\\.\VIII XLI I 



od 



(ill). The following data ;uv for I In- liv,ju,-n<-i,-s ,,| |it], 

 of cloudiness as observed at Greenwich during ih- y. U-H 1890 1900, 1902 1904 

 for the month of July, there being usually four observations a day. 



We are dealing with a continuous variate which can only lie between zero, that 

 is entirely clear sky, and 10, entirely overcast sky. But the continuous variate has 

 been grouped in eleven classes. We cannot make the first group extend from 10*5 

 to 9'5, or the last from 0'5 to + 0'5, for the sky cannot be more than entirely 

 overcast or less than completely clear. We are thus driven to suppose the 10 group 

 to extend from 9*5 to 10 and the group from to 0'5, while any group such as 9 

 extends through a full unit from 8*5 to 9'5 and so on. Thus our ranges are not all 

 alike, the terminal ranges being | unit each and the rest a whole unit each. It is 

 needful therefore in order to apply abruptness-coefficients to break up the fre- 

 quency on the whole unit subranges into two frequencies on half-unit subranges. 



This may be done in the following manner*. Assume 



to give the total frequencies from x to 10 and suppose A, B, G, D and E to be 

 determined in terms of q and the frequencies w/, TJ/, n 3 ', ?i 4 ' and n s '. The resulting 

 values are 



-H 11% + ... + 115) 540 (iii +n* + >+ w/) 



(4-5)9 (3-5)9 



1134 (w/ + n/ + w/) 1260 (n/ + w/) 945n/ 



245 = 



(2-5) 



22 + 2 '-i-...- r -K 5 / ) 

 (4-5)9 



HI 



(1-5)9 

 i' + n/ +...+/) 



(-5)* 



(3-5)5 



225 (n/ 4- w/ + n/) _ 229(n/+ti/) 93/ ,' 



(2-5)5 



(1-5)5 



48(7 = 



(4-5)9 



390(w/+M/ + M/) 328 (w/ + H/) 

 (2-5)9 (1-5)9 



* Gertrude E. Pearse, Biometrika, Vol. xx*. pp. 339 346. 



(xv), 



B. II. 







