Page:Popular Science Monthly Volume 89.djvu/597

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Popular Srirnrr Monf/ih/


����The bridge will be erected over the shortest distance between the central shores of San Fran- cisco and Oakland, the bay there being very shallow and beyond the busy shipping district

��A Bridge Five and One Half Miles Long

SAN FRANCISCO is planning to build the greatest bridge in the world. It is to connect Oakland and its contiguous districts with San Fran- cisco, and is to relie\e five ferry systems of passenger and \cliicular traffic.

The proposed bridge will cost twenty- two million dollars and will be five and one half miles long. It will be one of the heaviest bridges ever built, carrying three roadways and four railroad tracks. Its main portion is to be made up of sixteen spans each two hun- dred and fifty feet long Near the San Francisco shore there will be two long and high spans under which the ships will pass.

The bridge will be a double-deck structure. Three roadways will ex- tend along the upper deck and four railroad tracks along the lower deck. Its capacil\' has been made great enough to provide for traffic for many years. It will have two tracks for overland passenger trains, two tracks for electric trains, and three separate roadways.

���A gear-wheel with a small pinion attached to a flexible shaft imparts the motive power of the chair to the fan

��Fanning Yourself with the Rocking- Chair

EVERY time you sit in the family rocker and move yourself backward and forward you are unconsciously wasting energy. Why not use the energy? Dozens of inventors have asked tliemselves that question. Charles H. Towers, of Philadelphia, has answered it by making the rocker drive a fan at the rate of four hundred and fifty revolu- tions a minute.

The accompanying illustration shows a young lady fanning herself by rocking the chair in which she sits. The fan, mounted on a pedestal at the right elevation for a good breeze, is connec- ted by a flexible shaft with a gear- wheel, which, to- gether with an operating lever resting on the floor, can be attachcxi to any chair-rocker.

The operating mechanism con- sists of a casing with a gear-wheel aftixed to an arm which travels over the floor on a small roller. As the chair rocks the arm tilts up and down, thus rotat- ing the gear-wheel. The gear-wheel meshes with a small pinion at- tached to a shaft.

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