Mathematicall recreations. Or, A collection of many problemes, extracted out of the ancient and modern philosophers as secrets and experiments in arithmetick, geometry, cosmographie, horologiographie, astronomie, navigation, musick, opticks, architecture, statick, mechanicks, chemistry, water-works, fire-works, &c. Not vulgarly manifest till now. Written first in Greeke and Latin, lately compi'ld in French, by Henry Van Etten, and now in English, with the examinations and augmentations of divers modern mathematicians whereunto is added the description and use of the generall horologicall ring: and the double horizontall diall. Invented and written by William Oughtred.

19. To shew what waters are heavier one than another, and how much.

PHysicians have an especiall respect unto this, judging that vvater vvhich is lightest is most healthfull and medicinall for the body, & Sea-men knovv that the heaviest vvaters do beare most, and it is knovvne vvhich water is heaviest thus. Take a piece of wax, and fasten Lead unto it, or some such like thing that it may but precisely swimme, for then it is equal to the like magnitude of water, then put it into ano∣ther vessell which hath contrary water, and if it sinke, then is that water lighter than the other: but if it sinke not so deep, then it argueth the water to be heavier or more grosser than the first water, or one may take a piece of vvood, and marke the quantitie of sinking of it into severall waters, by vvhich you may judge

which is lightest or heaviest, for in that which it sinkes most, that is infallibly the lightest, and so contrarily.