can you say me what are sundials, water clocks,and sand clock?
Sundials-A sundial is a device that determines the time of day by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, often a thin rod or a sharp, straight edge. As the sun moves across the sky, the shadow-edge aligns with different hour-lines.
Water clocks- A water clock is a timekeeping device which uses a flow of water to measure time. As you might imagine, a water clock is not as accurate as most modern time-keeping devices, but when waterclocks were first developed, they were quite adequate for the times. It is believed that waterclocks may be among the oldest of devices used to keep time, since written accounts of them date to around 4000 BCE, with physical examples from Egypt dating to 1500 BCE.
Sand clocks- sand timer, sand clock, measures the passage of a few minutes or an hour of time. It has two connected vertical glass bulbs allowing a regulated trickle of material from the top to the bottom. Once the top bulb is empty, it can be inverted to begin timing again. The name hourglass comes from historically common hour timing. Factors affecting the time measured include the amount of sand, the bulb size, the neck width, and the sand quality. Alternatives to sand are powdered eggshell and powdered marble (sources disagree on the best material). In modern times, hourglasses are ornamental, or used when an approximate measure suffices, as in board games.