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.

PROBLEM. LX. Of a fine lamp which goes not out, though one carry it in ones pocket: or being rolled upon the ground will still burne.

IT must be observed that the vessell in which the oile is put into, have two pinnes on the sides of it, one against another, being inclu∣ded within a circle: this circle ought to have two other pinnes, to enter into another circle of

brasse, or other solid matter: lastly, this second circle hath two pinnes, which may hang within some box to containe the whole lamp, in such manner, that there be 6 pinnes in different po∣sition: Now by the aid of these pegges or pinnes, the lamp that is in the middle will be alwayes well situated according to his Centre of gravity, though it

[illustration]

be turned any way: though if you endea∣vour to turne it up∣side downe, it will lie levell▪ which is plea∣sant and admirable to behold to those which know not the cause: And it is fa∣cil from his to make a place to rest quiet in, though there be great a∣gitation in the outvvard parts.