ENFANT IN

155 ENERGY 152 ENFANT IN and pointed out that the heat liber-; employed for driving mills wherever ated was, in another form, the energy | this type of power could be obtained spent in driving the blunt drill. Davy caused two pieces of ice to be rubbed together within a yacuum at a temperature below zero, and melted the ice, thus showing that, since ice has to absorb heat in order to melt, the supply of heat could not have come from the ice itself, but must have resulted from the work done in rubbing. It has to be remembered that, in the time of Rumford and Davy, the belief was prevalent that heat or caloric was a material substance, and not a form of motion. A further and most important step was made by Dr. J. P. Joule, of Manchester, who measured the amount of mechanical work which is spent in producing one unit of heat. This is known as the mechanical equivalent of heat, or Joule’s equivalent. Two hanging weights were geared to a set of paddles which could rotate within a cylindrical copper ve el filled with water, and supplied with fixed vanes. The weights were released, and in descending a measured distance caused the paddles to churn the water in the ve el, and thus the water was slightly warmed. This operation was repeated several times, and the rise of temperature of the water was measured by means of a delicate thermometer. When _ corrections for friction, cooling, and other lo es had been applied, Jowle calculated that 772 foot-pounds of work wore expended in raising 1 lb. of water 1° F. The experiment has been repeated in various forms, and the value now accepted for Joule’s equivalent is 777. Although energy cannot be destroyed, nor, itmay be added, created, it may be rendered le available for use. Whe various forms of energy may be cla ified aceording to their availability, and in this respect mechanical energy is one of the most available, and low-temperature heat is one of the least available. The latter is therefore cla ed as a lower form of energy, and when energy is converted from a more available to a le available form, it is said to be di ipated or degraded. Now, during any transformation of energy, a part of the energy is spent in overcoming friction forces, and is thus degraded. Industrial Application. The problem of economizing our stores of energy is one which is now attracting more attention than it did formerly. With the greater scarcity of coal, and the future prospect of its complete absence, other natural sources of energy are being investigated. Oil has been discovered in this country, but not in large quantities. Waterfalls have long been cheaply and conveniently; the resources of the Highlands in this respect have not been utilized to any great extent. At Kinlochleven, where the valley has been dammed acro to obtain sufiicient water-power, an aluminium industry has sprung up. There is a scheme on foot at the present time to make use of the tidal energy of the Severn. Here and there windmills may be seen which drive water-pumps employed for draining purposes. On the Severn, near Iron bridge, a ferry is in use which employs the force of the river current to propel the ferry-boat acro the river. In warmer countries batteries of mirrors have been employed to concentrate the sun’s heat for use in the absence of fuel. In large towns the presence of unconsumed carbon (soot) in the atmosphere raises the question not only of fuel economy but also of public health.—BIBLioGRAPHY: Kelvin and Tait, Natural Philosophy; Balfour Stewart, Conservation of Iinergy; Deschanel, Heat, Light, .; F- Bucking ham, Z'hermodynamics. ENFANT IN (an-fan-tan), Barthélemy Prosper, one of the chief founders of St. Simonism; born at Paris, 1796, died in 1864. In1825 he became acquainted with St. Simon, who in dying confided to him the task of continuing the work. This he did with succe until after the Revolution of 1830, when, as the representative of the social and religious theories of the school, he quarrelled with Bazard, the representative of its political ideas. Enfant in organized mode! communities, which quickly fell to pieces; the new organ of the sect, Le Globe, was a failure; their convent at Ménil montant, of which Enfant in was ‘supreme father,’ was broken up by the Government (1832). He himself was imprisoned as an offender against public morality (being an advocate of free love), and on his release attempted to found a model colony in Egypt, whieh was broken up in the second year. He then retired to Tain (Dréme), where he lived for some time as a farmer. In 1841 he was sent as member of a commi ion to explore the industrial resources of Algiers, and on his return published a work on the Colonization of Algiers (1848). On the Revolution of 1848 he started a new journal, Le Crédit Public, but after two years withdrew from public notice. He afterwards held a post on the Paris, Lyons and Mediterranean Railway until his death. Among his werks are: Doctrine de St. Simon, La Religion St. Simonienne. 156