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of Mr. Mallet, Avhich have so lately been before the Academy, 

 show that even the elasticity of granite is lowered by its joints 

 and veins almost to a parity with incoherent sand. A gradual 

 change of direction, such as is given by the little valley that 

 I have described as intervening between me and the Termi- 

 nus, has no effect ; but I think that a more considerable one 

 might exert considerable power in deadening the wave. It, 

 therefore, is not unlikely that a mass of discontinuous rock, 

 rising abruptly one or two hundred feet above a railway, 

 would be but little affected by it. 



