In describing a river on the west coast of Africa, Dr Daniell says—“When I visited it, I found two vessels moored a short distance from its mouth, one of which within the space of five months had buried two entire crews, a solitary person alone surviving. The other, which had arrived at a much later period, had been similarly deprived of one-half of its men, and the remainder were in such a debilitated condition as to be incapable of undertaking any active or laborious duty. Immediately before, another vessel had sailed from this port in such a deplorable state as to be solely dependent on the aid of Kroomen to perform the voyage.” In the statistical report of Sir Alexander Tulloch it is stated, that out of 1658 white troops sent out to military stations on the western coast of Africa, 1271 perished from climatic diseases; while of the 387 who remained to be sent home, 17 died on their passage; 157 were reported as incapable of further service; and 180 as qualified only for garrison service; thus leaving only 33 out of 1658 men who were fit for active service. As we pass out of the torrid zone a remarkable change takes place in the general character of epidemics. They lose more and more of their intermittent type, and become either remittent or continued. The remittent keeps its hold over the southern part of Europe, and continually breaks out in the form of Yellow Fever. As we proceed northward out of the yellow fever zone, that disease wholly disappears, and typhus and its kindred maladies take its place; typhus commencing precisely at the point where yellow fever ends. There is, indeed, one of the ordinary diseases of temperate climes, and only one, which appears capable of penetrating within the torrid zone, and of committing greater ravages there than in lower temperatures, and that is Small-pox. With this exception, the ordinary epidemics of temperate climates do not enter the tropics, while, on the other hand, the ordinary epidemics of the tropics every now and then decimate the temperate regions.