Hi: A colleague just sent me this information about the world’s oldest orrery at the Eise Eisinga Planetarium (in The Netherlands) and sent the attached photos of the orrery and the clockwork mechanisms. https://en.wikipedia.org/wiki/Eise_Eisinga_Planetarium http://www.bbc.com/travel/story/20180320-the-worlds-oldest-working-planetari... (Googling told me: "The London instrument maker John Rowley (circa 1668-1728) made the first orrery for Charles Boyle around 1713, but planetary models have existed since ancient times.” - from the Whipple Museum of the History of Science, Cambridge.) I’d never heard of this amazing huge clockwork “calculating” device, so couldn’t resist passing it on to SIGCIS. Cheers Brian Randell [cid:D66386F4-6978-4881-8F60-0BD555780DA4@ncl.ac.uk][cid:03E1B423-EF72-4562-952B-A62BA13C2D32@ncl.ac.uk][cid:41F00402-42F9-4AEC-AA1F-BCBD339C476A@ncl.ac.uk] — School of Computing, Newcastle University, 1 Science Square, Newcastle upon Tyne, NE4 5TG EMAIL = Brian.Randell@ncl.ac.uk<mailto:Brian.Randell@ncl.ac.uk> PHONE = +44 191 208 7923 URL = http://www.ncl.ac.uk/computing/people/profile/brianrandell.html