Bange's Artillery System

II.—Siege and Fortress Guns

Planetary Wheel-Trains

Proposed Suez Ship Rail Way

Profiling Machine

Notes on Pharmaceutical Apparatus

Auber's Tubular Boiler with Movable Fire-Box

Lawrence's Capillary Coolers

Retort and Condenser

The Great Discoveries in Electricity

The Play of the Needle

History of the Electric Telegraph

The Drawbaugh Telephones

The Source of Atmospheric Electricity

How to make an Incubator

Prof. Heyer on Comets

Submarine Explorations

The Six Gateways of Knowledge

Two useful Problems