Nine geometricall exercises, for young sea-men and others that are studious in mathematicall practices: containing IX particular treatises, whose contents follow in the next pages. All which exercises are geometrically performed, by a line of chords and equal parts, by waies not usually known or practised. Unto which the analogies or proportions are added, whereby they may be applied to the chiliads of logarithms, and canons of artificiall sines and tangents. By William Leybourn, philomath.

VIII. Of the TROPICKS.

THE Tropicks are lesser Circles of the Sphere, dividing it unequally, and are drawn parallel to the Aequino∣ctial, at 23 degr. 30 min. distance therefrom, equal to the Sun's greatest Declination on either side. That Tropick which is on the North-side is called The Tropick of Cancer, to which when the Sun cometh (which is but once in a year, about the 10. of June) it maketh the longest Daies to all the Northern In∣habitants of the World, and the shortest Nights. The other Tropick, which is on the South-side of the Aequinoctial, is cal∣led The Tropick of Capricorn, to which when the Sun cometh, which is about the 11. of December, it maketh the shortest Daies and the longest Nights to all Northern Inhabitants, and the con∣trary to all the Southern Inhabitants of the World. In the Projection the Tropick of Cancer is signfied by ♋ I ♋, and the Tropick of Capricorn by ♑ K ♑.