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Economy in Study

Psychological and Physiological Points on How to Study to the Best Advantage

By George Van Ness Dearborn

Gun-Primers and Detonators

A Radio Generator for Amateurs

Instructions for Fitting Up a Powerful and Efficient Source of Current

By Frederick E. Ward

Facts about Thunderstorms

Their Origin Formation and Structure

Problems of Geographic Influence

Its Relations to Sociology, Biology, and Climatology

Use of Electricty in Ships

Elements with Several Atomic Weights

The Manufacture of Chicory

A Franco-Belgian Industry Stopped by the War

By Jacques Boyer

Power with By-Product Recovery

Relative Merits of Various Prime Movers in Relation to Scientific Utilization of Fuel

By T. Roland Wollaston

Cleaning Discolored Marble

Indicating Temperatures

Recent Progress in Astrophysics—I

Many Important Discoveries That Add to Our Knowledge of the Heavenly Bodies

By C. G. Abbot

The Power of Telescopes

By W. E. Woolard

Identifying Minerals and Precious Stones

Chemical Lime

Some of the Technical Applications of This Economical and Useful Material

Treating Porous Cement

Petroleum Prospects in Chile


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    July 17, 1915

    20% Sitewide for President's Day