Feature

In Science Fields

Which Was the First Steamboat? “A Classic of Science”

Scientist Traces Evolution of Firefly Light Reaction

Nature Rambling: A Miner for Worms

Ancient Sun-Hole Device Added to Famous Calendars

Shrunken Heads of Sloths Are Trophis of Expedition

Booklists of the A. A. A. S.

Front Matter

Leaders of Invention Tell What the World Needs Most

Sugar Plays Leading Part in Pneumonia Germ’s Activity

High Blood Pressure May Be Compensatory Reaction

[Photograph]: Voltmeter