Page:Popular Science Monthly Volume 27.djvu/566

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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 peculiar 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.


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SKETCH OF M. CHEVREUL.

"PERHAPS never in the history of science," said the London "Lancet" a year and a half ago,[1] "has a distinguished career equaled in its length that of M. Chevreul; . . . and it is probably altogether 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 before 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 Academy 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

  1. December 24, 1883.