MIRACLES OF SCIENCE 



of the boundaries whatever the pressure may be at 

 any part of the structure. The grains are virtually 

 within a closed surface. Any change in the piling of 

 their granules, then, must result in increasing the 

 spaces or interstices between the granules, just as 

 in the case of the sand bag. And it is these spaces, 

 which in Professor Mackenzie's experiment were 

 filled with colored water drawn into the bag, which 

 in the mass of ether granules constitute fissures, or, 

 in Reynolds' words, "singular surfaces of misfit." In 

 everyday terminology these are particles of matter. 

 Such particles or gaps form "surfaces of weakness," 

 and it is shown that the pressure of the medium is 

 less between those "negative inequalities" or surfaces 

 of weakness than it is on the outside. There is a 

 strain set up in the granular medium which produces 

 a curvature in the normal piling. And it is this 

 "strained normal piling" that produces pressure 

 which we interpret as gravitation. 



"Strained normal piling," says Reynolds, "implies 

 that, although the shape of the medium is strained, 

 so that the distances of the grains from their twelve 

 neighbors [each spherical granule is in contact with 

 twelve others] are no longer equal since the suc- 

 cessive 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 

 neighbors; so that when the strain is removed each 

 grain will find itself in normal piling with the same 

 neighbors." 



It is because of this curvature in the medium that 

 the pressure is Jess between the "fissi;res" that con- 

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