Sundials - World's Oldest Clocks

North American Sundial Society

Ozanam1712TreatiseJacques Ozanam was a mathematician famous for his popular math texts. These included a math dictionary, a course of mathematics, and a text on mathematical and physical recreations. The last of these went through at least 18 editions over 2 centuries.

Ozanam's dialing was instructive and entertaining - it includes innovative ideas such as a geographic sundial showing the time anywhere in the world, various universal horizontal dials, and the first suggestion that one's own body could be the gnomon of an analemmatic dial. His texts also cover altitude, azimuth, lunar, reflection, refraction, portable and stereographic projection dials – all in addition to the standard instruction in drawing sundials on any plane.

This treatise is from the 1712 English translation (by the noted Newtonian scholar J.T. Desaguliers) of Ozanam's 1693 Course of Mathematics. The addendum is a 1708 English translation of the set of Problems of Dialling included in the 1st edition (1694) of his Recreations Mathematical & Physical.

This can be ordered from LuLu Books: Ozanam: A Treatise of Gnomonicks (1712)