"You have seen this diagram."

This image was in at least one and I think as many as three of my history textbooks:

But I had no idea it was drawn up with activist intent. From Adam Hochschild's stellar Bury The Chains: The British Struggle to Abolish Slavery:

Incapable of not organizing, Clarkson founded local offshoots of the abolition committee while on the road. The chairman of one new branch he set up, in the port city of Plymouth, soon produced something that immediately spread excitement in antislavery circles. ... The "plate" was a diagram, with top, side, and end views, of a fully loaded slave ship, the Brookes, owned by a Liverpool family of that name, which carried slaves from the Gold Coast to Jamaica. 

With the help of James Phillips and other committee members, Clarkson reworked and expanded the diagram. ... As in all its work, the committee took great care not to exaggerate: the diagram showed 482 slaves, although on several earlier voyages, under "tight-packing" captains, the Brookes had carried anywhere from 609 to 740. The diagram began appearing in newspapers, magazines, books, and pamphlets; realizing what a powerful new weapon it had, the committee also promptly printed up more than seven thousand copies as posters, which were hung on the walls of homes and pubs throughout the country.
...
You have seen this diagram.

Another gem (from the same page!): "[Lafayette] once told Clarkson, "I would never have drawn my sword in the cause of America if I could have conceived that thereby I was founding a land of slavery"

And this:

[During public hearings prior to the first parliamentary debate on the slave trade] James Penny, a former captain, made the slaves on the Atlantic crossing sound almost like cruise passengers: "If the weather is sultry, and there appears the least Perspiration upon their Skins, when they come upon Deck, there are TwoMen attending with Cloths to rub them perfectly dry, and another to give them a little Cordial. ... They are then supplied with Pipes and Tobacco ... they are amused with Instruments of Music peculiar to their own country ... and when tired of Music and Dancing, they then go to Games of Chance."

Striking to me that the public and the Parliament were so clueless that this could fly. But the important question is: do lobbyists and PR firms lie quite so brazenly today? I think the answer is probably closer to yes than no. At any rate it is a helpful anecdote to recall whenever you are feeling intellectually generous towards someone with skin in the game.

The book is the best history book I read last year. It is complimented well by the In Our Time podcast on the Lancashire Cotton Famine. Coincidentally as I type this I understand Manchester United and Liverpool are duking it out.