217 
1878.] to Health and Comjort. 
country will account for the prevalence of colds and coughs 
or the occurrence of rheumatic affections. The diseases of 
the changeable climate and water-laden winds of our colder 
Eastern States are bronchial and pulmonary ; and, without 
desiring to entrench on the province of the medical profes- 
sion, whose known duty at all times it has been to find the 
cause of disease) it may be safe to attribute them, to a 
great extent, to the effedt of alternate dry and damp air on 
the evaporating surface of the lungs when the skin has the 
protection of clothing to keep it warm. The disease of 
the warmer mountain-sides of our Middle States are rheu- 
matic, and may be attributed to the same cause operating, 
by warm currents of air, on the less unprotected skin. 
Beside this view, it can be averred that, for the resident 
or native of any country, there will have established as a 
habit a connection of moisture of air relative to its tempe- 
rature which is national, so to speak, in which the variations 
of humidity and heat are accepted as a general average. 
Thus, the American in England is chilled to great discom- 
fort by the low temperature endured by Englishmen, whose 
systematic evaporation provides for small loss of heat ; 
while the Englishman in America finds a suffocating heat 
in the dwelling of the American, from the faCt that his 
lungs and skin do not afford the moisture requisite for 
evaporation and consequent dispersion of heat. A long 
residence, often two or more years, is needed before the 
system of either is adapted to the novel condition. 
§. Although somewhat late in the course of this argument, 
and perhaps somewhat elementary as information, it may 
be well to state the physical laws of the relation of moisture 
to air. The property of water is to possess in contaCt with 
itself, at any and all temperatures, from the boiling-point 
downwards, an atmosphere of vapour, which vapour has an 
elastic force, or exerts a pressure bearing some definite 
relation to the sensible temperature of the water and of 
itself. The English measures of this elastic force are gene- 
rally expressed in inches of height of a mercury column, in 
the same way as shown by an English barometer, which of 
course applies to any unit of surface, and may be 
transformed to pressure in pounds per square inch or 
square foot, by a similar process to what we use for 
atmospheric pressures. According to Regnault (as quoted 
in Guyot’s tables), some of the elastic forces are as 
follows 
