New fathometer used at full speed. Washington, , May 7. Dr. Herbert Grove Dorsey of the Coast and Geodetic Survey has invented an instrument to secure the precise measurement. The machine sends a sound, pitched so high that it is above audibility, traveling thru the water a known speed, the sound hits the bottom and returns as an echo at 20 times per second. The fathometer is so accurate that a change in depth of three inches can be detected. the indications are made by a flash from a neon tube, viewed thru a rotating disc, the flash of light appearing to stand still and the depth is


New fathometer used at full speed. Washington, , May 7. Dr. Herbert Grove Dorsey of the Coast and Geodetic Survey has invented an instrument to secure the precise measurement. The machine sends a sound, pitched so high that it is above audibility, traveling thru the water a known speed, the sound hits the bottom and returns as an echo at 20 times per second. The fathometer is so accurate that a change in depth of three inches can be detected. the indications are made by a flash from a neon tube, viewed thru a rotating disc, the flash of light appearing to stand still and the depth is read as easily as a clock. The instrument indicator is installed in the pilot house (at the top of the machine) and the transceiver (the disc at the right of the machine [?]) is located in the hull of the ship, 5/7/1937


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