13 



Mr. Yeates' reports of his rain-gauge for the last seven years, 

 from 1843 to 1849 inclusive, and I have constructed my table 

 from them. 



" I began by arranging in so many parallel columns the 

 monthly quantity of rain which fell in the seven years com- 

 mencing in January, 1843, and ending in December, 1849, 

 and having then ascertained the mean quantity for each month 

 during those years, I assumed that it was the average quantity 

 of rain in that month. On comparing this mean quantity with 

 the actual fall of rain, I was surprised at finding the great irre- 

 gularity which it indicated. It appeared that there was not 

 any one month which was either wet or dry, or of average 

 weather, during the whole of that period. The most settled 

 weather was in August and December, and in those months 

 the weather was either very wet or very dry ; each was for four 

 years very wet, and for three years very dry. 



" I am aware that a period of seven years is too short to 

 afford a satisfactory average, but Mr. Yeates' tables did not go 

 farther back, and those years were marked by the epidemics I 

 have alluded to. We had cholera, influenza, murrain, and the 

 potato disease ; on that account they deserved a separate con- 

 sideration, even if the rain tables had gone further back. 



" In classifying the varieties of weather, as indicated by the 

 quantity of rain which fell, I took the mean, or any quantity 

 within a quarter of an inch, more or less, of rain in that month, 

 as average weather. For example, I found that about two 

 inches of rain was the mean quantity for the month of June ; 

 I marked it as average weather in June, if the fall of rain was 

 less than two inches and a quarter, and more than one inch 

 and three-quarters. If more than two inches and a quarter, I 

 marked it as decidedly wet ; and if less than an inch and three- 

 quarters, as decidedly dry. June was four times very dry and 

 three times very wet. Adopting this scale, I found that during 

 those seven years, the weather had a remarkable tendency to 



