Fellow Shadow Watchers,
Several years ago I spent many hours making a
large and very accurate 'swinging laser trigon' to mark out hourlines on
large public sundials but for a long time now I have been unable to find
the critical swinging laser unit. My workshop has been thoroughly
searched and all possibilites of where this precious object might be have
been exhausted in recent months/years.
Making a replacement was just too onerous to consider so I'd made up my
mind to do without this useful aid in future.
Christmas decorations and tree lights are stored in my roof space and,
while retrieving them, various bits of stored rubbish made access
difficult so a car load of discarded computer boxes and broken suitcases
were taken to the local civic amenity 'tip' for disposal today. As I
drove away it occurred to me that I hadn't looked inside the largest
suitcase of which the handle had ripped off due to excess weight. (I
recall now that it was last used for the trip to the NASS Montreal
Conference.) The tip supervisor doesn't approve of people scavenging
through materials left there but I persuaded him that the big green
suitcase had been my own. You've guessed it! There was my swinginging
laser packed in bubble wrap along with several other ex-display items
previously 'mislaid' and oh-so-nearly discarded by my own hand!
Oh Happy Day!!!
A very special Christmas has come a few days early for me this year!
Tony Moss.
P.S. When using an instrument of this type I would recommend
1. using direct solar-noon sun sights to make reference marks from which
to begin calibration. This sets 'zero' at the best interpretation of the
umbral/penumbral divide which is then carried through to the remaining
laser-marked lines.
2. Only mark the outer ends of the hourlines and use a taught string to
align with the dial origin.
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