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The Ziggurat of Tchoga-Zanbil

In the desert of southwestern Iran stand the remains of a temple that was originally 165 feet high. Built by the Elamites of 3,000 years ago, it is the same kind of structure as the Tower of Babel

By Roman Ghirshman

The Mechanism of Immunity

How does an animal make an antibody that neutralizes a single foreign substance, or antigen? The evidence favors the theory that cells able to make the antibody are “selected” by the antigen and then multiply

By Sir Macfarlane Burnet

The Human Thermostat

A newly discovered sensory organ in the brain precisely measures the body temperature and trips the heat-dissipating mechanisms that maintain the temperature within a fraction of one degree

By T. H. Benzinger

The Growth of Snow Crystals

Much of the world's precipitation is triggered by natural dusts that act as nuclei in causing water droplets in clouds to freeze. Some artificial nuclei work more effectively than natural ones

By B. J. Mason


With the vast spaces of most of the oceans for a habitat this delicate creature has developed a curious life cycle that stretches the reproductive processes to their limits

By N. J. Berrill

Re-Entry from Space

Before it lands, a vehicle returning from space must convert its enormous energy into heat. The problem of protecting the vehicle from this heat can be solved in a variety of ways

By John V. Becker


An ancient substance of steadily widening utility, it is still poorly understood. It may be regarded as both an undercooled liquid and as an inorganic polymer with a highly cross-linked structure

By Charles H. Greene

A New Scale of Stellar Distances

The distance of a star can be determined by comparing its apparent with its intrinsic brightness. A new index to intrinsic brightness has been found in the calcium absorption spectra of many cool stars

By O. C. Wilson


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