It had been arranged that we should make the voyage to Madeira in company with the _Caroline_, but an unexpected incident prevented it. The small-pox[9] made its appearance on board, and although in a mild form and in but a few cases, yet it was sufficiently alarming to interrupt, as a matter of precaution, all communication, and to postpone indefinitely her departure, as a great part of the crew might be overtaken with the disease whilst at sea, exposed to sudden changes of temperature, thereby causing the most serious consequences. Such is not the case with diseases which are in some degree localized, as cholera, yellow fever, dysentery, &c., when it is even prudent to set sail, notwithstanding the presence of the malady, as a change of place and climate is frequently accompanied with beneficial results. [Footnote 9: As there has lately been some difference amongst the medical men of Europe as to the utility of vaccination, the following observations from the report of Dr. Wawra, the principal physician on board the _Caroline_, regarding the appearance and the course of this epidemic, may not be out of place:--"A day before our departure from Trieste a man complained of a slight fever and headache, and his skin was covered with spots which were judged at once to be indications of an approaching eruption of small-pox. The man was immediately sent on shore as a matter of precaution; but, nevertheless, eight days after our departure we had a second, and ten days after that a third case: the epidemic was on board, and though in a mild form, yet serious consequences were apprehended. The _re-vaccination_ of the men was therefore decided upon, and carried out, as far as the virus on board would admit. Only five individuals of the whole had not been vaccinated at all; some had undergone the operation in their childhood, a great part of them, however, had been vaccinated on board other vessels, from two to five years before. Only fourteen cases occurred. Most remarkable, and evidently in favour of those who advocate re-vaccination, is the fact, that amongst most of those who had been vaccinated in their childhood, the disorder was more severe than among those who had been re-vaccinated on board the ship. Among those who had _never_ undergone the operation before, the vaccination on board was most successful; not one of them caught the disorder. Among the _re-vaccinated_ only four cases occurred, with slighter symptoms than among those who had been once only operated upon. We met with several instances of the kind at other places where we touched. At Buenos Ayres, where the vaccination laws are stricter than anywhere else, the small-pox is extremely rare. Among the Brazilians, who entertain an absolute prejudice against vaccination, the _variola_ is one of the most common and most frightful diseases. It prevails still worse amongst the negro slaves, among whom, from the ignorance and prejudice of their masters, vaccination is neglected. The