| 摘要 |
1,168,095. Seismic prospecting charges. IMPERIAL CHEMICAL INDUSTRIES Ltd. 26 Jan., 1968 [10 March, 1967], No. 11316/67. Heading F3A. [Also in Division H4] Elongated explosive charges for marine seismic prospecting are strung end-to-end by means of non-explosive intermediate members of sufficient length to prevent communication of detonation from one charge to the next and offering a drag sufficient to draw the charges into the water from a moving boat. In the Fig. 2 (Prov.) embodiment, 15 to 150 metre lengths of detonating fuze-cord 11 are linked by 15 to 50 metre lengths of string 12, the ends being joined by crimped metal sleeves 13. In use a disc or funnel-shaped metal member 18 is crimped to the first string length 12 to increase the drag offered by the string and draw the first charge 11 into the water from supply reel 14; an electrical detonator 19 is crimped to the charge end and a drag member 18 is added to the second string length 12; a metal slip-ring 21 around an insulated firing cable 16 is joined to charge 11 by string 22 and slides down cable 16 to engage a bare metal hook 17, whereupon a firing circuit comprising cable 16, hook 17, ring 21, detonator leads 24, 25 and the water is completed; the second string length 12 and drag member 18 draw the second charge 11 into the water. It is stated that the use of an elongated charge diminishes the effect on the seismographic record of the oscillation of the gas bubble produced by the detonation. Charges mentioned are detonating fuze-cords of granular P.E.T.N. (10 to 20 gm. per metre) or cyclotrimethylenetrinitramine surrounded by textile wrappings and encased in a flexible, waterproof, plastics envelope. |
