122 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. V. 



within the last quarter of a century been appreciably affected by deforest- 

 ation and drainage. These five year periods shew total precipitation in 

 inches as follows: 31.1, 36.6, 35.1, 32.5, and 32.1, a series from which it 

 would be rash to predict that the mean of the next period will not be as 

 great as of any of those preceding it. Taking the pentad means for 

 Toronto alone we have ten such means, and the sum of the first five 

 exceeds the sum of the last five, in fact the mean for the 1876-80 is the 

 only one in the last set that is as great as the smallest mean among the 

 first five. This looks suspicious, but we can throw additional light on 

 this subject, as we have in " Rainfall and Snow of the United States," 

 published by the Weather Bureau, a record of the total rain and snowfall 

 at several places in New York and Ohio for longer periods than at 

 Toronto. At Marietta, Ohio, the record goes back to 1818 ; at Albany, 

 N.Y., and at Troy, N.Y., to 1826 ; at Rochester, to 1834; Steubenville^ 

 Ohio, to 1835. Marietta, Steubenville, and Rochester will probably best 

 indicate the rainfall of the Lake Ontario drainage area since as a general 

 thing the same storm centres which cause rain in Ohio, cause it over the 

 Ontario district, while Albany and Troy are ofttimes affected by storm 

 centres moving up the Atlantic coast. A study of these records (see 

 table) shews pretty clearly that immediately south of Ontario and Erie,, 

 between 1834 and 1846, occurred a period of comparatively small precip- 

 itation, in fact to the present date we shall find no other period of 12 

 years with such a smiall rainfall ; then immediately following this we.find 

 a period of much heavier rain. To my mind the figures in the table 

 afford fairly strong evidence that the rainfall has not been appreciably 

 affected by deforestation, and that a deficiency of rainfall may be con- 

 sidered as only temporary. 



