23 8 SPECULATIVE SCIENCE 



in motion, dragging the huge tidal wave round and round our 

 earth ; performing, in fine, the great bulk of the endless labour 

 of this world and of other worlds, so that the energy of the 

 sun is continually being given away ; then we may say this 

 continual work cannot go on for ever. This would be precisely 

 the perpetual motion we are for ever ridiculing as an exploded 

 delusion, and yet how many persons will read these lines, to 

 whom it has occurred that the physical work done in the world 

 requires a motive power, that no physical motive power is infi- 

 nite or indefinite, that the heat of the sun, and the sum of all 

 chemical and other physical affinities in the world, is just as surely 

 limited in its power of doing work as a given number of tons of 

 coal in the furnace of a steam engine. Most readers will allow that 

 the power man can extract from a ton of coals is limited, but per- 

 haps not one reader in a thousand will at first admit that the 

 power of the sun and that of the chemical affinities of bodies on 

 the earth is equally limited. 



There is a loose idea that our perpetual motions are impos- 

 sible because we cannot avoid friction, and that friction entails 

 somehow a loss of power, but that Nature either works without 

 friction, or that in the general system friction entails no loss, 

 and so her perpetual motions are possible ; but Nature no more 

 works without friction than we can, and friction entails a loss 

 of available power in all cases. When the rain falls, it feels 

 the friction as much as drops from Hero's fountain ; when the 

 tide rolls round the world it rubs upon the sea-floor, even as a 

 ball of mercury rubs on the artificial inclined planes used by 

 ingenious inventors of impossibilities ; when the breeze plays 

 among the leaves, friction occurs according to the same laws as 

 when artificial fans are driven through the air. Every chemical 

 action in nature is as finite as the combustion of oxygen and 

 carbon. The stone which, loosened by the rain, falls down a 

 mountain-side, will no more raise itself to its first height, than 

 the most ingeniously devised counterpoise of mechanism will 

 raise an equal weight an equal distance. How comes it, then, 

 that the finite nature of natural actions has not been as gene- 

 rally recognised as the finite nature of the so-called artificial ' 

 combinations ? Simply because, till very lately, it was impos- 

 sible to follow the complete cycle of natural operations in the 



