sions when a ship would touch
there--usually not oftener than once a year. Then, within a week, half
the population would be blowing and sneezing. The great Samuel commented
upon the fact at length, and advanced the ingenious explanation that, as
the harbor was so difficult of entry, the ships could beat in only when
the wind was in a certain quarter, and that quarter was the nor'east.
_Hinc illae lacrimae!_ (Hence these weeps!) The colds were caused by the
northeast wind of unsavory reputation! How often the wind got into the
northeast without bringing a ship or colds he apparently did not
speculate.

To come nearer yet, did you ever catch cold when camping out? I have
waked in the morning with the snow drifting across the back of my neck,
been wet to the skin all day, and gone to bed in my wet clothes, and
slept myself dry; and have lain out all day in a November gale, in a
hollow scooped in the half-frozen ground of the duck-marsh, and felt
never a hair the worse. Scores of similar experiences will rise up in
the minds of every camper, hunter, or fisherman. You _may_ catch cold
during the first day or two out, before you have got the foul city air,
with its dust and bacteria, out of your lungs and throat, but even this
rarely happens.

How seldom one catches cold from swimming, no matter how cold the water;
or from boating, or fishing,--even without the standard prophylactic; or
from picnicking, or anything that is done during a day in the open air.

So much for the negative side of the evidence, that colds are not often
caught where infectious materials are absent. Now for the positive side.

First of all, that typical cold of colds, influenza, or the grip, is now
unanimously admitted by authorities to be a pure infection, due to a
definite germ (the _bacillus influenzae_ of Pfeiffer) and one of the most
contagious diseases known. Each of the great epidemics of it--1830-33,
1836-37, 1847-48, and, of most vivid and unblessed memory, 1889-90--can
be traced in its stately march completely across the civilized world,
beginning, as do nearly all our world-epidemics,--cholera, plague,
influenza, etc.,--in China, and spreading, _via_ India or Turkestan, to
Russia, Berlin, London, New York, Chicago. Moreover, its rate of
progress is precisely that of the means of travel: camel-train,
post-chaise, railway, as the case may be. The earlier epidemics took two
years to spread from Eastern Russia to New York; the later ones, f