Merkhet
（重定向自Merkhets）
The merkhet or merjet ("instrument of knowing") was an ancient timekeeping instrument. It involved the use of a bar with a plumb line, attached to a wooden handle. It was used to track the alignment of certain stars, if they were visible, in order to approximate the time at night (10 stars for the 10 hours of the night, with a total of 24 hours including 12 hours for the day, 1 hour for sunset, 1 hour for sunrise). In this way, it was more efficient than other contemporary devices, such as sundials, which were rendered useless during the dark.