ˈwater-ball
1. A globe of glass filled with water, used to collect and throw the rays of light upon an object.
| 1665 Hooke Microgr. 53. Ibid. 181 The Eggs of Silk⁓worms..afford a pretty Object for a Microscope..especially if..the light of a window be cast or collected on it by a deep Convex-glass, or Water-ball. |
2. hour water-ball [after hour-glass], a contrivance for measuring time by the rising and sinking of a ball in water.
| 1655 Marquis of Worcester Cent. Inv. Index, An Hour Water⁓ball. |
3. (See quots.)
| 1696 R. H. Sch. Recreat. 30 A Fire that will burn in the Water, or Water Ball. 1799 G. Smith Laboratory I. 43 Water-balls, or globes, made of wood, which swim and burn upon the water. |