In the almanacs published annually in Philadelphia, he procured articles to be inserted, which he believed would attract the notice of the reader, and make him pause, at least for a while, as to the licitness of the Slave-trade.

He wrote, also, as he saw occasion, in the public papers of the day.

From small things he proceeded to greater.
He collected, at length, further information on the subject, and, winding it up with observations and reflections, he produced several little tracts, which he circulated successively (but generally at his own expense), as he considered them adapted to the temper and circumstances of the times.
In the course of this his employment, having found some who had approved his tracts, and to whom, on that account, he wished to write, and sending his tracts to others, to whom he thought it proper to introduce them by letter, he found himself engaged in a correspondence, which much engrossed his time, but which proved of great importance in procuring many advocates for his cause.
In the year 1762, when he had obtained a still greater store of information, he published a larger work.

This, however, he entitled, A short Account of that Part of Africa inhabited by the Negros.

In 1767 he published, A Caution and Warning to Great Britain and her Colonies, on the Calamitous State of the enslaved Negros in the British Dominions;--and soon after this, appeared, An Historical Account of Guinea; its Situation, Produce, and the General Disposition of its Inhabitants; with an Inquiry into the Rise and Progress of the Slave-Trade, its Nature, and Calamitous Effects.