90 REPORT ON THE STATE CABINET. 



obtained by computing the temperature by multiplying the sine of the 

 sun's altitude into the length of the day (between sunrise and sunset), 

 divided by the constant divisor 12 ; and the other curve line — that which 

 departs most widely from the line of actual temperature — is that which I 

 obtained by computing in the same way the temperature, on the suppo- 

 sition that we receive an average of 60° Fahrenheit for the year. 



In this computation I have made no correction for the diversity in the 

 amount of heat which is " absorbed" or, as I prefer to consider it, " reflected 

 back " by the atmosphere, so that it never reaches the earth, or exerts 

 any influence upon the temperature of the atmosphere within the reach 

 of our observations. This correction I have not deemed of sufficient 

 importance in this connection to be worth the extra labor of making it. 

 If, however, it had been made, it would have made the difference between 

 the observed temperature and the computed temjjerature greater, both in 

 summer and in winter, than it now is by several degrees — possibly ten — 

 so that the modifying influences which I ascribe to the lakes, etc., would 

 have appeared to be greater than by the present showing. 



In the phenomena thus exhibited, I find six facts which I select for 

 comment : 



I. The maximum of heat and of cold is behind the time of the longest 

 and the shortest days respectively. 



II. Om- average for the year is not equal to what is due our latitude. 



III. The extremes of heat in summer and cold in winter, are not so 

 great as we should expect to find them. 



IV. The summer, that is, the period between the average temperature 

 in the spring and the recurrence of the same temperature in the autumn, 

 is larger than the winter, or the period between the average period in 

 the autumn and its return in the spring. 



V. The waviness or the irregularity of the line denoting the actual 

 temperature. 



VI. And, finally, the fact that about the last day of May there is an 

 arrest of the increase of average temperature, and a like arrest of the 

 decrease of it in the autumn, coming in the last of October. 



1. The greatest amount of solar heat received at any place in any one 

 day, is on the day Avhen the sun, at noon, approaches nearest to the 

 zenith. This, as we have seen, is for the equator the time of the equi- 

 noxes. For all places north of the Tropic of Cancer it is the 21st or 22d 

 day of June. The greatest height of the thermometer observed in this 

 place was July 17th, 1856, and the hottest average for the day, 84.7, 



