PROCEEDINGS 



OF 



THE ROYAL SOCIETY. 



1847. No. 70, 



November 25, 1847. 



GEORGE RENNIE, Esq., Treasurer, in the Chair. 



His Grace the Duke of Wellington was elected a Fellow of the 

 Society. 



Postscript to Mr. W. H. Barlow's paper on Alternating Diurnal 

 Currents of Electricity at the Terrestrial Surface. 



The author states that since his paper was read to the Society, he 

 had made further experiments to determine with greater accuracy 

 the direction in which the daily electrical currents travel, and also 

 how far the motions of the horizontal magnetic needle correspond 

 with that of the telegraph. With regard to the latter, he finds that 

 although they agree as to the general character of their Reflexions, 

 there is no decided simultaneous coincidence in their movements. 



**Magnetical experiments on board H.M. Iron Steam Vessel 

 ' Bloodhound.' " By Captain Edward Johnson, R.N., F.R.S. Com- 

 municated to the President by the Lords Commissioners of the Ad- 

 miralty, and communicated to the Society by the President. 



These experiments were undertaken with the view of ascertaining 

 whether the action of steam upon the hull of an iron vessel affects a 

 compass, properly placed, in any degree that may be of practical 

 importance in its navigation ; and also whether the keeling of the 

 vessel produces any alteration in the deviations, or disturbs a com- 

 pass so placed to any considerable extent. The former question is, 

 from the results of these experiments, resolved in the negative ; but 

 with respect to the second, it appears that the deviations produced 

 by keeling are very marked, and could not be safely disregarded. 

 These observations completely confirm those already made by Mr. 

 Walker and Commander Shaugh on board H.M. Iron Brig * Recruit,' 

 Commander A. Slade, and they prove the necessity that exists for 

 ascertaining the deviations of the compass in all ships, not only at 

 the beginning and end of their voyage, but lilcewise at intermediate 



