October 14, 1910] 



SCIENCE 



515 



ber, beginning with an era now nearly seven 

 thousand years ago. For example, January 1, 

 1911, will be Julian Day 2,419,038. The inter- 

 val between any two dates, one reckoned by 

 the old calendar, the other by the new, may 

 be easily found when their Julian numbers are 

 known, and these may be found or calculated 

 from almanacs. 



9. It is greatly to be hoped that, if a reform 

 is made in the calendar, we shall adopt the 

 plan of naming the hours in the day up to 

 24, so as to avoid the useless writing of a.m., 

 P.M., M., and the like, after the hour. In Italy, 

 for example, this simple plan is followed with 

 the best results. Andrew H. Patterson 



University of North Carolina, 

 Chapel Hill 



. 80IENTIFW BOOKS 

 Physical Science in the Time of Nero: Being 



a translation of the Qusestiones Naturales 



of Seneca. Pp. liv -|- 368. London, Mac- 



millan & Co. 1910. 



As the work of the most distinguished 

 thinker, and writer of his time, the " Quaes- 

 tiones Naturales " of Seneca (3-65 a.d.) com- 

 mands attention; and as a landmark in the 

 progress of human knowledge, it is of perma- 

 nent interest. In this volume of 368 pages, 

 the Roman philosopher did for his day what 

 Aristotle had done four centuries earlier in his 

 physical and meteorological treatises. Seneca 

 records the observations of previous writers, 

 adds many of his own and discusses all from 

 the lofty plane of the philosopher and moralist. 



This was only natural, as there was no 

 school of experimental science in Athens, 

 Alexandria or Rome in the lifetime of Seneca. 

 Indeed, many a century had to pass before the 

 inquirer into the phenomena and laws of na- 

 ture condescended to measure and weigh, to 

 use his hand as well as his intellect. 



The Greek mind had for abstract truth a 

 marked fondness which was unfavorable to 

 such drudgery as manipulation; the Roman, 

 while less subtle and more practical, also 

 showed a decided preference for general ob- 

 servation and philosophical speculation. 



Aristotle and his disciple Theophrastus were 

 the authoritative masters of the physical 



knowledge of Greek and Roman antiquity; 

 and to them Seneca frankly acknowledges his 

 indebtedness. But if from their pages on 

 meteorology, astronomy and physical geog- 

 raphy, he borrows the substance of some of 

 his chapters, a perusal of the seven books 

 which compose the " QuaBstiones Naturales," 

 will show that he has a clear way of describing 

 the phenomena of nature and an insistent way 

 of presenting his explanations and defending 

 his opinions regarding them. 



In the original, the work was divided into 

 eight books which, in course of transcription, 

 was reduced to seven by the union (probably) 

 of Books II. and III. 



Book I. treats of -the rainbow, halos and 

 mock suns; Book II., of lightning and thun- 

 der ; Book III., of the forms of water ; Book 

 IV., of snow, hail and rain; Book V., of winds 

 and general movements of the atmosphere; 

 Book VI., of earthquakes, and Book VII., of 

 comets. 



In discussing the rainbow, Seneca remarks 

 that it may be seen at night as well as during 

 the day, provided the moon is unusually 

 bright, to which he adds that the rainbow 

 colors are the same as those which are seen by 

 holding a glass rod obliquely in the path of 

 the sun's rays. The magnifying power of a 

 spherical water-lens did not escape his ob- 

 servant eye ; for he says that " letters, however 

 small and dim, are comparatively large and 

 distinct when seen through a glass globe filled 

 with water." 



In treating of earthquakes, he recognizes 

 three kinds of movements, viz., the quaking 

 " when the earth is shaken and moves up and 

 down " ; the tilting " when, like a ship, it leans 

 over to one side," and the quivering when " no 

 great damage is usually done." He also adds 

 the just observation that maritime districts 

 are those which are most frequently shaken. 



In his book on comets, he affirms that a 

 comet is not " a sudden fire, but one of na- 

 ture's permanent creations " ; and he does not 

 hesitate to berate one Ephorus for saying that 

 a certain great comet which had been " care- 

 fully watched by the eyes of the whole world 

 and which drew issues of great moment in its 



