ON THE DETERMINATION OF MAGNETIC FORCE ON BOARD SHIP. 81 



adjacent the plane of the circle can be immediately placed in the 

 magnetic meridian without the trouble of finding the meridian by the 

 usual method with the circle. 



Two instruments of the kind described are now in use in the Antarctic 

 ship ' Discovery,' and the German expedition in the Antai'ctic ship ' Gauss ' 

 have also one with two sets of needles. 



Experiments for improving the Construction of Practical Standards for 

 Electrical Measuremeyits. — Report of the Committee, consisting 

 o/Lord Rayleigh (Ghcdrman),'M.r. R. T. Glazebrook (Secretary), 

 Lord Kelvin, Professors W. E. Ayrton, G. Carey Foster, 

 J. Perry, W. G. Adams, and Oliver J. Lodge, Dr. J. A. 

 Muirhead, Sir W. H. Preece, Professors J. D. Everett, A. 

 Schuster, J. A. Fleming, and J. J. Thomson, Mr. W N. Shaw, 

 Dr. J. T. Bottomley, Rev. T. C. Fitzpatrick, Dr. G. Johnstone 

 Stoney, Professor S. P. Thompson, Mr. J. Rennie, Mr. E. H. 

 Griffiths, Professors A. W. Rucker, H. L. Callendar, and 

 Sir Wm. C. Roberts Austen, and Mr. George Matthey. 



Appendix. — Note on a Comparison of the Silver deposited in Voltameters 

 containing drferent Solvents, By S. Skinner page 32 



During the year a number of comparisons have been made at the Kew 

 Observatory among the standard coils of the Association. The temperature 

 conditions, however, in the temporary laboratory are not sufficiently 

 satisfactory to make it desirable to report fully on the results ; it is perhaps 

 sufficient to say that no evidence of any very marked change in the 

 relative values has shown itself. It is hoped that the coils and other 

 apparatus will be moved to Bushey during the autumn. 



In the room which has been planned for their reception an'ano-ements 

 will be at hand for controlling the temperature, and the work of inter- 

 comparison and control of the standards can go on as in former years at 

 Cambridge. 



Meanwhile some progress has been made in the preparations for the 

 construction of mercury standards. A number of tubes of ' verre dur ' 

 have been examined, and some of these have been calibrated ; when the 

 apparatus is set up at Bushey his work will go forward rapidly. There 

 has also been during the year some demand for the issue of standards of 

 capacity : this it has not been possible to comply with, but the air con- 

 densers will be set up again as soon as possible, and then capacity tests 

 can be made. 



With regard to platinum thermometry, Mr. Matthey supplied the 

 Committee with a further specimen of wire, for which he had made a 

 large stock. This was tested carefully, both at Kew and under Mr. Griffiths' 

 directions, by Mr. Green at Cambridge, and the values found for the 

 constants were as under : 



Riqq/Ro:^ 1*3892 



8=l-495±005 



The wire has proved in every way satisfactory, and the money voted 

 to this Committee last year (45?.) has been spent in purchasing it. 



