ON PRACTICAL STANDARDS FOR ELECTRICAL MEASUREMENTS. 85 
cadmium sulphate solution is added. The cell may be immediately sealed 
with the aid of a blowpipe, but the contents must not be abnormally 
heated thereby. The cadmium amalgam introduced should cover the 
amalgamated platinum wire; the depth of the paste should be from 
0-5 em. to 1:0 cm., and the depth of the Jayer of crystals about 0-5 em. 
twenty-four hours after the cell has been set up it may be used. Its electro- 
motive force at 15°C. is 1-018; volt. The electromotive force at any 
other temperature may be cbtained from the formula given by the Phys. 
Techn. Reichsanstalt, viz., 
E,= E3)—0-000038(¢— 20) —0-00000065(¢— 20)?, 
or from the formula obtained at the National Physical Laboratory, 
E,=E,, — 0:000034,(¢ —17) —0-00000066(¢—17)?. 
This specification is based on observations made at the National 
Physical Laboratory. 
Seismological Investigations.—Twelfth Report of the Committee, consist. 
ing of Professor H. H. Turner (Chairman), Dr. J. MILne (Secre- 
tary), Lord Kexvin, Dr. T. G. Bonney, Mr. C. Vernon Boys, Sir 
GerorGE Darwin, Mr. Horace Darwiy, Major L. Darwin, Professor 
J. A. Ewine, Dr. R. 'T. Guazeproon, Mr. M. H. Gray, Professor 
J. W. Jupp, Professor C. G. Knorr, Professor R. Metpoua, Mr. 
R. D. OLp#am, Professor J. Perry, Mr. W. E. PLummer, Professor 
J. H. Poyntine, Mr. CLEMENT REID, and Mr. NELSon RICHARDSON. 
(Drawn up by the Secretary.) 
[PLATE I.] 
CONTENTS. 
PAGE 
I. General Notes on Stations and Registers . 2 . : : : 5 GR) 
Il. The Situations of Stations . 5 : ‘ ; 4 : ; : , 84 
Ill. Photographie Record-receivers  . 5 ‘ : : = , . : 85 
IV. Origins and Relationships of Large Earthquakes in 1906 . ; : . 86 
V. On the Apparently Luminous Effeets from certain Rocks. : F % elt 
VI. Larthquakes and Changes in Latitude. By Professor C. G. Knorr . 2 78H 
VI. Note on the Duration of the First Preliminary Tremor in the San Francisco 
and Colombian Earthquakes. Py R. D. OLDHAM . : : ; se ER} 
I. General Notes on Stations and Registers. 
THE registers issued during the past year are Circulars Nos. 14 and 15. 
They refer to Shide, Kew, Bidston, Edinburgh, Paisley, Victoria (B.C.), 
Alipore, Bombay, Kodaikanal, Batavia, Cairo, San Fernando, Cape of 
Good Hope, Ponta Delgada (Azores), Toronto, Pilar, Beirat, Baltimore, 
Trinidad, Honolulu, Perth (W.A.), Christchurch (New Zealand), Mauritius. 
Records have not yet been received from Melbourne, Sydney, and Are- 
quipa ; while registers from Wellington, Philadelphia, and Mexico should 
be brought up to date. The Seismological Committee of the British 
Association would be greatly indebted to the Directors of observatories 
at these places if they would kindly forward copies of their observations. 
Some time ago a Milne seismograph, which records on a band 
a2 
