THERIACA THERMOMETER. 



5,93 



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 reli- 

 gious 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 con- 

 vents 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 

 poison, 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 coun- 

 teract 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 magistrates. 



THERMS (from the Greek S^pa,, 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 con- 

 structed with great splendour, 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. 



THERMIDOR, OTH, year II. (July 27, 1794); 

 celebrated, in the French revolution, for the over- 

 throw 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-magne- 

 tism, occasioned by disturbing merely the equili- 

 orium 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 pro- 

 duced. On heating two solderings, not contiguous, 

 the deyiation 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 ot 

 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. 



THERMOMETER ; an instrument for measur- 

 ing heat, founded on the principle that the expan- 

 sions 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 ther- 

 mometer. 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 thcr- 

 mometry. 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 begin- 

 ning of the tube at 32'', it will rise up and occupy 

 ten inches of it at 212. Hence, if the tube be uni- 

 form 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, ac- 

 cording 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 re- 

 present equal thermometric intervals, these equal 

 expansions will occupy uneqtml spaces in an irre- 

 gular tube. The attached scale should, therefore, 

 correspond exactly to these tubular inequalities; 

 or, if the scale be uniform in its divisions, we must 

 be certuin 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. Hav- 

 ing 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 (he 

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