The best account that could possibly be given, is that of a respectable committee, selected from among the best characters in this large assemblage of American prisoners. The greater part of this committee, were men of no mean talents. They were not young men, but had arrived at that period of life, when judgment is the soundest, and when passion does not betray reason. The anxiety of all to know the truth, and the solemn manner in which the evidence was collected and given, stamped the transaction with the characters of truth. I did not see the beginning of this affray. I was, with most of the other prisoners, eating my evening's meal in the building, when I heard the alarm bell, and soon after a volley of musketry. There were, I believe, before the alarm bell rung, a few hundred prisoners, scattered here and there about the yards, as usual; but I had no idea of any particular collection of them, nor had I any suspicion of any commotion existing, or meditated. But I forbear; and will here insert the report of the committee, in the correctness of which I place an entire confidence. DARTMOOR MASSACRE. Having seen in print several different statements of the massacre of the American prisoners of war at Dartmoor, and, on perusal, finding, that, though they corroborate each other, as to the leading facts, yet it seems the public are not in possession of all the particulars necessary to form a proper judgement of the same. While in prison, we having been members of the committee through whom was transacted all their public business, and through whose hands passed all their correspondence with their agent in London, and having in our possession several documents relating to the before mentioned brutal butchery, we deem it a duty we owe to our murdered countrymen and fellow-citizens in general to have them published.