Improvements in or relating to apparatus for drilling and working in underwater wells

摘要

873,482. Boring earth. SHELL OIL CO., CONTINENTAL OIL CO., SUPERIOR OIL CO., and UNION OIL CO. OF CALIFORNIA. Sept. 3, 1957 [March 28, 1957], No. 1109/61. Divided out of 873,480. Drawings to Specification. Class 85. The subject-matter of this Specification is substantially the same as that described in Specification 873,477 but the claims differ.