WHEEL-Animal. See ANIMALCULE, n° 16—22.
WHEEL of Orfyeus, a machine supposed by professor Gravesande to be a perpetual motion; of which we have the following account in a Letter from the Professor to Sir Isaac Newton. "It is an hollow wheel, or kind of drum, about 14 inches thick, and 12 feet diameter; being very light, as it consists of several cross pieces of wood framed together; the whole of which is covered over with canvas, to prevent the inside from being seen. Thro' the centre of this wheel or drum runs an axis of about 6 inches diameter, terminated at both ends by iron axes of th of an inch diameter, upon which the machine turns. I have examined these axes, and am firmly persuaded that nothing from without the wheel in the least contributes to its motion. When I turned it but gently, it always stood still as soon as I took away my hand; but when I gave it any tolerable degree of velocity, I was always obliged to stop it again by force; for when I let it go, it acquired in two or three turns its greatest velocity, after which it revolved from 25 to 26 times in a minute. This motion it preserved some time ago for two months, in an apartment of the castle: the doors and windows of which were locked and sealed, so that there was no possibility of fraud. At the expiration of that term, indeed his serene highness ordered the apartment to be opened, and the machine to be stopped; least, as it was only a model, the parts might suffer by so much agitation. The landgrave being himself present on my examination of this machine, I took the liberty to ask him, as he had seen the inside of it, whether, after being in motion for a certain time, no alteration was made in the component parts; or whether none of those parts might be suspected of concealing some fraud; on which his serene highness assured me to the contrary, and that the machine was very simple."