Osborne Reynolds

“ The singular surfaces which we call molecules are individuals, which, although they may cohere, cannot pass through each other and thus although the only mass, that of the medium, is changing every instant, at the extreme rates already mentioned, these singular surfaces or molecules preserve their individuality, the realization of which is a further tax on the imagination. ”

“ Thus for the last hundred years the idea of the structure of the universe, or the luminiferous ether, which has prevailed, is that of space occupied by an incompressible elastic jelly yielding to tangential stress, having a density which is all but indefinitely small. ”

“ Then as the general result of the research, in spaces in which the piling is normal, which spaces are almost indefinitely greater than those occupied by matter, it is shown, that there is one and only one conceivable purely mechanical system capable of accounting for all the physical evidence, as we know it, in the universe. ”

“ But, even so, the explanation is not what was expected; for gravitation is not the result of that dilatation which results from uniform parallel strains in the medium in normal piling, but results solely from those components of the dilatations caused by the space variation of the inward strains.
Thus, as long as the dilatation strains are parallel there is no attraction; but if there is curvature in the strains there will be efforts, proportional to the inverse square of the distance, to cause the negative inequalities to approach from a finite distance. ”

“ If the medium is stationary and the molecules are moving with the earth, the grains within the surfaces do not partake of the mean motion of these surfaces, being continuously replaced by other grains by the action of propagation, by which the singular surfaces in their motion are continually absorbing the grains in front and leaving those behind without any mean effect on the motion of the grains. ”

“ The dilatation diminishes as the centres of the negative inequalities approach, and work is done by the pressure, outside the singular surfaces, to bring the singular surfaces of the negative inequalities together.
The efforts to cause the approach of the centres correspond, exactly, to the gravitation of matter if matter represents the absence of mass, and thus the inversion of preconceived ideas is complete. Matter is measured by the absence of the mass necessary to complete the normal piling. And the effort to bring the negative inequalities together is also an effort on the mass to recede ”

“ Apart from the displacement of mass, the complex inequality differs from the gravitating inequalities.
In the complex inequalities the parameter of the dilatation is not the diameter of the grain, but is one half the linear dimension of the volume of the grain displaced taken as spherical.
The intensity of the efforts to revert, in the case of a complex inequality is the product of the pressure multiplied by the product of the volumes of the positive and negative inequalities, and again by the parameter. ”

“ Strained normal piling implies that, although the shape of the medium is strained, so that the distances of the grains from their twelve neighbours are no longer equal—since the successive layers of grain in the normal piling instead of being flat are subject to slight spherical curvature—the strains are such as do not allow any change of neighbours; so that when the strain is removed each grain will find itself in normal piling with the same neighbours. ”

“ Then, since the space occupied by inequalities is almost indefinitely small compared to the space in normal piling, it appears, even if there are as many positive inequalities as there are negative inequalities, the positive will present no evidence, being scattered, while the negative inequalities being brought together by gravitation, are in evidence. ”

“ And thus we may have the fullest confidence that the structure is purely mechanical, and that ideas, such as I have endeavoured to sketch, will ultimately prevail, displacing for ever such metaphysical conceptions as that of action at a distance, and accomplishing that ideal which, from the time of Thales and Plato, has excited the highest philosophical interest. ”

“ To show that there is an effort to expand the bag, while the pinch is on, it is only necessary to bring the bag into communication with a pressure-gauge, when the mercury shows that the pressure in the bag is only half of that of the atmosphere outside the bag. ”

“ The system being neither more nor less than an arrangement of indefinite extents of spherical grains in normal piling, so close that the grains cannot change their neighbours, although continually in relative motion with one another; the grains being of changeless shape and size. Thus constituting, to a first approximation, an elastic medium, with six axes symmetrically placed, see Fig. ”

“ The actions between such spheres is outside all experience. But it follows, since there is no elasticity, that for the conservation of energy, when these spheres, or grains, as they will now be called, come into collision, they will exchange their momenta, on the instant, and thus displace momentum and energy by instantaneous conduction. ”

“ Putting the bag between two vertical plates and slightly shaking and squeezing, so as to keep the sand at its densest, it still has a free surface and it can, in this way, be spread out until it is a broad flat plate; it is still soft, as long as it is squeezed, but when the pressure is removed the elasticity of the bag tends to draw it back to its rounded form, changing the shape, enlarging the interstices and absorbing the excess of water. This is soon gone and the bag remains a flat cake with peculiar properties; to pressures on its
Fig. ”

“ The downward slope in the upper chase being uniform for a small distance beyond the position of the stop; then varying, as an inverted S, so as to be horizontal at the level of the lower chase—when the stop is removed the balls start with nearly equal acceleration, then having accelerated, when they reach the steep slope they are separated. ”