Scientific American Magazine

April 1931

Volume 144, Issue 4

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Features

The Eyes and Ears of the Railroad

Francis X. Milholland

Did a Meteorite Strike the Crawfordsville Ford?

Charles Clayton Wylie

New Light on Old Foods

Unique Solutions of Bridge Construction Problems

The heaviest lift span in the world, weighing 1580 tons, in the new bridge. The bridge proper has a clearance of 70 feet, but the great lift span can be opened to a clearance of 135 feet in only 85 seconds

C. R. Harding

Vacuum Tubes in Industry

Raymond Francis Yates

A New Use for Radium

Robert F. Mehl

Radio Goes Man-Hunting

W. M. J. Barkley

New Temperature Measurements of the Sun, Moon, Mars

Henry Norris Russell

Chicago's 'Madison Square Garden'

Butterfly Farming

Adeline Taylor

When Locomotives Go to Sea

A Machine Age 'Milk Maid'

James A. Tobey

Centrifugally-Spun Concrete Piles

L. R. Need

Mass Production of Preserved Food

Salt Making in India

C. F. Strickland