| 摘要 |
745,980. Blasting rock. ASHURST, T. Feb. 5, 1954 [Feb. 5, 1953], No. 3463/54. Class 68(1) An explosive - charged borehole is stemmed on the wedging engagement of the complementary, obliquely-extending surfaces 3, 6 of the members 1, 5. The concave leading end 2 of the first inserted member is composed of a more friable material than the rest of the member. Recesses 4 and 4<SP>1</SP> are provided in the outer ends of the members 1, 5 to facilitate insertion or removal of the members. Grooves 8, 8<SP>1</SP> in the members align on the engagement of the members to provide a passage for a fuse or leads of the detonator of the explosive charge 10. The members may be formed of concrete, wood, or baked clay. |
