1895 G. K. Gilbert in Bull. Philos. Soc. Washington XII. 265 The inquiry has followed three lines. First, an investigation of the ellipticity of lunar craters; second, an experimental investigation of the relation between incidence angle and ellipticity of impact craters; third, a more refined investigation of the orbital relations affecting the incidence angles of moonlets.

1895 G. K. Gilbert in Bull. Philos. Soc. Washington XII. 291 Does the earth exhibit impact craters? If not, then erosion and sedimentation have destroyed them.

1965 R. B. Baldwin Fund. Survey Moon vii. 66 If it can be shown that the impact craters on earth are..similar to lunar craters..we will be on firm ground in considering that the lunar craters..were formed by the impacts..of meteorites.

1967 Listener 20 Apr. 521/2 Another impact crater is that at Wolf Creek in Australia, where the diameter is half a mile.

1935 Metal Industry 11 Oct. 373/1 A new..heavy duty press..for the cold impact extrusion of aluminium tubes and shells in one operation.

1963 H. R. Clauser Encycl. Engin. Materials 340/1 Parts produced by impact extrusion are essentially longitudinally oriented, e.g., collapsible tubes, cans, etc.

1928 G. Martin Treat. Chem. Engin. xvi. 3 A connection between the density of a fluid W and the power required to move it through a pipe of area A when the impact head is l₁ in. of water and the dynamic head is l in. of water.

1924 E. E. Mann Introd. Pract. Civil Engin. x. 166 Wind pressure on roofs is of the nature of an impact load.

1928 C. F. S. Gamble Story N. Sea Air Station 10 Her two stream-lined gondolas..were designed to be capable of sustaining severe impact loads when alighting on water.

1963 D. A. Firmage Fund. Theory of Struct. iii. 56 Impact load is only a minor portion of the total load on any bridge.

1948 R. Courant & K. O. Friedrichs Supersonic Flow & Shock Waves iii. 240 The basic problem of wave propagation in a bar of elastic-plastic material is concerned with the motion resulting from impact-loading, i.e., from a velocity being suddenly imparted to one end of the bar and then maintained there.

1973 Sci. Amer. Feb. 85/1 It has been equipped with a grille structure that distributes the impact loading more uniformly.

1919 A. B. Eason Flow & Measurem. Air & Gases xiv. 237 The increase in the value of the impact pressure in the case of wind blowing directly on an opening will be due to the fact that more of the momentum of the air is destroyed than when air blows on the small area of the Pitot tube mouthpiece.

1966 J. W. Daily & D. R. F. Harleman Fluid Dynamics vi. 128 For liquids of small viscosity, Eq. (6–71) can be used to compute the velocity from the stagnation or impact pressure measured on the blunt nose of a probe in a steady flow.

1970 Computers & Humanities 5 21 The board of directors..has approved a character set to be used on computer-driven impact printers handling machine-readable bibliographic information.

1985 Personal Computer World Feb. 111/1 (advt.) Being an impact printer, the M-loog will print on virtually any paper.

1966 IEEE Trans. Electronic Computers 15 794/1 The output includes an electromechanical actuator which propels a small hammer against a single or multipart paper pack and ribbon which together strike a moving font of type at the precise moment the type character desired to be printed is in collision position. Thus, this type of printing uses an ‘on-the-fly’ principle; it is called impact printing.

1934 B. Stoughton Metall. Iron & Steel (ed. 4) xiii. 404 Impact Resistance of Steel.—The resistance of steel to shock decreases very much with lowered temperature.

1958 C. L. Mantell Engin. Materials Handbk. iii. 12 The impact resistance of standard malleable iron, measured by the Charpy test using a notch, 0·394-in. square bar, and 0·079-in. depth of notch is about 16·5 ft-lb.

1909 H. Louis Dressing of Minerals 42 The Impact Screen..consists of a screen usually of fine mesh and set at a rather steep angle, which receives downward jerks from a cam at the rate of 600 per minute, the screen being thrown upwards again by a spring.

1904 Inst. Mech. Engineers: Proc. iv. 1227 The more or less consistent relation that appeared to exist in Messrs. Sankey and Kent-Smith's tests between impact strength and reduction of area.

1939 Proc. Amer. Soc. Testing Materials 38 ii. 39 There are..8,000,000 molded phenol plastic telephones in use... The extent to which..breakage occurs..is determined largely by the impact strength of the molding material.

1952 R. L. Wood & D. Von Ludwig Investm. Castings for Engineers x. 209 Both beryllium copper and aluminum bronze will develop higher tensile strength and hardness when heat treated, but they will not have good impact strength, whereas manganese bronze is one of the toughest cast metals available.

1967 M. Chandler Ceramics in Mod. World iv. 118 The impact strength of all ceramic materials..is rather low.

1899 W. C. Unwin Testing Materials of Construction (ed. 2) 239 (heading) Example of an impact test.

1915 J. J. Thomas in Proc. Amer. Soc. Testing Materials 15 62 The Charpy impact test appears to differentiate between steels of various degrees of brittleness.

1918 Machinery 31 Jan. 477/1 Tensile impact tests, in which a sudden tensile stress is applied to a specimen by means of a falling weight, have also been practised..in recent years.

1943 F. D. Jones Engin. Encycl. (ed. 2) II. 680 The torsion impact test breaks the specimen by twisting.

1971 B. Scharf Engin. & its Lang. iv. 24 The most common impact test in this country [sc. Great Britain] is the Izod test, in which a notched test piece fixed at one end is broken by a blow from a pendulum hammer, the energy absorbed in fracturing the specimen being recorded... Another method widely used in other countries and increasingly also in this country is the Charpy impact test, in which a notched test piece supported at both ends is broken by a blow from a striker, on the face opposite to and immediately behind the notch, the energy absorbed in fracturing the specimen being recorded.

1916 Trans. Amer. Soc. Mech. Engin. 37 1410 For high pressures, the manometer attached to the impact tube can be replaced by a mercury column or steam gage attached to a receiver in the main where velocity is largely reduced.

1934 J. H. Perry Chem. Engineers' Handbk. 689 The length and shape of the tip, so long as the opening faces upstream, usually have little effect upon the head indicated by an impact tube.

1966 J. W. Daily & D. R. F. Harleman Fluid Dynamics ix. 178 The actual readings from impact tubes will depend both on the viscous effect and on the size of the pressure-sensing hole in the probe tip.

1563 T. Gale Certaine Wks. Chirurg. iv. i. iv. f. 3 When..there are humours impacte in anye part.

1587 M. Grove Pelops & Hippodamia (1878) 81 From hir whose picture still I fynde within my brest impact.

1647 H. More Philos. Poems iii. 1. ix All these forms..That sense or phansie ever had impact.

1652 J. French York-shire Spaw iv. 43 A cold, crass slimy morbifick, or a hot impact matter.

1601 P. Holland tr. Pliny Hist. World II. xx. xxi. 73 The seed of this hearbe remooveth the tough humours bedded in the stomacke, how hard impacted soever they be.

1712 P. Blair in Philos. Trans. 1710–12 (Royal Soc.) 27 75 These Pyramids, which receive the Hairs, are impacted in the Cutis.

a1791 J. Wesley Serm. lxxxii. i. 5, in Wks. (1811) IX. 417 Impact fire into iron, by hammering it when red hot.

1897 T. C. Allbutt et al. Syst. Med. III. 835 A stone-like mass..which had become impacted in the lower ilium.

1677 T. Gale Court of Gentiles: Pt. IV iv. Proem 4 Ideas or notions impacted on the mind.

1677 T. Gale Court of Gentiles: Pt. IV iv. 442 Every..Creature has a law impacted or impressed on its Being.

1945 Jrnl. Sci. Instrum. 22 187 Experimental results for the efficiency of jets in impacting particles are correlated.

1964 K. Stewart in White & Smith High-Efficiency Air Filtration ii. 57 All impactors make use of the inertia effect which particles exhibit when the gas stream in which they are suspended is constrained to turn abruptly. The particle under suitable conditions cannot follow the stream lines and is impacted against a collecting plate.

1972 J. O. Ledbetter Air Pollution A. v. 187 An aerosol moving toward an obstacle may impact particles on the obstacle.

1916 ‘B. Cable’ Action Front 95 No ping and smack of impacting lead hailed about them.

1961 Sci. Amer. Nov. 58/2 The impacting bodies may have been asteroids or comets.

1972 Daily Tel. 17 Apr. 6/8 These particles..cannot be measured or analysed from the Earth's surface. On the Moon, however, the impacting particles leave trails in the detector.

1973 Nature 13 July 68/2 Craters of the size of St Magnus Bay and The Firth would be formed by impacting meteorites of masses about 1 million tons.