Man has been led to various views of the universe at various times in history.
Here's how he sees it today.
by H. P. Robertson
of a Gem Stone—or What to do Until the Appraiser Arrives
What makes a gem valuable? How can you tell the real thing from a piece of glass? An expert answers some basic questions about gems.
by Richard H. Jahns
by Norman R. Davidson
A progress report on the Caltech research into chemical reactions which take place in less than a thousandth of a second.
The Month at Caltech