A Reaction Propeller

The “Brennan” Torpedo

Carrying Water Mains across a River

Improved Collapsible Boat

How to make a Leyden Jar

Track Laying by Steam

The Use of the Magnetic Needle in Exploring for Iron Ore

On a New Method of Measuring Magnetic Susceptibility and Magnetic Permeability

Photography by Vital Phosphorescence

Caverns near Manitou, Colorado

Freezing Mixtures

Geology and Geography

What American Zoologists have Done for Evolution

A New Local Anæsthetic

Milton Josiah Roberts, M.D.

Harvard's New Observatory

From La Nature

The Principle of Inertia

Soap Bubbles

A Mathematical Game

The Taking of the Bastille

The Giant Arbor-Vitæ

(Thuja Gigantea)

Physics without Apparatus

The Annatto Bush

Building Plans and Specifications

A Delicate Test for Bismuth