Volume 21, Issue 20
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Features
The Tidal Wave
The “Dogwoods” Used in the Manufacture of Gunpowder in England
Condensed from a Paper in "The Student"
The Manufacture of Sulphuric Acid
Improvement in Frames for Spectacles and Eye Glasses
The Velocimeter–A New Aid in Mechanics
Aerial Navigation
Inflammable Gas-Engines
Implement for Sharpening Knives
Mica Brocades–a New Product of Art
What is to Become of Our Brown-Stone Fronts?
Is There Such a Thing as Social Science?
Boiler Explosions
Polar Expeditions
The Care of House-Plants
H. S. Patent Office
Horsford's Phosphatic Bread
Editorial Summary
Answers to Correspondents
Manufacturing, Mining, and Railroad Items
Recent American and Foreign Patents
Official List of Patents
Issued by the United States Patent Office.