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.

The golden Rule reuerse called in Latine regula euersa that is to say turned back-ward. Cap. 10.

WHat is the order of this rule?

Multiply the first by the second, and diuide the product therof by y^e third, as if a pennie Loafe must waigh 2. l. Wheate being at 3. s̄. the bushell, what shall a pennie Loafe waigh when Wheate is at 2. s̄. the hushell, the question must be framed thus, if 3. s̄. require 2. l waight, what shall 2. s̄. haue, then by working according to this rule you shall finde that the pennie Loafe must waigh. 3. l.

Another example of the same rule.

I would know how many yards of Bayes bearing in breadth 7/4. wil suffice to line 7. yards of Silke bearing in breadth 3. quar∣ters & a halfe. Here you must frame your question thus, if ¾. and ½ require 7. yards, what shall 7/4. require, but because the first and third number of this question are not of one selfe denomination by reason of the Fraction annexed to the first number, you shall doe well to reduce the first and third number both into halfe quarters, and then to worke as though they were all Integrums, which is more easie then to make al the numbers Fractions, wherefore say thus: If 7. halfe quarters doe require 7. yards, what shall 14. halfe quarters require, and in working by the rule Reuerse, you shall finde in the quotient 3. yards of Bayes and a halfe.