Feb. 24, 1876] 



NATURE 



129 



at the conclusion that the results obtained for the solar 

 and lunar actions did not exclude each other, but that 

 both sun and moon were concerned in the changes of the 

 earth's magnetic intensity ; and that possibly the varia- 

 tions in the character of the single oscillations were due 

 to the sun and moon sometimes acting in the same and 

 sometimes in opposite directions ; just as in the case of 

 the oceanic tides, for which the differences would be even 

 greater were the solar more nearly equal to the lunar 

 action. 



This conclusion is put to the test ; the mean variations 

 derived from the observations for each of two successive 

 years are calculated for periods of 26, of 27*3, and of 29*53 

 days, the two latter being the times of the lunar, tropical, 

 and synodical revolutions respectively. The variations 

 for each of these three periods corresponding to the posi- 

 tions of the moon and of a given solar meridian for each 

 day of the year are then added together; the sums should 

 represent the total actions of the two bodies for each day, 

 and if no other causes are in question, they should agree 

 with the observed variations. 



I have shown that when the calculated results are pro- 

 jected so as to form a red curve, on the same mean line 

 as a black curve representing the observations, the two 

 agree very nearly with each other throughout the two 

 years. The different durations and ranges of single oscil- 

 lations, and the total disappearance of the latter in certain 

 months, are found to be produced, as was supposed, by 

 the greater or lesser agreement or opposition of the three 

 actions. 



These results demonstrate, I think, not only that 

 the sun's rotation and the moon's revolutions produce 

 variations of the earth's magnetic force, but that all the 

 marked variations are really due to these causes. 



There appears to be one exception to the generality of 

 this conclusion, in sudden great changes, generally dimi- 

 r.utions, of the earth's magnetism, which appear of variable 

 magnitude tnd apparently at irregular intervals. I 

 have examined these cases, and find that if a consider- 

 able diminution of intensity happen suddenly when a 

 given solar meridian is in the same plane with the earth, 

 that a similar sudden diminution generally occurs twenty- 

 six days or some multiple of twenty-six days after, when 

 the same solar meridian and the earth are again in the 

 same plane. In one case the sudden loss of force begins 

 five times in succession at the exact interval of twenty-six 

 days. 



If we examine these cases of successive disturbance 

 when a given solar meridian arrives opposite the earth, 

 we are induced to conclude either that the solar action 

 exists only for this position, that is to say, that the earth 

 is its cause ; or that the action is continuous, but, unlike 

 light and heat, is propagated only in one direction (or 

 plane) ; or, which seems more probable, that the medium 

 through which these actions are transmitted proceeds 

 from the sun, is not uniformly distributed around it, nor 

 always distributed in the same way. This idea may aid 

 in explaining many facts in terrestrial magnetism for 

 which hitherto no clue has existed. 



We arrive then at the conclusions that the variations 

 of the daily mean magnetic force are due to causes ex- 

 ternal to the earth, depending on the sun's and moon's 

 motions ; that all the principal variations of this force 

 can be calculated approximately for each day in twelve 

 months, on the hypothesis that the actions of these bodies 

 are constant throughout the year for the same positions 

 relative to the earth ; and that the great magnetic dis- 

 turbances (accompanied by the aurora borealis) are due 

 to actions proceedmg from certain parts of the sun's 

 surface, since so many of them repeat themselves at inter- 

 vals of twenty-six days, when the same solar point returns 

 opposite the earth. It appears from other investigations 

 that the sun's rotation produces marked effects on oiar 

 atmosphere. J. Allan Broun 



PHYSICAL SCIENCE IN SCHOOLS 



VWE have received the following important commu- 

 ^ ^ nications on this subject : — 



Dr. Watts has shown in last week's Nature, p. 311, 

 how the Regulations of the Oxford and Cambridge 

 Schools Examination Board affect injuriously the in- 

 terests of science in certain schools, viz., those in which 

 boys have "studied science instead oj the older well- 

 established subjects of classics and mathematics." 



But it is fair to say that these are not the schools 

 which are common in the country, even if they are to be 

 found at all ; and the business of the Board was rather 

 to examine effectively what schools profess to teach, than 

 to direct their studies into a new line. 



I do not think, or mean to say, that the Board and the 

 headmasters, who are believed to have influenced its 

 regulations, have acted in the interests of science alto- 

 gether ; but the way they have damaged its interests in 

 all the principal schools of the country is not by making 

 it " a refuge of fools," as Dr. Watts suggests. 



I will, with your permission, point out how the Regu- 

 lations affect the position of science at Rugby and similar 

 schools. 



The main inducement a boy has to go in for a cer- 

 tificate is to be excused the " Little go," if he is gomg to 

 Cambridge ; or " Responsions," if he is going to Oxford. To 

 be excused any part of the Little go he must pass in Latin, 

 Greek, Elementary Mathematics, and Scripture Know- 

 ledge ; to be excused the whole of it, he must also pass 

 in Additional Mathematics. And since four subjects are 

 all that is required, these four or five are all that he wiU 

 take up. To be excused Responsions, he must pass in 

 Latin, Greek, and Elementary- Mathematics, and in some 

 one other subject. Naturally, he selects the easiest This 

 will be French, or Scripture Knowledge, or History, or 

 English, according to his tastes. That the three last of 

 these subjects are easier than any Natural Science is cer- 

 tain. All boys know something of them ; they are not 

 wholly new to any boy, and it is at any rate commonly 

 believed here that boys have passed and obtained distinc- 

 tions in them with very great ease. And boys have pro- 

 bably learned French for the last eight years of their lives. 



It follows that boys destined for Oxford who know 

 something of science do not take it up, as it would be 

 profitless to do so, unless it is distinctly easier to them 

 than any other subject they could select as a fourth sub- 

 ject ; and boys destined for Cambridge do not take it 

 at all. 



It should also be observed that though the examina- 

 tion papers last year were very easy, yet the range they 

 cover is rather large. What does " the Elementary Parts 

 of Inorganic Chemistry" mean? This can only be dis- 

 covered by a study of the examination papers. And 

 certainly the wording is loose enough to enable the ex- 

 aminers to set harder papers, if it is found that the 

 boys can do them. 



The only important alteration in the description of the 

 examination in Natural Science that I would make is a 

 very obvious one, and one that might at once be made if 

 any of the headmasters on the Committee would care to 

 ascertain and represent to the University Board the in- 

 terests of science at schools. It is to divide Group IV. 

 like Group II., making the present part the elementary 

 subjects, and adding to it an additional subject, viz., a 

 practical examination in analysis (inorganic, qualitative), 

 as necessary to be passed by those who wish to gain 

 honours in science. To make this change would at any 

 rate be a guide to a sound opinion on teaching science, 

 though, while the grouping remains as it is, few boys 

 will trouble the examiners. 



The study of science at schools has now, it seems to 

 me, entered on a fresh and not altogether unhealthy 

 phase. Ten or twelve years ago there was an outcrj- for 



