watch-glass

I placed under a microscope a watch-glass with a drop of distilled water, after having carefully ascertained that it did not contain any visible animalcules.

I had left it in the watch-glass, exposed to solar heat.

He then covered the part with a small watch-glass, kept in place with a bandage.

When a piece of plate-glass is pressed against a slightly convex lens, or a watch-glass, a series of coloured rings is formed by reflected light, with a black spot in the centre.

This is the cornea, a hard, perfectly transparent membrane, looking much like a curved watch-glass.