axis (1)

& a. [From Lat. aris = (1) an axle, a chariot; (2) the axis of the earth; (3) the pin on which a hinge turns; (4) the valve of a pipe; (5) ( Arch. ) the axes of a volute; (6) a board, a plank, from ago to drive. Akin to Eng. axle; A.S. æx, eax = an axis, an axletree; Dut. as; Ger. achse, axe; O. H. Ger. ahs a; Dan. & Fr. axe; Sp. exe; Port. eizo; Ru . os, osi; Lith. a io; Ital. a e; Gr. ἄξων (απόn), cognate with ἅμαξα (hamara) = a wagon, a chariot; Sansc. akshas a chariot.] [AXLE.] IMG:content-0956.png:[blocks in formation] "Meanwhile, the heart within the heart, the seat Where peace and happy consciousne should dwell, On its own azis restle ly revolues, Yet nowhere finds the cheering light of truth." Words worth Excursion, bk. iv. 2. A straight line, real or imaginary, pa ing through a body, around which the several parts of the body are symmetrically arranged. "The lofty mountains on the north side compose the granitic aris , or back hone of the country."- Dar win: Voyage round the World , ch. x. IL Technically : 395 1. Geom.: An imaginary line drawn through a plane figure, and about which the plane figure is supposed to revolve, with the result of defining the limits of a solid. Thus, a circle revolving about one of its diameters, and at right angles to that diameter, will constitute a sphere; hence the axis of a sphere is any one of its diameters. If an isosceles triangle revolve around an imaginary line connecting its apex with the centre of its base, it will constitute a cone; hence the axis of a cone is an imaginary straight line drawn from its apex to the centre of its base. A rectangle revolving around a straight line connecting the centres of any two of the opposite sides will produce a cylinder; hence the axis of a cylinder is a straight line drawn from the centre of its apex to the centre of its base. The axis of a parabola is the diameter which pa es through its focus. For the absci a of the axis, the subtangent, ., of the axis, see ABSCISSA, SUBTANGENT, . In an ellipse the axis major (Lat. = greater axis) is the diameter which pa es through the foci; and the axis minor (Lat. le er axis) the diameter at right angles to the axis major. In a hyperbola, the axis major is the diameter which pa es through the foci; the axis minor is the distance between two points formed when a straight line drawn through the centre of the hyperbola, and at right angles to its major axis, is intersected by a circle described around a principal vertex as its centre, and with a radius equal to the eccentricity of the hyperbola. Conjugate axis of an ellipse or of a hyperbola : The straight line drawn through its centre perpendicular to the transverse axis. Transverse axis of an ellipse or of a hyperbola: The straight line drawn through the two foci. The axis of symmetry of a body : Any line in a regular polygon bisecting an angle or bisecting a side perpendicularly. a rotation of a body of regular figure about its aris of symmetry."-Herschel: Astron. (5th ed., 1868), § 56. 2. Astron. The axis of the earth , or the axis of rotation of the earth , is that diameter about which it revolves. It is the one which has for its extremities the north and south poles. The term is similarly used of the sun, the moon, and the planets. (Herschel: Astron., 3rd ed., 1858, §§ 22, 57, .) both Venus and Mercury have been concluded to revolve on their azes in about the saine time as the Earth." Herschel: Astron. (5th ed., 1858), § 509 Axis of the celestial sphere: The imaginary line around which the heavens appear to revolve. It is the axis of the earth produced. Axis of an orbit . The major axis of the orbit of a planet is the line joining the aphelion and perihelion points. The minor axis is the line perpendicular to the former, and pa ing through the centre of the ellipse. 3. Min . The term aris of a prismatic or other crystal is used in the same sense as in Geometry. ( Phillips : Mineral ., 2nd ed., 1819, p. lxxxiii.) 4. Mechanics: The axis of suspension of a pendulum is the point from which it is suspended, and consequently around which it turns. The axis of oscillation of a compound pendu lum is an axis constituted by a series of points, so situated that their motion is neither retarded nor accelerated by their constituting part of a solid body, which, of course, can only move together. ( At kins on : Ganot's Physics , 3rd ed., 1868, § 70.) Aris of a balance: The line around which it turns. Axis in peritrochio . [Gr. περί ( peri ) = round about, and τροχός ( trochos ) = a wheel.] The same as the wheel and axle. One of the six mechanical powers, consisting of a peritro chium, or wheel and an axle. 5. Magnetism: The line supposed to connect the north and south poles of a magnet. 6. Optics : Axis of a lens: A line pa ing through the centre of its curved, and perpendicular to its plane, surface. ( Brewster : Optics , 1831, § 34.) Optic axis: The line corresponding to this in the eye. The ray of light pa ing along it is the only one which is not refracted. The other ways of light entering the eye have axes also, but this is the only one to which the term optic axis is applied. 396 Visual axes : The axes of the several rays of light which enter the eye. [See Optic Axis above.] due convergence of the visual axes..."- Herbert Spencer: Psychol., 2nd ed., vol. ii., p. 170, § 327. Axis of refraction: A straight line drawn perpendicular to the plane of a transparent body, and pa ing through the point of incidence of a luminous ray, striking it from without. Axes of double refraction: All doubly rofracting substances have one or more lines, or one or more planes, along which no doubly refracting force exists. If there is one such line or plane, then the body is said to have one axis, or plane of axes, of double refraction; if two, two axes, or planes of axes, of double refraction, and so forth. A real axis , or plane of axes of double refraction , is one in which the doubly refracting force really does not exist; whilst a resultant aris , or plane of axes , or an axis or plane of compensation, is one in which it exists, but is neutralised by a counter force of equal intensity. A positive axis of double refraction is the term used when the refracted ray is bent towards the axes, or plane of axes, of the body; and a negative axis of double refraction is the expre ion employed when it is bent in the contrary direction. 7. Architecture : Spiral axis : The axis of a spirally-twisted column. Axis of an Ionic capital : A line pa ing perpendicularly through the middle of the eye of the volute. 8. Geology : An imaginary line on the opposite sides of which the strata dip in different directions. If the angle formed at their point of junction be a salient one, they form an anticlinal aris, or ANTICLINAL (q.v.); but if it is a re-entering one, then they constitute a synclinal axis, or SYNCLINAL (q.v.). ( Lyell : Man. of Geol., 4th ed., 1852, p. 57.) [1., 2.] 9. Botany : The axis is that part of a plant around which the organs are symmetrically arranged. The ascending axis means the stem. (Lindley: Introd. to Bot ., 3rd ed., 1839, p. 69.) The descending axis is the root. ( Ibid .) Rece ory axes are axes in addition to the main one, found in the stems of Calycanthus, Chi mon an thus, and some other plants. ( Ibid ., p. 96.) The appendages of the aris are scales, leaves, bracts, flowers, sexes, and fruit. ( Ibid ., p. 110.) The axis of inflorescence is a peduncle which proceeds in a nearly straight line from the base to the apex of the inflorescence. ( Ibid . , p. 153.) 10. Anatomy: (a) The axis of the body: The vertebral column around which the other portions of the frame are arranged. "When the skull remains in connection with the vertebral column, it will be seen that its axis is a continuation forwards of the axis of that column, consisting of the bodies of the vertebræ."- Flower : Osteol. of the Mammal i a , p. 96. "In the Deer the the axis of the face is nearly in the saine line with that of the cranium.."- Ibid . , p. 171. "The bones of the Cranio-facial Azis p. 105. ."-Ibid., (b) The second vertebra of the neck, or the joint by which it is connected with the first vertebra. [ATLAS.] "... the vertebral being slightly bent between the atlas and axis."-Todd & Bowman: Physiol. Anal., vol. i., p. 295, B. As adjective: Pertaining to an axis in the anatomical sense. [II., 10.] "On entering the innermost capsule, the nerve-tube suddenly loses its envelope of white substance and becomes pale, the axis cylinder alone remaining..." -Todd & Bowman: Phys. Anat., vol. 1., p. 398. It is ǎx'-is (2), s . [Lat. aris an Indian quadruped, probably the deer described below.] A species of deer, the Cervus aris , found in India. spotted like the Fallow-deer, from which, however, the adult males at least may be distinguished by their po e ing round horns without a terminal palm. There are several varieties, if, indeed, they are not distinct species. All are called by Anglo - Indian sportsmen Hog-deer.