100 
Analyses of Books. 
[February, 
Solar Physics, an Almanack of the Christian Era. By A. H. 
Swinton. London : W. H. Allen and Co. 
Have the sun-spots a definitely recurrent period of increase and 
decrease, — a maximum alternating with a minimum ? So say 
astronomers not a few who have made it their especial business 
to watch for years the aspedt of the sun. They maintain, fur- 
ther, that this alternate waxing and waning of disturbance in 
the solar photosphere occurs in a cycle of from ten to twelve 
years. Thus, in a table in the book before us, we find the years 
i860, 1870, and 1882 laid down as those when sun-spots were 
most numerous. At the intermediate dates, 1867 the spots were 
fewest. Here, then, there can be no scope for argument. Nothing 
but prolonged observation can show whether the spots have a 
period, and, if so, of how many years does it consist ? 
We come now to the second question : admitting the cyclical 
character of the sun-spots, and ascribing to them — provisionally 
at least — a period of from ten to twelve years, we ask can a cor- 
responding cycle be traced in any terrestrial phenomena ? Many 
observers here reply in the affirmative. They trace a periodicity 
in the occurrence of earthquakes, tempests, floods, severe frosts, 
heat-waves, &c. Not less is the organic world said to be simi- 
larly affedted ; inroads of destructive insedts, pestilence, cattle- 
plague, diseases in crops, commercial depressions, wars, nay 
even social and moral phenomena, such as outbursts of fanati- 
cism, “revivals,” political “reforms,” and the like,— all, it is 
asserted, display the same periodicity. From an a priori point 
of view there is here nothing to be sneered at. To pronounce 
it impossible for one series of phenomena to be causally con- 
nedted with another is extremely rash, until close observation 
has proved the contrary. But we cannot detedt a cyclical suc- 
cession in earthquakes, floods, and tempests without colledting 
notices of their occurrence. Hence we fail to see anything ridi- 
culous in the author s habit of cutting out from the morning 
papers, and assorting all allusions to earthquakes, floods, gene- 
ral meteorology, and corn statistics. If he perseveres in such a 
course he will obtain the fadts and their dates ; he will be able to 
find, c.g., whether such convulsions of Nature are more plenti- 
ful in yeais of maximum or of minimum sun-spots, or whether 
the two classes of phenomena have any apparent connedtion at 
all. It would, of course, be preferable if Mr. Swinton had a 
legion of agents distributed over the globe, each duly equipped 
with seismometer, rain-guage, anemometer, &c., and at once 
sending in to some central station the results of his observa- 
tions. But in default of such an organisation, which it might 
exhaust the lesouices of a nation to maintain, the next best 
method is to avail himself of the public press. 
The question whether the subjedt is in itself worth examina- 
