544 THE POPULAR SCIENCE MONTHLY. 



CUEIOSITIES OF TIME-EECKONING. 



By M. L. BARKE. 



THE natural unities for the measurement of time are three, and are 

 afforded by the rotation of the earth upon its axis, the revolution 

 of the moon around the earth, and the revolution of the earth around 

 the sun ; of which the mean values respectively are 24 hours ; 29 days, 

 12 hours, 44 minutes, 2*9 seconds ; and 365*2422 days. These num- 

 bers are incommensurable and wholly independent of one another. 

 But men have tried to connect them from the most remote ages, and 

 have devised the lunar-solar year, the duration of which is related to 

 the movements of the sun and the moon. Although this system may 

 appear complicated, it is in reality quite simple, for the sun and moon 

 spare man the trouble of calculating the days, while the years and 

 months write themselves in large characters in the appearance of the 

 sky and of vegetation. 



The lunar-solar year thus having its origin in Nature, is found in 

 the most ancient form of the Jewish calendar. The Israelite year was 

 so regulated that the feast of the Passover was celebrated on the four- 

 teenth day of the first month, when the barley to be offered in sacri- 

 fice was ripe at the full moon. This marked the first month of the 

 year, named Nisan, and served as the point of departure for the 

 twelve usual months. But, if the ripening of the barley did not occur 

 during the fortnight following the end of the year, another month 

 was intercalated, and the new year began with the next new moon. 

 If we desire an exact and rigorous measure, this form of year is 

 simply confusing. The Jews have years of twelve lunar months, of 

 twenty-nine or thirty days, to which is added a thirteenth month, 

 when the year is embolismic ; and they might contain 353, 354, 355, 

 383, 384, or 385 days. The Jewish calendar also included a period of 

 nineteen solar years, or a lunar cycle of 235 months. The years date 

 from the creation of the world, which is fixed by the Jews at October 

 7th, b. c. 3761. 



The Chinese month begins with the new moon ; the first month 

 when the sun enters Pisces, the second when it enters Aries, etc. But 

 if the sun does not enter a new sign of the zodiac with the new 

 month, an additional month is introduced, which is given the same 

 name as the preceding one, with a distinctive sign. The months are 

 of twenty-nine and thirty days, but there is no absolute rule for their 

 succession, nor for the place of the supplementary month, nor for the 

 intercalation of complementary years ; and, as the beginnings of the 

 months and the years are calculated from the movements of the celes- 

 tial bodies, the whole year is uncertain and changeable. In the diffi- 

 culty of ascertaining from what tables the ancient Chinese calculated 

 their astronomical elements, there would be great uncertainty in com- 



