Rensselaer Union, Volume 8, Number 43, Rensselaer, Jasper County, 13 July 1876 — A Carious Phenomenon. [ARTICLE]

A Carious Phenomenon.

’ At a recent meeting of tlie Physical and Natural History Society of Geneva M. Theod. Turiettini, who has to make frequent visits to the boring of die Bt. Gothard tunnel, gave an account of a phenomenon whtehls frequently produced during the progreas as the work in the granltie mass of the mountain. When the rock is shaken by tlie explosion of a mine, the reports resulting from the explosion are not the only immediate ones produced. Afterward, and at equal intervals, other spontaneous explosions are produced at considerable distances from the mine hole, of which the cause is unknown, and which cause numerous accidents to die workmen. The phenomenon is new, and it appears to indicate in the very substance of the granite a species of tension inherent in its formation, and which, agitated at one point, is transmitted to a distance so as suddenly to disengage large fragments of material. It may be compared with the experiment daily made by the quanymen who work the erratic blocks in the valleys

of tbe Alps to obtain building materials. In order to obtain them they use wedges of wood which they drive into holes pierced for the purpose, and which, being wetted, chase by their expansion thi disjunction of the granitic masses. This disjunction is not produced by gradual fissures, as Jn the case of millstones, for example. It is always accompanied by an explosion more or less violent, and the two aisjolned surfaces cannot again be exactly fitted to each other. There is deformation of the material, leading to tbe presumption of a state of latent tension existing in tbe constitution of the rock itself, and which, a point hitherto quite mysterious, may throw light on the mode of formation of these ancient rocks. — Nature.