COMMON THINGS TIME. 



mulated effect of the past errors was that the real epoch of the 

 spring equinox had fallen ten days behind the nominal day of its 

 occurrence, which was the 21st March. The future cause of error 

 was that an additional day every fourth year was too much, but 

 that 129 years must elapse before the redundancy would cause the 

 equinox to be one day behind its time. 



104. To remedy the consequence of past errors, it'was decreed 

 that the days of the months should be all expressed by number;-;, 

 greater by 10 than those by which, according to the succession of 

 time, they were expressed. Thus the llth March, 1582 (the year 

 in which the reform took place) was decreed to be the 21st March, 

 and in like manner all the other days of the year were augmented 

 by 10. By this expedient the last ten days of 1582 were thrown 

 over into 1583, inasmuch as the 21st December, 1582, became 

 31st December, 1582, and consequently 22nd December, 1582, 

 became 1st January, 1583. 



The day of the vernal equinox thus recovered the date - of 

 21st March. How it was secured in the undisturbed possession of 

 that date, we shall now see. 



By following the established rules of the Julian calendar, it 

 would have been one day behind its date in 129 years from 1582, 

 that is in 1711. To prevent this, it was decreed that the year 

 1700, which would by the Julian calendar be a leap year, should 

 be a common year. One day being thus omitted, the equinox of 

 1711 would be restored to its date of 21st March. In like manner 

 it would be again a day behind in 1840. This was in like 

 manner to be prevented by making 1800 a common year, which 

 ought to be a leap year. Again it would be a day behind its 

 time in 1969, which would be set right as before by making 1900 

 a common instead of a leap year. Another period of 129 would 

 go to 2098, which was remedied by making 2100 a common instead 

 of a leap year. 



Thus the equinox would be kept right by making three suc- 

 cessive secular years 1700, 1800, and 1900 common years instead 

 of leap years, leaving 2000 a leap year, but making 2100 a 

 common year instead of a leap year, and going on from century to 

 century in the same manner, leaving every fourth secular year a 

 leap year, but making all the others common years. The series 

 of secular years would therefore be as follows : 



1700 Common 2300 Common 



1800 ,, 2400 Leap 



1900 ,, 2500 Common 



2000 Leap 2600 ,, 



2100 Common 2700 ,, 



2200 ,, 2800 Leap, 

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