Telescopic Photography

Instruments for Drawing Curves

Hydraulic Hoisting Carriage for Purifier Covers

Some Type Writers—Their Origin and Uses

Instantaneous Photography

An Absolute Barometer

The First Type Writing Machine

The Strength of Fly-Wheels

The SS. Nulli Secunda

Concrete in Harbor Work

Benz's Gas Motor

Unsuspected Dangers with Frictional Electricity in Blasting

Pure Ice and Snow

Solution

Opening of the Discussion by Prof. Tilden

Fifty Years of Sanitation