“The febrile diseases of Upper Canada are by no means uniform in their prevalence. Even in years when the degree of temperature, fall of rain, or extent of vegetation have been much the same, the proportion of cases, particularly of intermittents, is very different. A general impression exists, that their prevalence is in some measure dependent on the height of the waters in Lake Ontario, which attain their maximum in June or July. If, from the quantity of snow or moisture in the course of the year, this is found to be greater than usual, febrile diseases are expected to abound, and the reverse if the maximum has been under the average. As Lake Ontario is the reservoir into which all the waters of Upper Canada are drained off before finding their way to the ocean, this theory, if accurately substantiated, would tend to show how far the origin of these diseases depended on moisture, and we therefore instituted the following comparison between the height of the waters in the lake, as measured at Kingston for a series of years, and the prevalence of fever in Upper Canada during the same period: +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ | |1818.|1819.|1820.|1821.|1822.|1823.|1824.|1825.|1826.|1827.|1828.| +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ |Average height of| | | | | | | | | | | | |lake in Kingston | | | | | | | | | | | | |Harbour in each | 14 9| 13 3| 12 3|11 11| 12 1| 13 5|13 11| 12 5|12 10| 14 3| 15 7| |year | | | | | | | | | | | | |(feet and inches)| | | | | | | | | | | | +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ |Cases of inter- | | | | | | | | | | | | |mittent fever | 110 | 319 | 509 | 348 | 222 | 143 | 171 | 135 | 111 | 220 | 489 | |in Upper Canada | | | | | | | | | | | | +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ |Cases of other | 109 | 54 | 150 | 152 | 132 | 69 | 168 | 190 | 155 | 185 | 300 | |fevers | | | | | | | | | | | | +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+