Migrations Of Yellow Fever

i enow lever, like the encuera, is one of the great migrating diseases. Shirtiiig from somc point within tho tropics, it travels steadily onward from poiiit to point as long as it does not meet freezing ueather; and it travels northward by preference - comparatively seldom to the soutiiward of the zone from which it sets out. Tlius Brazil has suffered companitively little from its epidemie visitations, though, as we shall see, the disease plantcd its germs long ago in Rio de Janeiro, on the extreme southern limit of tho tropies. But its favorite course is toward the north. " Upon our Atlantic eou-sts," says Dr. J. C. Nott, a careful student and observer of its phenomena, " as on the coast of the Mediterranean, it comes from time to time in one of those immense waves that know no bounds and stop at no impediments. The distance to whioh the disease extends seems to depend much npon the strength of the wavt. It first strikes the gulf, and generally gocs no farthcr. . Occasionally it will break over tho peninsula of Florida and ronoh Savannah and Charleston. In 1855, af ter many years of immunity, it struck Norfolk with fult foree, and önly a few ripples, as in 1853, 1856, 1870, have for half a cenfcury reached the Delaware rivor and the Bay of New York." And the ame observer, writing eiglit years ago, adds some words which have a grave significance to-day : " Yellow fever, aftor a long absence, never makes its reappearance in our Northern cities without a warning from tlie Gulf of Mexico. It is seennotonly for months, but Óiten for séverál years, in -igorous action in its nativo habitat before it leaps over its accustomed bounds ; but, wlien once on the tramp, it may travel from Buenos Ayres to Quebec, leaving moro graves in its track than Asintió cholera. There is reason to fear that one of these eruptions is now niarshaling its forces." Let us glance at the course of one of these typical epidemies - at the one, for instonce, which startod as fur away as Kio de Janeiro, twenty-oight years ago, and tvaveled in six years all the way to New York - a journey of nearly 4,000 j miles - in a great eircle. A great many years before, so many that the inhabitants of Kio had lost nearly all recollection or tradition of the faet, the yellow fever had vieited their city; but now i the epidemie broke upon tliem like lightning from a elear sky. " ïhis outbreak," says Dr. Xott, " commenced in Rio in January, 1850, and traveled night and day for six years, making its expiring effort in New York bay in 1856. I had my eye upon this epidemie from its commencement, watching its steady course and ravages along the Atlantic, Caribbean sca and Gulf of Mexico for several thousand miles. "Wlien it struck New Orleans (1853) it was olear to my mind that our own coast was doomed ; and, before it reached Mobile, I was so certain it would come that I moved my family into the healthy pin 3 hills, se ven miles from the town, where the disoase had never been. But, in spite of all my prudence, the disease not only came to Mobile, but followed my family out to Spring Hill, where I lost four of my ohildrcn in one week." - Dr. T. M. Coan, bi Harper's Magazine for December.