sentences:  The Deep-Tow instrument was notably used in Project FAMOUS, the first-ever geologic mapping of the median rift valley of the Mid-Atlantic Ridge.Spiess recognized that obtaining detailed images of the sea floor was only one component that is necessary for making geologic maps of the deep-sea floor.The position of the deep-tow vehicle must be known to within a few meters, thus leading to the development of the first sea-floor acoustic-transponder positioning system for working in deep water.