The book of sun-dials; originally compiled by the late Mrs. Alfred Gatty; now enl. and re-edited by H. K. F. Eden and Eleanor Lloyd (1900)
Gatty, Alfred, Mrs., 1809-1873, Eden, Horatia K. F. Gatty, Lloyd, Eleanor, Evans, Lewis · London, G. Bell · leaf 531
of the centre in Fig. 2 the small italic letters indicate thechord, etc., for 30 degrees, thus : xd is called the Chord of the Arc of 30 degrees.ds is called the Tangent of 30 degrees.tix is called the Sine of 30 degrees.Cs is called the Secant of 30 degrees. It is evident that the anglemay be set… … °G y To construct a Horizontal Sun-dial for the latitude of 54,- degrees. Fig. 3.—Drau* a square,,-■ or rectangle, as shown in Fig. 3,and near the centre draw a per-pendicular line P S. On theleft of this draw a parallel line, and makeits distance from 1 S equal to the thick-ness of the gnomon.…
Sundials
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