Engineering Wonders of the World
Volume I

64 ENGINEERING WONDERS OF THE WORLD. peculiar resonance of the tunnel, it is hard to locate the cause of a noise by the ear with the accuracy possible in the upper world. After quite a long tramp the distant shaft is reached, and many stairs have to be mounted. Presently the visitor emerges through a door- way, and finds himself overlooking wharves, where derricks are slinging cargoes into the holds of barges and small vessels. Looking back across the river, he is surprised to find how near the opposite bank seems to be—only a couple of stone-throws away. Open ex- panses of water dwarf distances in an amazing manner. After this preliminary canter our traveller should seek the road entrance, and walk right through, the tunnel to the farther approach. This course will give him a far better concep- tion of the true magnitude of the enterprise than could be conveyed by the mere words of the above account; which will, we hope, in turn enable him to appreciate more fully the constructional details that are still distinguish- able. Note.—The illustrations to this chapter are from photographs kindly supplied by the author. GAUGE ARCH.