On Thursday, June 23, 2011 9:33 AM, Frank King<[email protected]>, commenting on Kevin Karney's <[email protected]> posting, said
> > ...the master of all mechanical EoT > > generators must be the device in the > > Strassburg cathedral clock. > > You overlook the mechanism in the > Jens Olsen World Clock in Copenhagen. > > This clock calculates the EoT using a > long train of gear wheels. Essentially > you have a digital calculation in a > pre-digital era, ca. 1940. > > All mechanical representations of the > EoT suffer from a fundamental defect: > the EoT keeps changing year on year, > albeit slowly. This applies to any > once-off analemma too of course. > How about the Meccano mechanisms shown to us in Newbury by Patrick Briggs a few years ago? Stunning what can be done with a few off-the-shelf components. Brilliant use of Hooke's joint to model the obliquity element. I haven't studied the Copenhagen Town Hall clock but am surprised you say it is digital. Gears, although limited to an integral number of teeth, are essentially analogue devices, aren't they? The cardboard orreries sold by Leonard Honey even overcome that limitation by using drivebelts. It isn't clear to me that all mechanical representations suffer from a fundamental defect - Kevin has shown us (at a BSS Conference) a copy of the EoT cam from the Clock of the Long Now (I may have the name slightly wrong, sorry) which takes the long-term variation into account. And I'm sure the same thing could be done in other ways, if anyone had the inclination. Chris 51.3N 1.3W --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
