Chemical Change A change that produces one or more new substances and may release energy. Chemical Property A second set of properties in all kinds of matter. Circuit A path that is made from an electrical current. Claws A sharp, usually slender, and curved nail on the toe of an animal.
Originally, sandglasses were used as a measure for periods of time like the lamps or candles, but as clocks became more accurate they were used to calibrate sandglasses to measure specific periods of time, and to determine the duration of sermons, university lectures, and even periods of torture.
And midnight means the start of the next day, so we don't count that again. 2 x 11 = 22 times in any 24 hours. You can confirm this by taking any clock that you can set the hands on, like a wall clock or alarm clock-start the hands at 12 am, and spin the hands manually, counting all the times that the hands meet.