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Carbon Dioxide and Climate

A current theory postulates that carbon dioxide regulates the temperature of the earth. This raises an interesting question: How do man's activities influence the climate of the future?

By Gilbert N. Plass

Pulsating Stars and Cosmic Distances

Because the rate at which a cepheid variable star pulsates is related to its luminosity, it serves as an astronomical yardstick. Corrections in the yardstick have again raised estimates of the age of the universe...

By Robert P. Kraft

The Perception of Motion

Relativity of motion furnishes the chief clues to the perception of it, yet we ascribe motion to objects as if they had acquired an absolute quality. This way of perceiving plays strange tricks...

By Hans Wallach

The Exclusion Principle

It governs both matter and antimatter, explains the internal structure of atoms and nuclei, and enables us to predict the behavior of a confusing assortment of fundamental particles

By George Gamow

The Life of a Sand Dune

The region near the surface of these wind-driven hills can be an almost intolerably hot and arid environment, yet an entire community of plants and animals have become adapted to it

By William H. Amos

The City of Midas

Gordion, where Alexander cut the Gordian knot, dominated Asia Minor in the eighth century B.C. Recent excavations indicate that it was a link between preclassical Greece and the East

By Machteld J. Mellink


This ill-defined group of plant compounds includes many that are both useful and toxic. Though most of them strongly affect human physiology, their functions in plants are still obscure

By Trevor Robinson

The Moment of Fertilization

When a sperm attaches itself to the surface of an egg, the egg is almost immediately impervious to other sperm. What happens in the egg during this critical biological event?

By Robert D. Allen


  • 50 and 100 Years Ago: July 1959

  • Science and the Citizen: July 1959

  • Letters

    Letters to the Editors, July 1959

  • Recommended


  • Mathematical Recreation

    Mathematical Games

  • Amateur Scientist

    The Amateur Scientist

  • Departments

    The Authors

  • Bibliography

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