Water Clocks
Remember that Jim Croce song about saving “time in a bottle?” The Ancient Greeks had something like this centuries before 1973. One of the earliest types of timekeeping device, the Ancient Greek clepsydra used the flow of water to measure the passage of time. Clepsydras used either intake or outtake methods … water filling a container or water emptying from a container … to measure time. Unfortunately, clepsydras were not portable. In fact, disturbing the clocks in any way messed up the timekeeping.