TER 



TER 



Linnaeus among the class of fulcra^ or 

 props. 



TE'NNANTITE. Sulphuret of copper, 

 occurring in Cornwall in copper veins 

 which intersect granite and clay-slate, 

 associated with common copper pyrites. 

 It is a variety of grey copper ore, and 

 was named in honour of Mr. Smithson 

 Tennant. 



TENOR {teneo, to hold). That com- 

 pass of the voice which is hetween the 

 highest and the lowest; neither raised to 

 a treble, nor lowered to a base, but rang- 

 ing from C, the second space in the base, 

 to G, the second line in the treble. The 

 term alludes to the air, in part-compo- 

 sitions, being held by the tenor. Tenor- 

 clef is the C, or mean clef, placed on the 

 fourth line for the use of the tenor voice. 



TENSION or INTENSITY. Terms 

 employed in electricity to denote the de- 

 gree to which a body is excited, as esti- 

 mated by the electrometer. It must be 

 distinguished from quantity. 



TENTA'CULA {tentaculum, from 

 tento, to feel). Feelers ; organs by which 

 certain animals attach themselves to sur- 

 rounding objects, &c. 

 % TENTH. An interval in Music, con- 

 I sisting of nine degrees and five spaces. 



TENTHREDI'NIDiE. The Saw-flies ; 

 a family of the phytophagous Terehrantia, 

 named from the genus tenthredo, and cha- 

 racterized by the saw-like character and 

 operation of the ovipositor. By Latreille, 

 the family is termed Securifera, or the 

 hatchet-bearers. 



TE'NUES {tenuis, thin). The correct 

 distinction of the letters called tenues, as 

 opposed to those which are called me- 

 dials, is, perhaps, this, that in the pro- 

 nunciation of the tenues p, k, t, the 

 organs employed in articulation have only 

 a small portion of their surfaces brought 

 into contact, and that but for a short 

 time ; while in the articulation of b, g, d, 

 the surface in contact is more extensive, 

 and the effort less rapid. 



TE'NUIRO'STRES {tenuis, slender, 

 rostrum, a bill). A group of the Inses- 

 sores, or Perching birds, characterized by 

 a very slender and elongated, straight or 

 curved, bill. They include the hum- 

 ming-birds, the sun-birds, the hoopoes, 

 the honey-suckers, and the birds of para- 

 dise. 



TERCINE. The botanical name for 

 the epidermis of the nucleus of the 

 ovule, when it separates in the form of a 

 third coating or integument. 



TEREBRA'NTIA {terebro, to bore). 

 332 



A section of Hymenopterous insects, 

 which are furnished with an ovipositor, 

 by means of which they are enabled to 

 bore a hole in certain substances for the 

 deposition of their eggs. See Ovipositor. 



TE'REBRATING {terebra, a perfo- 

 rating instrument). A term applied to 

 those testaceous animals which take up 

 their abode in other substances, as the 

 pholas. 



TERGE'MINATE. This term is em- 

 ployed, in Botany, when each of two 

 secondary petioles bears towards its sum- 

 mit one pair of leaflets, and the common 

 petiole bears a third pair at the origin of 

 the two secondary petioles, as in mimosa 

 tergemina. 



TERM, LOGICAL. A proposition 

 consists of two terms ; that which is 

 spoken of is called the subject ; that which 

 is said of it, is the predicate ; and these 

 are called the terms (or extremes), be- 

 cause, logically, the subject is placed 

 first, and the predicate last. In the 

 middle is placed the copula, which indi- 

 cates the act of judgment, as by it the 

 predicate is affirmed or denied of the 

 subject. 



Every syllogism has three, and only 

 three terms : viz. the middle term, and 

 the two terms (or extremes, as they are 

 commonly called) of the conclusion or 

 question. Of these, 1st, the subject of 

 the conclusion is called the minor term ; 

 2nd, its predicate, the major term ; and 

 3rd, the middle term (called by the older 

 logicians ** argumentum") is that with 

 which each of them is separately com- 

 pared, in order to judge of their agree- 

 ment or disagreement with each other, 

 Whately. 



TERMS, ALGEBRAICAL. In Alge- 

 bra, those parts of an expression, which 

 are connected by the sign -i- or — , are 

 called its terms, and the expression itself 

 is said to be simple or compound, accord- 

 ing as it contains one or more terms. 

 Thus a2 and — 6^ are each simple quan- 

 tities, and a'^ + ab — b^ is a compound 

 quantity, whose terms are a^, + ab, and 

 -63, 



When one quantity is said to be ex- 

 pressed in terms of another, the expres- 

 sion generally means merely that the 

 former is to be an explicit function of 

 the latter. Thus, m x + y = a, Wf: have 

 expressed x + y in terms of a; deduce 

 y = a—x, and we have y expressed in 

 terms of a and x. 



TE'RMINAL. "Term is a word of 

 geometry very little used, and signifying 



