A $25,000 Stope Drill Prize
A Chance for American Inventors

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A Chance for American Inventors
A Scientific Explanation of a Toy's Vagaries
Protective Apparatus
A Combination of the Two
The Value of Tar as a By-Product
How Their Fantastic Effects are Obtained
An Explanation of Arithmetical Precocity
A Suggestion for the Tropics
The Compensating System and Other Details of the Apparatus by the Paris Correspondent of the Scientific American