90 TWENTIETH ANNUAL REPORT ON THE STATE CABINET. 



III. The extremes of heat in summer and cckl in winter, are 

 not so great as we should expect to find them. 



IV. Xlie summer, that is, the period between the average tem- 

 perature in the spring and the recurrence of the same temperature 

 in the autumn, is larger than the winter, or the period betweeii 

 the average period in the autumn and its return in the spring. 



Y. The waviuess or 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 when the sun, at noon, approaches 

 nearest to the zenith. This, as we have seen, is for the equator 

 the time of the equinoxes. 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, July 20th, 1854. But the 

 above averages show that the maximum of heat is not reached on 

 the averao'e until about the first of Auoust, when it is 73.29. The 

 maximum of cold is reached on the third of February ; and the 

 coldest day I have on record was February 6th, 1855, when the 

 average for the day was 14.2 degrees below zero. 



It may be worth observing, that the greatest heat and the 

 greatest cold in the day are reached only after noon and after 

 midnight ; and the distance of time after noon, for example, 

 when the day is the hottest is about the same in proportion to the 

 length of the day as the time of greatest heat in the summ.er, after 

 the solstice, is to the length of the year. The hottest time in the 

 day is generally about three o'clock p. m. ; a little before in win- 

 ter, and a little after in summer ; and both phenomena are doubt- 

 less to be ascribed to the same cause — the equilibrium of heating 

 and radiation. From the 21st of December the amount of hea-t 

 received from the sun begins to increase, both because the days 

 are longer and because the sun runs higher. But, as appears from 

 the Table, it is not until the third of February that the l)alance 

 comes to be in favor of the heat ; and from this time on till Aug. 

 1st, the earth receives and absorbs more heat than it gives ofi" by 

 radiation and conduction, and consequently is growing Avarmer. 



However, ])()lh processes are going on together. Duiing the 



