Hello,
I got my copy of Willard's text from Willman-Bell in Richmond, VA.
Their phone number is 804-272-5920, the cost was around 17.00 USD. It is
a good book about a very remarkable man and it does have several pages
specifically describing his sundial designs accompanied with pictures,
some of the designs esp. his sunclocks are very ingenious. Most of his
Sundial's were designed while he was at CalTech working with the Mt
Palomar design group, alas I can't find any vertical sundials he may
have done that are very interesting. I too wasn't able to find any
mention of Porter in the 1996 NASS Sundial Registry! However, a picture
of the stolen CalTech sundial that Porter designed can be seen by
accessing the URL below.
http://www.caltech.edu/cgi-bin/arctohtml?30.19-1
Porter's Garden Telescope was what might be called an "active" instead
of passive sundial. The telescope was moved in equatorial mode (it could
function in alt/azi too) until a complete image of the Sun's disk was
formed on a piece of paper at the focal plane of the eyepiece. Then the
Right Ascension (hour angle) was read and with a correction for local
longitude and the equation of time Standard time can be calculated. This
can be done with any equatorial mounted scope. An article p75 of
October's Sky and Telescope gives a good account of Porter's Telescope.
Regards,
Luke
