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Rh was done in 1612 by Christoph Schemer, who fully described his method of solar observation in the Rosa Ursina (1630), demonstrating very clearly and practically the advantages and disadvantages of using the camera, without a lens, with a single convex lens, and with a telescopic combination of convex object-glass and concave enlarging lens, the last arrangement being mounted with an adjustable screen or tablet on an equatorial stand. Most of the earlier astronomical work was done in a darkened room, but here we first find the dark chamber constructed of wooden rods covered with cloth or paper, and used separately to screen the observing-tablet.

Various writers on optics in the 17th century discussed the principle of the simple dark chamber alone and with single or compound lenses, among them Jean Tarde (Les Astres de Borbon, 1623); Descartes, the pupil of Kepler (Dioptrique, 1637); Bettinus (Apiaria, 1645); A. Kircher (Ars Magna Lucis et Umbrae, 1646); J. Hevelius (Selenographia, 1647); Schott (Magia Universalis Naturae et Artis, 1674); C.F.M. Deschales (Cursus, seu Mundus Mathematicus, 1674); Z. Traber (Nervus Opticus, 1675), but their accounts are generally more interesting theoretically than as recording progress in the practical use and development of the instrument.

The earliest mention of the camera obscura in England is probably in Francis Bacon’s De Augmentis Scientiarum, but it is only as an illustration of the projected images showing better on a white screen than on a black one. Sir H. Wotton’s letter of 1620, already noted, was not published till 1651 (Reliquiae Wottonianae, p. 141), but in 1658 a description of Kepler’s portable tent camera for sketching, taken from it, was published in a work called Graphice, or the most excellent Art of Painting, but no mention is made of Kepler. In W. Oughtred’s English edition (1633) of the Récréations mathématiques (1627) of Jean Leurechon (“Henry van Etten”) there is a quaint description, with figures, of the simple dark chamber with aperture, and also of a sort of tent with a lens in it and the projection on an inner wall of the face of a man standing outside. The English translation of Porta’s Natural Magick was published in 1658.

Robert Boyle seems to have been the first to construct a box camera with lens for viewing landscapes. It is mentioned in his essay On the Systematic or Cosmical Qualities of Things (ch. vi.), written about 1570, as having been made several years before and since imitated and improved. It could be extended or shortened like a telescope. At one end of it paper was stretched, and at the other a convex lens was fitted in a hole, the image being viewed through an aperture at the top of the box. Robert Hooke, who was some time Boyle’s assistant, described (Phil. Trans., 1668, 3, p. 741) a camera lucida on the principle of the magic lantern, in which the images of illuminated and inverted objects were projected on any desired scale by means of a broad convex lens through an aperture into a room where they were viewed by the spectators. If the objects could not be inverted, another lens was used for erecting the images. From Hooke’s Posthumous Works (1705), p. 127, we find that in one of the Cutlerian lectures on Light delivered in 1680, he illustrated the phenomena of vision by a darkened room, or perspective box, of a peculiar pattern, the back part, with a concave white screen at the end of it, being cylindrical and capable of being moved in and out, while the fore part was conical, a double convex lens being fixed in a hole in front. The image was viewed through a large hole in the side. It was between 4 and 5 ft. long.

Johann Zahn, in his Oculus Artificialis Teledioptricus (1685–1686), described and figured two forms of portable box cameras with lenses. One was a wooden box with a projecting tube in which a combination of a concave with a convex lens was fitted, for throwing an enlarged image upon the focusing screen, which in its proportions and application is very similar to our modern telephotographic objectives. The image was first thrown upon an inclined mirror and then reflected upwards to a paper screen on the top of the box. In an earlier form the image is thrown upon a vertical thin paper screen and viewed through a hole in the back of the camera. There is a great deal of practical information on lenses in connexion with the camera and other optical instruments, and the book is valuable as a repertory of early practical optics, also for the numerous references to and extracts from previous writers. An improved edition was published in 1702.

Most of the writers already noticed worked out the problems connected with the projection of images in the camera obscura more by actual practice than by calculation, but William Molyneux, of Dublin, seems to have been the first to treat them mathematically in his Dioptrica Nova (1692), which was also the first work in English on the subject, and is otherwise an interesting book. He has fully discussed the optical theory of the dark chamber, with and without a lens, and its analogy to the eye, also several optical problems relating to lenses of various forms and their combinations for telescopic projection, rules for finding foci, &c. He does not, however, mention the camera obscura as an instrument in use, but in John Harris’s Lexicon Technicum (1704) we find that the camera obscura with the arrangement called the “scioptric ball,” and known as scioptricks, was on sale in London, and after this must have been in common use as a sketching instrument or as a show.

Sir Isaac Newton, in his Opticks (1704), explains the principle of the camera obscura with single convex lens and its analogy with vision in illustration of his seventh axiom, which aptly embodies the correct solution of Aristotle’s old problem. He also made great use of the simple dark chamber for his optical experiments with prisms, &c. Joseph Priestley (1772) mentions the application of the solar microscope, both to the small and portable and the large camera obscura. Many patterns of these two forms for sketching and for viewing surrounding scenes are described in W. J.’s Gravesande’s Essai de perspective (1711), Robert Smith’s Compleat System of Optics (1738), Joseph Harris’s Treatise on Optics (1775), Charles Hutton’s Philosophical and Mathematical Dictionary, and other books on optics and physics of that period. The camera obscura was first applied to (q.v.) probably about 1794, by Thomas Wedgwood. His experiments with Sir Humphrey Davy in endeavouring to fix the images of natural objects as seen in the camera were published in 1802 (Journ. Roy. Inst.).

 CAMERARIUS, JOACHIM (1500–1574), German classical scholar, was born at Bamberg on the 12th of April 1500. His family name was Liebhard, but he was generally called Kammermeister, previous members of his family having held the office of chamberlain (camerarius) to the bishops of Bamberg. He studied at Leipzig, Erfurt and Wittenberg, where he became intimate with Melanchthon. For some years he was teacher of history and Greek at the gymnasium, Nuremberg. In 1530 he was sent as deputy for Nuremberg to the diet of Augsburg, where he rendered important assistance to Melanchthon in drawing up the Confession of Augsburg. Five years later he was commissioned by Duke Ulrich of Württemberg to reorganize the university of Tübingen; and in 1541 he rendered a similar service at Leipzig, where the remainder of his life was chiefly spent. He translated into Latin Herodotus, Demosthenes, Xenophon, Homer, Theocritus, Sophocles, Lucian, Theodoretus, Nicephorus and other Greek writers. He published upwards of 150 works, including a Catalogue of the Bishops of the Principal Sees; Greek Epistles; Accounts of his Journeys, in Latin verse; a Commentary on Plautus; a treatise on Numismatics; Euclid in Latin; and the Lives of Helius Eobanus Hessus, George of Anhalt and Philip Melanchthon. His Epistolae Familiares (published after his death) are a valuable contribution to the history of his time. He played an important part in the Reformation movement, and his advice was frequently sought by leading men. In 1535 he entered into a correspondence with Francis I. as to the possibility of a reconciliation between the Catholic and Protestant creeds; and in 1568 Maximilian II. sent for him to Vienna to consult him on the same subject. He died at Leipzig on the 17th of April 1574.

See article by A. Horawitz in Allgemeine deutsche Biographie; C. Bursian, Die Geschichte der klassischen Philologie in Deutschland (1883); J. E. Sandys, ''Hist. Class. Schol.'' (ed. 1908), ii. 266. 