File:The Bell System technical journal (1922) (14753619354).jpg

Identifier: bellvol36systemtechni00amerrich (find matches)
Title: The Bell System technical journal
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company
Subjects: Telecommunication Electric engineering Communication Electronics Science Technology
Publisher: (Short Hills, N.J., etc., American Telephone and Telegraph Co.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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Text Appearing Before Image:
■V- AQ -AP -AO AT \ \AR ^AU AS - 38 45 44 43 42 Fig. 9 — Profiles across the mid-ocean canj^on. 1067
Text Appearing After Image:
Fig. 10 — Location of cores, rock dredges, and bottom-photograph sites of Columbia Ujvarsity expeditions in the North Atlantic, 1946-1956. 1068 OCEANOGRAPHIC INFORMATION FOR SUBMARINE CABLES 10G9 (c) Sound investigations. (d) Investigations of magnetic and gravity fields, and heat flow.Visual inspections have been performed by divers in depths up to only about two hundred feet. Vessels such as the bathyscaphe must beemployed for greater depths but their design precludes any extensiveobservation of the sea floor. Bottom photographs in shallow waters are fairly numerous but thosetaken in depths greater than 1,000 fathoms are still rare. Good photo-graphs usually show an area approximately 5 ft by 8 ft and are focussedwell enough to make objects and organisms ; inch in diameter clearlyidentifiable. A compass and a current indicator are often lowered withthe camera and included in the photograph. These provide indicationsof current velocity and direction and a means of orienting the bot

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