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The Solar Wind

Comet tails and other phenomena indicate that a thin, hot gas of solar particles flows past the earth at supersonic speeds. This gas is simply the expanding corona of the sun

By E. N. Parker

The Petrified Forests of Yellowstone Park

The most extensive fossil forests of their kind in the world, they contain much information about the climate and geologic history of the Rocky Mountain region some 55 million years ago

By Erling Dorf

The Interaction of Light with Light

Intense beams of laser light interact with crystals to yield novel optical effects. For example, when two beams meet in a crystal they can add or subtract to produce beams of two new wavelengths

By J. A. Giordmaine

The Hallucinogenic Drugs

These powerful alkaloids, tools for investigating mental illness and perhaps for treating it, have become the subject of a debate: Do their constructive potentials outweigh their admitted hazards?

By Frank Barron, Murray E. Jarvik and Sterling Bunnell Jr.

The Chemistry of Concrete

The chemical reactions that occur when water is added to portland cement in the mixing of concrete continue for months. Recent studies have elucidated the process

By Stephen Brunauer and L. E. Copeland

Sound Communication in Honeybees

It has been known for some time that bees perform an intricate dance in directing their hivemates to a source of food. Now it appears that they also transmit information by means of sound

By Adrian M. Wenner

Chromosome Puffs

These enlarged regions on the giant chromosomes found in some insect cells have been shown to be active genes. They probably produce the nucleic acid that translates the genetic information

By Wolfgang Beermann and Ulrich Clever

A Neolithic City in Turkey

An ancient mound now known as Catal Hüyük has yielded evidence that communities with highly developed economic structure, religion and art existed as long ago as 7000 B.C. and perhaps even earlier

By James Mellaart

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