{ 
28 ANNIVERSARY ADDRESS. 
I may perhaps just mention, as an illustration of the tremen- 
dous forces in operation about us, but all unheeded, the ‘mechani 
cal power of the sunshine. It appears from the experiments ee 
Sir John Herschel, confirmed by Pouillet, that ordinary sunshine — 
exerts a force on every 14 feet of surface of 1-horse power, and on 
an acre of 3,200 horses ; or, to put it in another way, if we could | 
utilize the sun’s heat falling on a single acre of ground, we should — 
have a steam-engine of 3,200 horse-power, working steadily in 
sunshine, or a power equal to lifting 47 tons of water 1,000 feet high 
every minute. If we try to conceive of this power accumulating 
on a square mile or 100 square miles, or the whole country, W° 
shall get some notion of the forces at work in the production of 
rain, and what it means if we try to interfere with them. But at 
the same time one cannot contemplate such an enormous fore?” 
without seeing that it is a possible solution of the real difficulty 
of our sunny interior. There abundance of water lies below the 
‘surface, and sunshine often too plentiful above it. We have only 
to supply the sun-engine, and forthwith sunshine draws Up water 
in abundance. ! 
It is often said that if we could tap the clouds and let off the 
a electricity we should at once get plenty of rain ; but thisis Par | 
assumption. Science has not yet been able to ascertain what part, 
if any, electricity plays in the suspension of clouds. Franklin's | 
‘memorable experiment is often quoted as a proof that rain would 
follow if a conductor were sent up to the clouds ; but the facts - 
‘must be overlooked, for the rain fell before there was any appear 
ance of electricity, and hundreds of similar experiments We 
made subsequently without bringing down the rain ; and if ther? 
"were any truth in the supposition the facts would be paten* 
"enough in large manufacturing districts with tall chimneys, light 
-ning-conductors, and smoke extending upwards as a continuatio? 
Of the conductors, for there would be such frequent downpours yes 
_ would convince the most superficial observer. And Crosse’ 
ments proved that lightning could be withdrawn from * 
Ne a ae ee. etricity - 
