a kind of sonorous phials or glasses, chiefly made in Germany, which have the property of being flexible, and emitting a vehement noise by the human breath. They are also called vexing glasses by the Germans (vexier glaser), on account of the fright and disturbance they occasion by their resillion. The anaclastic glasses are a low kind of phials with flat bellies, resembling inverted funnels, whose bottoms are very thin, scarce surpassing the thickness of an onion peel. This bottom is not quite flat, but a little convex; but upon applying the mouth to the orifice, and gently inspiring, or as it were sucking out the air, the bottom gives way with a prodigious crack, and the convex becomes concave. On the contrary, upon expiring or breathing gently into the orifice of the same glass, the bottom with no less noise bends back to its former place, and becomes gibbous as before.