lows the observer to change the position of his eye considerably without ceasing to see the image of the object he is tracing. The prism in this case is triangular in shape, and one of the angles is a right angle. In using it, the right angle is turned upward, SO that one of the perpendicular faces is turned toward the object in an oblique direction, while the edge of the other perpendicular face meets a transparent glass plate at right angles. The rays from the object falling upon the face of the prism which is turned toward it are, after being more or less refracted, thrown upon the base of the prism, from which they are totally reflected in the direction of the other perpendicular face. In emerging from the prism at this face they are again refracted and thrown upon the transparent glass plate. By this, again, the rays are partially reflected, being thrown upward in the direction of the eye of the observer, who, looking through the plate, sees an image of the object on a sheet of paper beneath, the outlines of which can be traced by a pencil as before.

FIG. 2

Camera Obscura ("dark chamber"), an optical instrument employed for exhibiting the images of external objects in their forms and colors, so that they may be traced and a picture formed. From certain scattered observations in the writings of Friar Roger Bacon, in the 13th century, it would appear that he was acquainted with the principle upon which the camera obscura is constructed, but the first complete description of the instrument is found in the Magia Naturalis of Giambattista della Porta, published in 1569, and Porta is commonly credited with its invention.

In its simplest form the camera obscura consists of a darkened chamber, into which no light is permitted to enter excepting by a small hole in the window-shutter. 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. The images thus obtained become sharper as the size of the hole is diminished; but this diminution involves loss of light, so that it is impossible by this method to obtain an image at once bright and sharp. This difficulty can be overcome by employing a lens. If the objects in the external landscape are all at distances many times greater than the focal length of the lens, their images will all be formed at sensibly the same distance from the lens,

and may be received upon a screen placed at this distance. The images are inverted, and are of the same size whether the lens is in position or not, so long as the screen remains fixed; but they are far sharper and more distinct when the lens is used. As exhibited at seaside resorts and other places of amusement, the camera obscura consists of a small building or of a tent surrounded by opaque curtains, and having at its top a revolving lantern, containing a lens with its axis horizontal, and a mirror placed behind it at a slope of 45°, to reflect the transmitted light downward on a sheet of white paper lying on the top of a table. Images of external objects are thus depicted on the paper, and their outlines can be traced with a pencil if desired. It is still better to combine lens and mirror in one by the arrangement represented in section in the figure. Rays from external objects are first refracted at a convex surface, then totally reflected at the back of the lens (or prism), which is plane, and finally emerge through the bottom, which is concave, but has a larger radius of curvature than the first surface. The two refractions produce the effect of a converging meniscus. The camera obscura, which was formerly chiefly employed for purposes of amusement, has now become well-known from its application to photography.

The instrument employed by photographers (and called simply a "camera") varies in general design according to the use to which it is to be put. It consists essentially, however, of a light-tight box, the length of which can be adjusted by means of a bellows. A lens or object-glass is secured to the front end of the box, and the bellows is drawn out until the lens throws a distinct image of the object upon a ground-glass screen at the back of the camera. The object-glass is usually compound, consisting of two single lenses, an arrangement which is very commonly adopted in optical instruments, and which has the advantage of giving the same effective focal length as a single lens of smaller radius of curvature, while it permits the employment of a larger aperture, and consequently gives more light. When the image upon the ground-glass screen has been rendered as sharp as possible, the screen is withdrawn and replaced by a sensitized plate, which is affected chemically by the light rays so as to retain a permanent impress of the image. The impression thus produced upon the sensitized plate is not visible at first, but is brought out, or "developed," by subsequent treatment with chemicals. See PHOTOGRAPHY.

Camera, Photographic, a camera obscura so constructed that sensitized plates or films may be placed at the back and receive the image. There are many styles of camera in use, those of the tripod variety being used for portraits, and landscapes where a long exposure is required, and the hand camera used by tourists on account of its convenient shape and size. See CAMERA OBSCURA; PHOTOGRAPHY.

Camerarius, Joachim, yō'äн-im kä-mā-rä're-oos, German scholar: b. Bamberg, 12 April 1500; d. Leipsic, 17 April 1574. He contributed to the progress of knowledge, in the 16th century, by his own works as well as by editions of Greek and Latin authors with com

mentaries, and by a better organization of the universities at Leipsic and Tübingen, and of the gymnasium at Nuremberg. He also took an important part in the political and religious affairs of his time. He was a friend of Melanchthon, and was held in great esteem by the emperors Charles V., Ferdinand I., and Maximilian II. In 1555 he was deputy of the University of Leipsic to the Diet of Augsburg. His proper name was Liebhard, but he changed it to Camerarius, because his ancestors had been chamberlains (late Latin camerarii) at the court of the bishops of Bamberg. His son Joachim (1554-98) became known as a botanist.

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Camerarius, Rudolph Jakob, roo'dolf yä'kōb, German botanist: b. Würtemberg, Feb. 1665; d. Tübingen, 11 Sept. 1721. To him is ascribed the discovery of the sexual relation in plants. He was in charge of the botanic gardens at Tübingen and was also a medical professor.

Camerino, kä-mä-ṛē'no (ancient CAMERINUM), Italy, a town in the province of Macerata, 41 miles southwest of Ancona. It is the seat of an archbishopric, and contains some good public buildings, among which are the archiepiscopal palace and the cathedral. There is a university, founded in 1727. Silk is grown and manufactured here. Pop. (1901) 12,542.

Camerlen'go (It. camerlingo, "a chamberlain"), one of the highest officers of the Vatican court. A cardinal Camerlengo, during a vacancy in the holy see, takes charge of all the temporalities, and presides over the apostolic chamber or palace.

Cam'eron, Archibald, American clergyman: b. Scotland, about 1770; d. 1836. After studying at Transylvania Seminary, Lexington, Ky., he was ordained in 1796, and in the same year assumed charge of churches at Big Spring, Akron, and Fox Run. Until 1828 he performed itinerant services, and then became minister of the churches at Mulberry and Shelbyville. The Presbyterian Church in Kentucky owes much to his pioneer labors. His published works include: The Faithful Steward' (1806); 'An Appeal to the Scriptures (1811); A Defense of the Doctrines of Grace' (1816); and A Reply to Some Arminian Questions on Divine Predestination' (1822).

Cameron, Arnold Guyot, American educator: b. Princeton, N. J., 4 March 1864. He was graduated at Princeton University in 1886, and during the next two years studied abroad. In 1888-91 he was professor of French and German languages and their literatures in Miami University; in 1891-7, assistant professor of French in the Sheffield Scientific School of Yale University; and in 1897 accepted the chair of French at the John C. Green School of Science of Princeton University. He is editor of the text-books: 'Daudet'; Mérimée'; 'Loti'; 'Coppée and Maupassant'; and The Gon

courts.'

Cameron SIR Charles, Scotch journalist and politician: b. Dublin, 1841. He was educated at Madras College, St. Andrews, Trinity College, Dublin, and at medical schools in Paris, Berlin, and Vienna. He edited the North British Daily Mail from 1864 to 1874, and from the latter year till 1885 was member of Parliament

for Glasgow. From 1885 to 1895 he sat for the College division, Glasgow, and for the Bridgeton division 1897-1900. The adoption of sixpenny telegrams was the result of a resolution which he introduced in the House, and he was likewise instrumental in the conferring of municipal franchise upon women in Scotland. His publications include many pamphlets on political, social, and medical subjects.

Cameron, SIR Charles Alexander, Irish physician: b. Dublin, 16 July 1830. He was elected public analyst for the city of Dublin in 1862. He was the only one who succeeded in applying the Adulteration of Food Act of 1860. In 1867 he was elected professor of hygiene or political medicine in the Royal College of Surgeons, in Ireland. His lectures on hygiene, open to ladies, were largely attended. He was knighted in 1886, in recognition of his services to public health. He has written: 'Chemistry of Agriculture' (1857); Lectures on Public of Surgeons, Ireland, etc.) (1886); ElemenHealth' (1868); History of the Royal College tary Chemistry and Geology) (1896); etc.

Cameron, Charles Duncan, English soldier: d. 1870. He served in the Kaffir war (1846-7), in the Crimean war, and later at Kars. In 1862 he became British consul in Abyssinia, and having undertaken to deliver a letter from Queen Victoria to King Theodore, was imprisoned by the king for two years on the charge of interfering in the politics of that country. He was released only to be shortly imprisoned again, together with Rassan, agent of the British government, and others, their final release being effected by the advance of English troops upon Theodore's territory. An account of these matters by Cameron was published in the Parliamentary Printed Papers' (1868–9).

Cameron, Donald Andreas, English civil servant b. 1856. He filled the post of consul at Suakin, 1885-8, and at Bengazi, 1888-9. He was judge of the native court of appeals at Cairo 1889-97 and then, returning to the consular service, became consul at Port Said for the Suez Canal. He has published Arabic-English Vocabulary (1892); Egypt in the 19th Century) (1898).

Cameron, Emily Lovett, English novelist: b. Walthamstow; married to H. Lovett Cameron, about 1876. Her novels deal mostly with personal complications, and include: Juliet's Garden (1877); 'Deceivers Ever (1878); 'Vera Nevill (1880); In a Grass Country (1885); The Cost of a Lie (1886); The Dead Past (1886); Pure Gold' (1887); A North Country Maid'; Jack's Secret'; A Sister's Sin'; A Bad Lot'; A Soul Astray); The Craze of Christina'; 'Bitter Fruit'; An Ill Wind.'

Cameron, George Frederick, Canadian poet: b. New Glasgow, Nova Scotia, 1854; d. 1885. He was educated at Queens' University, Kingston, Ontario; resided for a time in the United States; returned to Canada, and edited the Kingston News. As a lyrical poet he has received high praise from leading critics, and was accorded an eminent position by some of the great contemporary English poets. See Stedman, Victorian Anthology) (1895).

Cameron, Henry Clay, American educator: b. Shepherdstown, Va., 1 Sept. 1827.

He was graduated at Princeton College in 1847, and at the Princeton Theological Seminary in 1855; and has been connected with the department of Greek at Princeton since 1852. He has twice been chosen to the Presbyterian General Assembly, and has written Princeton Roll of Honor History of the American Whig Society); Old Princeton: Its Battle, Its Cannon, etc.)

Cameron, Hugh, Scottish artist: b. Edinburgh, 1835. He is a well-known and popular painter of portraits and figure pieces, and among his works are: 'Maternal Care); Age and Infancy; Haymakers Resting A Lonely Life'; 'The Rivals'; 'The Timid Bather.'

Cameron, James Donald, American capitalist and politician: b. Middletown, Pa., 14 May 1833. He is the oldest son of Simon Cameron (q.v.), and was graduated from Princeton College in 1852. He devoted himself to business pursuits and in 1861 was made vice-president and two years later president of the Northern Central R.R. He remained in this office till 1874. In 1876 President Grant appointed him secretary of war, and in 1877 he succeeded his father as United States senator from Pennsylvania. He was re-elected in 1885 and 1890.

Cameron, John, Scottish scholar: b. Glasgow, 1579; d. 1625. In 1600 he went to the Continent, where his ability and erudition secured for him several appointments at Bergerac, Sedan, Saumur, and other seats of learning. Returning to Great Britain in 1620, he was two years later appointed principal of the university of Glasgow; but in less than a year returned to Saumur, and thence to Montauban, where he received a divinity professorship. Here, as at Glasgow, his doctrine of passive obedience made him many enemies, by one of whom he was stabbed in the street, and he died from the effects of the wound in 1625. Sir Thomas Urquhart styles him a "walking library," and Milton, "an ingenious writer in high esteem." He was considered one of the best scholars of his day; in biblical criticism he was inclined to be perverse; where there was a difficulty he usually chose the opposite view to that held by other divines, especially Beza. His theological opinions were of a somewhat lax character, his eight works, in Latin and French (10 vols., 1616–42), being said to be the foundation of Moses Amyraut's doctrine of universal grace (1634). His followers are sometimes called Cameronites.

Cameron, Richard, Scottish Covenanter: b. Falkland, Fifeshire, 1648; d. Ayrsmoss 22 July 1680. He was at first a schoolmaster, and for a time was tutor in the family of Sir Walter Scott of Harden. Being converted by the field-preachers, he became an enthusiastic votary of the Covenant. On the 20th of June 1680, in company with about 20 other persons, well armed, he entered the village of Sanquhar, and proclaimed at the cross that he and those who adhered to him renounced their allegiance to the king on account of his having abused his government, and also declared a war against him and all who adhered to him, at the same time avowing their resolution to resist the succession of his brother the Duke of York. The privy council immediately put a reward of 5,000 merks upon Cameron's head, and 3,000 upon

those of Cargill and Douglas, his associates; and parties were sent out to waylay them. The little band kept together in arms for a month in the mountainous country between Nithsdale and Ayrshire. But on the 22d of July, when they were lying in Ayrsmoss, near Auchinleck in Ayrshire, Bruce of Earlshall approached them with a party of horse and foot much superior in numbers. A brief skirmish took place, in which the insurgents were allowed even by their enemies to have behaved with great bravery; but nothing could avail against superior numbers. Cameron being among the slain, his head and hands were cut off and carried to Edinburgh, along with the prisoners. The name of Cameron was applied to the small but zealous sect of Presbyterians which he had led in life, and was also used in a wider and looser sense. The 26th Regiment, which was raised at the Revolution out of the westcountry people who flocked to Edinburgh, was styled on that account the Cameronian Regiment. It is now known as the Cameronians or Scottish Rifles. Consult Herkless, 'Richard Cameron' (1896). See CAMERONIANS.

capitalist: b. Williamstown, Ontario, 25 July Cameron, SIR Roderick William, Canadian 1825; d. 24 Oct. 1900. He entered mercantile life in New York as a youth and acquired a large fortune as an exporter and importer. He was knighted in 1883. He was well known as a turfman and yacht owner, and was prominent in Canadian-American diplomacy.

Cameron, Simon, American statesman: b. Maytown, Lancaster County, Pa., 8 March 1799; d. there, 26 June 1889. He learned printing and in 1820 he was editor of a paper in Doylestown, Pa., and in 1822 held a similar post in Harrisburg. He then interested himself in banking and the building of railroads, and for a time served as adjutant-general of Pennsylvania. From 1845 to 1849 he was United States senator from Pennsylvania, elected by the Democratic party. He became a member of the Republican party on its formation, and in 1856 was again elected United States senator. He was unsuccessfully supported for the offices of both President and Vice-President in the National Convention of 1860, and in 1861 was appointed secretary of war by President Lincoln. He advocated the arming of fugitive slaves and other extreme measures. In January 1862 he resigned from the Cabinet, and was appointed minister to Russia. He succeeded in gaining the support of the Russian government for the Union. In November of the same year he resigned, and lived in retirement till 1866, when he was again elected to the United States Senate. In 1872 he became chairman of the Committee on Foreign Affairs. In 1877 he retired from the Senate in favor of his son, James Donald Cameron. His influence over the Republican party was strong, and his power in the politics of his State practically absolute. He was a vigorous opponent of civil service reform during the administration of President Hayes.

Cameron, Verney Lovett, English travcler in Africa: b. Weymouth, I July 1844; d. Leighton Buzzard, 26 March 1894. He entered the British navy in 1857, and in 1872 was chosen by the Royal Geographical Society of London to conduct an expedition for the relief

of Dr. Livingstone. He was only in time to meet the remains of Livingstone at Unyanyembe, but pushed onward to Ujiji on Lake Tanganyika, and partly circumnavigated this great sheet of water, establishing the fact that its outlet was the Lukuga. Not being able to follow the Lualaba River downward, he continued his journey westward to Benguela, and was thus the first to cross tropical Africa from east to west. Returning to England in 1876, he was raised to the rank of a commander. In 1878 he made a journey through Asia Minor and Persia in order to satisfy himself as to the feasibility of a railroad connecting India with the Mediterranean, and in 1882 with Sir Richard Burton explored the country behind the Gold Coast. He published accounts of his journeys in his Across Africa' (1877); 'Our Future Highway to India' (1880); and To the Gold Coast for Gold' (1883, with Sir R. F. Burton). He died from an accident in the hunting field.

Camero'nians, a sect of Scotch Presbyterian dissenters, named after Richard Cameron. James I. had enforced on his Scottish subjects a liturgy which the people abhorred, and this led, in 1638, to the formation of the covenant, "in behalf of the true religion and the freedom of the kingdom." The organization of the Scottish presbytery was still further completed in the adoption of the Presbyterian form of Church government, a Calvinistic confession of faith, and the two catechisms, which documents are the standards of the Scottish kirk to this

day. Throughout the revolution of 1688 the Cameronians maintained inflexible hostility to the royal usurpation of religious freedom. They supported the Prince of Orange on his assuming the crown of England, but were displeased and disappointed by the form in which the Presbyterian Church was restored. In 1709 they exerted all their influence against the union of Scotland and England. The presbytery of this denomination was not organized until I Aug. 1743, when an act of toleration was procured in their favor. They still have a distinctive existence in Great Britain and America, under the name of Reformed Presbyterians.

Cameroons, kä-mē-roon', Or Kamerun, a German colonial possession in West Africa extending inland from the Bight of Biafra to the northeast and north as far as Lake Chad, and having an area of 191,130 square miles. It is separated from the British territory on the northwest by a line running northeast from the Rio del Rey to a point on the river Benue east of Yola, and from there northnortheast to the south shore of Lake Chad. From French Congo on the south it is marked off by a line running east from the mouth of the Campo River to the river Sanga, and from

there the eastern boundary proceeds first northwest to lat. 4° N., lon. 15° E., then along that meridian to about lat. 8° 30′ N., when it proceeds northwest to the parallel of 10°, which forms the boundary eastward to the Shari River. This river itself to its mouth in Lake Chad serves as the northeastern boundary. The territory receives its name from the Cameroon River, which enters the Bight of Biafra by an estuary nearly 20 miles wide. The swamps along the banks of the river render this district unhealthy for Europeans. Northwest of the river lies the volcanic group called the Cameroon Mountains, which rise to a height of 13,760 feet. The lower slopes of these mountains are more healthy, and are covered with ebony, redwood, and palm-trees. More important than the Cameroon River is the much longer Sannaga or Mbam, entering the Bight of Biafra a little south of the former, and navigable for 40 miles inland to Idia. Among cultivated plants are the banana, oil-palm, cocoanut, groundnut, manioc, yam, sweet-potato, and colocasia; of more recent introduction are cacao, coffee, tobacco, etc. Among the minerals are gold and iron. There is a considerable trade in cotton, ivory, and oil. The inhabitants are almost entirely of the Bantu stock, widely diffused throughout the more southerly portion of the continent, and many of them have almost regular European features. The coast of the Cameroon territory was annexed by Germany in 1884, and the interior has since been acquired, the whole being now a German colony under a governor. The seat of government is at Cameroons, a group of native villages on the estuary of the Cameroon River, but the greater part of the territory is only nominally under German rule. Pop. 4,500,000.

Camil'la, in Roman fable, a virgin, said to have been a daughter of Metabus, a Volscian king, and to have aided Turnus against Æneas (Virgil, Æneid,' vii.).

Camille, ka-mēl ("La Dame Aux Camélias"), a novel by Alexandre Dumas the younger, pubit appearing in 1852 at the Vaudeville Theatre lished in 1848, the celebrated play founded upon the play is owing, perhaps, to the fact that in Paris. The popularity of both the novel and the incidents of the story admit of many interpretations of the character of the heroine.

Camil'lus, Marcus Furius, Roman patrician: d. 365 B.C. He is famous as the deliverer of the city of Rome from the Gauls. In 396 B.C. he was made dictator during the Veientine war, and captured the town of Veii by mining, after it had defied the Roman power for 10 years. In 394 B.C. Camillus besieged the Falerii, and by an act of generosity induced them to surrender. Three years later the envy and jealousy of enemies caused him to exile himself for a time, and he was living in retirement when the Gauls, under Brennus, invaded and captured Rome, with the exception of the capital. Camillus was now appointed dictator a second time, and was successful in repelling the invaders. After he had been four times appointed dictator, a new invasion of the Gauls called him, at the age of 80, once more to that position, and he defeated and dispersed the barbarians. There is a certain amount of myth in the story of his life.