260 



P.KPORTS ON THE STATE OF SOIENCE, ETC. 



being about 7m., or one-third of the 21. It seems probable that this feature 

 is related to the liability mentioned earlier but not yet illustrated. An example 

 may now be given. In Seismological Notes No. 2 (dated March 1922 and 

 received in the early stages of this investigation), Prof. Omori deals with 'The 

 Severe Earthquake of December 8, 1921,' and his assistant, Mr. Yasida, gives 

 a list of forty-four afte-shocks. If these are arranged in lengths of 21m., 

 taking 21h. 31.7m., the time of the main shock, as origin, then the counts for 

 consecutive minutes are as below : — 



Minute Count 



Minute 



Count 



The sum of the three columns of counts given in the last column shows an 

 obvious maximum and minimum. This was the way in which the matter pre- 

 sented itself at the time— there is a noticeable third harmonic. But in the 

 light of the remarks ju3t made we should now arrange the material symmetrically 

 on both sides of the main shock (which is the zero-point) as below : — 



Sum 



10 



(6) 



Comparing this line with the ' Total ' line of 1913-17, we can hardly doubt 

 that the feature, which is a plain fact of observation with regard to a simple 

 series of repeated shocks, has been traced in the whole mass of earthquakes 

 wherever they occur. It is not so emphatic as in the simple Tokyo case— that 

 is scarcely to be expected, for several systematic terms have only been roughly 

 evaluated, especially the correction for latitude— but it is clearly there ; and 

 we can scarcely doubt that the earth generally is subject to some disturbance 

 of an oscillatory character with this period of 21.001548m., which has been 

 traced already over nearly five years and may possibly be permanent. The 

 matter must be left at this point, but naturally investigations are being 

 continued. 



Tides. — Report of Committee to assist work on the Tides (Professor 

 H. Lamb, Chairman ;I)r. A. T. Doodson, Secretary; Col. SirO. F. 

 Close, Dr. P. H. Cowell, Sir H. Darwin, Dr. G. H. Fowler, 

 Admiral F. C. Learmonth, Sir J. E. Petavel, Professor J. 

 Proudman, Major G. I. Taylor, Professor D'Arcy W. Thompson, 

 Sir J. J. Thomson, Professor H. H. Turner). 



Investigations carried out during the year, and still under consideration, at 

 the Tidal Institute at Liverpool have been concerned with 



1. Attempts to reduce to law the residual semi-diurnal oscillations left from 



the tide-gauge record at Newlyn; 

 2 Meteorological effects at Newlyn, Liverpool, and other places; 



