The March 1977 issue of The Compendium - Journal of the North American Sundial Society includes an article which provides both graphic and formula approaches to drawing Oughtred's double horizontal dial. The issue also includes a reprint of Oughtred's own brief description of how the dial is to be used - sort of an early user's manual. The digital edition of The Compendium includes a program which, when combined with the Graphica shareware package, will draw a double horizontal dial face for any latitude.
Copies of this issue of The Compendium are still available from editor Fred Sawyer at [EMAIL PROTECTED]
