Page:The New International Encyclopædia 1st ed. v. 04.djvu/108

* CAMEO. skillfully utilized by intelligent engravers, so that at (litferont depths of the cutting very beautiful and efFective gradations of color are obtained. Shell, perhaps, gives the most deli- cate results, owing to the nearness of the color to that of flesh, and the general use made of the human figure and head as subjects for cameo engraving. The art is one, of great antiquity, and the engraving of precious stones and of shells in distinct bands of color has been prac- ticed since about B.C. 150. Probably stone and shell, more or less engraved as ornament, talis- man, and seal, are of still more remote times. Inasmuch as Egypt was the birthplace, as it were, of belief in amulets, charms, and phylac- teries of all kinds, it naturally came to pass that it was the earliest country to develop and to encourage the production of these emblems which, for the individual, possessed a magical and religious significance. From the time of the dynasties of the first Pharaohs to the period of the domination of the Romans, the inhabitants of the valley of the Xile, men and women, all wore about the neck, on the finger, or hung some- where on their garments, cut or engraved gems of a talismanic character, which also served, in seme sort, as a personal seal. It is safe to say that no country of ancient times has produced in such profusion jirecious stones in relief and in intaglio. It was in the Greek and Koman period that the cameo reached its perfection. The century of Scopas, Praxiteles, Lysippus, and Apelles produced an artist in gems whom all antiquity praises, but from whom there has not come down to us a single signed work. This artist is Pyrgoteles. Pliny and many others speak of him as the ablest engraver of all time, and place him in the same rank as the above- mentioned sculptors and painters. Pyrgoteles probably engraved several portraits of Alexan- der in cameo and intaglio, though none can be authenticated. Although cameo is sculpture in miniature, we see by this that it engaged the talents of really great artists. Among the largest examples of ancient cameo work is the Sainte Chapelle agate in Paris (13 x 11 inches), repre- senting the apotheosis of Augustus, and the Vienna onyx, an allegorical rejjresentation of the coronation of Augustus. These suijiass, in size an<l beauty of execution, the best of modern productions in this art. BiBi.iouR.riiy. Agostini, Gemmw et Sculp- turw AnlUituv DepicUc ab L. Autjustino (Paris, 16,S.5) ; Zanetti, /-e (jemme antiche (Venice, 17.50); Marsh, Cameo Cutting (London. 1891); Thompson, "On the Working of Shell Cameos," in Art .Journal (ib. 189S) ; Davenport. Cameos (ib. 1!)00) ; and especially Furtwiingler, Die Aniiirn Ci-mmrn I Leipzig and Berlin, 1900). CAMEKA LTJ'CIDA (Lat., light chamber). A device fitted to the eyepiece of a compound microscope to enable the observer to trace upon a sheet of paper the magnified image of the ob- ject as seen. It is constructed in various forms, the simplest of which is a small plate of glass attached to the eyepiece at an angle of 45 de- grees, as shown in Fig. 1. A portion of a slide or cover glass fixed to the eyepiece with wax can be employed for this purpose. In using the camera lueida, the tube of the microscoiie is placed in a nearly horizontal position, and a sheet of paper laid on the table beneath the eyepiece. 82 CAMERA LUCIDA. The rays coming through the eyepiece are re- flected into the eye from the glass, though com- ing apparently from the paper below, where an enlarged image of the object is seen. The out- FIG. 1. SIMPLE C.MERA LUCTDA. line of the image can readily be traced with a pencil, and in this way an accurate representa- tion of the object can be quickly made. Instead of the simple mirror of glass, Sonunering em- ployed a flat, circular ])iece of polished steel or specuhim metal, whose diameter was somewhat smaller than that of the pupil of the eye. The rays are reflected vertically, and enter the eye, as do also those from the paper which come to the eye, after passing by the edges of the mir- ror. A prism, so constructed that total reflec- tion occurs one or more times, is often employed, and the arrangement of Wollaston, which is fre- quently used, is illustrated in the figures and described below. It consists of a small quadri- lateral prism of glass, which Fig. 2 shows in FIG. 2. WOLLASTON'S CAMERA LUCIDA. perpendicular section, held in a brass frame, which is fitted in front of the eyepiece by a suita- ble mounting, or attached to an upright rod. having at its lower end a screw-clamp, to fix it to the edge of a table. The prism, being at the height of about a foot from the table, has its upper face horizontal. Two of its faces, as in