GO Royal Society : — 



From the preceding experiments (6. and 7.) it seems to result, 

 that whatever length of wire is connected with the battery, if a gal- 

 vanometer is placed at tlie farther extremity of the wire and a con- 

 stant length added to the other termination of the galvanometer, its 

 indication remains always nearly the same. Thus the galvanometer 

 indicated 6j°when it was placed close to the battery and 110 miles 

 of wire were subjoined beyond it ; and 5° when 550 miles were in- 

 terposed between the battery and galvanometer, the same length, 

 110 miles, being subjoined. In like manner, when 220 miles were 

 added beyond the galvanometer placed near the battery, the indica- 

 tion was 12°; precisely the same as when 440 miles were interposed 

 and 220 added. So also when 330 miles were added, the deviation 

 of the galvanometer was 18°; and 15" when 330 miles were inter- 

 posed and 330 added. I have no doubt that the correspondence 

 would have been closer had it not been for the fluctuations of the 

 battery. 



It would appear from this, that whatever be the length of wire 

 attached to the insulated pole of a battery, it becomes charged to 

 the same degree of tension throughout its entire extent ; so that 

 another insulated wire brought into connexion with its free extre- 

 mity exhibits precisely the same phsenoinena, in kind and measure, 

 as when it is brought into immediate connexion with a pole of the 

 battery. Some important practical consequences flow from this 

 conclusion, which I will not develope at present, as I have not yet 

 had an opportunity of submitting thera to the test of experiment. 



April 19, 1855. — The Lord Wrottesley, President, in the Chair. 



The following communication was read : — 



" On the Descent of Glaciers." By the Rev. Henry Moseley, 

 M.A., F.R.S. 



If we conceive two bodies of the same form and dimensions (cubes 

 for instance), and of the same material, to be placed upon a uniform 

 horizontal plane, and connected by a substance which alternately 

 extends and contracts itself, as does a metallic rod when subjected 

 to variations of temperature, it is evident that by the extension of 

 the intervening rod each will be made to recede from the other by 

 the same distance, and, by its contraction, to approach it by the 

 same distance. But if they be placed on an inclined plane (one 

 being lower than the other), then when by the increased temperature 

 of the rod its tendency to extend becomes sufficient to push the 

 lower of the two bodies downwards, it will not have become suffi- 

 cient to push the higher upwards. 'Jlie effect of its extension will 

 therefore be to cause the lower of the two bodies to descend whilst 

 the higher remains at rest. The converse of this will result from 

 contraction ; for when the contractile force becomes sufficient to 

 pull the upper body down the plane it will not have become suffi- 

 cient to pull the lower up it. Thus, in the contraction of the sub- 

 stance which intervenes between the two bodies, the lower will re- 

 main at rest whilst the upper descends, As often, then, as the ex- 



