motivated primarily by the desire to profit from the dis-
counting of slave bills and other bills resulting from the credit relationship
between the slave-merchants and producers of goods for the slave trade.^13
The special shipping requirements of the trade stimulated considerable
activities in British shipyards for the building of a special class of vessel and
for the repair and costly outfit of slave vessels. From a calculation based on
137 slave-ships, measuring 24,180 tons, it is found that about 60 per cent of
British slave vessels were built in British shipyards, the remaining 40 per cent
being made up of prizes taken in wartime, and foreign-built ships purchased
abroad, mostly in the colonies. After deducting this proportion, an elaborate
calculation based on a large amount of shipping data, shows that between
1791 and 1807 about 15 per cent of all tonnage built in Great Britain was
destined for the Guinea trade, about 95 per cent of which went into the shipping
of slaves.^14 Between 1750 and 1807, an average of £2,625,959 per decade was
invested by British slave-merchants in the building, repairing and outfit of their
vessels in British shipyards, ranging from an average of about £1£ million per
decade for the period 1750-80, to an average of almost £4 million per decade
in the period, 1781-1807. The input requirements of these activities had import-
ant linkage effects on other industries, particularly the metal and metal-using
trades, and hence the mining of metal ore and coal, and their transportation.
They also made an important contribution to the process of urbanization.
The manufacturing sectors significantly influenced were the metal and
metal-using industries, copper, brass and iron. The manufacture of guns for