NATURAL PHILOSOPHY. 121 



The experiment was made as follows : a platinum plate forming the 

 anode of the battery was immersed in a capsule of distilled water, the 

 temperature of which was raised. A cathode, or negative terminal of 

 platinum wire, was now made to touch for an instant the surface of the 

 water, and immediately withdrawn to a distance of about a quarter of 

 an inch ; the discharge took place, the extremity of the wire was fused, 

 and the molten platinum attached to the wire, but kept up by the 

 peculiar repulsive effect of the discharge, was exhibited as it were sus- 

 pended in mid-air, giving an intense light, throwing off scintillations 

 in directions away from the water, and only detaching itself from the 

 wire when agitatc'd. Here water in the vaporous state must be trans- 

 ferred, for the immersed electrode gave off ga's, without doubt oxygen, 

 and the molecular action on the negative fused platinum resembled, if 

 it were not identical in character with, the currents observed on the 

 surface of mercury when made negative in an electrolyte. It may be 

 objected to the theory proposed, that electrical effects are obtained in 

 what is called a vacuum, where there is no intermedium to be polar- 

 ized ; but this objection though not applicable to the projection of the 

 terminals, could hardly be discussed until experimenters had gone 

 much farther than at present in the production of a vacuum. The 

 experiments of Davy and others had shown that we are far from 

 obtaining any thing like a vacuum where delicate investigations are 

 concerned. The view of ancient philosophers, that nature abhors a 

 vacuum, which had been much cavilled at, and was supposed to be 

 exploded by the discovery of Torricelli, Mr. Grove thought had been 

 unjustly censured ; giving the expression some degree of metaphori- 

 cal license, it afforded a fine evidence of the extent and accuracy of 

 observation of those who were unacquainted with inductive philosophy 

 as a system, but who necessarily pursued it in practice. Whether a 

 vacuum was possible might be an open question ; experimentally it 

 was unknown. 



TERRESTRIAL MAGNETISM. 



COL. SABIXE, in his address before the British Association at their 

 last meeting, gives the following summary of the recent progress of the 

 study of terrestrial magnetism. 



The magnetic phenomena, or as it is now customary to call them, 

 the three magnetic elements, declination, inclination and magnetic 

 force, appear to be everywhere and in both hemispheres the resultants 

 of a duplicate system of magnetic forces, of which one at least under- 

 goes a continuous and progressive translation in geographical space, 

 the motion being from west to east in the northern hemisphere, and 

 from east to west in the southern. It is to this motion that the secular 

 change in all localities is chiefly, if not entirely, due ; affecting syste- 

 matically and according to their relative positions on the globe the 

 configurations and geographical positions of the magnetic lines, and 

 producing conformable changes in the direction and amount of the 

 magnetic elements in every part of the globe. The comparison of the 



