LOCAL CLIMATOLOGY. 



89 



Month. 



Average. 



Month. 



Average. 



Month. 



Average. 



January 



February .... 



25.29 

 25.39 

 32.26 

 43.21 





55.66 

 64.93 

 70.28 

 68.08 



September .... 



October 



November 



December 



60.47 

 49.66 

 39.12 

 25.56 







Api'il , 



August 





From which it appears, as we should expect, that July is the hottest 

 month in the average, and January the coldest. 



The average for the season is as follows: Spring, 44.21; Summer, 

 67.68; Autumn, 49.52; Winter, 25.41. 



The average for the year is found to be 47°.20. ' This is obtained, 

 however, not in the usual way of adding together the averages of the 

 months and dividing by 12, or the average of the half months and 

 dividing by 24, but by taking the average for the days and dividing by 

 365, neglecting the one-fourth day due to February, on account of the 

 bissextile addition. I then made an average for each week in the year, 

 which, together with some other computations, I have also thrown into 

 the accompanying tabular form. In the first column is the day of the 

 month on which the week ends ; in the second is the average for the week, 

 obtained from the observations and the above averages for the days in 

 the year. For the third column I have computed what the temperature 

 for the day for each seventh day (beginning with January 4th) should 

 be, provided the 47°.20 were distributed according to astronomical 

 influences alone, namely, the sun's altitude and the length of the day. 

 For a fourth column I have', in like manner, computed what the tempera- 

 ture for the day for each seventh day, beginning, likewise, with the 4th 

 of January, would be, if Ave had the 60° due to our latitude as by the 

 table given in the first part of this essay. 



But as our coldest day does not occur until about five weeks after the 

 winter solstice, and as the warmest day comes in like manner about five 

 weeks after the summer solstice, I have placed the third and fourth 

 columns five weeks forward in the year, for the greater convenience of 

 comparison. 



These results I have constructed into a diagram, in order to present 

 them more obviously to the eye. The straight lines running across the 

 diagram, from the right hand to the left, denote the degrees of tempera- 

 ture ; the continuous irregular line denotes the temperature as obtained 

 from observation, and indicated in the second column in the table; the 

 dotted line, most nearly corresponding with this irregular line, is that 



Cab. Nat. 12 



