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.

How to knowe the Epact by the Mariners rule vpon your thumbe. Chapter. 3.

FIrst, you must suppose the inside of your left thumbe to be diuided into thrée spaces, and the nethermost space to containe 10. the middle space 20. and the highest space towards your thumbes end, to containe 30. and knowing first the golden number, begin to tell the same at the nether space saying there 1. at the middle space 2. at the thirde space 3. then

beginne againe at the lowest space, and there say 4, and so con∣tinue your account still after that manner, vntil you haue the full summe of the Golden number, and marke vpon what space the full summe falleth, for the Golden number being added to the number of that space, doeth shewe the Epact, so as the totall summe doth not excéede 30. for then you must subtract 30. and the remainder shall bée the Epact: as for example, in the yeare 1591. the Golden number is 15. which béeing counted vppon your thombe in such order as is before taught, it will fall vpon the highest space, which is 30. to which if you adde the Golden number, which is 15. it will make in all 45. from which summe if you subtract 30. there will remaine 15. which shall bee the E∣pact for that yeare, so as the Epact and Golden number in that yeare are like numbers. For euery thrée yeares they are alwayes like, as when the Golden number is either 3. 6. 9. 12. 15. or 18. the Epact hath also like number.