Analysis of information sources in references of the Wikipedia article "מדידת עומק המים" in Hebrew language version.
{{cite web}}: (עזרה); (עזרה), USACE publication EM 1110-2-1003.{{cite web}}: (עזרה){{cite web}}: (עזרה)In answer to the need for a more accurate depth registering device, Dr. Herbert Grove Dorsey, who later joined the C&GS, devised a visual indicating device for measuring relatively short time intervals and by which shoal and deep depths could be registered. In 1925, the C&GS obtained the very first Fathometer, designed and built by the Submarine Signal Company.
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