130 Proceedings of the 



with what actually takes place on the surface of the earth. But the 

 needle cannot be made to remain in that position. The attraction 

 of one of the poles always overcomes the attraction of the other, and 

 the needle floats towards the nearest pole a fact quite contrary to 

 what takes place when the earth acts on the same floating needle. 



But it may be asked, how are these currents generated ? Are 

 they voltaic or thermo-electric ? From the constitution of our globe, 

 we can scarcely doubt that they belong to the latter class. The earth 

 abounds with metalliferous veins, and these veins are undoubtedly 

 of different temperatures, and, consequently, thermo-electric effects 

 must take place. The rapid change in the direction of the magnetic 

 equator, when approaching South America, renders this supposition 

 highly probable. 



The effect of voltaic electricity in forming temporary magnets was 

 exhibited; but as that was fully described in the last Number of our 

 Journal, we refer to it for further information. Mr. Ritchie re- 

 marked, in concluding, that we were fast approaching to the period 

 when all the phenomena of heat, light, electricity, &c., would pro- 

 bably be referred to the same great cause, merely acting in different 

 ways ; and concluded by quoting the following prediction of the 

 late Professor Playfair, which we shall give in his own words : 

 4 If, on the other hand, we consider how many different laws seem 

 to regulate the other phenomena of the material world, as in the 

 action of impulse, cohesion, elasticity, chemical affinity, light, mag- 

 netism, galvanism, electricity, the existence of a principle more 

 general than any of these, and connecting all of them with that of 

 gravitation, appears highly probable. 



* The discovery of this great principle may be an honour re- 

 served for a future age, and science may again have to record names 

 which are to stand on the same levels with those of Newton and 

 La Place. About such ultimate attainments it were unwise to be 

 sanguine and unphilosophical to despair.' 



June Wth. Mr. Faraday on the Arrangements assumed by par- 

 ticles on the surfaces of vibrating Elastic Bodies. This was the 

 subject of a paper read before the Royal Society a few weeks ago, 

 of which Mr. Faraday was the author. He stated, that his principal 

 reasons for bringing it forward on the present occasion arose from 

 a desire to illustrate the characteristic differences between the Royal 

 Society and the Royal Institution, in their modes of putting forth 

 scientific truths ; and his conviction that every thing, whether small 

 or great, originating in the latter establishment, should be placed, 

 as soon as possible, in the possession of the members at large. 



When a plate or pane of glass is held horizontally by a pair of 

 tongs griping the glass at the centre, and a violin- bow drawn over the 

 edge of the glass, it is made to vibrate ; and sand having been pre- 

 viously sprinkled upon the surface of the plate, the particles arrange 

 themselves into regular forms, figuring forth the quiescent parts of 



