80 REPORT—1885. 
only takes the precaution to eliminate through linear interpolation any 
sudden and individual disturbances which in such days at times 
show themselves. The differences of all the observed data from the so 
obtained values of the normal daily path in each month I regard as 
deviations from the normal, effected by some disturbing circumstances. 
Should, e.g., all these deviations for all hours’ values be put in the form 
of a table, and should each be distinguished as positive and negative, 
either by certain signs or, according to Balfour Stewart, by different 
colours, we should recognise at once, from the similarity of the signs and 
the nearly similar size of the figures, whether a day was disturbed uni- 
formly positive and negative, and from the recurrence of the positive 
figures at certain hours, and negative in certain cther hours on different 
days, whether the disturbance points to a new period different from 
the normal daily periods. In order to establish these conclusions with 
numerical correctness, it is best to group the deviations according to their 
extent, separating negative and positive, and then to investigate their 
periodicity as Buys Ballot has proposed. 
Herr D. Miller has worked out according to these principles the 
jottings of the magnetograph in the Observatory of Pawlowsk for the 
period of the International Polar Expedition, August 1882 to August 1883. 
His important results have been laid by me before the Imperial Academy 
of Science, May 21 and June 2, 1885, and are at present published 
in the ‘ Repertorium for Meteorology.’ Without entering into the details 
of Herr Miiller’s results, I only remark that the success of the first 
attempt seems to speak well for this method. The course of the contained 
normal daily path in the separate months has unexpectedly become regular 
for all three elements—declination, horizontal and vertical intensity, and 
also for inclination and total intensity. The days’ means of the normal 
days show proportionally small differences, and only the greater devia- 
tions have a pronounced different periodicity, which again is different for 
the positive and negative. Herr Miiller has therefore only pointed out 
the latter as disturbances, and the former as simple oscillations about the 
normal path. For two months, October 1882 and March 1883, I have 
prepared a comparison of Sabine’s method for the declination with that 
got by Miiller from my method. Here, in the calculation according to 
Sabine, + 2 is assumed as the limiting value for the expulsion of dis- 
turbances ; and these operations for individual hours were repeated as 
often as eight times. In spite of this, there is shown by a glance at the 
enclosed table that even by the Sabine method the influence of the pre- 
vailing positive disturbances late in the forenoon, and of the maximum of 
the negative disturbances in the afternoon, could not be eliminated from 
the result. I have the intention to get worked out according to this new 
method, which, in short, is applicable to all these data, certain traces of 
magnetographs in St. Petersburg and later in Pawlowsk from 1870, and 
have for this purpose for the whole period chosen the normal days out of 
the photograms. 
From this came the unexpected result that the number of these at the 
time of the minimum of the sun spots is not so much greater than at the 
time of the maximum. 
