an, invading all
the lines of commerce of Europe, Hamburg in the North and Marseilles in
the South being especially affected. In the summer of 1893 a few cases
appeared in New York Bay and several in New York city, but rigorous
quarantine methods prevented any further spread.

Typhus fever is now a rare disease, and epidemics are quite infrequent.
It has long been known under the names of hospital-fever,
spotted-fever, jail-fever, camp-fever, and ship-fever, and has been the
regular associate of such social disturbances as overcrowding,
excesses, famine, and war. For the past eight centuries epidemics of
typhus have from time to time been noticed, but invariably can be
traced to some social derangement.

Yellow Fever is a disease prevailing endemically in the West Indies and
certain sections of what was formerly known as the Spanish Main.
Guiteras recognizes three areas of infection:--

(1) The focal zone from which the disease is never absent, including
Havana, Vera Cruz, Rio, and the other various Spanish-American points.

(2) The perifocal zone, or regions of periodic epidemics, including the
ports of the tropical Atlantic and Africa.

(3) The zone of accidental epidemics, between the parallels of 45
degrees north and 35 degrees south latitude.

In the seventeenth century Guadaloupe, Dominica, Martinique, and
Barbadoes suffered from epidemics of yellow fever. After the first half
of the seventeenth century the disease was prevalent all through the
West Indies. It first appeared in the United States at the principal
ports of Boston, Philadelphia, and Charleston, in 1693, and in 1699 it
reappeared in Philadelphia and Charleston, and since that time many
invasions have occurred, chiefly in the Southern States.

The epidemic of 1793 in Philadelphia, so graphically described by
Matthew Carey, was, according to Osler, the most serious that has ever
prevailed in any city of the Middle States. Although the population of
the city was only 40,000, during the months of August, September,
October, and November the mortality, as given by Carey, was 4041, of
whom 3435 died in the months of September and October. During the
following ten years epidemics of a lesser degree occurred along the
coast of the United States, and in 1853 the disease raged throughout
the Southern States, there being a mortality in New Orleans alone of
nearly 8000. In the epidemic of 1878 in the Southern States the
mortality was nearly 16,000. South