310 Dr. C. Chree on Deductions from 



Grouping Mr. Maunder's numbers, we have 





Easterly. Westerly. 



Total. 



Average 

 per hour. 



Oto 11a.m. (12 hours) 



Noon to 7 p.m. (8 hours) ... 

 8 to 11 p.m. (4 hours) 



12 59 

 89 3 

 6L 9 



71 

 92 



70 



6 



171 



The average per hour between noon and 7 p.m. is certainly 

 greater than between and 11 a.m. ; but it is just as con- 

 spicuously less than the average from 8 to 11 p.M., a period 

 when Mr. Maunder's times of commencement of storms are 

 relatively few. 



§ 4. The next point where I differ from Mr. Maunder is as 

 regards his conclusion (I. c. p. 669) that in his tables u The 

 'great' disturbances are distributed throughout the 24 hours 

 with almost complete impartiality.''' As some importance 

 attaches to this point in connexion with the theory of 

 disturbances I shall discuss it in some detail. 



In Mr. Maunder' s first paper, storms were divided into four 

 classes, G, V, A, M, in descending order of magnitude, and 

 to each storm only one letter was attached. In his second 

 paper he combined the two first classes into one, called G, 

 and when a storm lasted over two or more days a letter 

 was attached to each day. I have adopted the three classes 

 of Mr. Maunder's second paper ; but have attached to a 

 single storm, however long it lasted, only one letter, that 

 letter corresponding to the most violent part of the storm. 

 It must, I think, be conceded that this is the proper choice 

 of letter if the disturbance be assumed all one storm. 



Table II. shows what the incidence of the commencements 

 really was for each class of storm, the number occurring in 

 the 24 hours being taken in each case as 100. 



Table II. —Actual percentage incidence of storms (for normal 

 incidence to 11 a.m., 50 ; noon to 7 p.m., 33 ; 8 to 

 11 p.m., 17). 





Midnight to 11 



A.M. 



Noon to 7 



P.M. 



8 to 11 r 



M. 



a 



A | 



M 



G 



A 



M 



G 



A 



M 



Period 1848-81... 



34 



27 ; 



16 



57 



52 



62 



9 



21 



22 



„ 1882-1903 



39 



28 



19 



49 



61 



70 



11 



n 



12 



„ 1848-1903 



37 



' 27 ' 



17 



53 



56 



64 



10 



17 



18 



