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Bridge Over the Mississippi, at Brainerd, Minn.—Northern Pacific Railway

Collecting and Removing Scums from Boilers

A Navigable Balloon

The Parkes Silver Extracting Process in Germany

Rotary Engines

Determination of High Degrees of Heat by the Melting of Ice

Hallidie's Wire Rope Way for Transporting Ores

Precipitation of Arsenic by Heat in Marsh's Test

By John C. Draper

Scientific and Practical Information

Beach's Spark Catcher and Consumer

Himmer's Electric Battery

Ketchum's Pitman Connection

The Electro Magnetic Telegraph

The Problem of Flight

Light Versus Heavy Shafting

Recent American and Foreign Patents


  • From the Editor

    Answers to Correspondents - March 23, 1872

  • Letters

    Correspondence - March 23, 1872

  • Recommended

    New Books and Publications - March 23, 1872

  • Departments

    Notes and Queries - March 23, 1872

  • Business and Personal - March 23, 1872

  • Index of inventions - March 23, 1872

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March 23, 1872

Science for the Modern World