60 Dr. van Rijekevorse] on Irregularities in the Yearly 



irregularity in one yearly curve, either for any magnetic or 

 any meteorologic phenomenon, a corresponding irregularity 

 will be apparent in all the other curves for the same region, 

 if not alwavs. as will be shown, for the same station. But 

 even if some doubtful point should remain. J. think proof is 

 so abundant even now that, even if I should be found ulti- 

 mately to have overrated it in some instances, this can no 

 more invalidate the principle. 



Another very valuable test for my opinion that the ana- 

 logies pointed out here cannot be accidental, is furnished by 

 Ihis diagram for Paris *. The uppermost line shows the 

 temperature as resulting from 130 years' observations. The 

 lower one shows the magnetic declination, but this is the 

 result of only 12 years of observation between 1785 and 1796 

 bv Cassini. Xot verv good observations we should now call 

 them : there are several breaks and changes of continuity 

 which I had to bridge over as best 1 could. Moreover, the 

 readings were not taken rigorously at the same hour of the 

 day. 1 think this is more than sufficient, with such a short 

 series, to account for a certain number of doubts and queries 

 which I cannot explain away. But upon the whole 1 think 

 it will be admitted that the concordance between the two curves 

 is inst as satisfactory as in the large diagram. Therefore, at 

 least also in this respect, things a century ago were what they 

 are now. 



One possibility I must point out. It may be that one or 

 more of these curves ought in reality to be inverted. This 

 seems preposterous. Still, with so many maxima and minima 

 following each other in rapid succession, it is not so. (I have 

 numbered 17 maxima; but I am perfectly sure that a larger 

 number than this are just as real as these, only they are so 

 small as not to be detected yet, as long as we are obliged to 

 smooth down the curves to such an extent.) Take a maximum 

 and the following minimum, which slightly precedes the cor- 

 responding feature of the other curves, and invert the curve : 

 they will then simply be converted into a maximum and a 

 preceding minimum slightly lagging behind a similar feature 

 in the other curves. One of my magnetic curves is inverted 

 — needless to say which, because a scale may read from right 

 to left or from left to right. But also I have had serious 

 doubts as to the advisability of inverting one or two others. 



You will see at once that in some cases my vertical lines f 



* This diagram is not reproduced, as the text is sufficiently clear 

 without it. 



f Continuous verticnl lines connect the maxima, lines of long dots the 

 minima belonging together. 



