Mac, Gordon Taylor's original article describing this dial type was "Equiangular Sundials" in Journal of the British Astronomical Association, 1975,86(1):7-17. He notes at the end of that article that I had contacted him after having the opportunity to see the paper in proof to point out that his treatment could be further generalized. In my letter to him I had also pointed out that the dial type had been described in print by Samuel Foster (1654) before the Greenwich Observatory was in existence.
There was also an article (with cover photo) in a 1975 issue of Sky and Telescope. I can't locate my copy at the moment, so I can't give you the specific issue. I subsequently had a letter to the editor printed in the Dec 1975 issue [50(6):355,382], pointing out how the dial related to Foster's work. Fred Sawyer
