raine (Nancy, 1728, 4 vols.; 2d ed. 1745-47, 6 vols.) is founded on original researches. Solid criticism and independent judgment are wanting in all his works. For his life, consult: Fangé (Senones, 1762); A. Digot (Nancy, 1861); and on his correspondence, P. E. Guillaume (Nancy, 1875).

CALM LATITUDES. The portion of the ocean which lies between the northern and south ern trades, and where calms of long duration are likely to prevail. They vary with the season of the year and the consequent shifting of the trade-wind belts. The term is also applied to the region along the polar edge of the trade-wind belts, which is called the Horse Latitudes. See DOLDRUMS.

CALMON, kåľ'môn', MARC ANTOINE (18151890). A French statesman. He was born in Tamniès (Dordogne), and studied law in Paris. In 1871 he became Under-Secretary of State in the Department of the Interior, and in December, 1872, he was appointed prefect of the Department of the Seine, which position he held until the downfall of the Thiers Ministry. In 1873 he was elected to the National Assembly. His valuable works on political economy include the following: Les impôts avant 1789 (1865); William Pitt, étude financière et parlementaire (1865); Histoire parlementaire des finances de la Restauration (1868-70); Etude des finances de l'Angleterre depuis la réforme de Robert Peel, jusqu'en 1869 (1870). He also edited Thiers's Discours parlementaires (15 vol., Paris, 187983).

CALOMARDE, kå’ló-mär’dâ, FRANCISCO TADEO, Count (1775-1842). A Spanish statesman. He was born at Villel, in Aragon, studied in Saragossa, and became an advocate. During the wars of Napoleon he remained loyal to the national cause, and after the expulsion of the

French and the return of Ferdinand VII. in

1814, Calomarde was among the first to hurry to Aragon and do homage to him as absolute monarch. As a reward of his obsequious celerity he obtained a post in the Council for the Indies, but lost it on account of accepting a bribe.

On the restoration of the Constitution in 1820 he unsuccessfully courted the favor of the Liberals; but when the French Army in 1823 restored the authority of Ferdinand VII. Calomarde was appointed secretary of the cámara del real patronato, one of the most influential offices in the kingdom. Not long after the King made him Minister of Justice. While he held this office he showed himself an uncompromising enemy of free thought and progress, and a friend of the old ecclesiastical supremacy. He also secretly favored the party of Don Carlos, but by treating any unseasonable outbreak with great cruelty he preserved himself from the suspicion of being implicated in Carlist schemes. In 1832, when Ferdinand was supposed to be on his death-bed, he was prevailed on by Calomarde to reintroduce the Salic law, by which the Infanta Isabella was excluded from the throne, and Don Carlos, the favorite of the Absolutists, was appointed successor. The unexpected recovery of the King frustrated Calomarde's schemes, and he fled in disgrace to France. He died in Toulouse. Consult.Cardenas, Vida de Calomarde (Madrid, 1841-49).

See MERCURY.

CALONNE, kå'lun', CHARLES ALEXANDRE DE (1734-1802). French Minister of Finance under Louis XVI. He was born January 20, 1734, in Douai. As advocate-general, procurator-general and intendant, he had displayed many brilliant but unsubstantial qualities, when, in 1783, at the instance of his patron, Comte d'Artois, and Marie Antoinette, he was summoned by the King to become Comptroller-General of the Finances. The treasury then was in hopeless disorder, and the whole financial system of the kingdom was inadequate to meet the demands of the extravagant Court and administration. Calonne's policy, whereby he hoped to give satisfaction where the others had not, is best exhibited in his own words: "A man who wishes to borrow money must appear to be rich, and in order to appear rich it is necessary to make a display of expenditure. Economy is doubly fatal; it warns the capitalists not to lend to a treasury involved in debt; it causes the arts to languish, while prodigality enriches them." Thus he won the enthusiastic admiration of the Court, by actually encouraging that bolster up credit. When the Queen came to him extravagance which he regarded as necessary to for an unusually large sum of money, he is said to have replied: "What you wish, madame, shall be done, if it is possible; and if it is not possible-it shall still be done!" But Calonne soon found that public credit requires some more substantial foundation than mere display. Both credit and taxation had reached their absolute limits. A crisis had arrived, with which neither Minister nor King could deal. An Assembly of Notables was therefore called and Calonne opened its session in February, 1787, with a glowing necessity of certain reforms in taxation. account of the national prosperity, but urged the The mismanagement, and he was dismissed and exNotables required an account, which revealed his iled. He died in 1802. Consult the authorities. referred to under FRANCE for this period.

CAL'OPHYLLUM (Neo-Lat., from Gk.κaλós, kalos, beautiful + pov, phyllon, leaf). A genus of trees of the order Guttiferæ, natives of warm climates. Some of the species yield valuable timber, as the piney-tree (Calophyllum angustifolium), which grows at Penang and in the islands to the eastward of the Bay of Bengal, attaining large proportions in ravines and narrow, moist valleys, and furnishes the beautiful straight spars called 'Poon.' The resinous products of some species are valuable, and among

them are some of the substances known by the name of Tacamahaca. Calophyllum inophyllum is a very large and beautiful umbrageous tree, often planted for its shade and the fragrance of its flowers, which are white and in loose axillary racemes. It is one of the most valuable timbertrees of the South Sea Islands. The timber resembles mahogany, being of equally close texture, although of lighter color, and very durable. The leaves are oblong and obtuse; the fruit is a globose drupe or stone-fruit, about the size of a walnut, and a fixed oil is expressed from its kernel, which is used for lamps, etc. In the Hawaiian Islands this oil is extensively applied to bruises and in rheumatism. A similar oil is expressed from the seed of Calophyllum calaba, a native of Ceylon, which also has white sweetscented flowers, and whose timber is used for various purposes, particularly for staves, caskheadings, and house-building. Considerable difference of opinion exists as to the species producing the Tacamahaca resin and the Poon spars. The more recent authors state that Calophyllum calaba yields the true Tacamahaca and Calophyllum inophyllum a resin quite similar. Doubtless several species furnish the Poon Spars. There are a number of other species, some of which yield heavy, durable timber that is valuable for engineering purposes.

CALOR'IC (Fr. calorique, from Lat. calor, heat). An early term for heat, when it was considered an invisible, imponderable fluid. See HEAT.

CALORIC ENGINE, or HOT-AIR ENGINE. An engine in which the pressure acting on the piston is produced by increasing the temperature of air through the application to it of heat by transfer through a separating metal wall. This definition distinguishes the hot-air engine from the compressed-air engine (see COMPRESSEDAIR ENGINE) on one hand, and the internal combustion engine (see GAS-ENGINE) on the other hand. There are, however, hot-air engines which employ both previous compression and internal combustion. The action of hot-air engines, like that of all other heat-engines, consists in admitting the air at a high temperature and pressure, and by allowing it to perform work on the piston reducing its pressure and temperature, after which it is either exhausted into the atmosphere and a fresh supply is introduced, or else it is again heated for a repetition of the former process. In their principal working parts hot-air engines are very similar to ordinary steam-engines. The heated air is introduced into a cylinder in which works a tightly fitting piston, which is thus compelled to move up and down and transfer its motion to a revolving shaft by means of piston and connecting rods and the other usual mechanisms of steam-engines. (See STEAM-ENGINE.) Hotair engines are of several types, which may be described and explained as follows: Closed-cycle engines are those which operate continuously with the same mass or weight of air, only taking in a fresh charge to replace leakage or to increase the mass in use. Open-cycle engines are those in which at each stroke a new charge is drawn in from the atmosphere, and after being heated and expanded is exhausted again into the atmosphere. Regenerative and non-regenerative engines are those which, respectively, use or do not use a regenerator to absorb the heat of the exhaust air and to restore it to the incoming

cooler air. Finally, closed-cycle engines may be divided into two sub-classes, which differ by hav ing the temperature change take place in the air at constant pressure or at constant volume. Each of these types is identified with the name of some designer or engineer. Hot-air engines have been designed in great numbers, but the limited extent to which they have been used makes most of them but little more than names. The hot-air engine as defined at the beginning of this article seems to have been invented by the Rev. Robert Stirling, an Englishman, in 1816. His first successful engine was built in 1827, and one afterwards was used in a foundry in Dundee, Scotland, developing 20 brake horse-power on the consumption of 50 pounds of coal per hour. In this engine, shown diagrammatically in Fig. 1, the same volume of air was alternately heated

and cooled, producing a variation of pressure which actuated a working piston. The heating and cooling were effected by changing the air by means of a plunger, D, from end to end of a cylinder, A, one end of which was kept hot by, a fire and the other cool by a coil of water-pipe, C. On its way from end to end the air passed through a passage partly filled with thin plates of metal, E, which alternately absorbed the heat from the air and gave it back on the return. This was the first application of the economizer or regenerator, and its invention is said to be due to James Stirling, a civil engineer. This engine failed through the giving out of the heaters, which required to be kept red-hot. In 1844 Franchot, a Frenchman, patented an arrangement of the Stirling engine with large and efficient heating and cooling surfaces. Further attempts at improvement were made by Rankine and Napier, and by Professor Jenkin in England, and also by Lauberau in France. The Stirling engine belongs to the type of hot-air engines with temperature changes at constant volumes. Another hot-air engine which has much the same classic and historical interest as the Stirling engine is that invented by John

Ericsson (q.v.). The engines of Ericsson differed from the Stirling engine in that they drew their supply of air from the atmosphere at each stroke, heated it, allowed it to expand while doing work, then exhausted it again into the external air; they belonged to the type of hot-air engine with temperature changes at constant pressure. The first engine was installed in the ship Ericsson in 1852, but the idea dates from 1833, and it enjoys the distinction of having been built on the largest scale and of having made the most noted failure of any hot-air engine. To Ericsson is to be credited also the term 'caloric engine,' which he applied as a sort of trade name to his invention. Briefly described, Ericsson's first engine was designed for a 2200ton seagoing ship; it was intended for 600 horsepower, but actually ran at about 300 horsepower. There were four cylinders, each 14 feet in diameter and having 6 feet stroke, and the engine ran at nine revolutions per minute. As stated above, the engine proved a failure after several attempts had been made to remedy its faults. First the 14-foot cylinders were removed and replaced by others, which also failed; and finally the engine was replaced entirely by a steam-engine. Afterwards Ericsson made other attempt to drive a ship by an air-engine. The Primera was built and fitted with horizontal engines drawing their supply from, and exhausting into, an artificial atmosphere of high presAs in the former attempt, however, the

sure.

FIG. 2. ERICSSON CALORIO ENGINE.

an

heating surface proved inadequate and the available pressure was too small to give much power, so that again steam was substituted after a short trial. Economizers were employed with both of his large engines, but in the small engines, to the design of which Ericsson turned his attention after the failure of his large motors, the economizer was abandoned. Ericsson's first design for a small motor was brought out in 1860, and in 1880 the latest form for pumping purposes was produced. Fig. 2 shows this type of engine.

The fire of coal or gas is below the cylinder d, which is water-jacketed at the upper end, a x. In tank pumping engines, the pumped water cir-, culates through the water-jacket. At A is the hollow displacing piston, and B is the working piston proper. The displacer is coupled to the bell crank k, and so to the crank e, to which the beam a is linked directly by g. These engines do not use less fuel than steam-engines of similar size, but as they require no water or licensed engineer, they have come into considerable use. The Stirling engine and the Ericsson engine between themselves embodied all the characteristic features of the several types of hot-air engines defined above. The Ericsson engine is an open-cycle, non-regenerating engine, with temperature changes at constant pressure; the Stirling engine was a closed-cycle, regenerating engine, with temperature changes at constant volume. The hot-air engines produced by other inventors of this kind of prime motor have resembled sometimes the Ericsson engine and sometimes the Stirling engine, but have had the details of operation worked out in different ways. Two of these only need be mentioned for the purpose of illustration: The Wilcox engine, of which large numbers were made about 1860 to 1865, was, like the Ericsson ship engine, an open-cycle, regenerative engine, with temperature changes at constant pressure. Its distinctive characteristic was a peculiar supply cylinder fitted with a piston operated from the main shaft. This supply cylinder took in the atmospheric air and passed it through the regenerator to the operating cylinder, where it was heated and expanded to perform its work, after which it was exhausted through the regenerator into the external air. The Merrill engine, one of which of 10 horsepower was used for some years previous to 1885 to run a factory at Winchendon, Mass., worked on the same principle as the Stirling engine; that is, it used the same volume of air over and over. It had two working cylinders, each of which was double-acting (see STEAM-ENGINE), and two reverser plungers, which affected the transfer of the air between the heating and cooling devices.

Mention was made at the beginning of this article of hot-air engines employing previously compressed air. These are commonly known as compression engines. In them a constant quantity of air is constantly changed in volume, being compressed while cold and expanded while hot. There are usually two cylinders, one cold and kept cold by a water-jacket or other means, and the other hot and kept heated by external means. The piston in the hot cylinder is generally timed from one-sixth to one-quarter revolution in advance of that in the cold cylinder, whereby the air is first changed into the cold cylinder, sometimes through a regenerator, then compressed therein, then changed to the hot cylinder back through the regenerator, taking up again the stored heat, and finally expanded in the hot cylinder. The first engine of this kind seems to have been invented by Charles Louis Felix Franchot, a Frenchman, in 1853, and it is deserving of brief mention for the clear manner in which it illustrates the working principle. Hot and cold cylinders of different areas were placed side by side, as shown by Fig. 3, with their pistons connected to cranks 135° apart. The bottom of the cold cylinder, 4, was connected to the

hot at one end and cold at the other, all connected to one shaft, and so arranged that the hot end of one communicated through a regenerator with the cold end of the next. The heat was supplied by hot products of combustion from producer gas in a chamber connected with the hot ends of the cylinders, while the opposite ends were fitted with refrigerating devices. One of the latest forms of compression engines is the Rider, shown by Fig. 4. In this sectional view C is the cold cylinder or compression cylinder, surrounded by the water-jacket, E, and D is the hot cylinder. The compressed air from the cold cylinder is changed through the regenerator, H, to the hot cylinder, where it is expanded by the heat from the grate underneath the cylinder.

A

FIG. 3.

the pistons was such that the air was compressed in the cool cylinder; passed through the regenerator into the hot cylinder, where it was expanded; then transferred to the cold cylinder through the cooling chamber, and the cycle repeated. From four to six cylinders, each double-acting, were proposed to be combined in a series. A model of

蔥蔥

FIG. 5. HOT-AIR PRODUCT OF COMBUSTION ENGINE.

Hot-air engines employing internal combustion, like compression engines, form a separate class of this type of motor. At the outset of their consideration, however, it is important to note a somewhat arbitrary distinction between them and the internal combustion motors known as gas-engines. The true gas-engine is limited generally to internal-combustion engines, in which the air, mixed with gas or with oil-vapor, is admitted to the cylinder and ignited after its admission. Liquid or gaseous fuels are essential in this type of engine. Hot-air internal-combustion engines, or, more properly, hot-air products of combustion engines, operate by forcing atmospheric air through a closed fire, which may be and generally is a solid fuel fire, and carrying the air and gases of combustion to the engine cylinder. One form of such air-engines is shown by Fig. 5. The furnace was placed in a chamber strong enough to withstand the pressure. The compressing pump B forced air below the ash-pit up through the fire, where it was expanded by heat and by combustion with carbon. Being admitted to the working cylinder against the piston, it was exhausted into the chimney. The furnace had to be charged with fresh fuel through a combination of double doors, D, working on the principle of an air-lock. A hot-air product of combustion engine was described by Sir George Cayley, an Englishman, in 1807 and 1825, and again in 1837 this inventor patented a modification of the same design and built several engines, none of which gave any marked success. In 1821 Dr. Neil Arnott (q.v.), the celebrated scientist, took up the same idea and patented a form of engine in which, to avoid the abrading action of

the ashes on metal pistons and cylinders, he used oil pistons. Following Cayley and Arnott, a number of inventors worked on the idea, among them being the Americans Stephen Wilcox, S. H. Roper, and Philander Shaw, each of whom built and sold a number of engines. Broadly speaking, the difficulties of operating these engines were so great that they recorded a general failure. These difficulties were caused by flue-dust and the grit in the cylinders, the rapid destruction of the working surfaces and valves by the intense heat, and the practical impossibility of lubrication. They were also more bulky than other types of hot-air engines in proportion to the power developed.

a

The possibilities of the hot-air engine as competitor of the steam-engine are often urged, but so far it has never reached any practical success which warranted much hope that the competition would prove serious. The two sides of the question are fairly and concisely summarized by Prof. F. R. Hutton as follows:

"The hot-air engine in small sizes is more economical than the steam-engine of the same capacity. In larger sizes it has about the same economy as the less economical steam-engine, measured in coal consumed per horse-power. It has the advantage of avoiding the steam-boiler as a magazine or reservoir of energy which may be liberated by accident so suddenly as to be explosive. It can be run by less skilled and expensive labor, and no steam-runner's license is demanded. It is safe and odorless. The objections to the hot-air engine are the greater bulk and greater weight for the same power than is required with the steam-engine; the low mean pressure with high initial pressure, which latter compels great strength of structure; the deterioration of heating surfaces exposed to high heats and consequent oxidation; the difficulties of packing and lubricating at high temperatures; the difficulty of regulation closely to varying resistances. If there is any danger to the present supremacy of the steam-engine, it will be in relatively small plants that a hot-air engine can be a substitute; the gas or internal-combustion engine is more to be feared than the hot-air engine proper."

A theoretical and practical discussion of hotair engines and heat-engines generally is contained in Hutton, Heat and Heat-Engines (New York, 1899).

CAL'ORIM'ETRY (from Lat. calor, heat + Gk. μérpov, metron, measure). The science of the measurement of quantities of energy when manifested by heat effects. By the name 'heat effects' is meant the changes produced in material bodies when they are exposed to what is called a 'source of heat,' e.g. a flame or the rays of the sun. Among these changes which may take place are expansion, fusion, evaporation, alteration in electrical and magnetic properties, etc. It is now believed that these changes are occasioned by increase in the energy of the smallest portions of the bodies. When a body is 'heated' or 'warmed,' we mean that its minute parts gain energy; and opposite changes, e.g. freezing, condensation, cooling, etc., take place when these parts lose energy. It is the province of calorimetry to measure these amounts of energy gained or lost. The erg (see MECHANICAL UNITS) is the unit of energy and work, and therefore all quantities of energy should be measured in terms of it; but

it rarely happens that heat effects are due directly to mechanical work except in case of friction. Consequently the erg is not a convenient unit. Heat effects and the energy required to produce them are almost invariably compared with one definite heat effect, viz. rise in temperature of water; and the practical unit employed for measuring thermal energy may be defined as the quantity of energy required to raise the temperature of one gram of water from 15° to 16° C. on the thermometric scale of the constant-pressure hydrogen thermometer. (Other definitions of a practical unit have been proposed, e.g. by the substitution of 20° to 21° in place of 15° to 16° C.; or the one-hundredth portion of the quantity of energy required to raise the temperature of one gram of water from the freezing-point to the boiling-point under normal pressure.) This practical unit is called the calorie, and its value is very nearly 4.187 joules, or 4.187 X 10' ergs. See HEAT.

By the 'specific heat' of a substance at a given temperature and under definite conditions is meant the number of calories required to raise the temperature of one gram of the substance one degree by the hydrogen scale (see THERMOMETER), at that temperature, and under those conditions. By the latent heat' of a substance for a definite change of state (e.g. fusion, evaporation, sublimation, dissociation), under definite conditions, is meant the number of calories required to produce the particular change of state in one gram of the substance under the specified conditions. Thus we speak of the 'specific heat of air at constant pressure,' or the 'latent heat of evaporation of water at normal atmospheric pressure.' In general, however, we can learn simply the average specific heat, i.e. the number of calories required to raise the temperature of one gram through t degrees, divided by t. Calorimetry is, then, chiefly, the science of measuring specific and latent heats.

There are two general methods for the measurement of specific heats, which may be regarded as satisfactory-the method of mixtures and the use of an ice or a steam calorimeter. In the method of mixtures a known quantity of the substance at a known temperature is mixed with a know quantity of some liquid at a different known temperature and the temperature of the mixture is observed. The specific heat of the liquid for the given range of temperature being known, and allowance being made for losses by radiation and conduction, and for the calories spent in changing the temperature of the vessel containing the liquid, the specific heat of the substance may be at once deduced. The most improved form of apparatus for use in this method is that of Prof. T. A. Waterman, a full description of which is given in the Physical Review, Vol. IV., p. 161 (1896).

In the ice-calorimeter, the substance whose specific heat is desired is introduced into an apparatus which allows the heat energy withdrawn from the body to be spent entirely in melting ice. The change in temperature of the substance and the quantity of ice melted may be observed; and thus, assuming that the latent heat of ice is known, the specific heat of the substance may be calculated. This method is due to Black; and the most improved apparatus is that designed by the late Professor Bunsen, of Heidelberg. The most accurate method of using