Physics Classroom
The Physics Classroom: Cavendish and the Value of G
A short description of how Cavendish measured the value of G - the universal gravitation constant and supported Newton's theory. Illustrated.
NASA
Nasa: Kepler's Second Law
This site from NASA states Kepler's second law of planetary motion and depicts its meaning with an informative diagram. Relates the law to conservation of energy principles and discusses the eccentricity of a satellite's (or a planet's)...
Wolfram Research
Wolfram Science World: Huygens, Christiaan
This ScienceWorld site provides a short biographical sketch of Christiaan Huygens and describes his most notable scientific discoveries and contributions. Links are provided throughout for additional information as well.