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, and the chains thus shortened attached to the cross-head by other clamps, and all was prepared for another lift. In the practical operation of the machine each lift of six feet occupied from thirty to forty-five minutes.

The towers were formed of three massive piers of solid masonry, so that each tube just filled up the space between the inner and an outer pier. As the tubes were elevated by the action of the press the vacant spaces beneath were closely packed with blocks of wood. It was very fortunate that this course was adopted, as an accident occurred, which must have resulted in the destruction of one of the tubes had the packing process been omitted. The water contained in one of the presses, not content with lifting the tube, thought fit to make a display of its power by thrusting the bottom out of the cylinder, thereby killing an unfortunate workman. The monster tube fell one inch, but was prevented from falling any further by the packing beneath; had it fallen six feet it would have been shivered into atoms.

When all the tubes were elevated to their permanent position the great work was completed, and Aladdin gazed at the new wonder with delighted eyes. These aërial galleries, nearly fifteen hundred feet in length, are marvellously strong, each being capable of bearing, spread over its whole surface, the enormous weight of 4000 tons—a weight nine