The art of dialling : performed geometrically ... arthmetically ... instrumentally ... (1700)
Leybourn, William, 1626-1716 · London : T. Braddyll · leaf 177
, and perpendicular thereunto another line C D, for the Meridian and Hour-line of 12. Secondly , Take 60 deg. out of your line of Chords, and letting one foot in C, with the other defcribe the Semicir¬ cle E F G. Thirdly^ Becaufe the diftance of the Subftile from the Meridian was found to be 17… … Fourthly,
![An illustration from L'optique divisée en trois livres : ou, l'On démontre d'une maniere aisée tout ce qui regarde 1. la propagation & les proprietez de la lumiere. 2. La vision. 3. La figure & la disposition des verres qui servent à la perfefectionner [sic] (1682)](https://img.insideoutlibrary.com/img/200/ia-loptiquedivise00ango-77-8.webp)
