Improvements in and relating to blasting when using water tamping

摘要

960,199. Blasting devices. D. BAAS. Sept. 17, 1962 [April 14, 1962], No. 35357/62. Addition to 939,049. Heading F3A. A modification of the circuit-breaker described in the parent Specification comprises an open-ended cylinder 1 having an electrically conductive inner coating divided into parts 3a, 3b by a ring 2 of insulating material and a contact maker 6 freely suspended within the cylinder 1 by resilient threads 8 fastened to cross-members 5, Fig. lb (not shown). The contact maker 6 is a closed buoyant cylinder having an electrically conductive coating 7. When water enters the cylinder 1, the contact maker floats upwards and bridges the ring and so connects the two leads 4. Instead of the cylinder 1, a perforated hollow ball may be used to hold the contact maker, which is then spherical.