Rolling LAMP, a machine AB, with two moveable circles DE, FG, within it; whose common centre of motion and gravity is at K, where their axis of motion cross one another. If the lamp KC, made pretty heavy and moveable about its axis HI, and whose centre of gravity is at C, be fitted within the inner circle, the common centre of gravity of the whole machine will fall between K and C; and by reason of the pivots A, B, D, E, H, I, will be always at liberty to descend: hence, though the whole machine be rolled along the ground, or moved in any manner, the flame will always be uppermost, and the oil cannot spill.
It is in this manner they hang the compass at sea; and thus should all the moon-lanterns be made, that are carried before coaches, chaises, and the like.