Page:A hundred years hence - the expectations of an optimist (IA hundredyearshenc00russrich).pdf/116

 its nature. Perhaps before our store of heat gives out and reduces earth to the state of a dead world like the moon, we shall already have exhausted our stock. No economies in the use of scrap metal and the re-employment of the material of machines which have been superseded can save us from ultimate metallic bankruptcy in a future calculated perhaps in thousands (but not many thousands) of years. Our only succour seems to lie in a conception for which (despite the efforts of some lively thinkers who have been obliged to ignore but the least important difficulties of the the conception subject) we have no material—the conception of means by which the cold depths of interplanetary space may be traversed. Even if we allow imagination, untrammelled by the most evident necessities of the case, to suggest a speed of transport computable only by astronomical analogies, we still lag behind anything which could serve this purpose, unless we concurrently believe that human life shall, by that time, be lengthened into centuries. Otherwise, however recklessly we may conceive of speed in interplanetary travel, man would almost require to live for many centuries in order to reach and return from any destination which would not inevitably destroy him by fire or cold when he arrived at it. Most likely man is for ever destined to accept the bounds of his own planet, and to be limited