8 



A New Method of Treating 



the time of the year that it is only likely to occur, for that week, once in three years, 

 and very light if it is likely to occur, for that week, only once in twelve years ; other- 

 wise it is called moderate. When the week has been without rain, the word "nought " 

 is inserted in the column for the district. 



Sunshine.— The week's sunshine is called abtmdant if it is so much above the 

 average for the time of year that, in the long run, it is likely to occur, for that week, 

 only once in three years, and it is marked very abundant if it is likely to occur, for that 

 week, only once in twelve years ; similarly it is called scanty if it is so much below 

 the average for the time of year that it is likely to occur, for that week, only once in 

 three years, and very scanty if it is likely to occur, for that week, only once in twelve 

 years. Otherwise it is called moderate. When the week has been without sunshine 

 the word " nought " is inserted in the column for the district. 



A graphic method has been adopted for fixing the limits 

 for determining which adjective shall be used to define the 

 characteristics of a given week. Fig. 3 is a reproduction of the 

 diagram used for the purpose for District 5, "England 

 South." The thick lines in the centre of the shaded belts 

 in each section of the diagram represent the average values 

 " for the time of year " for accumulated temperature above 

 and below 42 0 , sunshine and rainfall. In order to eliminate 

 minor irregularities which will probably disappear when a 

 longer series of records becomes available, the " crude " 

 averages obtained from the figures have been smoothed by 



the formula A + 26 + C? in which B stands for the crude 

 4 



average of the week under consideration, A and C stand for the 

 crude averages for the preceding and succeeding weeks. These 

 smoothed averages have been adopted as averages " for the time 

 of the year." 



When the smoothed average values had been plotted, the 

 frequency distribution of the divergencies from the average was 

 found for suitable intervals for each element, and with its help a 

 curve was set off above the line of averages at such a distance from 

 it that one-third of the total number of values in the 25 years 

 fell above it and two-thirds fell below it. The chance that the 

 value for a given week falls above the corresponding subsidiary 

 line is then one in three and the limits are thus set for identifying 

 the values to be described as " unusual," " abundant," and 

 "heavy." 



Similar curves were then set off below the lines of averages 

 for each element at such distances from them that one- 

 third of the values fell below them. These in turn gave 

 the limit? for identifying the values to be described as 



