M. Blundevile his exercises containing sixe treatises, the titles wherof are set down in the next printed page: which treatises are verie necessarie to be read and learned of all yoong gentlemen that haue not bene exercised in such disciplines, and yet are desirous to haue knowledge as well in cosmographie, astronomie, and geographie, as also in the arte of navigation ... To the furtherance of which arte of navigation, the said M. Blundevile speciallie wrote the said treatises and of meere good will doth dedicate the same to all the young gentlemen of this realme.

6 To find out the ascentionall difference of the sunne or any starre in the firmament, knowing the declination thereof, and also the latitude of your region.

MVltiply the Tangent of the declination of the Sunne or star by the Tangent of the latitude of the place, and deuide the product by the totall sine: the sine of the quotient is the sine of the ascentionall difference, the arch wherof is the desired ascentionall difference. For example let the declination of the sunne, starre, or other point in the firmament be 10. degrées 3′· and suppose the la∣titude to be 52. degrées, the Tangent of 10. degrées 3′· is 1772268. the tangent of 52. degrées is 12799416. which being mul∣tiplyed together, the product will be 22674995395488. which being deuided by 10000000. the totall sine, the quotient is 2267499. for which number I looke amongst the sines, the arch an∣swering thereunto is 13. degrées 6′· which is the ascentionall difference desired.