I NT 



INT 



merly called the inverse method of flux- 

 ions; the function itself was called the 

 fluent, or flowing quantity; it is now 

 termed the integral or sum of the pro- 

 posed differential. 



INTEGRAL PARTICLES {integer, 

 entire). The most minute particles into 

 which any substance, simple or com- 

 pound, can be divided, similar to each 

 other, and to the substance of which they 

 are parts. Thus, the smallest portion of 

 powdered marble is still marble ; but if, 

 by chemical means, the calcium, the 

 carbon, and the oxygen of this marble be 

 separated, we shall then have the ele- 

 mentary or constituent particles. 



INTENSITY. The degree or rate of 

 the power or energy of any quality, as of 

 heat and cold. In electricity, it denotes 

 the degree to which a body is electrically 

 excited. 



INTENTION, FIRST and SECOND. 

 In Logic, the "first intention" of a term 

 is a certain vague and general significa- 

 tion of it, as opposed to one more precise 

 and limited, which it bears in some par- 

 ticular art, science, or system, and which 

 is called its •• second intention." Thus, 

 the term "bird" in its first intention 

 signifies any individual of the feathered 

 tribes ; in the language of sportsmen, or 

 its second intention, it is limited to the 

 partridge. — Whately. 



I'NTERAMBULA'CRA. The imper- 

 forate plates which occupy the intervals 

 of the perforated plates, or ambulacra, in 

 the shells of the Echinoderms. See Am- 

 bulacra. 



I'NTERCALA'TION. The insertion of 

 a supernumerary or intercalary day into 

 the calendar for the purpose of preserving 

 the account of time. See Calendar. 



INTERCE'LLULAR SPACES. Spaces 

 existing between the cells and other 

 simple tissues of plants. 



FNTEREST. The consideration paid 

 for the use of money. The rate of in- 

 terest is the sum paid for the use of a 

 certain sum for a certain time, generally 

 one year. The sum originally lent is 

 called the principal; the principal, to- 

 gether with its interest for any time, is 

 called the amount for that time ; the prin- 

 cipal is also called the present value of 

 the amount. Interest is called simple, 

 when it is paid as soon as due, or when, 

 if deferred, interest is not charged on 

 interest ; when the latter charge is made, 

 the interest is called compound. 



INTERFE'RENCE. A term applied, 

 in Optics, to certain phenomena occa- 

 182 



sioned by the mutual action of the rays 

 of light on one other : according to the 

 distances respectively from which the 

 rays of light proceeding from two lumi- 

 nous points fall upon the same spot, the 

 eflTect is diminished or increased ; and it 

 is this mutual action which is called 

 interference. 



INTERJE'CTION. A sound uttered 

 under the impulse of strong emotion. 

 Interjections are indeclinable, stand in 

 no close connexion with the sentences in 

 which they occur, and cannot be properly 

 considered as a distinct part of speech. 



INTERME'DIATE. A term applied 

 to a third substance, employed for com- 

 bining together two other substances ; 

 thus, alkali is an intermediate between 

 oil and water, forming soap. 



FNTERNODE {inter, between, nodus, 

 a node or knot). Merithallus. That por- 

 tion of the stem of a plant which occurs 

 between two nodes. 



INTERPOLATION. This term de- 

 notes, simply, the insertion of something 

 into original matter. In Algebra and 

 Astronomy, it is a method adopted for 

 filling up the intermediate terms of a 

 series of numbers or observations, by 

 numbers which follow the same law. 



INTERROGATION, FALLACY OF. 

 A logical fallacy, which may be referred 

 to the head of " Ambiguous Middle." It 

 consists in asking several questions which 

 appear to be but one ; so that whatever 

 one answer is given, being of course ap- 

 plicable to one only of the implied ques- 

 tions, may be interpreted as applied to 

 the other. The refutation is, to reply 

 separately to each question, i. e. to detect 

 the ambiguity. 



INTERRU'PTED. A term denoting 

 a disturbance of a normal arrangement. 

 A leaf is said to be interruptedly pinnate, 

 when some of the pinnae are much smaller 

 than the rest, or absent. 



INTERSCE'NDENT. A term applied 

 by Leibnitz to those algebraical quan- 

 tities of which the exponents of their 

 powers are irrational ; the term denotes 

 their holding an intermediate place be- 

 tween algebraic and transcendental quan- 

 tities. 



INTERVAL, MUSICAL. A term 

 applied to a certain relation between 

 musical notes, which depends on the 

 number of their vibrations. The sim- 

 plest or most consonant interval is that 

 of the octave, in which the higher note 

 makes twice as many vibrations as the 

 fundamental note from which it is de- 



