This is a small dry, white membrane, oval in shape, convex on the outer side, and crossed along its larger diameter by a bundle of three or four brown nervures, which give it elasticity.

Its entire circumference is rigidly fixed.

Let us suppose that this convex scale is pulled out of shape from the interior, so that it is slightly flattened and as quickly released; it will immediately regain its original convexity owing to the elasticity of the nervures.

From this oscillation a ticking sound will result.
Twenty years ago all Paris was buying a silly toy, called, I think, the cricket or _cri-cri_.

It was a short slip of steel fixed by one end to a metallic base.