Electrical Propulsion in Space
Economy of propellant is the chief advantage of electrical rocket engines now being developed. Their low thrust will limit their use to vehicles previously boosted into an orbit by other means...
Features
New Penicillins
By altering the groups of atoms that are attached to the core of the penicillin molecule, chemists have produced penicillins that are effective against resistant strains of microorganisms...
Pre-Cambrian Animals
Until recently the fossils of organisms that lived earlier than the Cambrian period of 500 to 600 million years ago were rare. Now a wealth of such fossils has been found in South Australia...
Gravity
Albert Einstein showed that gravitation can be interpreted as a geometrical property of space-time. His further hope, of relating gravity and electromagnetism, is still unfulfilled
How Themistocles Planned the Battle of Salamis
A newly discovered tablet is the great general's decree on the eve of the battle. It reveals that he called for an orderly evacuation of Athens and deliberately chose to meet the Persians in a strait...
Lee Waves in the Atmosphere
Formed downwind from hills and mountains, the waves create many strange and beautiful cloud types. Meteorologists neglected lee waves until sailplane pilots began exploiting them to reach great altitudes...
Shadows and Depth Perception
The ability to see that a surface curves toward or away from us depends upon how light and shadow are distributed. Investigators have undertaken to determine if the ability is innate or learned...
Monomolecular Films
Many physical, chemical and biological processes involve thin films of material at surfaces. In these processes the most important role is played by a film just one molecule thick
Departments
50 and 100 Years Ago: March 1961
Science and the Citizen: March 1961
- Letters
Letters to the Editors, March 1961
- Recommended
Books
- Mathematical Recreation
Mathematical Games
- Amateur Scientist
The Amateur Scientist
- Departments
The Authors
Bibliography
