LAMP

(Gr. \auiras.) The general term for the well known contrivances used in producing artificial light from the combustion of liquid or other inflammable bodies. The peculiar applicability of oil to the production of artificial light, which could not fail to be discovered at a very' early period, rendered the use of lamps universal among the nations of Antiquity. The Egyptians, the Hebrews, Greeks, and Roman vied with each other in the construction of these instruments; and the specimens of some that have been transmitted to our times display much taste and elegance of external design. It would seem, however, that the ancients had confined themselves merely to the external embellishment of the lamp; for it is a singular circumstance, that notwithstanding the simplicity of the invention, and its obvious capability of improvement, it is only within the last sixty years that any material improvement has been effected in its original construction. To give anything like a complete view of the principles and structure of the numerous lamps of which the present age has witne ed the invention, would be quite impracticable without a multiplicity of illustrative diagrams, which would be foreign to the purpose of this work; but a brief notice of the principle on which the action of every lam]), both simple and complicated, depends, and of some of the most celebrated improvements in their structure, may not be considered out of place. The most simple lamp consists in a ve el of any shape filled with oil or other inflammable liquid, and having a short depre ion or spout on one side, in which lies a wick composed of any fibrous substance, and capable of imbibing the oil by its capillary attraction. The oil thus raised and diffused through the wick, when ignited, admits of being heated to such a degree of temperature as is capable of vola tilizing the oil, the vapour of which, in a state of comb us tion, constitutes the flame of the lamp. The wick of a lamp serves only for the purpose of raising up the oil by capillary attraction, and thus giving a constant and adequate supply to the flame. It furnishes no part of the light by the com uustien of its own substance; for the quantity consumed is too small to merit attention, and it is usually coated over with a broad deposit of carbonaceous matter, which cannot burn for want of the acce of air, from which it ' [s. 652]