[ad. late L. expansiōn-em, n. of action f. expandĕre to EXPAND.] The action of expanding, the fact or state of being expanded.
I. Spreading out, unfolding, opening out.
1. The action or process of spreading out or unfolding; the state of being spread out or unfolded; the opening of a bud, flower, etc. Also, † a spreading out to view, a display.
1646. Sir T. Browne, Pseud. Ep., IV. v. 191. The … distance betwixt the extremity of the fingers of either hand upon expansion.
1656. trans. Hobbes’ Elem. Philos. (1839), 458. Whereupon there will follow a great expansion of light, with vehement flame.
1664. Power, Exp. Philos., II. 101. The Spring of a Watch … if the String be broke … flyes out into its fullest expansion.
1701. Grew, Cosmol. Sacra, I. v. 28. The easie expansion of the Wing of a Bird.
1731. Pope, Ep. Burlington, 145. The gilded clouds in fair expansion lie.
1847. De Quincey, Sp. Mil. Nun, § 8 (1853), 18. A mob orator, whose brawling mouth open to its widest expansion, [etc.].
1867. Jean Ingelow, Laurance. She … knew … The pleasure of the leaf in exquisite Expansion.
b. The detailed expression of what is implicitly contained in a statement; the writing out in full the meaning of graphical contractions. Also in Alg. the process of working out a contracted expression (cf. EXPAND 1 b.) and stating the result in full; the result or statement thus obtained.
1858. Todhunter, Algebra, xxxvi. § 519. The subject of the expansion of expressions is … properly a portion of the Differential Calculus. Ibid., xxxvi. § 524. To find the number of terms in the expansion of any multinomial.
1886. J. Edwards, Diff. Calc., 96. Now assuming the possibility of such an expansion, let [etc.].
2. concr. Anything that is spread out; an expanse; esp. the expanse of heaven, the firmament.
1611. Bible, Gen. i. 6. And God said, Let there be a firmament [marg. Hebr. Expansion] in the midst of the waters: and let it diuide the waters from the waters.
1659. Pearson, Creed, 94. This house of God … is not all of the same materialls…; there is a vast difference between the heavenly expansions.
1760. Beattie, Lucretius, I. 6. All that lies Beneath the starr’d expansion of the skies.
1823. Lamb, Elia, Ser. I. xxvi. (1865), 211. Less time … than it took to cover the expansion of his broad moony face … with expression.
a. 1845. Hood, Kilmansegg, cxl. Venus and Mars Are rolling along in their golden cars Through the sky’s serene expansion.
1862. Ansted, Channel Isl., I. iv. (ed. 2), 64. Some … flat expansions of hard … rock, afford a kind of irregular pavement.
fig. 1662. R. Mathew, Unl. Alch., § 57. 61. What is that to that ocean or expansion of wrath prepared?
† 3. Extent; space to which anything is extended. b. Pure space (see quot. from Locke).
1690. Locke, Hum. Und., II. vii. § 10. 54. The capacious Mind of Man … extends its thoughts often even beyond the utmost expansion of Matter. Ibid., II. xv. § 1. 93. Distance or Space, in its simple abstract conception, to avoid confusion, I call Expansion, to distinguish it from Extension, which by some is used to express this distance only as it is in the solid parts of Matter.
1712. Blackmore, Creation, IV. (1718), 121. Lost in expansion, void and infinite.
1755. in Johnson.
4. The action or process of causing something to occupy or contain a larger space, or of acquiring greater volume or capacity; dilatation; an instance of this.
1664. Phil. Trans., I. 29. To prove the expansion of glass by heat. Ibid. (1665), I. 49. What Bodies are expanded by being frozen, and how that expansion is evinced.
1692. Bentley, Boyle Lect., viii. (1693), 27. The condensation and expansion of any portion of the Air is always proportional to the weight and pressure incumbent upon it.
1782. Specif. Watt’s Patent No. 1321. 5. The piston continues to descend by virtue of the expansion of the steam.
1830. R. Knox, Béclard’s Anat., 235. They are furnished with tensor muscles, whether proper, or simply by expansion of their tendons.
1875. Ure, Dict. Arts, II. 319 s.v., Some remarkable examples of expansion are furnished by the influence of sunshine on the Britannia Tubular Bridge.
1882. Vines, Sachs’ Bot., 874. These movements depend not upon alternate expansion and contraction of the tissue … but [etc.].
fig. 1634. Habington, Castara (Arb.), 103. My heart Expanssion wants, to thinke what now thou art.
b. of immaterial things.
1682. Sir T. Browne, Chr. Mor. (1716), 19. Spread not into boundless Expansions either of designs or desires.
1856. Sir B. Brodie, Psychol. Inq., I. i. 31. A high education … may … have the effect of preventing the full expansion of genius.
1864. D. G. Mitchell, Seven Stories, 59. I felt, I will confess (if I may use such an expression), an unusual expansion.
1879. M. Arnold, Mixed Ess., Pref. p. vii. The love of liberty is simply the instinct in man for expansion.
c. Comm. and Finance. (a) An extension (of business transactions). (b) An increase in the amount of the circulating medium. More fully expansion of the currency.
1847. Craig, Expansion, in commerce, an increase of issues of bank notes.
1864. in Webster.
1891. Pall Mall Gaz., 10 Nov., 7/1. In some directions there has been expansion, so that the losses have been partially neutralized.
5. The amount or degree of dilatation.
1790. Blagden, in Phil. Trans., LXXX. 322. The whole expansion of pure spirit from 30° to 100° of FAHRENHEIT’s thermometer, is not less than 1/25th of its whole bulk at 30°.
1816. J. Smith, Panorama Sci. & Art, II. 32. Taking a proportional part of the difference of the two expansions.
1875. Ure, Dict. Arts, II. 319 s.v., The expansion of the solid corresponding to two degrees of the thermometer, is twice the expansion which corresponds to one degree.
6. concr. a. An expanded or dilated portion. b. A product of expansion; what (a thing) is expanded into.
1860. Tyndall, Glac., II. vii. 261. This lake [Geneva] is simply an expansion of the river Rhone.
1865. Ruskin, Sesame, 178. A man has a personal work … and a public work … which is the expansion of the other.
1866. Huxley, Phys., ix. (1869), 239. The structure … of the sensory expansion in which the optic nerve terminates.
1882. Vines, Sachs’ Bot., 544. The membranous expansions or appendages.
7. Steam-engine. The increase in bulk of the steam that takes place in a partially filled cylinder after communication with the boiler is cut off.
The improvement introduced by Watt’s patent of 1782 consisted in the economizing of steam by allowing the piston to be propelled, during the latter portion of its excursion, by the ‘expansion’ of the steam first introduced. An engine in which this is done is said to work ‘by expansion.’ A double (or triple) expansion engine is one in which the steam passes from one cylinder into another, so that the expansive force is used twice (or thrice).
1782. [see 4].
1819. Rees’s Cyclop., XXXIV. sig. M. 2 b (art. Steam-Engine), Mr. Watt’s principle of expansion.
1874. Knight, Dict. Mech., I. 817/1. An automatic expansion is one which is regulated by the governor, and varies with the amount of power required.
1875. R. F. Martin, trans. Havrez’ Winding Mach., 80. The engineman must be able to work his engine with a variable expansion with as great ease as an ordinary high-pressure engine. Ibid. MM. Scohy and Crespin … took out a patent for applying a system of expansion to winding engines.
8. attrib. and Comb., as expansion theory; expansion-coupling, -curb, -drum (see quots.); expansion-engine (see 7); expansion-gear, an apparatus for cutting off steam from the cylinder at a given point of the stroke; expansion-joint (see quots.); expansion-slide, a slide belonging to the expansion-valve, a valve that shuts off the steam in its passage to the cylinder.
1874. Knight, Dict. Mech., I. 816/2. *Expansion-coupling. The coupling represented consists of an expansion-drum of thin copper x between the extremities of two pipes a i, Fig. 1901, which, in elongating, press the sides of the drum in, and draw them out in cooling.
1847. Craig, *Expansion curb, in Horology, a contrivance for counteracting expansion or contraction.
1874. Knight, Dict. Mech., I. 816/2. *Expansion-drum. An arrangement by which an occasional change of speed may be effected.
1847. Craig, *Expansion engine.
1886. Pall Mall Gaz., 21 Sept., 13/2. These steamers … are provided with triple expansion engines.
1850. Pract. Mech. Jrnl., III. 28. (heading), Whitelaw’s steam-engine *expansion gear.
1875. R. F. Martin, trans. Havrez’ Winding Mach., 80. MM. Scohy and Crespin add to the regular form of cylinder the expansion gear of M. Meyer.
1849–50. Weale, Dict. Terms, *Expansion-joint, a stuffing-box joint connecting the steam pipes, so as to allow one of them to slide within the enlarged end of the other when the length increases by expansion.
1864. Webster, Expansion-joint, an attachment of the framing to the boiler, which allows the boiler to expand without bending the framing.
1882. Worc. Exhib. Catal., iii. 5. Samples of improved expansion joints.
1848. E. Alban, Steam Engine, 261. The *expansion slide is made to act through the motion of the principal slide below.
1886. F. B. Jevons, in Jrnl. Hellenic Studies, VII. 292. The inconsistencies in the Iliad are as fatal to every form of the *expansion theory [i.e., the theory that the Iliad is an ‘expansion’ of a smaller poem].
1849. Fairbairn, in Mech. Mag., LI. 255. A new construction of *expansion valves for condensing steam engines.
