MOUNT WILSON OBSERVATORY. 



211 



The reversal of polarities observed at the last sun-spot minimum has led 

 us to keep a close watch for spots in high latitudes, which sometimes appear 

 well in advance of the coming cycle. The first case of this kind was detected 

 by Ellerman on June 24. A small single spot, found at N. lat. 31°, was 

 classed magnetically as V 4. No companion was seen, and the spot did not 

 appear again. But in view of its high latitude and the fact that its polarity 

 was opposite to that of regular preceding spots in the northern hemisphere, 

 it appears to be a forerunner of the coming cycle. Owing to partial cloudiness, 

 no calcium spectroheliograms could be made, and the position of the spot 

 with reference to the surrounding flocculi is uncertain. 



A very exceptional number of irregular spots (those having polarities 

 opposite to the regular rule) was discovered during the first four months of 

 1922. This led us to tabulate the irregular spots of previous years, with the 

 results given in the following table: 



Polarity of sun-spots 1908-1 913 and during present cycle. 



x The first 8 months of the year. 



Five irregular spots, out of a total number of 46, were observed during the 

 first eight months of 1922, giving the unusually high proportion of 10 per 

 cent. In 1921, however, 4 of the 5 irregular spots recorded during the year 

 were among the 32 spots seen in the third quarter, thus corresponding to 

 nearly 13 per cent. In the first quarter of 1920 over 5 per cent of the 39 

 spots were irregular in polarity. The important feature of the irregular spot 

 of June 24, 1922, is its very high latitude, which almost certainly marks its 

 inclusion in the next cycle. 



In the above table the proportion of irregular spots is given as a percentage 

 of the number of spots classified, not of the total number of spots. The 

 ranges in latitude and the average latitudes are for all the spots, but no ten- 

 dency for the irregular spots to be grouped in any special latitude has been 

 found. 



A satisfactory plan of publishing the daily magnetic observations made 

 with the 150-foot tower telescope, by which the polarities and field-strengths 

 of all spot groups can be seen at a glance, has been worked out during the year 

 with the assistance of Mr. John L. Ridgway, who has made admirable speci- 

 men drawings. Similar drawings covering our entire series of records will be 

 prepared, and published after the close of the present spot-cycle. 



