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 LAMP 129 rooms. They give a dim smoky light, in con- sequence of the carbonaceous matter not being sufficiently spread by an open wick to be reach- ed by the oxygen of the air before it is dis- sipated in sooty vapor. (See COMBUSTION, and FLAME.) The external form of the lamp was more of a study to the ancients than the prin- ciples of combustion. They gave to it the most graceful outlines, and ornamented it with gro- tesque figures and fanciful designs which were often of great beauty. They suspended their lamps from the ceiling or from the hands of or- namental figures of boys or men, or they were placed upon stands. As at the present day in Aleppo and Egypt, they were kept by the He- brews burning all night ; and to this much im- portance was attached, the putting out of the light being significant of the extinction of the family and desertion of the house. The first improvement in the construction of lamps was removing the beak by a long neck to a distance from the reservoir of oil, thus reducing the width of the shadow cast by the lamp. Be- sides this object, it was soon found by those who investigated the matter, that the following were subjects for improvement : 1, the wick, which as used presented a bundle of fibres, the inner portion of which, though saturated with oil, was removed from the reach of the air re- quired for its combustion ; 2, the level of the surface of the oil, that from first to last it should bear the same relation to the level of the burning part of the wick, thus securing uniformity in the supply of oil for combustion ; and 3, the concentration of the light by reflec- tors at points where it is wanted. The wick was first improved and much used in the coun- tries bordering on the Rhine by platting its fibres together to make it flat and ribbonlike; a flat socket was provided for it, and it was made to move up and down by a horizontal spindle and toothed wheel ; this is known as the Worms lamp. A greater improvement was that of the Argand burner, in which the wick was made in the form of a hollow cylinder, and so arranged that a current of air could pass up within it, as well as come to its external sur- face. The addition of a chimney of sheet iron, as originally made by Argand, increased the supply of air by producing an upward draught. The effect of the chimney was after- ward much increased by contracting its up- per portion and forming a shoulder, against which the ascending current impinges, and is turned inward upon the flame. The so-called astral lamps were provided with these wicks, and the reservoir for the oil was arranged in the form of a hollow ring encircling the hol- low central stand that supported the burner, and with which it was connected by one of the tubular braces that held it up. Thus the level of the oil in the shallow ring could not undergo much change, and it continued very nearly the same as that of the burning part of the wick until it was almost exhausted. In consequence of the thin and peculiar shape given to the ring, the lamp cast no shadow at a little distance off, and a vase of ground glass surrounding the flame served to render the light still more diffusive or scattered. In the year 1800 Carcel devised an ingenious piece of clockwork machinery for pumping the oil from a reservoir at the foot of the lamp up to the burner, and thus supplying this always from the same point, while the excess of oil flowed back into the reservoir. This being at the base of the stand and the flame at the top, there was consequently no shadow. The lamp, afterward slightly improved by other manufacturers, was in many respects the most perfect of these contrivances; but its great cost restricted its use to the wealthy. It was moreover so inconveniently large and heavy, that it could be moved only with diffi- culty ; and the complicated nature of its me- chanism required access to skilful workmen, such as can be found only in large cities, to keep it in repair. The attention directed in the early part of the present century to the subject of producing artificial light by con- venient and efficient methods caused many more forms of lamps to be introduced than can here be named. Some were designed to burn the crude whale oil, which on account of its viscidity requires to be heated before it can pass along the fibres of the wick. Parker's hot oil or economic lamp was especially adapt- ed for its use. The reservoir was a double cylinder of metal surrounding the upper por- tion of the chimney, which was also of metal, the lower part being of glass. It was support- ed by a side arm, which was made hollow to convey the oil to the burner below. A paper shade served to conceal the apparatus above the flame, and also to reflect the light downward. This lamp is very highly commended by Dr. Ure for its illuminating power and economy. The lamps of Benkler, constructed in Wiesba- den in 1840, introduced a peculiar contrivance in the form of the burner, which caused the draught of air to impinge at an angle upon the flame, making the combustion more vivid and the light more brilliant. It rendered prac- ticable the use of poor qualities of oil, such as in other lamps were very imperfectly con- sumed, and only with the production of much smoke and disagreeable smell. The so-called solar lamps, first made by Mr. Smith in Bir- mingham, depended on this principle; and it was essential to the excellent solar lamps made by Cornelius of Philadelphia, which, by means of a metallic cylinder passing from the burner down into the reservoir, permitted the use of lard instead of oil, sufficient heat being conveyed from the flame to keep it in a melt- ed state. The solar lamps, on account of the cheap materials they consume, have been very extensively used; but they require particular care to keep them clean. The wick must be frequently changed, and always freshly trim- med with every using ; and the reservoir also must be freshly filled at the same time. A re-