234 REPORTS ON THE STATE OF SCIENCE, ETC. 
cost being borne by this Committee. At the request of Prof. Plaskett the 
Committee considered the question what tables should be used in the 
International Summary for 1930 and subsequent years and recommended 
the adoption of the new Jeffreys-Bullen Tables. It is anticipated. that the 
utility of the Summary will be greatly increased, not only by higher accuracy 
in the determination of epicentres but also by the facilities for comparing 
the times of passage of waves from an individual earthquake with the 
standard times. 
It may be recalled that Prof. Turner regarded the accumulation of material 
for providing standard tables as one of the objects of the Summary and that 
in his last Presidential Address to the International Seismological Associa- 
tion he expressed the hope that new tables would be available for use in 
the 1930 Summary. 
Mr. J. S. Hughes has kindly prepared the following statement as to the 
present state of work on the Summary. 
International Seismological Summary.—The preparation of the third 
quarter of 1930 is well in hand. Delay has been inevitable owing to the 
necessity of awaiting the decision of the Seismology section of the Inter- 
national Geophysical and Geodetic Union at Lisbon, and from other 
causes, but at present the work is going forward at a satisfactory rate, in 
spite of the increasing number of observing stations now sending to Oxford. 
Beginning with 1930, certain modifications have been introduced. ‘The 
arrangement of the printing has been slightly altered in the interest of 
clarity and the method of making determinations has been revised so as to 
depend almost entirely on the P phases when these are available. ‘Through- 
out the work the new tables by Dr. Jeffreys and Mr. Bullen have been used. 
These are a revised form of Dr. Jeffreys’s earlier work, ‘ Tables of the 
Times of Transmission of the P and S waves of Earthquakes,’ 1932. 
The Introduction to the Summary for the year 1930 contains an account 
of the alterations made and also the Bullen-Jeffreys travel-times for all 
the phases tabulated. These are P, S, PP, SS, PcP, ScS, PS, PKP, PKS, 
SKS, PKP,, SKKS, SKSP. Residuals for the phases P, PcP, PKP, 
PKP, and S, ScS, SKS, SKKS may now appear in the columns headed 
‘ O—C’ (observed minus calculated) instead of just P, PKP and S, SKS. 
The Constants of Seismological Observatories. As a preliminary to the 
work on the travel times of seismic waves Mr. K. E. Bullen calculated the 
constants of about 350 seismological observatories. ‘These constants are 
used as Cartesian co-ordinates but are actually the direction cosines of the 
vertical at each point. The table of constants has been published by the 
British Association during the year. , 
The importance of the distinction between Cartesian Co-ordinates and 
direction cosines has recently been emphasised by the discussion in a 
paper by B. Gutenburg and C. F. Richter of the “ Advantages of using 
geocentric latitude in calculating distances.’ It may be that the time is 
approaching when the spheroidal form of the earth will have to be taken 
into account in estimating all the distances used in detailed seismological 
investigations. 
Seismographs—The Milne-Shaw seismographs belonging to the British 
Association have remained in operation at Oxford, Edinburgh, Perth (West 
Australia) and Cape ‘Town. 
The seismograph which had been in operation at the Royal Observatory, 
Cape Town, was transferred in 1931 to the University a few miles away, 
the new site being much less subject to change of level and to disturbance 
by wind. Prof. Alexander Brown, who had accepted the custody of this 
instrument was impressed by the need for records of both horizontal com- 
