698 
POPULAE SCIENCE EEVIEW. 
able writer on fever in the last century any person will 
take tbe trouble to stand in the sun, and look at his o’vwi 
shadow on a white plastered wall^ he will easily perceive that 
his whole body is a smoking dunghill, with a vapour exhaling 
from every part of it. This vapour is subtle, acrid, and 
offensive to the smell; if retained in the body, it becomes 
morbid ; but if re-absorbed, highly deleterious. If a number 
of persons, therefore, are long confined in any close place not 
properly ventilated, so as to inspire and swallow with their 
spittle the vapours of each other, they must soon feel its bad 
effects. Bad provisions and gloomy thoughts will add to 
their misery, and soon breed the seminium of a pestilential 
fever, dangerous not only to themselves, but also to every 
person who visits them or even communicates with them at 
second-hand. Hence it is so freqnentl}^' bred in gaols, hospitals, 
ships, camps, and besieged towns. A seminmm once pro- 
duced is easily spread by contagion But if overcrowding 
produce typhus, why is it that the disease prevails in the 
epidemic forni, and then in a great measure disappears ? 
The explanation is in this way. All the great epidemics of 
typhus have occurred during seasons of famine or of unusual 
destitution. One of the most common consequences of 
general destitution is the congregation of several families 
in one house, in consequence of their inability to pay their 
rents,- and of the concentration in the large towns of many 
of the inhabitants of country districts. Famine predisposes 
to typhus by weakening the constitution ; and it also tends 
to produce it, in so far as it causes an unusual degree of 
overcrowding. It has been the custom with many writers 
to refer epidemics of typhus to some subtle epidemic in- 
fluence;^^ and thus, where a failure of the crops has been 
followed by typhus, both of these disasters have been ascribed 
to a common atmospheric cause. But of such atmospheric 
influences capable of producing typhus we know nothing ; 
their very existence is doubtful, and the employment of the 
term has too often had the effect of cloaking human igno- 
rance, or of stifling the search after truth. If. typhus be 
due to any epidemic influence,^^ why does this influence 
select large towns and spare the country districts ? why 
does it fall upon large towns in exact proportion to the 
degree of privation and overcrowding among the poor ? in 
large towns, why does it infect the crowded dwellings of 
the poor and spare the habitations of the rich ? and why 
did the varying prevalence of typhus among the French 
and English troops in the Crimea correspond exactly to the 
varying degree of overcrowding in either army ? Moreover, 
famine artificially induced by warfare, by commercial failures. 
