136 



SCIENCE. 



LVol. IV., No. 80. 



and also that the great circle through Krakatoa and 

 Washington passes nearly over the poles, and in this 

 direction the velocity seems to be still smaller; so 

 that the phenomena for this region become more and 

 more complicated for each succeeding transit, and, 

 after the first two or three in each direction, rather 

 difficult to unravel. Unfortunately, the other few 

 barographs in use on this side the Atlantic — to all 

 of which the great circles from Krakatoa take an 

 entirely different direction from that to all the eastern 

 stations — are not so sensitive as the best Washington 

 barograph, and do not help much beyond the first 

 two transits of the waves in each direction. 



It is noteworthy that these barometric disturbances 

 were first noticed at Mauritius early in September, 

 soon after their occurrence, and were at once inde- 

 pendently attributed to the Krakatoa eruption, but 

 were supposed to be due to successive series of ex- 

 plosions day after day, until the publication long 

 after, in Nature, Dec. 20, of the discovery of Mr. Scott 

 and Gen. Strachey, showed them to be due to a single 

 series of waves, travelling round and round the globe, 

 from the explosions of Aug. 27. 



Perhaps the most interesting and important fact 

 appearing from these Mauritius records, in connec- 

 tion with these waves, is the difference in time of 

 transit round the earth, as compared with that de- 

 duced from the European stations by Gen. Strachey. 

 The paths of the waves from Krakatoa to the latter 

 stations are, on the average, something like 40° north 

 of west (from Krakatoa), and, to Mauritius, about 

 20° south of west; so that the great circles make an 

 angle of about 60°. The difference in time of transit 

 on these circles, and in the two directions on each, 

 are best shown in the table below, where, following 

 Gen. Strachey's nomenclature, the successive waves 

 are numbered from i. to vii., and the odd numbers 

 denote the transits from east to west, and the even 

 those from west to east. 





o 



> 



o 



o 

 > 



c 

 a 



> 

 o 



> 

 > 



c 

 a 





S. E. to N. W. 



N. W. to S. E. 



European . . . 



h.m. h.m. h.m. 



37 4 36 54 36 48 



1 



h.m. 

 36 57 



35 24 



h.m. 

 35 9 



h.m. 

 35 17 





N. E. to S. W. 



S. W. to N. E. 



Mauritius . . . 



h.m. 

 34 34 



h.m. 

 34 37 



h.m. 

 34 43 



h.m. 

 34 38 



h. m. 

 35 15 



h.m. 

 36 13 



h.m. 

 35 44 



Of course, all the above numbers are liable to an 

 uncertainty of several minutes; but, even when this is 

 considered, the differences are quite marked. While 

 the average time of transit via Europe is lh. 40 m. 

 greater going west than going east, via Mauritius 

 it is lh. 6m. less; indicating, as far as atmospheric 

 currents are concerned, an opposite effect on these 

 two great circles, which make, roughly, an angle of 60° 



with each other. The peculiar progression in the 

 individual periods for successive transits can hardly 

 be wholly accidental, and is in opposite directions; 

 the waves via Europe going (in each direction) faster 

 and faster, and via Mauritius being retarded. Per- 

 haps the most striking difference is, that the mean 

 period, regardless of direction, is nearly 1 h. less via 

 Mauritius than via Europe, — a fact most strikingly 

 shown by taking the whole interval vii.— i., which, for 

 the five European stations where vii. was traced, gives 

 110 h. 50 m., and, for Mauritius, 103 h. 54 m. ; showing 

 the wave to have gone three times round the earth 

 seven hours quicker via the more equatorial route, 

 which is probably partly due to the higher tempera- 

 ture of the atmosphere along this path, and also, 

 perhaps, to the fact that this great circle pas:?es over 

 about as little land as any that can be drawn through 

 Krakatoa. 



These facts show more forcibly how complicated 

 the phenomena must have been near the antipodes 

 of Krakatoa, and also at the latter place, upon the 

 returns of the waves there. It is evident, that, when 

 the Krakatoa committee of the Royal society shall 

 have collected all the data, many interesting problems 

 will arise in connection with these atmospheric 

 waves; and, in connection with the distribution of 

 Krakatoa dust by the upper currents (which, it may 

 now be regarded as pretty well settled, was the cause 

 of the wide-spread red-sunset phenomena), the explo- 

 sive eruption of Krakatoa promises, if thoroughly 

 investigated, to teach us more about the circulation 

 of our atmosphere than years of ordinary meteoro- 

 logical study could have done. H. M. Paul. 



Washington, July 29. 



OVERWORK IN GERMAN SCHOOLS. 



After forty-two years' experience, it is now vir- 

 tually conceded in Germany that physical exercise is 

 not a sufficient antidote to brain-pressure, but that 

 where the evil exists, the remedy must be sought in 

 the removal of the cause. 



Official action with reference to over-pressure has 

 been taken in Prussia, Saxony, Wiirtemberg, Baden, 

 Hesse, and Alsace Lorraine. In each instance it is 

 based upon the report of a commission of inquiry, 

 consisting of school directors, and members of school 

 boards, as well as physicians. 



The official action based upon the reports of the 

 commissions is embodied in decrees dealing with the 

 scope and method of teaching, the number and 

 hours of study in school, and the amount of home- 

 study. 



The Hessian government issued decrees about 

 home-study in 1877, and again in 1881. Complaints 

 of overwork increasing, a commission was appointed 

 to make further investigation, and report in full. 

 Their recommendations were, in the main, embodied 

 in the decrees of Feb. 23, 1883. By these decrees a 

 maximum of home-study was fixed for each class, 

 amounting for the lowest classes to an hour a day; 

 the quantity of Latin and Greek required was dimin- 

 ished; and all tests of the student's progress that 



