Fig: Dean Bumpus teaching Navy submariners BT class., 1943. Credit: WHOI Image Archives; Photo courtesy of WHOI Archives; with special permission of WHOI Digital Assets Licensing; from: https://images.whoi.edu/view-item?key=SXsiUCI6eyJ2YWx1ZSI6IjM5NDgzIiwib3BlcmF0b3IiOjEsImZ1enp5UHJlZml4TGVuZ3RoIjozLCJmdXp6eU1pblNpbWlsYXJpdHkiOjAuNSwibWF4U3VnZ2VzdGlvbnMiOjUsImFsd2F5c1N1Z2dlc3QiOm51bGx9fQ&WINID=1643768606696#6PlW-aAH2KcAAAF-uD5aUQ/39483

Background image: Bigelow Interior, office workers listed below(Brown, Patricia; Gallagher, Gloria S.; Lumbert, Doris; Post, Louis A.; Scharff, Eileen; Worthington, L. Valentine)., 1946. Credit: WHOI Image Archives; Photo courtesy of WHOI Archives; with special permission of WHOI Digital Assets Licensing; from: https://images.whoi.edu/view-item?key=SXsiUCI6eyJ2YWx1ZSI6Ijk4NDgzIiwib3BlcmF0b3IiOjEsImZ1enp5UHJlZml4TGVuZ3RoIjozLCJmdXp6eU1pblNpbWlsYXJpdHkiOjAuNSwibWF4U3VnZ2VzdGlvbnMiOjUsImFsd2F5c1N1Z2dlc3QiOm51bGx9fQ&WINID=1643768606696#6PlW-aAH2KcAAAF-uD5aUQ/98483

References:

Revelle, R., 1980. The Oceanographic and how it grew. In Oceanography: the past (pp. 10-24). Springer, New York, NY.

p. 16:

“Maurice Ewing and Allyn Vine streamlined the BT, as it was soon called, and shortened its response time, so that it could be lowered and raised from a fast-moving vessel.”

p. 20:

“Before the War began, naval officers testing the new acoustic echo-ranging gear for detecting and tracking submarines had found that this equipment was very effective at night and in the early morning, but in the afternoon the range at which a submarine could be detected diminished to a few hundred yards. These officers thought that the cause might be biological. Columbus sent Atlantis down to the Caribbean to exchange sonar pings and echos with the Navy’s test destroyer, and he and Maurice Ewing soon demonstrated that the “afternoon effect” resulted from the downward-bending of the sound rays and the formation of an acoustic “shadow zone” because of the heating of the surface waters during the daytime. They produced a seminal report on the transmission of sound in the sea in which they showed that the afternoon effect and many of the other vagaries of the sonar gear could be detected and allowed for by using the newly-developed bathythermograph.”

“The oceanographers attacked numerous problems that seemed to have military importance, such as the behavior of smoke at sea and the drift of life rafts, but they contributed most to the effectiveness and safety of American submarines. They invented a submarine bathythermograph which gave a continuous plot of the ocean water temperature against depth as the submarine dove. They then installed these instruments and showed the submariners how the temperature traces could be used to find an acoustic shadow zone, and ocean layers where the water density rapidly increases with depth. The submarine could float on these layers for hours with its engines off, not making a sound.”