400 



SCIENCE 



[N. S. Vol. XL. No. 1029 



earlier; the second curve contains those of 

 the earth's longitude; the third, those of 

 Mercury's longitude. [By accident the 

 mean motion correction has been left in the 

 earth curve; the zero line is therefore in- 

 clined instead of being horizontal.] It 

 will be noticed that the scales are different 

 and that the earth curve is reversed. In 



satellites the same way but to different de- 

 grees. 



The lowest curve is an old friend, that of 

 Wolf's sunspot frequency, put there, not 

 for that reason, but because the known con- 

 nection for the last sixty years between 

 sunspot frequency and prevalence of mag- 

 netic disturbance enables us with fair prob- 



MoON 



Mercury 



<Zl?) 



yvA^/\k^A^/(\/\^/\/M/ 



.A 



..«— .Q-.-tl 



spite of the fact that the probable errors of 

 the results in the second and third curves 

 are not much less than their divergencies 

 from a straight line, I think that the cor- 

 relation exhibited is of some significance. 

 If it is, we have here a force whose period, 

 if period in the strict sense it has, is the 

 same as that of the effect : the latter is not 

 then a resonance from combination with 

 another period. "We must therefore look 

 for some kind of a surge spreading through 

 the solar system and affecting planets and 



ability to extend the latter back to 1750. 

 With some change of phase the periods of 

 high and low maxima correspond nearly 

 with the fluctuations above. The eleven- 

 year oscillation is naturally eliminated 

 from the group results for the earth and 

 Mercury. One might expect it to be pres- 

 ent in the lunar curve, but owing to its 

 shorter period we should probably not ob- 

 tain a coefficient of over half a second. 

 [Notwithstanding this fact, it is a valid ob- 

 jection to the hypothesis that there is no evi- 



