On 04/01/2011 05:27, John Carmichael wrote:
Oh, by the way, on a related subject, I've been thinking about a neat
way of firmly attaching a gnomon to a glass sundial that would prevent
the glass from breaking if something bumps into the gnomon (i.e. a
window washer or house painter) You could attach a gnomon that has a
flat steel base to the outside of the glass by placing a magnet on the
inside of the glass.I've already tested this and it works great!If
somebody bumps into the gnomon, instead of cracking the glass, it
simply falls off and you just stick it back on.This method of gnomon
attachment is especially easy to do with a perpendicular rod gnomon
since it just has one point of attachment... just put a flat steel
base on the rod that will attract the magnet.Simple!No drilling, nuts,
washers, or soldering needed!
Great idea John but I think I would take it a stage further and have a
magnet within the base of the gnomon for a mutual strong pull through
the thickness of the glass. Ultra-powerful 'rare earth' magnets are
easily available these days in a variety of forms. I have a pair which
are 1/4" cubes and are impossible to separate by hand with a straight
pull. Even sliding them apart is difficult.
Google < rare earth magnets > for infor' and availability.
Tony Moss
---------------------------------------------------
https://lists.uni-koeln.de/mailman/listinfo/sundial
