http://web.mst.edu/~rogersda/military_service/periscopes.jpg Submarines carry all kinds of extendable devices in their sail which allow them to sense
{"Image DocumentName": "Submarines carry all kinds of extendable devices in their sail which allow them to sense above the ocean s surface. This shows a deployed periscope (on left) and other electronic surveillance and communications probes.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}