"Water supply in relation to health and disease [review essay, including MCC2]"
PDF from photocopy, courtesy of the U.S. National Library of Medicine.
I have transcribed several excerpts from Richardson's essay that bear on the degree of his support for Snow's theory as set forth in Continuous Molecular Changes and the more recently published MCC2.
"The subject . . . has within these last four or five years received a degree of attention quite unprecedented, in consequence of the fact that a London physician, whose scientific reputation in the medical world stands deservedly high, has, in a manner neither to be overlooked nor forgotten, made the bold statement that the last two epidemics of cholera were mainly due to the distribution of impure water; and that to this cause alone all epidemics of cholera are chiefly attributable" (130).
Richardson then evaluates six objections that have been raised against Snow's theory and states what he believes are several facts about the nature of the cholera poison, after which he concludes:
"With these facts before us, one inference may therefore be drawn, that Dr. Snow and his objectors are both right in the main; and that while the specific poison of cholera (for we must presume the existence of such a poison, though we may not understand its nature), may, by accident, be carried into the intestinal canal by the medium of water, it may also be wafted into the lungs by the medium of the air.
Many of Dr. Snow's objectors would, we doubt not, join us in this view of the case; which is more than we could expect from him, since it is opposed to his essential idea . . . .
Now, although, as it will be inferred, we are prepared to go great lengths with Dr. Snow to support of his peculiar views, we are obliged to stop whenever we meet with this absolute conclusion" (134).
On the next page, Richardson writes: "The view that the specific cause of cholera may be carried by the air into the lungs, we are glad to see supported by Dr. Wm. Budd (who is a firm believer in the general truth of Dr. Snow's hypothesis). In his admirable and scholarly letters, Dr. Budd offers many remarkable facts in support of this argument" (135).
Richardson concludes his essay with a brief overview of Snow's investigation of cholera mortality in South London, focusing on the inquiries Snow made during the first four weeks of the 1854 epidemic.