In the reports referred to in the above letter, there is the most ample evidence of the true cholera having appeared at different points in the colony _before the_ arrival of the Topaze frigate, the ship _accused_ by contagionists _par metier_, of having introduced the disease; so that, contrary to what Dr. Macmichael supposes, those who disbelieve the communicability of cholera, have no necessity whatever in this case for pleading a coinsidency between the breaking out of the disease, and the arrival of the frigate; indeed, his friend Dr. Hawkins seems to be aware of this, when he is obliged to have recourse to such an argument as that "it is, at all events, clear that the disease had not been _epidemic_ at the Mauritius before the arrival from Ceylon;" so that the beginning of an epidemic is to be excluded from forming a part or parcel of the epidemic! Why is it that in medicine alone such modes of reasoning are ever ventured upon! We know, from the history of cholera in India, that not only ships lying in certain harbours have had the disease appear on board, but even vessels sailing down one coast have suffered from it, while sailing up another has freed them from it, without the nonsense of going into harbour to "expurgate." Now, with respect to the _Topaze_, it appears that while lying in harbour in Ceylon, the disease broke out on board her; that after she got into "_clene air_" at sea, the disease disappeared, seventeen cases only having occurred from the time she left the island, and she arrived at the Mauritius, as Dr. Hawkins admits, without any appearance whatever of the cholera on board. On the day after her arrival, she sent several cases ("chronic dysentry, hepatitis, and general debility") to hospital, but not one of cholera; neither did any case occur on board during her stay there, at anchor a mile and a half from shore, and constantly communicating with shore,[5] while a considerable number of deaths took place from cholera _in the merchant vessels anchored near shore_. [Footnote 5: Somebody is said to have seen a man on board with vomiting and spasms, on the day before she moved to this anchorage, but the surgeon of the ship has not stated this.]