"Temperance & intemperance "thermometer""
(11 October 1844): 52
John Snow adopted temperance as a personal habit sometime in his late teens, most likely shortly after reading John Frank Newton's Return to Nature. In late 1835 or early 1836, however, he took the "moderation pledge" of abstinence after meeting John Andrew, Jr. Snow maintained a personal commitment to teetotalism for about a decade, when his personal physician recommended a return to temperance after Snow developed kidney problems.
From 1845 until the end of his life, Snow would occasionally augment his meals with wine or porter. The "moral and physical thermometer" seen in the PDF depicts how this dietary change did not violate established temperance principles.