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Features

A Rail Wear Testing Machine

Electricity in Refrigeration

Guncotton and its Manufacture

An Account of Modern Methods

By Frederic L. Nathan

Imitation Parchment Paper

Marine Producer-Gas Power

A Comparison of Producer-Gas and Steam Equipments

By C. L. Straub

A Handy Testing Chart

What to do when the, Engine Stops

By Roger B. Whitman

Casting a Colossal Bronze Statue

The Monument to King Victor Emmanuel II in Rome

Radioactivity in Relation to Geology and other Sciences

By M. P. Besson

Weekly Weather Forecasts

By E. B. Garriott

New Photometric Units

An Important International Agreement

Permanent Magnets of nearly Pure Copper

How the Earth Looks from the Moon

Studies of Earthlight

By Wilhelm Krebs

The Mount Wilson 60-Inch Reflector

Flowers and Insects Transformed into Metal

By T. C. Hutchinson

Revolving Balloon Sheds

A New Type of Airship Shed that has Several Advantages

Cocoons and how they are made

Why Insects Spin Them

By S. Frank Aaron

The Duration of Life on the Earth

The Influence of Sea and Carbon Dioxide

By J. C. Gregory

Correspondence

The Curiosities of Numbers

Proof that a Conic Section must be Described under Gravity

Estimation of Nitrates and Nitrites in Water

Electrical Notes

Engineering Notes

Trade Notes and Formulæ

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    July 10, 1909

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