68 



Lieut-General Strachey. On the 



be T V(12— n)c\ and the corrections of the quantities d, 0, 2, and yfr 

 are all equal to + c, those of A being 0, and of c being + 2c. 



The correction for the mean value p will be -^c. This is equiva- 

 lent to calculating the mean for the 24 hours, by adding together 

 half of the 1st and 25th observations and the whole of the 23 inter- 

 mediate ones, and dividing the sum by 24. This mean will corre- 

 spond to the middle of the series, noon. As commonly calculated the 

 mean corresponds to half an hour before noon if the series is supposed 

 to begin with midnight, and to half an hour after noon if it begins 

 with 1 a.m. It is to be regretted that meteorologists have not yet 

 adopted any uniform system in these respects. 



The correction for the p q coefficients as determined from the 

 equations (2) will be as follows r — 



For p the mean value -^c, 



» p\> P2* p& n iV c = * 083c > 



For q l -f "633c, 



„ % -f*311c, 



„ 23 +-201c, 



» 2 4 +-144* 



For£ 5 .. -f*112c, 



» % +-083c, 



» q 7 + -064c, 



,, q 8 -f "048c. 



For the values obtained from the equations (3) they will be- 





... 2 4 o, 



For q l . 



. + 10c x -06583 = 



Pi • 



... + fcx '06583, 



n 2-2 • 



.. -f 5c x -06699 = 





... -f- c x '06699, 



» 2s- 



. . + 3c x -06904 = 



Ps • 



... -fcx *06904, 





+ 2c x -07217 = 



P4 ' 









8. 



As it may happen that the values of the initial observation and of 

 that corresponding to the hour immediately after the end of a series 

 of mean hourly values, are not known, an approximate value of 2c 

 may be obtained either graphically or by calculation as follows : — 



If the mean values for two or three hours preceding midnight, say 



* As the multipliers are here the same as those which enter into the expressions 

 (3), the corrections may most conveniently be applied to the quantities within the 

 brackets in those expressions. 



