horsepowern.
1.
a. The power or rate of work of a horse in drawing; (hence in Mechanics) a conventional unit for measuring the rate of work of a prime motor, commonly taken (after Watt) as = 550 foot-pounds per second (which is about 1⅓ times the actual power of a horse). Abbreviated H.P.
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the world > matter > physics > energy or power of doing work > [noun] > specific quantities or units of energy or work
horsepower1806
foot-pound1847
foot-ton1860
kilogrammetre1866
erg1873
kilerg1873
indicated horsepower1881
metre-ton1881
joule1882
watt-hour1888
manpower1893
horsepower-hour1899
horse1904
1806 O. G. Gregory Treat. Mech. II. 357 The usual method of estimating the effects of engines by what are called ‘horse powers’ must inevitably be very fallacious.
1891 Electrician Sept. 551 A new and shockingly unscientific unit, the electrical horse power, is insensibly coming into use.
1897 Preece in Glasgow Herald 6 Feb. 3/5 The term ‘horse-power’ has probably seen its best days..As a scientific term it has been much abused, and as a commercial term it conveys no meaning.
b. With prefixed numeral, expressing the power or rate of work of an engine, etc.; as ‘an engine of 40-horse power’, or ‘a 40-horse-power engine’.Originally the numeral + ‘horse’ formed an attributive phrase qualifying ‘power’ (as in ‘four-horse coach’; cf. two-foot rule, half-mile race); but the whole phrase (esp. when used attributive) is often now analysed as numeral + ‘horse-power’.
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1823 Ld. Byron Don Juan: Canto X 98 (note) A metaphor taken from the ‘forty-horse power’ of a steam-engine.
1840 F. Marryat Olla Podrida I. iv. 32 She..preferred the three-horse power of the schuyt to the hundred-horse power of the steam-packet.
1851 Official Descriptive & Illustr. Catal. Great Exhib. II. 214 Oscillating steam-engine, of 10-horse power.
1872 R. B. Smyth Mining Statist. 50 One 25 horse-power engine, 16-inch cylinder.
c. With qualifying words, esp. brake horsepower n. the power available at the shaft of an engine, measurable by means of a brake; indicated horsepower n. the power produced within the cylinders, as shown by an indicator.
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the world > matter > physics > energy or power of doing work > [noun] > specific quantities or units of energy or work
horsepower1806
foot-pound1847
foot-ton1860
kilogrammetre1866
erg1873
kilerg1873
indicated horsepower1881
metre-ton1881
joule1882
watt-hour1888
manpower1893
horsepower-hour1899
horse1904
the world > matter > physics > energy or power of doing work > [noun] > capacity for exertion of mechanical force > power or rate of work known as horse-power > brake horsepower
brake horsepower1887
shaft horsepower1908
power rating1917
1859 W. J. M. Rankine Man. Steam Engine v. 479 Nominal Horse-power is a conventional mode of describing the dimensions of a steam engine, for the convenience of makers and purchasers of engines, and bears no fixed relation to indicated or to effective horse-power.
1881 Encycl. Brit. XII. 207/1 Nominal horse-power is a purely conventional term adopted by makers of steam-engines, and has no fixed relation to indicated horse-power.
1887 Encycl. Brit. XXII. 493/2 The efficiency of the mechanism is the ratio of the ‘effective’ or ‘brake’ horse power to the indicated horse power.
1888 Lockwood's Dict. Mech. Engin. Actual Horse-Power, or Available H.P.—Sometimes called Dynametrical H.P. The net useful power given out by an engine.
1904 Westm. Gaz. 30 Mar. 10/2 The Good Hope and the Drake..are of 14,100 tons displacement and 30,000 indicated horse-power.
1943 A. P. Fraas Aircraft Power Plants vi. 110 The power required to turn the engine over, or friction horsepower,..increases rapidly with rpm.
1968 R. H. Bacon Car ii. 17 The power developed in the cylinder..is called the indicated horsepower or i.h.p. Some of this power is absorbed by the friction of various parts of the engine. The power remaining, that is the power that can be used for work, is called the brake horsepower or b.h.p.
1972 Daily Tel. 15 Mar. 11/5 The latest car is almost a hundredweight heavier while the net brake horsepower is only up by six.
2. transferred. Power or rate of work as estimated by this unit; number of horse-powers. Also figurative.
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the world > matter > physics > energy or power of doing work > [noun] > capacity for exertion of mechanical force > power or rate of work known as horse-power
horsepower1860
traction power1908
poke1965
1860 M. F. Maury Physical Geogr. Sea (ed. 8) iv. §268 What is the horse~power of the Niagara?
1867 R. W. Emerson Progr. Culture in Wks. (1906) III. 235 Enthusiasm is the leaping lightning, not to be measured by the horse-power of the understanding.
1871 J. Tyndall Fragm. Sci. I. xx [He] calculates the equivalent of that heat in horse-power.
3. The power or agency of a horse or horses as employed in driving machinery; hence, a machine by which the pull or weight of a horse is converted into power for driving other machinery.
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the world > matter > physics > energy or power of doing work > [noun] > capacity for exertion of mechanical force > power of a horse
horsepower1853
society > occupation and work > equipment > machine > machines driven by specific energy source > [noun] > by horse-power
horsepower1853
the world > action or operation > advantage > usefulness > use (made of things) > instrumentality > [noun] > (a) means > resources > of horses
horsepower1853
1853 Catal. Royal Agric. Soc. Show Gloucester 50 A One Horse Power Portable Horse Gear.
1853 Catal. Royal Agric. Soc. Show Gloucester 51 A useful and economical thrashing machine to be either worked by hand or horse power.
1864 Webster's Amer. Dict. Eng. Lang. Horse-power..3. A machine operated by one or more horses; a horse-engine.
1875 E. H. Knight Amer. Mech. Dict. II. 1126/2 An ordinary horse-power, such as is used for thrashing-machines, drag-saws, clover-hullers.
Compounds
C1. General attributive.
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1884 E. H. Knight Pract. Dict. Mech. Suppl. (at cited word) Horse-power Computing Scale... Horse-power Jack... Horse-power Pump... Horse-power Regulator.
C2.
horsepower-hour n. a unit representing the work performed or energy consumed in working at the rate of one horsepower for one hour.
ΘΚΠ
the world > matter > physics > energy or power of doing work > [noun] > specific quantities or units of energy or work
horsepower1806
foot-pound1847
foot-ton1860
kilogrammetre1866
erg1873
kilerg1873
indicated horsepower1881
metre-ton1881
joule1882
watt-hour1888
manpower1893
horsepower-hour1899
horse1904
1899 J. Perry Steam Engine xvi. 250 Units of Energy used Commercially. 1 horse-power hour = ..1,980,000 foot-pounds.
1906 Westm. Gaz. 28 June 2/1 An output of 36 cubic feet of oxygen per horse-power hour.
1949 G. P. Sutton Rocket Propulsion Elem. i. 18 The specific fuel consumption is based on the horsepower output, and its units are pounds of fuel per horsepower-hour.
1963 F. D. Jones & P. B. Schubert Engin. Encycl. (ed. 3) 662 1 horsepower-hour = 0·746 kilowatt-hour.
This entry has not yet been fully updated (first published 1899; most recently modified version published online June 2022).
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n.1806