of families-Chemin, Mareau, Janes, Haüy (brother of the celebrated philosopher),and Mandar-associated themselves, and, December 16, held their first meeting for the purposes of divine worship and moral instruction, according to the dictates of natural religion. These assemblies were held weekly: the exercises consisted of prayer, moral discourses, and singing, and the numbers of the society rapidly increased. The directory granted them the use of the ten parish churches of Paris, in which their services were performed at first on Decadi, and afterwards on Sunday, at the hour of noon. The temples were appropriately fitted up, and adorned with religious and moral inscriptions, an ancient altar, with a basket containing flowers, as an offering to the Supreme Being, a pulpit, and allegorical paintings, and banners, with inscriptions and emblematic devices. The theophilanthropists had no peculiar spiritual order; but the officers of the society were an overseer, a president of the temple, a reader, and an orator, who wore a long white robe over a blue dress, with a sash or girdle of various colors, during the performance of divine worship, but who enjoyed no privileges and received no pay. Their dogmas consisted solely of a belief in the existence of God, and in the immortality of the soul; their doctrine was pure deism, derived chiefly from the Scriptures, and containing a practical morality, which differed from that of Christianity chiefly in its leaning to eudæmonism. (q. v.) Their liturgy was simple and touching: the pardon of sins was implored of God; but Jesus Christ was considered only as a man of extraordinary wisdom, and not as a savior. The writings of the theophilanthropists, which proceeded chiefly from Chemin, dwelt principally upon the moral duties. The festivals of nature, of love of country, of conjugal fidelity, &c. (see Festivals), were scrupulously observed. Instead of baptism, a sort of consecration or initiation by exhortations to the parents and godparents was solemnized; for confirmation was substituted a reception into the society with vows, and in place of marriage, a symbolical union by rings and bands, wound round the hands of the wedded couple these were the only ceremonies. Distinct schools were established for the instruction of youth in theophilanthropism. The expenses of public worship were paid by means of collections and the contributions of the members, and the directory also granted small sums. The

example of the Paris theophilanthropists was followed in many of the provincial cities of France, and some attempts were made to introduce their principles into other countries, but without success. The revival of the Catholic religion, and particularly the concordate (q. v.) with Pius VII, hastened the decline of the society, which had already lost many of its members, when the consuls, in 1802, prohibited them: from holding their meetings in the churches; and from this time, they no longer appear as a body. (See Revellière-Lépaux, end of volume x.)

THEOPHRASTUS, a native of Eresus, in the island of Lesbos, was the son of a fuller, and became famous as a naturalist and philosopher. He was born 371 B. C., and studied at Athens, in the school of Plato, and afterwards under his rival Aristotle, of whom he was the favorite pupil and successor. His original name was Tyrtamus, which his master, in admiration of his genius and eloquence, exchanged for that of Euphrastus, or the fine speaker, and afterwards for that of Theophrastus, or the divine orator, by which he is familiarly known. On the departure of Aristotle from Athens, after the judicial murder of Socrates, he became the head of the Peripatetic school of philosophy, where two thousand students are said to have attended his lectures. His fame extended to foreign countries; kings and princes solicited his friendship; and he was treated with particular attention by Cassander, the sovereign of Macedon, and Ptolemy Lagus, king of Egypt. Theophrastus composed a multitude of books dialectic, moral, metaphysical and physical-the_titles of 200 being specified by Diogenes Laertius. About twenty of these have escaped the ravages of time, among which are his Natural History of Stones, of Plants, of the Winds, &c.; and his Characters, or Ethic Portraits, by far the most celebrated of all his productions, and the model of numerous imitators, including the moral satirist La Bruyère. Some of his moral sentences are striking; e. g. "Respect yourself, and you will have no occasion to blush before others." He died about 286 B. C., and, consequently, if the preceding date of his birth be correct, he must have been but eighty-five at the time of his decease, though some state him to have survived to the age of a hundred and seven. To his care we are indebted for the preservation of the writings of Aristotle, who, when dying, intrusted them to the keeping of his favorite disci

ple. The works of Theophrastus were published collectively by Dan. Heinsius (Leyden, 1613, folio), and by Schneider (Leipsic, 1818-1821, 5 vols., with a Latin translation); and among the numerous editions of his Characters may be noticed those of Needham (Cambridge, 1712, 8vo.), of Fischer (Coburg, 1763, 8vo.), and the recent English translation, with notes, and the Greek text, by Mr. F. Howell. THEOPHRASTUS PARACELSUS. (See Paracelsus.)

THEORBO (tiorba); an instrument, no longer in use, similar to the lute (q. v.), at least in regard to the body and the neck, which is, however, longer. It has 14-16 strings, of which the eight large ones in the base are twice as long and thick as those of the lute. It was principally used for accompaniment. The system of the theorbo has five lines with proper notes; that of the lute has six lines with letters.

THEORY (from the Greek Owola, contemplation) originally signified the investigation and knowledge of supernatural subjects by means of contemplation. The most common significations of the word at present are, 1. speculation; a doctrine which terminates in speculation or contemplation without a view to practice. Here it is taken in an unfavorable sense, as implying something visionary. 2. An exposition of the general principles of any science, as the theory of music. 3. The science distinguished from the art; e. g. the theory of medicine as distinguish ed from the practice. 4. The philosophical explanation of phenomena, either physical or moral, as Lavoisier's theory of combustion, Smith's theory of moral sentiments. Theory is distinguished from hypothesis thus:-A theory is founded on inferences drawn from principles which have been established on independent evidence; a hypothesis is a proposition assumed to account for certain phenomena,, and has no other evidence of truth than that it affords a satisfactory explanation of those phenomena.

THEOSOPHY (from 0cos, God, and copia, wisdom); according to its etymology, the science of divine things. But the name of theosophists has generally been applied to persons who, in their inquiries respecting God, have run into mysticism, as Jacob Böhme, Swedenborg, St. Martin, and others.

THERAMENES; an Athenian philosopher and general in the age of Alcibiades. He was one of the thirty tyrants at Athens, but had no share in the cruelties and

oppression which disgraced their administration. He was accused by Critias, one of his colleagues, because he opposed their views, and was condemned to drink hemlock, though innocent, and defended by Socrates. He drank the poison with great composure, and poured some of it on the ground, with the sarcastical exclamation of "This is to the health of Critias," about 403 B. C.

THERAPEUTE. (See Essenes.)

THERAPEUTICS (from Ocpancvw, to attend to the sick) is that part of medicine which teaches the way of curing diseases. It treats of the symptoms of disease, and the conclusions to be drawn from them, of the power of nature, and how far it may be relied on, of the mode of cure to be adopted, and the different systems which have acquired reputation.

THERESA, Maria. (See Maria Theresa.)

THERESA, ST.; a religious enthusiast, born at Avila, in Spain, in 1515. At an early age, the perusal of the Lives of the Saints inspired her with the desire to become a martyr; and she eloped from home to seek death at the hands of the Moors. Being brought back, she erected a hermitage in her father's garden for retirement and devotion. She took the veil among the Carmelites, at Avila, at the age of twenty-two. Her rapturous piety and religious zeal inspired general admiration; and, being dissatisfied at the relaxation of discipline which she noticed in the order to which she belonged, she undertook to restore the original severity of the institute. She founded the first convent of reformed Carmelite nuns at Avila, in 1562, and a monastery of friars, in 1568, at Dorvello, where originated the order of Barefooted Carmelites. (See Carmel.) She lived to witness the foundation of thirty convents for her followers; and members of the order subsequently obtained settlements in most Catholic countries. She died at Alba, in October, 1582, and was canonized by pope Gregory XV. Her life, by herself, is curious.

THERIACA; a celebrated antidote against poisons, in the form of an electuary, formerly in great repute, the composition of which is attributed to Andromachus of Crete, physician to the emperor Nero. (See Poison.) That physician has described its composition in a poem, which has been preserved by Galen (De Antidotis I, c. 6). This theriaca is composed of about seventy ingredients, some of which are altogether inoperative, and some counteract each other's effects. It,

however, preserved its reputation till modern times; and it is not long since the apothecaries in Venice, France, and other places, were obliged to compound it, with great solemnity, in the presence of magis

trates.

THERME (from the Greek Ocopat, signifying originally warm or hot springs); properly warm baths, but also applied generally to the baths of the ancients. (See Bath.) During the Roman empire, the buildings for this purpose were constructed with great splendor, and adorned with paintings, statuary, libraries, gymnasia, and public walks. The baths of Nero, Titus, Caracalla and Diocletian were distinguished for the magnificence and luxury displayed in their construction. THERMIDOR. (See Calendar, vol. ii, p. 403.)

THERMIDOR, 9тH, year II (July 27, 1794); celebrated, in the French revolution, for the overthrow of Robespierre and the Mountain party, which put an end to the reign of terror. Tallien (q. v.) was the first to denounce Robespierre and his adherents, St. Just, Couthon, Henrion, who were arrested by order of the convention (9th Thermidor), and executed on the following day. (See France, division History.)

THERMO-ELECTRO-MAGNETISM; the phenomena arising out of a flow of electro-magnetism, occasioned by disturbing merely the equilibrium of temperature. The apparatus for exciting it is composed of three bars of bismuth and three of antimony, soldered alternately together, so as to form a hexagon, which includes three elements, or three pairs. The length of the bars is about 4.7 inches, their breadth 0.6 of an inch, and their thickness 0.16 of an inch. This circuit is put upon two supports, and in a horizontal position, observing to give to one of the sides of the hexagon the direction of the magnetic needle, which is placed below the side, and as near it as possible. On heating one of the solderings with the flame of a lamp, a very sensible effect on the needle is produced. On heating two solderings, not contiguous, the deviation becomes considerably greater; and, on heating the three alternate ones, a still greater effect is produced. By resorting to an inverse process, i. e. by reducing to 32° Fahr. by melting ice, the temperature of one or more solderings of the circuit-the solderings not cooled being regarded as heated in reference to others and by combining the action of the ice with that

of the flame, viz. by heating three solderings and cooling the other three, the deviation of the needle amounts to 60°.

THERMOLAMPE; the name given by Lebon to his apparatus for illuminating by gas. (See Gas-Lighting, page 388, vol. v.)

THERMOMETER ; an instrument for measuring heat, founded on the principle that the expansions of matter are proportional to the augmentations of temperature. With regard to aeriform bodies, this principle is probably well founded; and hence our common thermometers may be rendered just by reducing their indications to those of an air thermometer. Solids, and still more liquids, expand unequally, by equal increments of heat, or intervals of temperature. With regard to water, alcohol and oils, this inequality is so considerable as to occasion their rejection for purposes of exact thermometry. But mercury approaches more to solids than ordinary liquids in its rate of expansion, and hence, as well as from its remaining liquid through a long range of temperature, is justly preferred to the above substances for thermometric purposes. A common thermometer, therefore, is merely a vessel in which very minute expansions of mercury may be rendered perceptible, and, by certain rules of graduation, be compared with expansions made on the same liquid by other observers. The first condition is fulfilled by connecting a narrow glass tube with a bulb of considerable capacity filled with mercury. As this fluid metal expands one sixty-third by being heated in glass vessels, from the melting point of ice to the boiling point of water, if ten inches of the tube have a capacity equal to one sixty-third of that of the bulb, it is evident that, should the liquid stand at the beginning of the tube at 32°, it will rise up and occupy ten inches of it at 212°. Hence, if the tube be uniform in its calibre, and the above space be divided into equal parts by an attached scale, then we shall have a centigrade or Fahrenheit's thermometer, according as the divisions are 100 or 180 in number. Such are the general principles of the construction of thermometers. The tubes drawn at glass-houses, for making thermometers, are all more or less irregular in the bore. Hence, if equal apparent expansions of the included mercury be taken to represent equal thermometric intervals, these equal expansions will occupy unequal spaces in an irregular tube. The attached scale should, therefore, correspond exactly to these tubular inequali

ties; or, if the scale be uniform in its divisions, we must be certain that the tube is absolutely uniform in its calibre. The first step in the formation of this instrument, therefore, is to graduate the tube into spaces of equal capacity. A small caoutchouc bag, with a stop-cock and nozzle, capable of admitting the end of the glass tube when it is wrapped round with a few folds of tissue paper, must be provided, as also pure mercury, and a sensible balance. Having expelled a little air from the bag, we dip the end of the attached glass tube into the mercury, and by the elastic expansion of the caoutchouc, we cause a small portion of the liquid to rise into the bore. We then shut the stop-cock, place the tube in a horizontal direction, and remove it from the bag. The column of mercury should not exceed half an inch in length. By gently inclining the tube, and tapping it with the finger, we bring the mercury to about a couple of inches from the end where we mean to make the bulb, and, with a file or diamond, mark there the initial line of the scale. The slip of ivory, brass or paper, destined to receive the graduations, being laid on a table, we apply the tube to it so that the bottom of the column of mercury coincides with its lower edge. With a fine point, we then mark on the scale the other extremity of the mercurial column. Inclining the tube gently, and tapping it, we cause the liquid to flow along till its lower end is placed where the upper previously stood. We apply the tube to the scale, taking care to make its initial line correspond to the edge as before. A new point for measuring equal capacity is now obtained. We thus proceed till the requisite length be graduated, and we then weigh the mercury with minute precision. The bulb is next formed at the enameller's blow-pipe, in the usual way. One of a cylindrical or conical shape is preferable to a sphere, both for strength and sensibility. We now ascertain and note down its weight. A tubular coil of paper is to be tied to the mouth of the tube, rising in a funnelform an inch or two above it. Into this we pour recently boiled mercury, and, applying the gentle heat of a lamp to the bulb, we expel a portion of the air. On allowing the bulb to cool, a portion of the mercury will descend into it, corresponding to the quantity of air previously expelled. The bulb is now to be heated over the lamp till the included mercury boil briskly for some time. On removing it, the quicksilver will descend from the

paper funnel, and completely fill the bulb and stem. Should any portion of air appear, the process of heating or boiling must be repeated, with the precaution of keeping a column of superincumbent mercury in the paper funnel. When the temperature of the bulb has sunk to nearly that of boiling water, it may be immersed in ice-water. The funnel and its mercury are then to be removed, and the bulb is to be plunged into boiling water. About one sixty-third of the mercury will now be expelled. On cooling the instrument again in melting ice, the zero point of the centigrade scale, corresponding to 32° of Fahrenheit, will be indicated by the top of the mercurial column. This point must be noted with a scratch on the glass, or else by a mark on the prepared scale. We then weigh the whole. We have now sufficient data for completing the graduation of the instrument from one fixed point; and, in hot climates, and other situations, where ice, for example, cannot be conveniently procured, this facility of forming an exact thermometer is important. We know the weight of the whole included mercury, and that of each gradus of the stem. And, as from 32° to 212° Fahr., or from 0° to 100° cent., corresponds to a mercurial expansion in glass of one sixty-third, we can easily compute how many of our graduating spaces are contained in the range of temperature between freezing and boiling water. Thus supposing the mercurial contents to be 378 grains, one sixtythird of that quantity, or six grains, correspond to 180 of Fahrenheit's degrees. Now, if the initial measuring column were 0.6 of a grain, then ten of these spaces would comprehend the range between freezing and boiling water. Hence, if we know the boiling point, we can set off the freezing point; or, from the temperature of the living body, 98° Fahr., we can set off both the freezing and boiling points of water. In the present case, we must divide each space on our prepared scale into eighteen equal parts, which would constitute degrees of Fahrenheit; or into ten equal parts, which would constitute centigrade degrees; or into eight, which would form Réaumur's degrees. When we have ice and boiling water at hand, however, we may dispense with the weighing processes. By plunging the instrument into melting ice, and then into boiling water, we find how many of our initial spaces on the stem correspond to that interval of temperature, and we subdivide them accordingly.

If the

tube be very unequal, we must accommodate even our subdivisions to its irregularities, for which purpose the eye is a sufficient guide. Thermometers are used for two different purposes, each of which requires peculiar adaptation. Those employed in meteorology, or for indicating atmospherical temperature, are wholly plunged in the fluid; and hence the stem and the bulb are equally affected by the calorific energy. But when the chemist wishes to ascertain the temperature of corrosive liquids, or bland liquids highly heated, he can immerse merely the bulb and the naked part of the stem under the scale. The portion of the tube corresponding to the scale is not influenced by the heat, as in the former case; and hence one sixty-third part of the mercury, which, at 32° Fahr., was acted on, has, at 212°, escaped from its influence. Hence a meteorological and a chemical thermometer ought to be graduated under the peculiar conditions in which they are afterwards to be used. The former should have its stem surrounded with the steam of boiling water, while its bulb is immersed an inch or two beneath the surface of that liquid, the barometer having at the time an altitude of thirty inches. A thermometer for chemical experiment should have its boiling point determined by immersion only of the bulb, and the naked portion of its stem below the scale, in boiling water. The water, of course, must be pure; and it ought to be contain

So that the number of degrees of each, included between these two points in each, is 180° Fahr., 100° centig., 80° Réaum., 150° De Lisle; and of course 9° Fahr. 5° centig. 4° Réaum. 7 De Lisle. Fahrenheit's is, therefore, the smallest degree, and Réaumur's the largest. The 0° is called the zero: all degrees below this are called minus, and are prefixed by a dash, thus -20°. In the Réaumur and centigrade scales, the degrees above zero are also called plus, and marked thus, +20°, to prevent one kind being mistaken for another.-Rules for changing the degrees of any one of the scales into equivalent degrees of another:-Fahrenheit into Réaumur. Each degree of Fahrenheit is equal to four ninths of one of Réaumur. As Réaumur, however, reckons his degrees from the freezing point, and Fahrenheit

ed in a metallic vessel. Before sealing up the end of the tube, we should draw it into a capillary point, and heat the bulb till the mercury occupy the whole of the stem. A touch of the blow-pipe flame on the capillary glass will instantly close it, and exclude the air from reëntering when the bulb becomes cool. If this has been skilfully executed, the column of mercury will move rapidly from one end of the tube to the other when it is inverted with a jerk. An ivory scale is the handsomest, but the most expensive. Those used in Paris consist of a narrow slip of paper enclosed in a glass tube, which is attached in a parallel direction to the thermometer stem. It is soldered to it above by the lamp, and hooked to it below by a ring of glass.

Comparative Scales of Thermometers. A fertile cause of error in estimating and comparing the statements of temperature, is the very different manner in which they are made by scientific men of different nations. Wherever the English language prevails, the graduation of Fahrenheit is generally_preferred. By the German authors Réaumur is used; and the French have, within a few years, decided to adopt that of Celsius, a Swedish philosopher, calling it thermomètre centigrade. The Russians still use the graduation of De Lisle. The two remarkable temperatures of the boiling and the freezing of water are thus expressed by the several thermometers mentioned:

32° below this point, we must, when the number o Fahrenheit's degrees to be reduced indicates a temperature above the freezing point, first deduct thirty-two, and then multiply the remainder by four, and divide the product by nine. The quotient is the corresponding number of degrees on Réaumur's scale. If the temperature indicated was less than the freezing point, we must also be careful to take the actual number of degrees, reckoning from the freezing point. Thus four degrees above Fahrenheit's zero is twenty-eight below his freezing point; and this is the number to be reduced to Réau

mur's scale.-Réaumur into Fahrenheit. Each degree of Réaumur is equal to 24 of one of Fahrenheit. Multiply the given number of degrees of Réaumur by nine, and divide the product by four. If the degrees of Réaumur were minus, the