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The Abrasion-Meter

A Device for Determining the Cutting Efficiency of Abrasive Wheels

By Raymond Francis Yates

The Electric Dog

Use of the Selenium Cell to make an Orientation Mechanism

By Benjamin Franklin Miessner

The Races of Russia—II

A Brief Outline of the Ethnic Background of the Czar's Former Domain

By Ale*amp*scirc; Hrdli*amp*ccirc;ka


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    June 14, 1919

    Reanimate Your Brain

    31% Off for Halloween