SUNSPOTS AND BRITISH WEATHER. 
237 
for, say, three or six months in advance, meteorologists must 
succeed in proving a connexion between our weather and some 
extra-terrestrial or other phenomenon which, being regular and 
periodic in its variations, would give us the necessary warning 
of approaching climatic change. 
The apparent success attending the work of the Sunspot 
theorists, induced me to take a ‘ Sunspot period/ and by care- 
fully working through it, having regard to the meteorological 
elements of rainfall, temperature, and weather, to find out 
whether some parallelism might not be discovered between the 
number of Sunspots and the weather experienced. Everyone is 
aware that nearly every important climatic alteration is due, 
directly or indirectly, to cosmical changes ; and the first efforts 
of the advocates of the Spot theory having apparently been 
crowned with success, droughts, floods, and more recently com- 
mercial crises, have been ascribed to the presence or absence of 
spots on the surface of the Sun. 
It is now matter of everyday knowledge, from the investiga- 
tions of Wolf, Balfour Stewart, and Lockyer, that the number 
of spots which appear on the surface of the Sun has a regular 
period of increment and decrement, and that these changes 
proceed during a cycle of about 11 T years. For long these 
spots were believed to he cooled solid bodies, or even clouds 
sailing about on the surface of the Sun, hut it is now supposed 
that they are vortices in the surrounding atmosphere, caused by 
the descent of upper and cold currents into the interior of the 
Sun. Their numbers consequently indicate increased activity in 
the Sun’s atmosphere, and hence, probably in solar radiation ; and 
as all changes in our atmosphere depend on the intensity of solar 
radiation, the importance of their indications cannot he too highly 
estimated. It happens, unfortunately, that considerable divergen- 
ces of opinion exist among the authorities who have investi- 
gated this matter. Some, among whom are Messrs. Baxendell 
and Blanford, maintain that solar radiation is much more 
intense in years of Sunspot maximum than in those of minimum, 
believing, in fact, that the spots themselves are indications of 
the intensity of solar radiation ; while other writers, relying on 
the observations of Dr. Koppen, believe that while the electrical 
phenomena of our atmosphere are in some manner intensified 
according to the abundance of Sunspots, periods of high air 
temperature correspond rather with years of minimum than of 
maximum spots. A decision on this important point would assist 
considerably in all discussions as to the effect of these cosmical 
changes on the meteorology of the Earth ; but until the establish- 
ment of observatories, in such almost cloudless districts as some 
parts of Africa, Arabia, or India, so that actinometrical observa- 
tions can he continued for long periods under almost unvarying 
