Meteorology of N'eio Haven. 



233 



sumecl instant; (T), A,, Bj, A2, Bg, etc., being constants derived 

 from the mean temperatures determined for certain epochs. In order 

 that these constants may be moat conveniently determined, it is neces- 

 sary that the epochs should divide the year into equal intervals ; and 

 it is also necessary to deduce from the mean temperatures for the sev- 

 eral months, the mean temperatures of 12 equidistant epochs; viz., 

 for a; z= 0°, a; = 30°, and so on up to x =. 330°. 



Now the mean temperature of all the days of a month does not 

 coincide with that of a day placed at the middle of the month, be- 

 cause the temperature does not change uniformly ; that is, the varia- 

 tion of temperature is represented by a curved line rather than by a 

 straight line ; and when we have obtained the mean temperature for 

 the middle of each month, these temperatures do not correspond to 

 the epochs a^^O", a;:=:30°, etc., because the months are of iinequal 

 length. It is therefore necessary to reduce the temperature of the 

 middle of each month to that which corresponds to the epochs 0", 

 30°, etc. In order to obtain these two corrections, a provisional 

 formula was compvited, which differed but little from the one given 

 below, and from this was computed the mean temperature of each day 

 of the year. The following table shows the corrections thus obtained 

 for the curvature of the line of mean temperature, and for inequality 

 of intervals, the dates being reckoned from Jan. 15th. The last col- 

 umn shows the results after these two corrections have been applied. 



Computing from these corrected temperatures the values of the 

 constants in our assumed formula, we obtain 



Tar=49°-ll-f 22°-92 sin(i«-j-263° 38')-}-0°-29 sin(2a;-|-345'' 24') 

 -f 0°-45sin(3a;-f 229° 50')-f0'»-02 sin(4a?-{-150°)-|-0°-38 sin(5x+54° 31') 



-0°-08cos6a;, 



in which x is reckoned from January 15th. 

 30 



