Feature

Nature Ramblings: Overworking Our Mother

To Improve Mayan Farming Used Thousands of Years

First Glances at New Books

Front Matter

American Scientists Take Part in Physiological Congress

Windpipe’s “Lid” Not Used during Swallowing of Food

New Type Boiler May Bring Great Changes in Navies

Seven-Point Plan Offered for Mineral Conservation

[Photograph]: Steam’s Answer to Diesel

Echo-Sounding Device Locates Schools of Fish

Severe Vitamin Lack Causes Nerve Breakdown

South American Quake Almost on Equator