EPIDEMICS^ PAST AND PEESENT. 
597 
3. Measles vfas long confounded with, scarlet fever^ and^ like 
it, is supposed to have been originally imported from the 
East. During twenty-four years (1838 — 1861) this disease 
destroyed 31,595 of the population of London, and 181,868 
persons in England and Wales. It is known to occur in all 
parts of the world, and is highly contagions. There is no 
evidence that any hygienic defects or meteorological con- 
ditions can generate the poison of measles. Hildenbrand, a 
great authority, thought it might arise where numbers of 
men and cattle were confined together in close nnventilated 
buildings ; and in later times American and Irish physicians 
have described a disease corresponding in every respect with 
measles, which appeared to arise from sleeping on old musty 
straw, or from the inoculation of the fungi of wheat- straw. 
Measles in England is much less of an epidemic disease than 
either small-pox or scarlet fever. The number of deaths 
which it causes in years when it is most prevalent is rarely 
much more than double what it causes in years when it is least 
prevalent. Although often most fatal in winter, there is no 
proof that its prevalence is influenced by season. 
4. T'ij]jhus Fever has been well known for upwards of three 
centuries, and there are grounds for believing that from 
remote ages it has prevailed in most parts of the world under 
favourable conditions. It is impossible to estimate the precise 
extent of its prevalence, inasmuch as many other diseases are 
included under the designation ‘^Myphns^'’ in the reports of 
the Eegistrar-Greneral ; but it is the acknowledged scourge of 
the poor inhabitants of onr large towns. There is no evidence 
that typhus, such as we see it in this country, has as yet been 
observed in Australia, New Zealand, Asia, Africa, or the 
tropical parts of America. Even in Britain it is confined, for 
the most part, to the large towns, and to the poorest and 
most densely crowded parts of them. It is a disease almost 
unknown among the better classes, except in the case of 
clergymen and doctors who visit the infected poor. It is 
undoubtedly contagions ; but in a spacious dwelling with a 
free ventilation it almost ceases to be so. There is also 
ample evidence that the poison may be generated de novo ; 
and the circumstances under which this occurs are over- 
crowding, with defective ventilation and destitution. Hence 
it is that the disease was formerly so apt to show itself in 
prisons and ships, and that, even at the present day, it is so 
common an attendant on warfare and so prevalent in the 
wretched hovels of the poor. This was the disease that 
before the days of Howard was never absent from onr prisons 
and hospitals, and that decimated the armies of the first 
Napoleon and of the allies in the Crimea. “ If,^-’ says an 
