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-♦- 29 



20 

 It, 

 II 

 8 



By E. Marriott. 



The heat of our summers might be measured in various 

 ways. Thus we might count, in each year, the number 

 of days on which the thermometer reached or exceeded a 

 certain limit, say eighty degrees. We might do the same 

 with a lower limit, say seventy degrees. Greenwich 

 supplies tables of such data from 1841, and we shall 

 employ both series. Again, we might find the mean 

 temperature of summer proper — that is, of June, July, 

 August ; or do the same with four or five months, including 

 (with summer) May or September, or both. We shall, in 

 a third method, use the mean temperature of the four 

 months. May to August. 



In the rough diagrams herewith, A relates to summers 

 as measured by the number of days with the thermometer 

 going up to or beyond eighty degrees. Summers are 

 here " pigeou-holed," so to speak, in eleven columns, 

 according as they fall in a sunspot maximum year, or 

 the year before or the year after, or the second year 

 before or after, and so on ; the series extending from the 

 third year before to the seventh year after, in accordance 



2 X I In* I 



s b y 



LONDON SUMMERS NEAR SUN- 

 SPOT MINIMA. 



By Alex. B. M-^cDowall, m.a. 



THREE stages might perhaps be 

 distinguished in meteorological 

 science : — First : observation and 

 record of phenomena. Second; 

 elucidation of those phenomena, as 

 regards their proximate, terrestrial causes 

 (explaining, ..</., the physics of cyclones, 

 thunder, dew, A.C.). Third : reference 

 of weather to periodic changes of the sun 

 or the moon, or perhaps some other outside 

 influences. 



If a beginning may be said to have been 

 made in this third stage of " cosmic meteo- 

 rology," the amoimt of undisputed gain to 

 knowledge is not, thus far, perhaps, so 

 extensive and definite as to be of great 

 practical use. Thus it probably occurs to 

 few at present to ask what part of the 

 sunspot cycle has been reached, with a 

 view to getting some clue to the weather' 

 of approaching years. Such inquiries may 

 in time, however, prove to be not wholly 

 useless. 



The last sunspot maximum occurred 

 in 189i (by one estimate), and we are now 

 on the downward slope, and probably 

 nearing a minimum. The exact time of 

 this minimum cannot be fixed, but if we 

 consider these dates of minima since ISil — viz., 1843, 

 1856, 1867, 1879, 1890— we shall probably be not far 

 wrong in looking for a minimum in or about 1901. 



Do our summers give any indication of sunspot influence ? 

 And does our past experience of summer near sunspot 

 minima give any hint as to what kind of summer weather 

 we -might Expect near this next minimum ? These practical 

 questions we may briefly consider. 





 IZo 



no 

 too Y 

 qo 



10 

 (.0 



So 



uc 



J A^ J' 



77 



la 



B 



A. Summei-s measured by number of days with thermometer 80° or more (max. 

 simspot group). 



B. Summers measiu'cd by number of days with thermometer 70° or more (max. 

 sunspot group). 



C. Summers measured by mean temperature of May to August (max. sunspot 

 group). 



D. Same as A (min. sunspot gi-oup). 



with the average course of the sunspot cycle (four years of 

 growth, seven years of decrease). Each mark (dot or 

 smaU o) stands for a summer season, and the distance 

 of each mark from the average line (fifteen days) shows 

 how hot the summer is (dots), or how cool (smalljj'sj ; 

 that is, how much more than the average number of days 

 with thermometer up to or above eighty degrees it had, or 

 how much less. Five summers are thus represented in 



