Page:Popular Science Monthly Volume 88.djvu/737

 Popular Science MontJily

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���pipes to embed the tube sections solidly in the rock and to join the sections, one to the other.

The work is done by divers where the elaborate mechanical system is inadequate, and at last

compressed air forces the water out and the final joining is completed. This method requires

less time and is less expensive than the use of a driving-shield

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