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Improvement Needed in Secondary Batteries

Patent Office Report for 1890

A Proposed Apparatus for a Fall of 1,000 Feet

A Roller Pressure Regulator for Cane Mills

A Velocipede Operated by Hand Levers

An Improved Gauge Cock

An Improved Bicycle Treadle

The United States Life Saving Service

Triple Expansion Engines for a Tugboat

Serpollet's Steam Carriage

Centrifugal Action of Air

By Geo. M. Hopkins

Engineering and Mechanics

The Scientific American

Experimental Science- February 21, 1891

By Geo. M. Hopkins


  • Letters

    Correspondence- February 21, 1891

  • Departments

    Business and Personal- February 21, 1891

  • Recently Patented Inventions- February 21, 1891

  • Notes and Queries- February 21, 1891

  • Notes & Queries- February 21, 1891

  • Index of Inventions- February 21, 1891

  • To Inventors- February 21, 1891

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February 21, 1891

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