CAMENZ CAMERA OBSCURA. 



829 



young camelopard is said, by travellers, to be an ac- 

 ceptable article of diet. Little is known of the ges- 

 tation of this animal, though it is said, like that of 

 the camel, to endure for twelve months. 



The giraffe lias long been known to naturalists, 

 though opportunities of examining living specimens 

 have always been rare. They were brought living to 

 Rome, to adorn the public games and festivals, as 

 Pliny states, during the dictatorship of Cassar. Fig- 

 ures of the animal are still preserved in the Praenes- 

 tine pavement, wrought under the orders of Sylla. The 

 figure of the giraffe also occurs among the hierogly- 

 phic monumental drawings of the Egyptians. The 

 giraffe moves with great celerity, and it requires a 

 swift horse to equal its speed, when only in a trot. It 

 has not been tamed, or applied to any useful purpose, 

 as far as we know, though a few specimens have, at 

 different times, been sent to Europe, as presents to 

 sovereigns, or for exhibition. The pacha of Egypt, 

 some years ago, sent one to the king of France, and 

 one to the king of Britain (George IV.). The latter 

 is dead. 



CAMENZ ; a village in the Prussian government of 

 Reichenbach, circle of Frankenstein, on the Neiss; 

 remarkable for the rich Cistercian abbey of the same 

 name, now abolished, which was built in 1094, and 

 numbered, from 1249 to 1810, fifty-three abbots. The 

 most celebrated abbot was Tobias Stusche, who ac- 

 quired the favour of Frederic the Great in a way till 

 lately inexplicable. According; to a manuscript his- 

 tory in the Latin language, left by a friar of C., dur- 

 ing the war of 1741, the abbot suddenly summoned 

 the monks, one evening, to the chapel, at an unusual 

 hour, by the sound of the bell. With him came a 

 stranger in a clerical dress. Scarcely had the monks 

 begun to pray, when a great tumult was heard. Aus- 

 trian troops had arrived from Wartha, and were seen 

 in the monastery, and even in the church. They 

 searched the building for king Frederic, but found 

 and seized his aids only. The address of the abbot 

 saved the king of Prussia and the monarchy. Fre 

 deric refers to this adventure in the Histoire de man 

 Temps, i. chap. 3. The monastery was dissolved by 

 the edict of Oct. 30, 1811. The beautiful castle was 

 burnt in 1817. 



CAMEO, or CAMAIEU ; in the proper sense, a gem 

 engraved in relievo. The ancients generally used the 

 onyx for this purpose. At first, such onyxes, and, 

 afterward, all gems carved in relief, were called 

 cameos. They were carved according to the layers of 

 the stone, so that the ground should be of a different 

 colour from the figure in relief. One of the most 

 famous cameos is the onyx at present in Paris, called 

 Apotheosis of Augustus, one foot high and ten inches 

 wide : its history is also singular. See Gem Sculp- 

 ture. 



CAMKRA JEouA ; a contrivance for blowing the 

 fire, for the fusion of ores, by means of water falling 

 through a funnel into a vessel, which emits a quantity 

 of air or vapour continually, sufficient to keep up a 

 strong fire. 



CAMERA CLARA (clear chamber) ; an optical instru- 

 ment invented by Reinthaler, which supplies the de- 

 ficiencies of the camera obscura, and has this advan- 

 tage over that instrument, that the object to be re- 

 presented need not be illuminated by the sun. All 

 objects appear in it with great distinctness. It can 

 be used equally well in bright and dark weather, in 

 the light of the sun or that of the moon. 



CAMERA LTJCIDA. or light chamber, an optical in- 

 strument employed for delineating views from na- 

 ture, or copying drawings. This instrument was in- 

 vented by Dr Wollaston, about the year 1807, and in 

 its present form consists of a four-sided glass prism, a 

 section of which is shown in the accompanying cut, 



where A represents an ob- 

 ject, the rays proceeding 

 from which enter the prism 

 at B, and are refracted on 

 to the surface C, from 

 whence they pass by reflec- 

 tion to the surface D. An 

 LJ \ image of the object is seen 

 on the surface D by the eye 

 at E. The observer is thus 

 led to suppose that he sees 



the object delineated on the sheet of white paper G H. 

 The point of a pencil placed on the paper may 

 also be seen, so that it is easy to trace the outline of 

 the object A on the surface G H. From the laws of 

 optics it follows, that the magnitude of the picture, 

 compared with that of the image, will be in propor- 

 tion to the distance of the eye from the object, com- 

 pared with that of the eye from the sheet, where- 

 fore in the construction of this instrument there is at- 

 tached a brass slider, by means of which the distance 

 between the prism and the paper can be varied at 

 pleasure. To procure steadiness of vision, there is 

 affixed a thin brass plate to the upper surface of the 

 prism, having a small hole in it tor the observer to 

 look through ; and to suit the instrument to long- 

 sighted persons, a convex lens may be placed before 

 the surface of the prism, or it may be accommodated 

 for those of short sight by placing a concave lens on 

 the eye-hole at E. Great care must be taken in the 

 formation of the prism, so that its sides shall be ac- 

 curately ground to their proper angles the side B 

 should make with the side F an angle of 90', C with 

 B 67^, D with C 135. There are various modifica- 

 tions of this instrument which it would be unnecessary 

 here to describe, being all dependent on the principle 

 stated above ; and the attentive reader will have no 

 difficulty, should he desire it, to carry the minute de- 

 tails of the instrument into execution. 



CAMERA OBSCURA (dark chamber), an opfical instal- 

 ment employed for exhibiting the images of external 

 objects in their forms and colours, so that they may 

 be traced and a picture formed. The invention of the 

 camera obscura is due to Friar Bacon, although by 

 some it has been attributed to Baptista Porta, who, a 

 century afterwards, published a description of it at 

 Antwerp. The simplest form of this instrument con - 

 sists of a darkened chamber, into which no light is 

 permitted to enter excepting by a small hole in the 

 window-shut. A picture of the objects opposite the hole 

 will then be seen on the wall, or a white screen placed 

 so as to receive the light coming through the opening. 

 A much better form of the camera obscura is repre- 

 sented by the cut fig. 1 below, where A represents the 



object, and B a convex lens contained in a tube, fixrd 

 in the end of a rectangular box. At the other end of 

 this box there is placed a plane mirror C, fixed at an 

 angle of 45. Now the light from the object A pass- 

 ing through the lens B, is received by the mirror C, 

 and reflected on to the surface D, which consists of a 

 piece of plate glass ground to a state of semi-transpa- 

 rency by emery or sand. Glass thus ground is CO'n- 

 monly said to be frosted. 1 1 is ground plate glass 

 does not extend to the whole length of the bj\ ," ml 



