It will be readily understood that the special and always menacing dangers attending the slave trade made marine insurance upon that sort of cargoes exceedingly high. Twenty pounds in the hundred was the usual figure in the early days. This heavy insurance led to a new form of wholesale murder committed by the captains. The policies covered losses resulting from jettisoning, or throwing overboard the cargo; they did not insure against loss from disease. Accordingly, when a slaver found his cargo infected, he would promptly throw into the sea all the ailing negroes, while still alive, in order to save the insurance. Some of the South American states, where slaves were bought, levied an import duty upon blacks, and cases are on record of captains going over their cargo outside the harbor and throwing into the sea all who by disease or for other causes, were rendered unsalable--thus saving both duty and insurance. In the clearer light which illumines the subject to-day, the prolonged difficulty which attended the destruction of the slave trade seems incredible. It appears that two such powerful maritime nations as Great Britain and the United States had only to decree the trade criminal and it would be abandoned. But we must remember that slaves were universally regarded as property, and an attempt to interfere with the right of their owners to carry them where they would on the high seas was denounced as an interference with property rights. We see that even to-day men are very tenacious of "property rights," and the law describes them as sacred--however immoral or repugnant to common sense and common humanity they may be. So the effort to abolish the "right" of a slaver to starve, suffocate, mutilate, torture, or murder a black man in whom he had acquired a property right by the simple process of kidnapping required more than half a century to attain complete success. The first serious blow to the slave-trade fell in 1772, when an English court declared that any slave coming into England straightway became free. That closed all English ports to the slavers. Two years after the American colonists, then on the threshold of the revolt against Great Britain, thought to put America on a like high plane, and formally resolved that they would "not purchase any slave imported after the first day of December next; after which time, we will wholly discontinue the slave-trade, and will neither be concerned in it ourselves, nor will we hire our vessels, nor sell our commodities or manufactures to those who are concerned in it." But to this praiseworthy determination the colonists were unable to live up, and in 1776, when Jefferson proposed to put into the Declaration of Independence the charge that the British King had forced the slave-trade on the colonies, a proper sense of their own guilt made the delegates oppose it.