The other chief occasion of ship typhus was the emigration to the American and West Indian colonies from Britain and Ireland. The Irish emigration was especially active from the beginning of the 18th century, owing to rack-renting and other causes. Madden[206] professed to know that one-third of the Irish who went to the West Indies (perhaps he should have included Carolina) perished either on the voyage or by diseases caught in the first weeks after landing; and as we know that typhus attended the Irish emigration in the 19th century, we may infer that the same was the cause of mortality in the 18th. The trouble from ship-fever in the navy was so great all through the 18th century that many ingenious shifts were tried to overcome it. Towards the end of the century, the favourite device was fumigation with the vapour of mineral acids; one such plan, for which the Admiralty paid a good sum, ended in the burning of several ships to the water’s edge. An earlier plan was ventilation of the hold and ’tween decks by means of Sutton’s pipes[207], which found a strong advocate in the Rev. Stephen Hales, of the Royal Society[208]. Twice in the course of a paper to that learned body[209] he asserts that the noxious, putrid, close, confined, pestilential air of ships’ holds and ’tween decks “has destroyed millions of mankind”; on the other hand, according to the testimony of a captain of the navy, Sutton’s pipes had kept his ship free from fever. Lind caps this with the case of H.M.S. ‘Sheerness,’ bound to the East Indies. She was fitted with Sutton’s pipes, the dietary being at the same time so arranged that the men had salt meat only once a week. After a very long passage of five months and some days she arrived at the Cape of Good Hope without having had one man sick. “As the use of Sutton’s pipes had been then newly introduced into the king’s ships, the captain was willing to ascribe part of such an uncommon healthfulness in so long a run to their beneficial effects; but it was soon discovered that, by the neglect of the carpenter, the cock of the pipes had been all this while kept shut[210].” Ship-fever was at length got rid of by more homely and more radical means than scientific ingenuity. Lind had shown one root of the evil to lie in the pressing of men just out of gaol. Admiral Boscawen, by his unaided wits, discovered another means of checking it. He avoided the mixing of fresh hands with crews seasoned to their ships, unless when some evident utility or necessity of service made it proper; “and upon this principle he used to resist the solicitation of captains, when they requested to carry men from one ship to another when changing their command[211].” Towards the end of the 18th century many reforms were made in the naval service--in the dietary, in the allowance of soap, in keeping the bilges clean, in the use of iron and lead instead of timber; so that Blane dates from the year 1796 a new era in the health of the navy[212].