Marine Farming
Man gets food from the sea essentially by hunting and gathering. Yet the farming of fish and shellfish has been pursued for some 2,000 years, and its potentialities are far from being exhausted...
Features
The Absorption Lines of Quasi-Stellar Objects
Emission lines in the spectra of these objects, sometimes called quasars, are enormously shifted toward the red. Absorption lines in some of the spectra, however, are shifted by different amounts...
Auditory Illusions and Confusions
These failures of perception are studied because they isolate and clarify some fundamental processes that normally lead to accuracy of perception and appropriate interpretation of ambiguous sounds...
Human Embryos in the Laboratory
It is now possible to make human eggs mature, to fertilize them in vitro and to grow them in a culture medium through early embryonic stages. Such procedures may help to alleviate infertility and fetal abnormalities...
Optical Interference Coatings
The same phenomenon that is responsible for the iridescence of various natural surfaces, including peacocks' tail feathers, is exploited to produce a host of modern optical components
Rickets
Although it is still widely regarded as a dietary-deficiency disease resulting from a lack of "vitamin D," it results in fact from a lack of sunlight. In smoky cities it was the first air-pollution disease...
Permanent Magnets
New alloys of cobalt with rare-earth elements have magnetic properties so superior to those of former materials that they constitute virtually a new class
The Mule
This man-made animal is nearing extinction under the impact of mechanization. Its biology goes considerably beyond the mere fact that it is the result of a cross between a donkey and a horse...
Departments
50 and 100 Years Ago: December 1970
Science and the Citizen: December 1970
- Letters
Letters to the Editors, December 1970
- Recommended
Books
- Mathematical Recreation
Mathematical Games
- Amateur Scientist
The Amateur Scientist
- Departments
The Authors
Annual Index
Bibliography
