sb. Also 7–8 tention. [prob. a. F. tension (a. 1530 in Godef., Compl.), ad. late L. tensiōn-em, n. of action f. tendĕre to stretch (pa. pple. tens-us, tent-us). But the Eng. word may have been direct from 16th c. medical Latin.
With tension agree distension, extension, pretension; the variant tention agrees with attention, contention, intention.]
The action of stretching or condition of being stretched: in various senses.
1. Physiol. and Path. The condition, in any part of the body, of being stretched or strained; a sensation indicating or suggesting this; a feeling of tightness. (The earliest use in English.)
1533. Elyot, Cast. Helthe (1541), 59 b. There is felt within the bulke of a man … a weyghtynesse with tension, or thrustyng outwarde.
1603. Holland, Plutarch’s Mor., 656. The veines … upon the tention and commotion whereof … drunkennesse doth proceed.
1615. Crooke, Body of Man, 739. The first is a streatching or Tention not without strife or contention.
1704. F. Fuller, Med. Gymn. (1705), 30. What I mean by this Tension or Tone of the Parts.
1725. Bradley’s Fam. Dict., s.v. Vomiting, The tention of the Hypocondria and confus’d Sight.
1756. Burke, Subl. & B., IV. iii. An unnatural tension of the nerves.
1855. H. Spencer, Princ. Psychol., II. xi. 8. 55. 213. A correspondingly strong sensation of muscular tension.
b. Bot. Applied to a strain or pressure in the cells or tissues of plants arising from changes taking place in the course of growth.
1875. Bennett & Dyer, Sachs’ Bot., 708. Causes of the condition of Tension in Plants. The elasticity of the organised parts of plants results in tension chiefly from the operation of three causes. Ibid., 713. In a turgid cell, the cell-wall is … in a state of negative, the contents in a state of positive tension. Ibid., 720. It is only when the epidermis is becoming cuticularised and the walls of the bast-cells are beginning to thicken that the tensions become perceptible.
2. fig. A straining, or strained condition, of the mind, feelings, or nerves. a. Straining of the mental powers or faculties; severe or strenuous intellectual effort; intense application.
a. 1763. Shenstone, Economy, I. 151. When fancy’s vivid spark impels the soul To scorn quotidian scenes,… what nostrum shall compose Its fatal tension?
1826. W. Gifford, Lett., in Smiles, Mem. J. Murray (1891), II. xxv. 172. It is a fearful thing to break down the mind by unremitted tension.
1875. Jowett, Plato (ed. 2), IV. 12. The mind cannot be always in a state of intellectual tension.
b. Nervous or emotional strain; intense suppressed excitement; a strained condition of feeling or mutual relations which is for the time outwardly calm, but is likely to result in a sudden collapse, or in an outburst of anger or violent action of some kind.
1847. Disraeli, Tancred, IV. vi. The expression … of extreme tension … had disappeared.
1852. Mrs. Stowe, Uncle Tom’s C., vii. As the danger decreased with the distance, the supernatural tension of the nervous system lessened.
1878. Lecky, Eng. in 18th C., II. vii. 311. Society cannot permanently exist in a condition of extreme tension.
1885. L’pool Daily Post, 11 April, 64/7. A tension of feeling which has had no parallel since the outbreak of the Crimean war.
3. Physics. A constrained condition of the particles of a body when subjected to forces acting in opposite directions away from each other (usually along the body’s greatest length), thus tending to draw them apart, balanced by forces of cohesion holding them together; the force or combination of forces acting in this way, esp. as a measurable quantity. (The opposite of compression or pressure.)
1685. Boyle, Effects of Mot., viii. 92. If you cut the string of a bent bow asunder, the … extreams will fly from one another suddenly and forcibly enough to manifest that they were before in a violent state of Tension.
1782. V. Knox, Ess., xxi. I. 101. The string which is constantly kept in a state of tension will vibrate on the slightest impulse.
1825. J. Nicholson, Operat. Mechanic, 570. The strain occasioned by pulling timber in the direction of its length is called tension.
1853. Kane, Grinnell Exp., xxviii. (1856), 232. The tension of the great field of ice over which we passed must have been enormous. It had a sensible curvature.
1881. Metal World, No. 18. 277. A weight being placed on a beam or girder (… resting on the support at each end …), the top is … thrown into compression and the bottom into tension.
b. Inexactly used for the expansive force of a gas or vapor, properly called pressure.
1678. Cudworth, Intell. Syst., I. v. 851. A pressure upon the optick nerve, by reason of a tension of the intermedious air, or æther.
1826. Faraday, Exp. Res., xxxiii. 200. The air … has a certain degree of elasticity, or tension.
1844. Civil Engin. & Arch. Jrnl., VII. 155/1. The steam … is retained between the boiler and the plate until by its ‘tension’ or elasticity it is forced downwards and underneath the edge of the plate.
1863. Tyndall, Heat, i. § 9 (1870), 8. He wishes to apply the force of his steam, or of the furnace which gives tension to his steam, to this particular purpose.
c. transf. A device in a sewing-machine for regulating the tightness of the stitch. Also tension-device.
1877. Knight, Dict. Mech., s.v., By adjustment of the pressure at the tension device, the required tightness of stitch is obtained…. There are many … kinds of tensions, in different machines. Fig. 6309 shows the … automatic tension…. The automatic tension-device … is placed in the standard of the machine.
4. Electr. The stress along lines of force in a dielectric. Formerly applied also to surface density of electric charge, and until about 1882 used vaguely as a synonym for potential, electromotive force, and mechanical force exerted by electricity: still so applied, in industrial and commercial use, in high and low tension: see sense 5.
1802. Nicholson’s Jrnl. Nat. Phil., I. 137 (tr. Volta). In the one case, as well as in the other, the electric tension [la tensione elettrica] rises, during the contact, to the same point.
1833. Faraday, Exp. Res. (1855), I. 97. The attractions and repulsions due to the tension of ordinary electricity.
1837. Brewster, Magnet., 159. The sun heating and illuminating the earth, and producing a magnetic tension.
1839. G. Bird, Nat. Phil., 218. On their separation they are found to possess … a certain quantity of free electricity of low tension.
1841. W. Francis (tr. Ohm, 1827), in Taylor’s Sci. Mem., II. 416 (Ohm’s Law). The force of the current in a galvanic circuit is directly as the sum of all the tensions [die Summe aller Spannungen], and inversely as the entire reduced length of the circuit.
1849. Noad, Electricity (ed. 3), 135. Tension, Mr. Harris applies to the actual force of a charge to break down any non-conducting or dielectric medium between two terminating electrified planes.
1866. R. M. Ferguson, Electr. (1870), 64. Tension is the power to polarise and effect discharge.
1871. Tyndall, Fragm. Sc. (1879). II. xvi. 439. Such machines deliver a large quantity of electricity of low tension.
1873. Maxwell, Electr. & Magn. (1881), I. 59. Finding the phrase electric tension used in several vague senses, I have attempted to confine it to … the state of stress in the dielectric medium which causes motion of the electrified bodies, and leads, when continually augmented, to disruptive discharge.
1881. S. P. Thompson, Electr. & Magn., 203, note. The word tension … is so often misapplied in text-books…. The term would be invaluable if we might adopt it to denote only the mechanical stress across a dielectric, due to accumulated charges.
1882. Nature, 12 Oct., 570/2. M. Gariel breaks free from servitude to the consecrated term ‘tension,’ so often misused as a synonym for potential, electro-motive force, and we know not what.
fig. 1859. Kingsley, Misc. (1860), II. 75. Everything … has exasperated, not calmed, the electric tension of the European atmosphere.
5. High tension: a high degree of tension (of any kind); a. esp. in Electr. a term for a high degree of electromotive force or difference of potential: now chiefly used by makers of motor-cars, and of magnetic and induction coils. So Low tension. (See sense 4.) Chiefly attrib. as in high or low tension system (of electric lighting, etc.); also h. t. or l. t. charge, contact, current, fuse, etc.
1889. Daily News, 7 Oct., 3/1. Mr. Crompton does not say that the high tension system will not succeed. He says both will succeed; but that the low tension system is safer and cheaper.
1891. Cent. Dict., s.v. Tension, A body is said to have a high-tension charge, or a charge of high-tension electricity, and a conductor to carry a high-tension current, when the stress in the medium surrounding the body or the conductor is high.
1900. Engineering Mag., XIX. 715. When required for high-tension fuses, the armature of this exploder is wound with very fine wire; when for low-tension, with coarse wire.
1903. Motor. Ann., 221. The low tension system is one which will undoubtedly come to the fore. In this the actual current from the battery, or magneto machine, is interrupted inside the cylinder, thus causing a spark.
1906. Westm. Gaz., 13 Nov., 4/2. High-tension magneto, it is noted, is gaining in popularity—the low-tension system being confined almost exclusively to the very high-priced cars. Ibid. (1907), 5 Dec., 4/2. The low-tension make and break is made on platinum points by means of a cam, whilst the high-tension contact is made through metal contacts by a revolving carbon brush.
b. Of the pulse: cf. TENSE a. 1 (quot. 1802).
1898. Allbutt’s Syst. Med., V. 983. The low-tension pulse presents marked fluctuations of the base line. Ibid., 1024. Sir W. Broadbent considers that this modified high tension pulse is almost constant in mitral stenosis.
6. attrib. and Comb., as tension area, device (see 3 c), thrill; spec. applied to parts of a structure subjected to tensile stress, as tension-bar, -member, -rod; tension-bridge, a bridge in which there is tensile stress between parts of the structure, as a bowstring-bridge (see BOWSTRING 3, and quot. here); tension-fuse, a form of electric fuse that is fired by a spark at a break in a circuit; tension magnet (see quot.); tension-pulley, -roller, a free pulley or roller over which a belt, etc., passes to keep it stretched tight; a tightening-pulley; tension-rail, a rail for stretching cloth during the process of printing; tension-spicule, in sponges (see quot.); tension-spring, a spring for carriages, etc., composed of inner and outer leaves, connected at the ends, but free in the middle, so as to elongate independently under strain.
1871. Tyndall, Fragm. Sc., I. i. 20. At the beginning the vis viva was zero and the *tension area was a maximum.
1877. Knight, Dict. Mech., *Tension-bridge, a bridge constructed on the principle of the bow, the arch supporting the track by means of tension-rods, and the string acting as a tie.
1890. Cent. Dict., s.v. Fuse, *Tension-fuse, an electric fuse in which the conducting circuit is not complete, the firing being accomplished by the passage of a spark. Ibid. (1891), s.v., An electromagnet surrounded by a coil of many turns and high electrical resistance was called by Henry a *tension magnet.
1844. Stephens, Bk. Farm, II. 303. For the purpose of keeping a due degree of tension on the chain, a small movable *tension pulley is applied.
1890. W. J. Gordon, Foundry, 169. To … draw in the apparently endless plain white calico, zigzagging it over *tension rails, and running it on, giving it an extra colour at every turn.
1838. Civil Eng. & Arch. Jrnl., I. 126/1. Each pair of rafters is tied by means of a *tension rod. Ibid., 381/1. The platform, or roadway, was laid upon cast iron beams, suspended from the main chains by perpendicular iron bars or tension rods, about five feet apart.
1835. Ure, Philos. Manuf., 196. The *tension or stretching-roller has its axle mounted in the segment-racks as usual.
1886. Von Lendenfeld, in Proc. Zool. Soc., 21 Dec., 564. Called Flesh-spicules or Microsclera (*Tension-spicules of Bowerbank).
1877. Knight, Dict. Mech., *Tension-spring, a spring for wagons, railway-carriages, etc. … The outer leaves … impart a tensile strain to the inner ones.
1893. T. E. Brown, Old John, etc., 111. To him the sorrows are the *tension-thrills Of that serene endeavour.
Hence Tension v. trans., to subject to tension, tighten, make taut (hence Tensioned ppl. a., Tensioning vbl. sb.); Tensional a., of, pertaining to, of the nature of, or affected with tension; Tensionless a., without tension, unstrained.
1872. Daily News, 28 Feb. The whole nation was hanging in a *tensioned spasm of fear.
a. 1879. Tyndall (Webster Supp.). A highly tensioned string.
1893. De Long, in Chicago Advance, 28 Sept. How tensioned are our nerves!
1898. Cycling, 48. Upon the correct tensioning of the spokes [of a bicycle] depends the ‘truth’ of the wheel.
1906. Cycl. Tour. Club Gaz., Aug., 311. The tensioning is done by turning the three screws at the back of the saddle upwards from the right to left, so as to withdraw them. Most riders make the mistake when tensioning the saddle of turning the screws the wrong way.
1862. Catal. Internat. Exhib., II. X. 6. The *tensional parts of a pair of rigid trusses.
1881. Athenæum, 2 July, 16/3. The total energy of vibrations as being made up of two parts, one statical or tensional, and the other kinetic.
1905. Dundee Advertiser, 22 Dec., 9/2. A lecture on the subject of ‘The *Tensionless Drive.’ The lecturer treated of the efficacy of belts as a means of transmitting power.
