what a stupendous scale! This world, compared to the sun, is no larger than a single stone of St Paul's compared to the whole fabric. It is one of the most difficult problems in practical mechanics to transmit power to a distance, and we have to employ the rude device of long shafts, as in factories; rope and drum, as in the case of railway inclines; or air-pumps, as in the case of atmospheric railways; and, after all, we can only act at a very limited distance. But the sun transmits its power many millions of miles without the aid of mechanical contrivances, and so smoothly and silently that we are almost unconscious of its working. It is by the impalpable lever of the sunbeam that the central power acts on our distant globe. And mark how conveniently concentrated the sunbeams are for our daily use. Were we under the necessity of relying upon the diffused heat of the sun, it would be very difficult to apply its power. We might, no doubt, employ glasses to condense the rays of the sun upon steam-boilers, but the result would be more curious than useful. We have, in nature, a far more useful condensation, viz., fuel, which is just a vehicle for the sun's power. The water-fall is another convenient form of condensed power supplied to oar hand. The sun's rays are imprisoned by the very act of raising the water to a higher level; or, in other words, they are transformed and condensed into mechanical power.
This wondrous mechanism, by which the power of
