It has been maintained by Cleghorn[184], Hamilton[185], Clark[186], and Fordyce[187], that _all_ fevers are naturally contagious; a position which, if less mischievous in its tendency, is equally erroneous in principle, as that which rejects the doctrine of contagion altogether. It is most probable that none of those fevers which are produced by marsh _miasmata_ are ever propagated from one individual to another by contagion; ample evidence of this truth is afforded by the writings of Dr. James _Lind_[188], where it appears that the most malignant and fatal species of fever have been contracted on shore, but which had never been communicated to the ship’s company. Dr. Trotter[189] also says, “in a voyage down the coast of Guinea, in the Assistance, in the year 1762, we had scarcely a man indisposed. We wooded and watered at the island of St. Thomas, and with a view to expedition, a tent was erected on shore, in which the people employed on these services were lodged during the night. On the middle passage every man who slept on shore died, and the rest of the ship’s company remained remarkably healthy.” For similar facts see _Medical Observations and Inquiries, vol._ iv, _p. 156_; _Clarke’s Observations on the Diseases which prevail in long Voyages to Hot Countries, p. 124_; and _Dr. Robertson’s Meterological and Physical Observations, &c. 4to, p. 32, 33, and 98_. And in connection with this subject, it becomes our duty to offer a few remarks upon the nature of that peculiar Epidemic, called THE YELLOW FEVER.[190] Its doubtful affinity with bilious intermittent and remittent fevers, has furnished a subject for keen controversy; and while its contagious quality has been pertinaciously maintained by one set of Physicians,[191] it has been as warmly denied by others. The malady has raged repeatedly as an Epidemic in the United States, and was considered for some time as _Endemic_ to that country. “The interests of humanity,” says Dr. Rush,[192] “are deeply concerned in the admission of the rare and feeble contagion of the yellow fever, and Philadelphia must admit the unwelcome truth sooner or later that the yellow fever is engendered in her own bowels; or she must renounce her character for knowledge and policy, and perhaps with it, her existence, as a commercial city.” In the year 1811, one of the most acute and learned works[193] that has graced the literary annals of our country, appeared from the pen of Dr. _Bancroft_, in order to prove that the yellow fever is no other than an aggravated form of that multifarious disease, which is well known to result from the action of those exhalations commonly denominated _marsh miasmata_, and that, like all fevers from that cause, it possesses _no contagious_ quality; but he adds, “it is indeed probable that the _miasmata_ of particular towns, mostly either sea-ports, or accessible to shipping, in which the aggravated forms of yellow fever have almost exclusively prevailed in the West Indies, the