kind in America. This act was inspired largely by the general fear of
insurrection which succeeded the "Negro-plot" of 1712 in New York. It
declared: "Whereas, divers Plots and Insurrections have frequently
happened, not only in the Islands but on the Main Land of _America_, by
Negroes, which have been carried on so far that several of the
inhabitants have been barbarously Murthered, an Instance whereof we have
lately had in our Neighboring Colony of _New York_,"[29] etc. It then
proceeded to lay a prohibitive duty of £20 on all slaves imported. These
acts were quickly disposed of in England. Three duty acts affecting
Negroes, including the prohibitory act, were in 1713 disallowed, and it
was directed that "the Dep^{ty} Gov^{r} Council and Assembly of
Pensilvania, be & they are hereby Strictly Enjoyned & required not to
permit the said Laws ... to be from henceforward put in Execution."[30]
The Assembly repealed these laws, but in 1715 passed another laying a
duty of £5, which was also eventually disallowed.[31] Other acts, the
provisions of which are not clear, were passed in 1720 and 1722,[32] and
in 1725-1726 the duty on Negroes was raised to the restrictive figure of
£10.[33] This duty, for some reason not apparent, was lowered to £2 in
1729,[34] but restored again in 1761.[35] A struggle occurred over this
last measure, the Friends petitioning for it, and the Philadelphia
merchants against it, declaring that "We, the subscribers, ever desirous
to extend the Trade of this Province, have seen, for some time past,
the many inconveniencys the Inhabitants have suffer'd for want of
Labourers and artificers, ... have for some time encouraged the
importation of Negroes;" they prayed therefore at least for a delay in
passing the measure.[36] The law, nevertheless, after much debate and
altercation with the governor, finally passed.

These repeated acts nearly stopped the trade, and the manumission or
sale of Negroes by the Friends decreased the number of slaves in the