Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/226

 588000000 yards (for so many are in 56 diameters of the Earth) be passed? The rule for this work is, that the third number must be multiplied by the square of the second, of which doth come 14700000000, which ought to be divided by the first, that is, by 100, and the root square of the quotient, that is, 12124 is the number sought, namely 12124 min. secun. of an hour, which are 3 hours, 22 min. prim. and 4 seconds.

I have seen the working, but I know nothing of the reason for so working, nor do I now think it a time to ask it.

Yet I will give it, though you do not ask it, because it is very easie. Let us mark these three numbers with the Letters A first, B second, C third. A and C are the numbers of the spaces, B is the number of the time; the fourth number is sought, of the time also. And because we know, that look what proportion the space A, hath to the spuace C, the same proportion shall the square of the time B have to the sqare of the time, which is sought.

Therefore by the Golden Rule, let the number C be multiplied by the square of the number B, and let the product be divided by the number A, and the quotient shall be the square of the number sought, and its square root shall be the number it self that is sought. Now you see how easie it is to be understood.

So are all truths, when once they are found out, but the difficulty lyeth in finding them I very well apprehend it, and kindly thank you. And if there remain any other curiosity touching this point, I pray you let us hear it; for if I may speak my mind, I will with the favour of Simplicius, that from your discourses I alwayes learn some new motion, but from those of his Philosophers, I do not remember that I have learn't any thing of moment.

There might be much more said touching these local motions; but according to agreement, we will reserve it to a particular conference; and for the present I will speak something touching the Author named by Simplicius, who thinketh he hath given a great advantage to the adverse party in granting that, that Canon bullet in falling from the concave of the Moon may descend with a velocity equal to the velocity wherewith it would