emigrate from a region of sandstone, or primitive rock,
where water is soft, will find our limestone water to produce a slight
affection of the bowels, which will prove more advantageous to health
than otherwise, and which will last but a few weeks. Whenever disease
prevails in the western states, it may generally be attributed to one or
more of the following causes.

1st. _Variations of the temperature._ This cause, we have already
shown, exists to as great extent in the same latitude east of the
mountains.

2nd. _The rapid decomposition of vegetable matter._ In all our rich
lands, there are vast quantities of vegetable matter mixed with the
soil, or spread over the surface. Extreme hot weather, following
especially a season of much rain, before the middle of July, will
produce sickness. If the early part of summer be tolerably dry, although
a hot season follows, sickness does not generally prevail. The year 1820
was an exception to this rule. It was throughout, a very dry, hot,
sickly year through the West; indeed, throughout the world. A wet
season, with a moderately cool atmosphere, has proved healthy.

3d. _Marsh exhalations._ These, combined with heat, will always generate
fevers. Indeed, there is probably very little difference in the miasm
thrown off from decomposed vegetable matter, and that produced from
sluggish streams, standing waters and marshes. These, in the great
Valley, abound with decayed vegetable matter. Hence, along the streams
which have alluvial _bottoms_ (as low lands upon streams are called in
the West,) some of which are annually overflowed, and where the timber
and luxuriant vegetable growth are but partially subdued, the
inhabitants are liable to fevers, dysenteries and agues. Situations
directly under the bluffs adjacent to the bottom lands, that lie upon
our large rivers, especially when the vegetation is unsubdued, have
proved unhealthy. So have situations at the heads or in the slope of
the ravines that put down from the bluffs towards the rivers.

The principal diseases that prevail may be stated as follows. In the
winter, and early in the spring, severe colds, inflammation of the lungs
and pleurisies are most common. The genuine hereditary consumption of
New-England is rare, and families and individuals predisposed to that
disease might often be preserved by migration to this Valley. Acute
inflammation of the brain, and inflammatory rheumatism are not unusual
at that season.

Du