Haughton — Greemcich Observations of Hourly Temperatures, 639 



XXXVII. — Abstract op Discussion of the Geeenwich Obseevations 

 OP HouELY Tempeeatuees, By Ret. Samuel Haughton, M.D., 

 Dubl.; D.C.L., Oxon. ; LL.D., Cantab, and Edin. 



[Read, April 23, 1883.] 



Let 



dt 



= S + E, 



d9 



where -r- is the rise or fall of the thermometer. 

 at 



S is the rise due to 



sun heat; H is the fall due to radiation. I have found, after repeated 

 trials and errors, that S and E are best represented by the formulae — 



S = a cos z, 



{0 - OoY 



R=- 



P 



where a is an unknown coefficient depending on solar heat and the 

 atmosphere ; constant so far as the sun is concerned, and variable from 

 month to month, and day to day, with the varying conditions of the 

 atmosphere ; and % is the sun's zenith distance. In fact, a represents 

 the number of degrees through which the thermometer would rise 

 in an hour, if the sun were placed in the zenith. 



6 is the temperature at any hour of the day. 



00 is the temperature before sunrise, the average minimum for the 

 day. 



6 - $0= " range " of modern meteorologists. 



n, p are unknown coefficients to be determined by the observa- 

 tions. 



The results of my discussion are contained in the following 

 Table :— 





a. 



Qo. 



n. 



P- 



January, . . . 



7-18 



37°-0F. 



1-90 



12-09 



February, . 







7-24 



38 -1 „ 



1-87 



11-02 



March, . . 







7-27 



38 -8 ,, 



1-85 



16-51 



April, . . 







10-04 



42 -0 „ 



1-77 



13-63 



May, . . . 







10-50 



47 -7„ 



1-62 



8-55 



June, . . 







12-15 



51 -3 ,, 



1-53 



7-59 



July,. . . 







8-13 



57-3,, 



1-37 



5-89 



August, . . 







9-90 



56 -1„ 



1-40 



5-56 



September, 







10-36 



51 -3 ,, 



1-52 



10-41 



October, 







8-99 



46 -9 „ 



1-64 



9-08 



November, . 







6-97 



40 -2 „ 



1-81 



13-48 



December, . 







8-22 



38 -3 „ 



1-86 



11-20 



