We have quoted only a fraction of the evidence of Jacob Omnium with regard to the present aspect of affairs in Cuba. Much there is of painful and even sickening detail as to the treatment of the slaves, in order that an augmented supply may be thrown in upon our now unscrupulous market, for which we must refer our readers, if they wish to peruse it, to the pamphlet itself. But lest it should be thought that such testimony merely applies to the condition of the unhappy slaves at present in Cuba, we shall go further, and show that the late measure of the Whig Government has given a tenfold additional impetus to the slave trade; and that all our efforts to restrain it—efforts which, at the smallest calculation, cost this country annually a sum of half a million—are, as they must be under such circumstances, wholly futile and unavailing. “In February last,” says the author of the above letter, “the market value of field negroes had risen from 300 to 500 dollars—a price which would speedily bring a supply from the coast. The accounts thence of the number of vessels captured, and of the still greater number seen and heard of, but not captured by our cruisers, bear ready witness to the stimulus which you have afforded to that accursed trade. It is only during the last year that we hear of _steam-slavers_, carrying nine hundred and fifty slaves, dipping their flag in derision to our men of war.” The list of the slave captures between October 1846 and April 1847 amounts to no less than twenty-four vessels, from which between two and three thousand slaves were taken. This hideous amount of living cargo was crowded into five vessels, the other nineteen having been captured empty. This, however, is understood to be a mere fraction of the whole amount, and that the recent seizures have been much more numerous. One of our ships, the Ferret, is said to have taken no less than six slave vessels since she has been upon the coast. The impulse which the government measure of 1846 has given to the slave trade in every part of the world is something perfectly enormous; but its mischievous and inhuman effects will best be understood by a reference to ascertained facts. Prior to 1846, the traffic in slaves between the African coast and the Spanish colonies had been gradually declining, and had in fact almost disappeared. The exclusion of slave-grown sugars from our home market had nearly forced the Cuban proprietors into a different system, and arrangements were pending in that colony for the emancipation of the slaves, just at the time when Lord John Russell came forward in favour of the chain and the lash. The consequence was, that in the first instance the Cubans withdrew their slaves from the coffee cultivation, which was the least profitable, and set them to work at the sugar-canes. The price of the negro consequently rose, and the trade is prospering abundantly.