Or search by topic
Published 2011 Revised 2016
For more information and diagrams see: http://stars.astro.illinois.edu/celsph.html
Here is a link to a collection of films to show the position of the sun and the ecliptic. http://www.sonic.net/~rknop/php/astronomy/astromovies/
The link to this film shows the movement of the Sun around the ecliptic
Can you identify the mathematicians?
An article which gives an account of some properties of magic squares.
When in 1821 Charles Babbage invented the `Difference Engine' it was intended to take over the work of making mathematical tables by the techniques described in this article.