Page:The fairy tales of science.djvu/376

 "that the heaviest trains may pass over in safety at any speed. This bridge may have any form you please; but we wish you to remember that its rupture would be attended with most disastrous consequences, and we therefore urge upon you the necessity of making it strong enough to resist every strain."

"If you build a railway bridge across the Straits," said the Lords of the Admiralty, "you must not interfere with the navigation. Your viaduct must be at least one hundred feet above the level of the water, so that ships may pass beneath, and it must be constructed without the aid of scaffolding."

Even the elements seemed to set their face against the proposed bridge. The Straits are above twelve miles in length, the shores throughout being rocky and precipitous. The water that fills the passage is never at rest, and the fall of the tide is from twenty to twenty-five feet. Moreover, the wind blows through the Straits with such violence, that a bridge must be strong indeed to withstand its rude shocks.

Imagine an enchanted engineer with such a task before him as the construction of a bridge a hundred feet above the tumultuous waters, without scaffolding of any kind, and you will be able to get a faint idea of the difficulties which he had to overcome before a railway train could pass from Carnarvon to Anglesey.

We will not allude to the various plans which Stephenson conceived and discarded before the idea