AN ORTHOSCOPE

n. A?2n-o%rth’o%s-kop. From a priv., bpéés, straight, and oxomeiv, to observe. Fr., an orthoscope. Ger., An orthos kop. An instrument devised by Plateau, of the same nature as the thaumatrope. It consists of two small cylinders, of different diameters, the axes of which lie in the same straight line, one immediately behind the other. These cylinders are made to revolve by means of two endle cords running round a larger disc, the latter being tarned with a crank. On one cylinder there is a transpar- See AN ORCHID I A. Lat., an orgic us. Fr., an or- Gr., dvwpia, Untime- Gr., Prépogos Without a cranial cavity, or O, no; 07, not; 03, whole; Th, thin; T?, the; U, like vo in too; U?, blue; U3, lull; U4, full; U%, urn; US, like ü (German). ent disc on which a distorted figure is drawn; on the other cylinder there is a black dise with one or more slit-like openings. When the dises are rotated, a perfect, undistorted figure is seen. [* Bull. de l'Acad. de Bruxelles,” iii, pp. 7, 364 (F).]