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A time scale must be based on some happening which takes place regularly. The regular rotation of the Earth, which governs the rising and setting on the Sun, or the passage of a star across the true north-south line (meridian), gives us our time-unit, the day, which is subdivided into hours, minutes and seconds. The time between successive transits of a star across the meridian is known as a sidereal day (sider, sideris, a star), and standard clocks are checked against this time.

Although sidereal time is of great importance to the astronomer, it is the mean solar day (the average time between successive transits of the Sun across the meridian) which is the unit on which the hours, minutes and seconds of daily life are based.

The division of the day into its parts is brought about by means of clocks. The Egyptians made use of the rate at which water or sand flowed through a hole in a vessel, while some people used the regular burning of a candle or oil-lamp. Most modern clocks are based on some type of oscillating system. A pendulum swings to and fro in a time which is almost independent of the extent of the 'swing.

ft. = foot фут (30,5 см)

the further he goes чем дальше он удаляется

gallon (мера жидких и сыпучих тел; англ. 4,54 л, амер. 3,78 л)

Ib. = libra - pound фунт (англ. = 453,6 г)

mile миля (англ. = 1609 м)

ounce унция (28,3 г)

say the coin предположим, монета

a sidereal day звездный день

stone мера веса (около 6,35 кг)

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