Simon Cassidy studied mathematics in his native England and works as a software engineer on medical devices in California. His scholarly interests include calendar studies and the prehistory and history of mathematics and astronomy. He is an authority on the astronomy of Stonehenge, and is currently studying the role of John Dee in the history of mathematics, calendars, and geography. One of his current projects is to gain recognition for a correct understanding of the vernal equinox year, its role in the history of the calendar and its correct measurement.
He may be reached by email at email@example.com.
Documents on this site by Simon Cassidy
(these are mostly messages sent to the CALNDR-L mailing list):
- Stonehenge Speaks: An Open Letter to Umberto Eco (PDF file)
- Error in Statement of Tropical Year
- The Tropical and the Anomalistic Year
- Comment on Future Accuracy
- Re 4-1/8 yr. Leap Rule responses of Richard, Jim and Amos
- Implementing a correct 33-year calendar reform
- Re: How long is a year -- EXACTLY?
- Lengths of "seasons"
- Re: Calendar question for Simon Cassidy
- Multiplex Perpetual Solar Calendarium
- Re: Lunar systems (Jewish)
- Re: Query (Peter's reply)
- Re: Query (Buckley's reply)
- Re: Intel and Stonehenge
- Re: Stonehenge speculation (lunations and lintels)
- Stonehenge et al (75-stone model)
- The week of weeks, of nights of full-moon.
- The Week of Weeks of Nights of Full Moon
- Re: The Week of Weeks of Nights of Full Moon
- The Ideal Metonic Epacts for the Next 4K Vernal-Equinox Calendar-Years
Further messages by Simon Cassidy to the CALNDR-L mailing list
may be found by following the links at the bottom of
his web page at http://home.earthlink.net/~scassidy/.
Stonehenge central structure, ca. 20th century AD
(ruin of sarsen structure and bluestone additions).
Central sarsen reconstruction, ca. 20th century BC
(before bluestones were returned to the monument).
Simon Cassidy's photographic reconstruction of Stonehenge
(Reconstruction image © 1994 Simon Cassidy; reproduced here with permission.)
For more of Simon's imagery visit his image album at