Simon Cassidy

The late Simon Cassidy studied mathematics in his native England and worked as a software engineer on medical devices in California. His scholarly interests included calendar studies and the prehistory and history of mathematics and astronomy. He was an authority on the astronomy of Stonehenge, and studied the role of John Dee in the history of mathematics, calendars, and geography. One of his projects was to gain recognition for a correct understanding of the vernal equinox year, its role in the history of the calendar and its correct measurement.


Documents on this site by Simon Cassidy
(these are mostly messages sent to the CALNDR-L mailing list):

  1. Stonehenge Speaks: An Open Letter to Umberto Eco (PDF file)
  2. Error in Statement of Tropical Year
  3. The Tropical and the Anomalistic Year
  4. Comment on Future Accuracy
  5. Re 4-1/8 yr. Leap Rule responses of Richard, Jim and Amos
  6. Implementing a correct 33-year calendar reform
  7. Re: How long is a year -- EXACTLY?
  8. Lengths of "seasons"
  9. Re: Calendar question for Simon Cassidy
  10. Multiplex Perpetual Solar Calendarium
  11. Re: Lunar systems (Jewish)
  12. Re: Query (Peter's reply)
  13. Re: Query (Buckley's reply)
  14. Re: Intel and Stonehenge
  15. Re: Stonehenge speculation (lunations and lintels)
  16. Stonehenge et al (75-stone model)
  17. The week of weeks, of nights of full-moon.
  18. The Week of Weeks of Nights of Full Moon
  19. Re: The Week of Weeks of Nights of Full Moon
  20. The Ideal Metonic Epacts for the Next 4K Vernal-Equinox Calendar-Years
  21. Response to Leap Week Calendar Proposal by W.Z.
  22. Response to Lars Osterdahl re ISO Leap Weeks

John Dee Initiates a Calendar Conspiracy with Queen Elizabeth in June 1564

See also:

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.)