Compress

“ Compressibility.—Porous substances can be considerably compressed. Force applied to them can bring their particles nearer together, making them to fill up in part their pores. The most familiar example you have of this is in sponge. The more porous wood is the more can it be compressed. But even such dense substances as the metals can be compressed in some degree; that is, the interstices between their particles can be made smaller. Medals and coins have their figures and letters stamped upon them by pressure, just as impressions are made upon melted sealing-wax. ”

“ They exist, in fact, in a state of compression, with but little mutual cohesion, and are only held together by the external skin. So long as the skin remains intact the tendency of the inner particles to expand and fill their proper space is checked and resisted by the superior compressive strain of the skin. ”

“ If we further consider that compression can rarely exist without irritation, and that sometimes of a formidable nature, there does not appear to be so much difficulty in the subject as is frequently represented, although the physiological explanation may not be so simple. ”

“ But if the air, when compressed, could be brought to the density of water, or wood to that of stone, there would be no need of any penetration of dimensions, and yet the compression would be much greater than they actually admit of. ”

“ The compression of the surface-elements into a quarter or half their known bulk cannot explain the great weight of the interior, for experiments indicate that a limit to the capacity of reduction of volume is soon reached. So far as we know, the reduction of bulk by pressure becomes less and less in proportion to the pressure exerted. ”

“ But at each alternate bend these outer layers, becoming concave, are subject to increased compression—a compression which they cannot withstand if they have become simply more extensible. To withstand this greater compression they must become harder as well as more extensible. ”

“ If a square or circular plate of glass therefore is compressed so that the axis of compression forms an angle of 45° or 135° with the plane of primitive polarization, the light passing through the centre of the glass at a certain degree of the pressure will be circularly polarized. ”

“ On y voit clairement la raison, qui est purement mécanique; chaque graine, dont la figure est cylindrique, tend par son renflement à occuper le plus d’espace possible dans un espace donné, elles deviennent donc toutes nécessairement hexagones par la compression réciproque. ”

“ For example, if we were to take a girl the natural size of whose waist was twenty-four inches, put on her a small pair of stays, and draw those stays in till the waist measured sixteen inches only, that girl would faint almost immediately, and, unless the stays were opened, would probably die from failure of the heart's action, owing to mechanical pressure on the heart—one of the evils brought about by the external compression. ”

“ This is why the distinction just made between special-scientific compression and useful special-scientific compression is essential—if we were to attend only to shifts that changed a system enough for a particular special science’s compression to fail entirely, then we wouldn’t be able to account for the uncontroversial reduction of complexity that coincides with the removal of the human from our kitchen-system. ”

“ The compression continues till the temperature of the air becomes that of the source, which we designate by T. The rise in pressure will be represented by the adiabatic line A B. Let O b represent the volume and B b the pressure at the end of the operation. ”

“ In the case of air, some portion may be compressed more than the rest, and the place of compression may move forward, so that as the compression is released in one place it makes its appearance in an adjacent one. ”

“ That there is no single instance of compression in a vertical member of the bowstring girder, b. That every one of the diagonals is subjected to compression at some point or other in the passage of the live load over the bridge, c. That the maximum horizontal component of the stresses in each of the diagonals is a constant quantity, not only for tension and compression, but for all the diagonals. ”

“ If a fluid be composed of particles mutually flying each other, and the density be as the compression, the centrifugal forces of the particles will be reciprocally proportional to the distances of their centres. And vice versa, particles flying each other with forces that are reciprocally proportional to the distances of their centres, compose an elastic fluid, whose density is as the compression. ”

“ From above pieces of blue towers and walls were falling downward with terrific speed . . . they will have perhaps hours or days to fly through the infinite. . . . Unseen threads were slowly floating through the air, planting themselves upon my face, and it was impossible to brush them off, impossible to rid myself of them.
I walked slowly toward the Ancient House, and in my heart I felt that absurd, tormenting compression. ”

“ All the parts of the system will be agitated with the same motions, as if they were placed in a vacuum, and would only retain their comparative gravity; unless so far as the fluid may somewhat resist their motions, or be requisite to conglutinate them by compression. ”

“ Is it not a task sufficiently difficult for the blood to climb from the feet to the heart, directly against the power of gravity, without being impeded, is its course, by compression of any sort—and above all, by ligatures.
But if these ordinary compressions of the surface of our bodies are so injurious, what are we to say of the practice of many females, and of most young women—at least in fashionable life—of compressing the chest? ”

“ The great resistance of liquids to compression makes it probable that their molecules must be at about the same distance from each other as that at which two molecules of the same substance in the gaseous form act on each other during an encounter. ”

“ Compression as a Mixing Means.—It will also be understood, that compression permits the bringing together of a much larger amount of fuel at each charge than would be possible without it, so that the two factors, namely, the volatilizing action of the air, the mixing of the air and vapor, and the compression, all serve to mix together the elements which will produce an explosion when the proper heat is finally applied. ”

“ To make it act most energetically the fibres were permanently compressed longitudinally, as in a vise, up to a certain point, similar to the strings, which, as we have just now seen, give forth tones of most satisfactory quality when stretched to the verge of breaking. ”

“ With regard to the second of the seven modes of operating above mentioned, it is particularly to be observed, that compression and such violent means have indeed with respect to local motion and the like a most powerful effect; as in machines and projectiles; an effect which even causes the destruction of organic bodies, and of such virtues as consist altogether in motion. For all life, nay all flame and ignition, is destroyed by compression; just as every machine is spoilt or deranged by the same. ”

“ Mayer, of Heilbronn, measured the work done in compressing air, and the heat generated by the compression, and assumed that the whole of the work done in the compression, and no more, was converted into the heat developed, which was the same thing as assuming that no work was done in altering the positions of the particles of gas. ”

“ To make experiments with compressed air, you must put your wits together to make a reservoir. Air, you know, is a gas consisting of particles called atoms. These atoms are at a certain distance from one another. They can be pushed further from one another as when you heat them, or closer together by cold and compression. So compressed air only means air whose atoms are pressed more closely together than as the case with the air around us. ”

“ If the fluid be much compressed, and the velocity of the moving body much less than that with which the particles of the fluid will rush into vacuum in consequence of the compression, it is clear that the space left by the moving body will be almost instantaneously filled up, (plate 23, fig. 2) ; and the resistance of such a medium would be less the greater the compression, provided the density were the same, because the velocity of rushing into a vacuum will be greater the greater the compression. ”

“ The greater or smaller force with which they resist compression may, upon many occasions, be owing partly to the same cause: but it may likewise be owing to the greater or smaller proportion of empty space comprehended within their dimensions, or intermixed with the solid parts which compose them. ”

“ As we know absolutely nothing of the manner in which the intellectual phenomena are produced in the brain, we cannot say whether compression prevents their development by stopping the motions with which the brain is habitually agitated, or by preventing the entrance of the arterial blood, or finally in some other way that we do not suspect. ”

“ Small round compressed bodies not exceeding the eighth of an inch in their longest diameters, and horizontally disposed, are connected by processes nearly of the fineness of a hair which pass from different parts of each of these bodies, and are attached to the surrounding ones ”

“ Suppose the medium to be press'd by an incumbent weight after the manner of our air; and let A be the height of a homogeneous medium, whose weight is equal to the incumbent weight and whose density is the same with the density of the compressed medium in which the pulses are propagated. ”

“ If you make a number of round holes close together in a soft substance, and then squeeze the substance evenly from all sides, the rounds will gradually take a six-sided form, showing that this is the closest shape into which they can be compressed. ”

“ Elastic bodies, in the recovery of their forms from a state of compression, after the removal of the compressing force, exert a greater power at first than at last, so that the whole progress of restoration is a retarded motion. ”

“ Elasticity implies susceptibility of compression, and the susceptibility of compression depends upon the porosity of bodies; for were there no pores or spaces between the particles of matter of which a body is composed, it could not be compressed. ”

“ Young computed that, at the earth's centre, steel would be compressed into one-fourth, and stone into one-eighth of its bulk.745 It is more than probable, however, that after a certain degree of condensation, the compressibility of bodies may be governed by laws altogether different from those which we can put to the test of experiment; but the limit is still undetermined, and the subject is involved in such obscurity, that we cannot wonder at the variety of notions which have been entertained respecting the nature and conditions of the central nucleus. ”

“ The strain produced by bending stress in a bar or beam is, as regards any imaginary filament taken along the length of the piece, sensibly the same as if that filament were directly pulled or compressed by itself. The resulting deformation of the piece consists, in the first place and chiefly, of curvature in the direction of the length, due to the longitudinal extension and compression of the filaments, and, in the second place, of transverse flexure, due to the lateral com- pression and extension which go along with the longitudinal extension and compression. ”

“ He describes his apparatus as follows:
A and B (Fig. 1) are two compound exhausting and forcing pumps, so coupled as to produce the widest possible difference between the pressures of exhaustion and compression. ”

“ Experiment shows that we have at one time a sphere of compression—that is to say, the air is packed closely together; and, again, a sphere
Fig. 5.—Propagation of Sound-Waves along a Cylinder.
of rarefaction, when the particles of air are torn farther apart than they are in the other position. The state of things, then, that travels in the case of sound, is a state of compression and rarefaction of the air. Hence, the particle of air travels differently from the particle of water; it moves backward and forward in a straight line in the direction in which the sound is propagated. ”

“ Compression, for example, might increase the rigidity or force-resisting power of the materials of the earth's substance in such sort that mines might be dug to any depth, and horizontal tunnelling carried out from the lowest parts of any mine. But experiment shows that the fact is otherwise. Under great pressures the most solid substances become plastic. ”

“ Insert into the cavity formed by the imposition of the ligneous fibre upon the inferior transverse ferruginous bar, a sheet of laminated lignin, or paper, compressed by the action of the digits into an irregular spheroid.
These preliminary operations having been skilfully performed, the process of combustion may be commenced. ”

“ If we could see the particles of the air in the concert-room, and fasten our attention upon any one of them, we should see it executing a most complicated motion under the combined action of these air-wave-producing instruments. We should be fascinated by the amazing dance of molecules to and fro and from side to side, as the medley of waves of compression or rarefaction embraced them and drove them hither and thither in their resistless grasp. ”

“ And not only paper, but cotton fibre, linen fibre, wool fibre, woody fibre, and bone, Kemp, flesh, Kemp, hair, Kemp, nails and nerves, Kemp, in fact the whole fabric of a man except the red of his blood and the black pigment of hair, are all made up of transparent, colourless tissue. So little suffices to make us visible one to the other. For the most part the fibres of a living creature are no more opaque than water.”
“Great Heavens!” cried Kemp. “Of course, of course! I was thinking only last night of the sea larvae and all jelly-fish!” ”