Clavis horologiæ; or, A key to the whole art of arithmetical dialling, In two Parts. The first shewing how to draw the hour-lines on all manner of regular dials and how to reduce all irregular dials into regular forms, by means of a new latitude and new declination, and that arithmetically. The second part sheweth how to place all manner of furniture on all sorts of dials, let them be never so irregular, and that arithmetically: whereunto is annex'd the tables of the attitude of the sun for every hour of the day, at his entrance into the 12 signs, from one degree of latitude to 90; with tables of azimuch to each latitude, and for every hour of the day, at his entrance into each sign; with many other tables useful in the art of shadows. Whereunto is annexed an appendix, being the explication of the pyramidical dial set up in His Majesty's garden at White-hall, 1669. In which very many sorts of dials are contained: by which, besides the hours of all kinds diversly expressed, many things relating to geography, astrology and astronomy, are by the sun's shadow made visible to the eye, by that Reverend Father Francis Hall, alias Line, of the society of Jesus, professor of the mathematicks at liege in Germany. By John Holwell, teacher of the mathematicks. illustrated with curious copper cuts.

Date:

1712