548 THE POPULAR SCIENCE MONTHLY. 



The ancient Irish year was curiously formed. The unit being the 

 week of seven days, they computed 12 months of 30 days each, to 

 which they added four supplementary days to give an even number of 

 weeks, and then every six or seven years they added a week, so that 

 the years might be of 52 or 53 weeks. 



The last essay in reforming the calendar was made during the 

 French Revolution, partly with the object of introducing the decimal 

 system into the calculation of time, and partly to eliminate everything 

 relating to the Roman Catholic or any other religion. The months, 

 of thirty days each, were given names, generally typical of some pe- 

 culiar feature characterizing them. They were divided into three 

 periods of ten days, or decades, to take the place of the weeks, with six 

 intercalated days (five in leap-years) at the end of the last month. The 

 intercalation was not periodic, but was based on exact astronomical 

 calculations. This calendar was used for thirteen years, beginning with 

 the proclamation of the republic, on the 22d of September, 1792. 



In the lunar year, the months are alternately of 29 and of 30 days, 

 the moon's synodical revolution taking place in about 29 days. The 

 lunar cycle of the Mohammedans comprises a period of thirty lunar 

 years, during which the seasons begin at all times of the year. If a 

 Turkish festival now falls in the middle of the winter, it will, fifteen 

 years hence, be celebrated in the summer. Translated for the Popular 

 Science Monthly from the Revue Scientifique. 



*+ 



SKETCH OF M. CHEVREUL. 



" ~T~)ERHAPS never in the history of science," said the London 

 J- "Lancet" a year and a half ago,* "has a distinguished career 

 equaled in its length that of M. Chevreul ; . . . and it is probably alto- 

 gether unique for a savant to be able, at one of the most distinguished 

 scientific societies in the world, to refer to remarks which he made be- 

 fore the same society more than seventy years previously." The allusion 

 is to a reference with which the veteran chemist had supplemented a 

 communication he had read a few days before to the French Academy 

 of Sciences : " Moreover, gentlemen, the observation is not a new one 

 to me. I had the honor to mention it here, at the meeting of the Acad- 

 emy of Sciences, on the 10th of May, 1812." When asked in 1883 if 

 he had seen a certain piece at one of the theatres, he answered, " No, I 

 have not been inside the doors of a theatre since Talma's death in 

 1824," or fifty-nine years previously. Talking of the weather during a 

 mild period in the winter of 1883, he said, " The severest winter I ever 

 experienced was that of 1793," indicating the recollection of a fact 

 ninety years old. M. Chevreul appears to have come from a long-lived 



* December 24, 1883. 



