MATHEMATICAL TABLES 269 
and Messrs. Gutenberg, Scrase, Byerly and Hodgson. This will be 
acknowledged more fully later. 
High Focus Earthquakes —That earthquakes with deep foci occur is well 
established, but the significance of the observations which led Turner to 
attribute high foci to certain earthquakes is not yet known. Mr. E. Tillotson 
has chosen for investigation an earthquake of this type, ‘ The African 
Rift Valley Earthquake of 1928, Jan. 6.’ Mr. Tillotson has examined about 
100 original records of this earthquake. There is no doubt as to the 
location of the epicentre, which is in the Subukia Valley, Kenya Colony. 
The anomalies in the observations are still under consideration. 
Microseisms.—The discussion, by Mr. A. W. Lee, of the microseisms 
recorded in all parts of the world during January 1930 has been completed 
and will be published shortly. Data are available for 57 observatories. 
The most disturbed of them are Reykjavik and Honolulu. 
In Europe microseismic storms do not occur in the absence of barometric 
depressions over the eastern part of the Atlantic, but some deep depressions 
are not accompanied by large microseisms. No evidence for a direct 
connection between microseismic disturbance and the sea-disturbance in 
particular regions has been found. 
Periodicity of Earthquakes.—Two notable papers by Dr. C. Davison (a 
former member of the Committee) on periodicity in earthquakes have 
appeared recently in the Philosophical Magazine (Ser. 7, Vol. 15 (1933) ). 
In the first paper the eleven-year period is discussed on the basis of statistics 
covering the whole globe and the last two centuries. It is found that in all 
parts of the world earthquakes are more frequent in the years of many 
sunspots. In the second paper a 19-year period is investigated. In this 
case the maximum frequencies of the northern hemisphere tally with the 
minimum frequencies of the southern hemisphere. The period seems to 
be identical with the nutation period of the earth and it is therefore demon- 
strated that the strains associated with the movements of the earth’s axis 
are factors in determining when earthquakes shall occur. 
Reappointment—The Committee asks for reappointment and for the 
confirmation of a grant of £100 from the Caird Fund. 
MATHEMATICAL TABLES, 
Report of Committee on Calculation of Mathematical Tables (Prof. E. H. 
NEVILLE, Chairman; Prof. A. LopcE, Vice-Chairman; Dr. L. J. 
Comrie, Secretary; Dr. J. R. Atrey, Prof. R. A. Fisuer, F.R.S., 
Dr. J.. Henperson, Dr. E. L. Ince, Dr. J. O. Irwin, Dr. E. S. 
Pearson, Mr. F. Rossins, Mr. D. H. Sapier, Dr. A. J. THompson, 
Dr. J. F. Tocuer, and Dr. J. WisHart). 
General activity. —Six meetings of the Committee have been held, in London. 
The grant of £50 has been expended as follows : 
Calculations connected with the Bessel functions co 2 
Fi(x), Fa(x), Fa(x), Fa(x) . a7, 19. 10 
Calculations connected with the confluent hypergeometric 
function . Io 0 Oo 
Calculations Eonnesteds with. the Bessel functions Y,(x) 
and Y,(x) for x = 6-o(o- any oO. , : F fa) 227 100" 
Secretarial expenses. ‘ : ; p at Me 5HrOwro 
