Page 8 Advertisements Column 5

Otago Daily Times, Issue 15824, 24 July 1913, Page 8

Although all underground borings such as mine galleries arc subjected to tha effects of the weight of overlying strata as a natural consequence, it appears to be found that the effects which are noticed in such cases aro not entirely duo to the weight of' the soil, so that 'other causes must be supposed, especially the action of the latent pressure coming from oarth movements which may. been maintained clear up to the pwent time, Tho French scientist, Lapiarcnt, was led to think that nil the rock Btrata of the globo are more or less compressed from moohanical movements which they underwent in the course of agos. Chief Engineer Marin, of tho Levin mines in France, made some observations on this subject. While mine tunnels were being put through, or shortly after, he noticed slow movements of tho ground, which cannot alwaye be accounted for by the simple weight of overlying earth," Certain places showed an abnormal pressure at various lovels underground, and at other points he found very great pressure at small depths, and on tne contrary low pressures at great depths. Considering various observations, he is led to believo in a latent pressure in rock strafe.