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lised nations now use, is based upon a close approximation to this length of the year.

The sidereal year is the interval between two passages of the sun past the same star. Its length is three hundred and sixty-five days six hours and nine minutes.

According to the Julian calendar, which was in use in Christendom until 1582, the year was considered to be exactly 365¼ days. This, it will be seen, was 11 minutes 14 seconds more than the true length of the solar year. Consequently, the seasons were slowly changing in the course of centuries. In order to obviate this, and have a year whose average length was as nearly as possible correct, a decree was passed by Pope Gregory XIII by which, in three centuries out of four, a day was dropped from the Julian calendar. According to the latter, the closing year of every century would be a leap year. In the Gregorian calendar 1600 was still to remain a leap year, but 1500, 1700, 1800, and 1900 were all common years.

The Gregorian calendar was adopted immediately by all Catholic countries, and from time to time by Protestant countries also, so that for the past 150 years it has been universal in both. But Russia has held on to the Julian calendar until this day. Consequently in that country the reckoning of time is now 13 days behind that in the other Christian countries. The Russian New Year of 1900 occurred on what we call January 13. In February of that year we only counted 28 days, but Russia counted 29. Hence, in 1901, the Russian New Year was carried still farther forward to our January 14.