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 530
an angle is to use a scaleof chords, which is usually marked on the ivory ruler of a box of compasses. Itis preferable, however, in each case, to make for yourself a scale of chords on alarge scale at the side of the drawing paper and, inasmuch as only two or threeangles for each dial are required,… … will be seen by referring to Fig. 2, which will also make clear other terms usedin treatises on sun-dials. From the centre, C, describe a circle with the radius of 60 on the scale ofchords. From the end of the diameter at D, measure off with the same radius, D X,and draw C X S. Draw N X and D S…
Sundials
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