272 Scientific Intelligence. 
Changes in the amount of heat received from the sun, sufficient to pro- 
duce the variatio 
no doubt t Soe ee ficult 
though not to the extent indicated by the observations; but it is di hi : 
to conceive that they could produce the differences in the epochs W 
: t 
action of the oer ring of nebulous matter is principally of a Dx” 
aetic, and but slightly of a thermal character. me 
It is suggested that the greater range of variation of the magnetic, ad 
compared with the temperature period, may be due to the inertia rr 
ae elasticity of the great currents of air, the inertia tending to arger? 
te temperature period, and the elasticity to shorten it; but as the hee 
| will act with greatest effect w magnetic period is at its minimum, 
oe 
