iNC 



IND 



verbal fallacy ; for that which has no 

 parts, cannot be enlarged. 



I'NCIDENCE (incido, to fall upon). 

 The direction in which one body strikes 

 on another. The term is used in different 

 senses by writers on mechanics and 

 writers on optics. See Angls of Incidence, 

 in each case. 



INCINERATION {incinero, to re- 

 duce to ashes, from cinis, a cinder). The 

 reducing to ashes by burning. The com- 

 bustion of vegetable or animal substances 

 for the purpose of obtaining their ashes 

 or fixed residue. 



INCI'SION {incido, to cut). This term 

 must be distinguished from the coesura 

 of metre. Incision is the coincidence of 

 the end of the foot with the end of the 

 word ; it is essential in some species of 

 verse, and is used also in the hexameter 

 under certain forms. 



INCLINATION. In mathematics, 

 the mutual approach of two lines, or 

 planes, towards each other, so as to make 

 an angle. The inclination of the orbit 

 of a planet is the angle which the plane 

 of the planet's orbit makes with the 

 ecliptic, or the earth's orbit. The in- 

 clination, or dip of the magnetic 

 needle is the angle which such needle, 

 when supported on its centre of gra- 

 vity, makes with the plane of the ho- 

 rizon. 



INCLINED PLANE. One of the 

 five simple mechanical powers, con- 

 sisting of a plain smooth surface, which 

 is inclined towards or from the earth. A 

 board, with one end on the ground, and 

 the other end resting on a blpck, becomes 

 an inclined plane. 



INCLU'SA {includo, to enclose). An 

 order of the conchiferous acephalous 

 moUusca, in which the mantle has only 

 one opening for the passage of the foot ; 

 at the posterior end it is prolonged into 

 tubes of great length, which can be ex- 

 tended far beyond the shell, as in the 

 common solens or razor-shells. 



INCOMBUSTIBLE CLOTH. A cloth 

 manufactured of the fibres of asbestos ; 

 on burning away the fibre, the mineral 

 texture remains. 



INCOMME'NSURABLES. Any two 

 magnitudes which cannot be represented 

 by meani^ of the same unit, and cannot 

 consequently have any common measure, 

 are said to be incommensurable, as the 

 diagonal and the side of a square. Num- 

 bers are said to be incommensurable 

 in power, when their squares or second 

 powers are incommensurable, as 2 and 3, 

 177 



the squares of which, 4 and 9, have no 

 common measure. 



INCOMPATIBLES, CHEMICAL. A 

 term applied to salts or other compounds, 

 which cannot exist together in solution, 

 without mutual decomposition, as the 

 salts of barytes and those which contain 

 sulphuric acid. 



INCOMPRESSIBILITY. That pro- 

 perty of a substance, whether solid or 

 fluid, by which it resists being pressed 

 or squeezed into a smaller bulk. The 

 ultimate particles of all bodies are sup- 

 posed to be incompressible. 



FNCREMENTS, METHOD OF. A 

 method of analysis, more commonly 

 called the calculus of finite differences. 

 In the higher mathematics, the terms 

 increment and decrement are employed, 

 when two quantities are considered toge- 

 ther, one of which is greater or less than 

 the other ; the latter is then said to be 

 the former with an increment or decre- 

 ment. 



INCU'MBENT {incumbo, to lie upon). 

 That which lies upon any thing ; a term 

 applied, in Botany, to the cotyledons of 

 those cruciferous plants, which are folded 

 with their backs upon the radicle. See 

 Accumbeni. 



INDE'FINITE. In Geometry, this 

 term is applied to a straight line, which 

 may be produced to any length in a given 

 direction, without affecting the conditions 

 of the problem. The term is sometimes 

 used in the sense of infijiite, as when we 

 hear of a magnitude being indefinitely 

 great, an indefinitely small arc being 

 equal to its chord, a circle being a poly- 

 gon of an indefinitely great number of 

 sides, &c. 



INDE'FINITE PROPOSITION. In 

 Logic, a proposition which has for its 

 subject a common term without any sign 

 to indicate distribution or non-distribu- 

 tion. In these cases, the quantity of a 

 proposition is ascertained by the matter, 

 or the nature of the connexion between 

 the extremes : in necessary and in impos- 

 sible matter, an indefinite is understood 

 as a universal ; in contingent matter, as 

 a particular. 



INDE'FINITE TERM. In Logic, a 

 privative or negative term is called inde- 

 finite, in respect of its not defining or 

 marking out an object ; and it is opposed 

 to a definite or positive term, which does 

 define or mark out. Thus, " organized 

 being" is a definite, "unorganized being" 

 an indefinite term. 



INDEHI'SCENT {in, not, dehisco, to 

 I 5 



