Hi Dialling colleagues,
Patrick Powers asked if anyone had practical experience of the bead-in-a-hole
(pinspeck) shadow sharpener.
I used one experimentally o my Isaac Newton mean-time equatorial dial (see
www.flowton-dials.co.uk). It consisted of a 3mm dia phosphor bronze bead
suspended in
Hello,
I also used Richard Holland's idea or measuing from
the center on some of the markers of my 9 meter dial.
(The markings near the North, East and West lines were
easer to do with the standard method.)
Then I got nervous that my measurements were wrong, so
I re-measured again using the
It seems as though the only practical use for a bead-in-hole is on the
alidade of an equatorial heliochronometer Since for it to work properly, as
John Davis pointed out, it must always be perpendicular to the suns rays. It
seems Patrick's excellent instructions on how to calculate its dimensions
John Carmichael wrote:
It seems as though the only practical use for a bead-in-hole is on the
alidade of an equatorial heliochronometer Since for it to work properly, as
John Davis pointed out, it must always be perpendicular to the suns rays.
A noon mark (possibly with an analemma) would be
