Rev. 1.32 (2005.02.04) fixing another typo.
Rev. 1.31 (2005.02.03) fixing a typo.
Rev. 1.3 (2005.02.03) adding eq. (13) in Appendix that shows the derivation of the Newtonian "gravitational force".
Rev. 1.21 (2004.11.10) fixing some typos
Rev. 1.2 (2004.05.31) fixing links to
Hammond's website
Rev. 1.1 (2004.03.05) adding the derivation of
eq. (6) in
Appendix
Rev. 1.0 first ever