30 RECORD AND DISCUSSION OF TEMPERATURES. 



It must be considered a fortunate circumstance that tlie observations extend 

 over two winters, and thus give us a more exact mean temperature for that season. 



The warmest month is July, and the coldest is March ; the temperature of 

 December, however, does not differ much from it, and December actually was the 

 coldest month in the second winter. The highest mean monthly temperature seems 

 to fall almost exactly to the middle of July, and the lowest would probably occur 

 in February, if we had a longer series of observations extending over several 

 winters. From the observations on hand, we find the December temperature only 

 5° higher than the March temperature. The range of the mean temperature for 

 the warmest and coldest month is 73°. 07. The temperatures for the meteorological 

 seasons — December, January, and February being regarded as winter — become as 

 follows : — 



'1 



Winter —28°. 59" 



Spring ..... — 10.59 [ Mean temperature for the 



Summer +33.38 



Autumn — 4.03 



whole year, — 2°. 46. 



The mean annual temperature is reached in the middle of spring (April), and 

 again in the middle of autumn (October). The difference in the winter and sum- 

 mer temperature is 61°. 9 7. 



The seasons of the second year compare with the corresponding ones of the first 

 as follows: — 



Autuma in the second year colder by 5°. 65 



Winter " " warmer by 1.03 



First two month.? of spring colder by 0.76 



The lowest mean monthly temperature of the first winter (March, — 36°.79) 

 was precisely the same as that of the second winter (December, — 36°.79), both 

 months falling in the year 1854. 



For the purpose of continuing the discussion of the atmospheric temperatures, 

 it becomes necessary to express the annual variation analytically. On account of 

 the great range of this variation, I have first applied a small correction to the pre- 

 ceding monthly means, in order to refer them to the middle of months of average 

 length of 30'i-.4 in common, and 30'i-.5 in leap years. Thus, the mean temperature 

 of January, 1854, refers to (noon) 15'i-.5, when it ought to refer to lb^-.1; differ- 

 ence, 0'i-.3. The fifteenth part of the difference of the January half monthly means 

 is — 1°.40; hence the correction +0°.40. For convenience of reference, the num- 

 ber of days for which a correction is to be applied to refer the means of the true to 

 an average month are here inserted. Commencing Avith January, these numbers 

 for the several months in their proper ordet become — 



The first line is for a common year, the second for a leap year. The maximum 

 correction applied was + 1°.34 (to the mean of March) . To the following monthly 



