EPIDEMIOLOGICAL SOCIETY. 
51 
that deceptions ma}' not arise from causes which, though in 
appearance general, are really only local and accidental. When 
the cholera first broke out at Bombay, bleeding proved so suc- 
cessful a remedy, if practised at the commencement of the 
attack, that many persons not of the medical profession learned 
to perform the operation, that no time might be lost ; and, ac- 
cording to the testimony of a near relative of mine, hundreds of 
lives were thus saved. The same treatment, pursued in Bengal, 
proved entirely abortive; the inevitable inference being, not 
that the essential disease differed in the two places, but that the 
various success of the treatment depended on some accidental 
though unknown circumstance. 
In the infancy of geology, first studied in this country, many 
phenomena observed in the arrangement of the earth’s crust, as 
it is found in this island, were supposed to furnish fixed laws ; 
and this gave rise, among our philosophers, to divers ingenious 
generalizations. But when these same philosophers had, from 
the establishment of universal peace, the opportunity of taking 
a wider range, and of studying the earth’s structure, not in this 
country alone, but over the whole surface of the globe, they 
discovered, in many instances, that what they had supposed to 
be general laws were, after all, only exceptional cases : we re- 
quire, therefore, in the study of epidemic diseases, as of geology, 
a wide field, in order that we may found theories on a suffi- 
ciently broad basis to avoid the risk of coming to partial and 
erroneous conclusions. When the phenomena of the migration 
of birds first attracted attention, how ridiculous were the notions 
of it entertained by philosophers ! We have a paper in the 
Philosophical Transactions, written to refute a belief, confidently 
stated by a Dutch writer of less than a century ago, that swal- 
lows lie immersed at the bottom of the ocean and other waters 
during the winter season. This is no bad illustration of the 
effects of partial observation, and of the absurdities to which it 
may lead. The welfare and prosperity of the people at large 
ought to be a main object with all good governments. It seems, 
therefore, to be matter of sound policy that they should facilitate, 
by all available means, the study of morbific phenomena which 
have so extensive an influence over the destinies of mankind. 
Commerce, agriculture, and manufactures, have on many occa- 
sions been deeply injured, and the progress of civilization itself 
been seriously impeded, by the outbreak of destructive epi- 
demics; and it is not easy to estimate the evil that has been 
caused by the imposition of strict quarantine laws, arising out 
of the fear of these visitations. 
Again ; a careful study of the sanitary arrangements which 
affect the health of our military and naval forces, falls legiti- 
