Page:The fairy tales of science.djvu/384

 times greater than it can ever be required to sustain. The hollow beam is not deflected more than an inch from the horizontal line by the passage of the heaviest luggage-train, and it is scarcely affected at all by the highest wind.

The enchanted engineer, whom we whilom saw beset with difficulties of no ordinary kind, can now point to the twin tubes across the Menai Straits, and say proudly, "My task is performed, the bridge has been constructed without scaffolding, and little Mona is no longer separated from her mighty sister." We need scarcely say that Mr. Stephenson is treated quite as badly as the ogre-guarded princess, for no sooner has he performed one task than the ogre, called "Nineteenth Century," finds him another still more impossible to all appearances than the last. Let us not forget that although the human mind may plan a Britannia Bridge or a Great Eastern, the human hands could never construct such wonderful fabrics without the assistance of those mighty powers of the material world which man by industry and patient observation has succeeded in enslaving. Steam, heat, light, electricity—indeed, every agent that is known to exert power in the natural world, can be made to labour in the world of art. These forces, then, are the genii that attend the lamp of science. This lamp, like that of Aladdin, must be rubbed before the genii will appear; in plain language, science will not reveal its mighty powers unless the student works diligently.