TIME AND PLACE 19
until it returns to it the following day. This is the exact time of one complete revolution of the earth upon its axis; it is the only absolutely uniform motion observed in the heavens, having undergone no change since the earliest observations on record.
Owing to the motion of the earth in its orbit about the Sun a solar day is longer than a sidereal day, for as the Sun moves farther to the east during the time of the earth’s daily rotation on its axis, the earth must turn further upon its axis before a certain meridian comes in line with the Sun. The solar day is therefore about four minutes longer than the sidereal day, but owing to the variable motion of the earth in its orbit and the obliquity of the ecliptic previously mentioned, this difference also varies each day.
In bygone days clocks in each city or hamlet differed from the timepieces of every other place because all were set to local time, but this caused much confusion to the traveling public; therefore America adopted what is called Standard Time on November 18, 1883. For persons born subsequent to that date a correction is necessary to convert the time shown by clocks to true local time, for that is the time used to calculate the horoscope. The diagram will aid students to understand what Standard Time is, how it overcame confusion, and how the before-mentioned correction is made.
It was suggested, that if the country be divided into time-zones each about fifteen degrees of longitude