TER 



TES 



boundary or extremity ; the words ' ter- 

 minal value' and 'terminal form' are 

 sometimes used to signify the last and 

 most complete value or form. When a 

 finite expression, added to a certain num- 

 ber of terms of a series, makes up the 

 equivalent of the expression from which 

 the series is deduced, or stands for all 

 the subsequent terms of the series, this 

 finite expression might be called the ter- 

 minal expression. Thus, in Taylor's 

 Theorem, we have one terminal expres- 

 sion in D'Alembert's form, another in 

 that of Lagrange." Pen. Cycl. 



Terminal Language. "All the use of 

 the terms ' infinitely small' and * infinitely 

 great' is entitled to this name : when we 

 say that a circle is a regular polygon with 

 an infinitely great number of infinitely 

 small sides, the language used is that of 

 an end arrived at, a transformation 

 actually made ; the circle is described as 

 actually consisting of straight lines ; and 

 the language is terminal, expressive of a 

 boundary actually attained. But the 

 meaning of this language is, or is gene- 

 rally held to be, false ; to obviate the 

 diflficulty, terminal language, properly 

 employed, may be made the means of 

 abbreviation of all those truths whose 

 announcement contains interminable ap- 

 proximation." Ibid. 



TERMINATE and INTERMINATE. 

 A terminate number is an integer, a 

 mixed mumber, or a vulgar fraction. As 

 a mixed number may be reduced to a 

 vulgar fraction, all terminate numbers 



m 

 may be expressed by — , where m and n 



are integers ; and when the number is an 

 integer, n = 1, and the number = m. 



Interminate Number. A number which 

 is not terminate, is called an interminate 

 number. Interminate numbers compre- 

 hend interminate decimals, excepting 

 repeaters and circulaters, which can be 

 reduced to vulgar fractions, and are, 

 therefore, terminate numbers, although, 

 however, in the form of decimal fractions, 

 they are called interminate decimals. 



TERMINO'LOGY. In every treatise 

 of science;, the preliminary part, whicli is 

 devoted to the explanation or definition 

 of the terms employed, is called the ter- 

 minology of that science. 



TERMI'TID^ {termes, the white ant). 

 A group of Neuropterous insects distin- 

 guished from the dragon-flies and the 

 day-flies by their terrestrial habits. 



TERMITI'NjE. a section of neuro- 

 pterous insects, named from the termes, 

 333 



or white ant, and comprising also the 

 genera mantispa, raphidia, and psocus. 

 By some naturalists these genera are 

 considered as constituting distinct fami- 

 lies. 



TE'RNARY. a term applied by Dal- 

 ton to any chemical substance composed 

 of three atoms. By ternary compounds 

 are now generally understood combina- 

 tions of binary compounds with each 

 other, as of sulphuric acid with soda in 

 Glauber's salt, and the salts generally. 



TERNATE, BITERNATE, &c. In 

 Botanical nomenclature, these terms re- 

 late to the composition or arrangement 

 of parts upon the stem. 1. Ternate de- 

 notes that three leaves or other organs 

 are in opposition round a common axis. 

 2. Biter nate signifies that three secondary 

 petioles proceed from the common pe- 

 tiole, and that each bears three leaflets, 

 as in fumitory. 3. Triternate implies 

 that the common petiole is divided into 

 three secondary petioles, each of which 

 is subdivided into three tertiary petioles, 

 each of the latter bearing three leaflets. 



TERRESTRIAL MAGNETISM. A 

 term denoting the action of the magnetic 

 fluid in or about the earth ; the effects of 

 that action being manifested in the phe- 

 nomena presented by magnetized needles 

 or bars. 



TERRI'COLA {terra, the earth, cola, 

 to inhabit). An order of the Annellida, 

 which includes the earth worms. 



TERTIARY STRATA A series of 

 sedimentary rocks, with characters which 

 distinguish them from two other great 

 series of strata— the secpndary and the 

 primary — which lie beneath them. 



TERTIARY SYSTEM. A compre- 

 hensive geological term, representing all 

 the regular deposits newer than the 

 chalk. It admits of three primary divi- 

 sions — eocene, miocene, and pliocene — 

 names which imply that, in the lowest 

 division, we only find the dawn of exist- 

 ing species; that, in the next division, 

 there are more living species, but that 

 extinct species still predominate ; and 

 that, in the uppermost division, extinct 

 species decline, and living species pre- 

 dominate. 



TE'SSELLATED {tessella, chequer- 

 work). Divided into squares or chequers, 

 either by a division of colours, or by the 

 crossing of striae. 



TEST {testis, a witness). A re-agent; 

 a substance which, when added to an- 

 other substance, tests or distinguishes its 

 chemical nature or composition. Test 



