THEBIT 



325 



THIRD 



line, poisonous, crystalline base, obtained 

 from opium. 



Thebit. A crater, 32 miles in diameter, in 

 the Moon. 



Theca, (the'ka). [Gk. theke, sheath.] 1. A 

 pteropod animal, known by fossil remains in 

 Silurian rocks. 2. In ferns=rSporangium : 

 the case containing the spores; generally a 

 strong fibrous case enclosing a soft body. 

 Thecaphora. (thg-kafo-ra). [Gk. theke, sheath; 

 phoreo, I bear.]=Sertularidse, q.v.'. a sub- 

 division of Hydrozoa. 



Thecidium, (the-sid'i-um). [Gk. thekidion, 

 small sheath.] A molluscous animal, known 

 by fossil remains in Trias rocks. 



Thecodont, (thek'o-dont). [Gk. theke, case; 

 odoits, tooth.] T. teeth: teeth that are fixed 

 in alveoli or sockets. 



Thecodontosaurus, ( thek-o-don-to-sau'rus ). 

 [Thecodont, q.v. ; Gk. saura, lizard.] A 

 reptile, known only by fossil remains found 

 in Triassic rocks, named from its thecodout 

 teeth. 



Theine, (theln). [Thea, g.v.]=Caffeine, q.v. 



Thelphusidae, (thel-fu'si-de). [Thelphusa, the 

 typical genus; eidox, 

 form.] A family of 

 crab-like animals 

 belonging to Brachy 

 ura. 



Thenard, (ta'nard). 

 [M. Thenard.] T.'s 

 blue : a pigment 

 deriving its colour 

 from cobalt. Thelphusian. 



Theobroma, (the-o-bro'ma). [Gk. theos, god; 

 broma, food.] A tree belonging to Sterculi- 

 aceae, from which cocoa is obtained. F. cacao 

 =Chocolate nut tree. 



Theobromine. ( the-o-br5'mln ). [Theobroma, 

 g.v.j=C 7 H 8 N 4 O 2 : an alkaline base found in 

 chocolate. 



Theodolite, (the-od'6-llt). An instrument for 

 the measurement of 

 horizontal angles, con- 

 sisting essentially of a 

 telescope mounted so aa 

 to move on a pivot both 

 horizontally and verti- 

 cally. 



Theophilus. A crater, 

 (54 miles in diameter, 

 in the Moon. 



Theorem, (the'6-rem). In 

 mathematics, a truth 

 which is proved by refer- 

 ence to already admitted Theodolite, 

 truths. 



Thermal, (ther'mal). [Gk. therme, heat.] Re- 

 lating to heat. T. unit: in Britain, the 

 quantity of heat required to raise one pound 

 of water from to 1 centigrade ; in France, 

 the quantity required to raise one kilogramme 

 of water the same. 



Thermo-, (ther'nio). [Gk. thermos, heated.] 

 A prefix implying some relation to heat. 



Thermochrosis, (ther-mo-kros'is). [Gk. thermo, 

 heated; chros, colour. ]= Heat tint: coloration 

 by heat. 



Thermo-dynamicB, ( ther - mo- dl - nam'iks.) 

 [Thermo and Dynamics, q.v.] The science of 

 the relations of heat and work. 



Thenno-electric,(tlier-m6-e-lek'trik). [Thermo 

 and Electric, q.v.] Related to thermo-elec- 

 tricity. T. current: produced when two 

 metals having different capacities for heat 

 are joined, and warmed at one end while the 

 opposite end is cooled. T. battery: a number 

 of thermo-electric couples. T. series: metals 

 arranged in order of their capacity to 

 generate a thermo-electric current when 

 heated. 



Thermo-electricity, ( ther-mo-e-lek-tris'i-ti ). 

 [Thermo and Electricity, q.v.] Electricity 

 generated by the action of heat, or derived 

 from heat. 



Thermograph, (ther'mo-graf). [Thermo, q.v. ; 

 Gk. prop/to, I write.] A record, usually 

 automatic, of the variations of temperature. 



Thermometer, (ther-mom'e-tr). [Thermos, 

 heated; Gk. metron, measure.] An ^fr=^ 

 instrument for measuring the rise 

 and fall of temperature, usually 

 by means of the expansions and 

 contractions of mercury, as indi- 

 cated by the rise and fall of a fine 

 column of the metal in a glass 

 tube. Maximum and minimum 

 T.: one which registers the highest 

 and lowest temperatures in a given 

 period. Differential T., v. Differ- 

 ential thermometer. Breguet's T , 

 v. Breguet's thermometer. 



Thermometric, (ther-mo-met'rik). 



ge 

 Thi 



[Thermometer, 9. v.] Related to the Thermo- 

 thermometer. T. scales, y. Cel- ^eter. 

 sius, Centigrade, Fahrenheit, and Reaumur. 



Thermopile, (ther'mo-pil). [Thermo, q.v., and 

 Pile. ]= Ther mo-electric battery, q.v. 



Thermopegology, (ther-mo-pe-gol'6-ji). [Gk. 

 thermos, hot; pege, spring; logos, discourse.] 

 =Scienca of the phenomena of hot springs, 

 ysers, &c. 



iacetic acid, (tln-a-se'tik). [Gk. theion, 

 sulphur; Acetic, o.v.]=C2H 4 OS : a liquid 

 obtained by the action of sulphide of phos- 

 phorus on acetic acid. 



Thialdine, (thi'al-din). [Gk. theion, sulphur.] 

 =CeHi3NS2 : an alkaline base obtained by 

 the action of sulphuretted hydrogen on alde- 

 hyde of ammonia. 



Thigh, (thi). [Theoh, the A.-S. word.] The 

 upper portion of the leg, above the knee. 



Thio- (thi'o). [Gk. theion, sulphur.] A pre- 

 fix implying the presence of sulphur as an 

 important constituent of a compound. 



Thiobenzol, (thi-o-ben'zol). [Thio and Benzol, 

 3.v.]=3C7HeS=Benzoyl hydride in which the 

 oxygen has been replaced by sulphur. 



Thioformic acid, (thl-o-for'mik). [Thio and 

 Formic, 5.v.]=:CH2SO: formic acid in which 

 part of the oxygen has been replaced by 

 sulphur. 



Third. In music, the interval between any 

 note and the one two notes higher. Major 

 2 T .=rTwo whole tones. Minor T.=A. tone 

 and a half; e.g. , from A to C is a minor third; 

 from C to E is a major third. 



