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The Elevated Tracks of the New York Central Railroad in New York City

The Hardie Compressed Air Motors

By Herman Haupt

Rock Dredging on the Rhine

The Curves described by the Pedals of a Bicycle

By A. Gillard

Know your Machines

How to Test the Relative Hardness of Metals

Measurement of Time by Clepsydras

Selected Formulæ

Test of a Compressed Air Reservoir taken from a Hardie Motor after having been in use Two Years

By Herman Haupt

Amber, Ancient and Modern

New Cock for Compressed or Liquefied Gas Receptacles

Electrical Notes

Miscellaneous Notes

Engineering Notes

The Restoration of the Venus De Milo

Electricity on Farms

Electrification of Air by Roentgen Rays

A Quarter of a Century's Work on Respiration

By C. F. Townsend

Common Freaks of Nature

Ants as Property Holders

By O. W. Oestlund

Horticulture and Health



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