[ad. F. superposition, ad. late L. superpositio, -ōnem, n. of action f. superpōnĕre, f. super- SUPER- 2, 13 + pōnĕre to place (see POSITION).] The action of superposing or condition of being superposed.
1. gen. The placing of one thing above or upon another.
1830. Herschel, Study Nat. Phil., § 26. Bergmann … showed how at least one species of crystal might be built up of thin laminæ ranged in a certain order, and following certain rules of superposition.
1853. Kane, Grinnell Exp., xlii. (1856), 394. The infraposition and superposition of two fluids of differing densities.
1861. Beresf. Hope, Eng. Cathedr. 19th C., ii. 43. The massiveness and squareness of its forms, the frequent use of superposition [in Norman architecture].
1879. Rutley, Study Rocks, x. 153. The superposition of one crystal on another sometimes gives rise to cruciform figures.
b. An instance of this; also, a series of things placed one above another.
1828–32. Webster, Superposition 2, that which is situated above or upon something else.
1836. Mrs. Somerville, Connex. Phys. Sci., xvii. (ed. 3), 161. The resulting figure varying with the number of the superpositions, and the angles at which they are superposed.
1894. ‘Max O’Rell,’ John Bull & Co., 295. The land is a succession, a superposition, of plateaus, hills, and mountains crowned with enormous boulders.
c. fig.
1871. Smiles, Charac., ii. (1876), 33. The child’s character is the nucleus of the man’s; all after-education is but superposition.
1872. Bagehot, Physics & Pol. (1876), 49. The superposition of the more military races over the less military.
1904. A. E. Wright, in Brit. Med. Jrnl., 10 Sept., 582/2. I must make some mention of the superposition of doses.
d. Eccl. Antiq. Of fasts (see quot.).
After eccl. L. superpositio (jejunii), eccl. Gr. ὑπέρθεσις τῆς νηστείας. Cf. F. jeûnes de superposition.
1710–22. Bingham, Antiq., XXI. i. § 25. Victorinus Petavionensis … speaks of several Sorts of Fasts observed among Christians, some of which were only till the Ninth Hour, some till Evening, and some with a Superposition or Addition of one Fasting-Day to another. Though we must note, That the Superposition of a Fast … sometimes denotes a new appointed Fast of any Kind.
2. Geom. The action of ideally transferring one figure into the position occupied by another, esp. so as to show that they coincide.
1656. Hobbes, Six Lessons, Wks. 1845, VII. 197. The superposition of quantities, by which they render the word ἐφαρμογὴ, cannot be understood of bodies, but only of lines and superficies.
1793. Beddoes, Math. Evid., 36. This measure of the eye would not be sufficiently exact to satisfy us that the angles are equal; we must obtain a measure by real or imagined super-position.
1837. Hallam, Lit. Eur., III. iii. § 77, note. Most of plane geometry may be resolved into the super-position of equal triangles.
1882. Proctor, Fam. Science Studies, 16. The perfect equality of the two triangles might be tested by superposition in our region of this surface world.
b. Physics, etc. The action of causing two or more sets of physical conditions or phenomena (e.g., undulations or other motions) to coincide, or co-exist in the same place; the fact of such coincidence or co-existence.
1830. Herschel, Sound, in Encycl. Metrop. (1845), IV. 790. The principle of the superposition of vibrating motions … must be admitted in Acoustics.
1831. Brewster, Optics, xxii. 195. The superposition of these two systems of rings would reproduce white light.
1879. G. Prescott, Sp. Telephone, 248. A composite curve which represents the effect produced by the superposition of one set of waves upon another.
fig. 1858. J. Martineau, Stud. Christ., 143. We accept them both (penal redemption and moral redemption), putting them, however, not in succession, but in super-position so that they coalesce.
3. Geol. The deposition of one stratum upon another, or the condition of being so deposited.
1799. Monthly Rev., XXX. 15. The many turnings and superposition of strata.
1823. trans. Humboldt’s Geogn. Ess. Superp. Rocks, Pref. p. v. The most remarkable superpositions of rocks in both hemispheres.
1832. De la Beche, Geol. Man., 202. This superposition of gravel, in which the rolled fragments are sometimes by no means small.
1870. Yeats, Nat. Hist. Comm., 27. A correct knowledge of the law of superposition of rocks.
1879. Encycl. Brit., X. 295/1. The underlying beds must be older than those which cover them. This simple and obvious truth is termed the law of superposition.
4. Bot. The relative position of leaves or other members on an axis, when situated directly above one another, not alternating.
1880. A. Gray, Struct. Bot., vi. § 3 (ed. 6), 179. Non-alternation of the members of contiguous circles: Anteposition or Superposition.
