482 Probable Extension of Solar Physics. [August, 
weakness, and not a few attempts have been made to corre- 
late them with seasons of famine, plague, cholera, and other 
epidemic visitations. But with all this scope of inquiry in- 
dicated or grappled with, many other phenomena which the 
record of the past would lead us to associate with certain 
meteorological conditions, and therefore with solar physics, 
remain for the most part the subject of vague conjecture and 
inane speculation. Chief among these come, perhaps, seis- 
mic phenomena, including earthquakes, volcanic emanations, 
and hot springs ; and entomological phenomena, such as 
inseCt multiplication and migration. As regards the first 
class of disaster — despite a prevailing astronomical bias to 
the theory propounded by M. Cordier, of a subterranean tidal 
disturbance governed by the moon, which yet remains a 
question — much that is. palpable can be adduced in favour 
of the influence of the sun, more especially perhaps in the 
frequent arrival of these manifestations simultaneously about 
the equinoxes, and their recurrence in periods more or less 
marked. As regards the second class of subordinate phe- 
nomena more can be affirmed, and taking the inseCt plagues 
best known in the commercial world — such as locusts, corn 
weevils, and wheat flies — it may be fairly stated that their 
periods of increase and diminution show fair promise of 
exaCt co-ordination with the solar registers. 
If we take, for instance, the rocky mountain locust 
( Caluptenus spretus), the scourge of the Western States of 
America, we shall find that its permanent region and native 
breeding-ground lies within the northern temperate zone, 
between 37 0 and 53 0 N. lat. Its migrations have been, on 
the whole, in a southerly direction east and west of this 
region ; and from an analysis of the table given in the 
“ Annual Report of the United States Entomological Com- 
mission for the year 1877 ” (p. 113) it is distinctly evident 
that the periods of migration and increase of this species 
coincide with the sun-spot minima, while its years of decrease 
as closely harmonise with the maxima, in neither case there 
existing the difference of a year. We also know as regards 
the multiplication and migration of various locusts in the 
cereal districts on the borders of Europe and Asia, from long 
tradition as from recent more exaCt evidence, that droughts 
coming about the minimum period of the sun-spot cycles 
are their time of increase. The evidence, however, is here 
of a more general description, and not so precise as in th$ 
case of Prof. Riley’s elaborate reports, it being well known 
that “ locust ” in itself is a very wide and indefinite word to 
an entomologist. However accepted as a term of common 
