306 British Association for the Advancement of Science. 



restored, and a fresh discharge from the buckets takes place, and 

 so the process is continued. 



Some iron constantly adheres to the magnets, but this is found of 

 no inconvenience as it bears but a small proportion to the total 

 quantity separated. 



The author has had an imperfect apparatus of the sort above de- 

 scribed at work for some time, and has found it to answer ; and 

 suggests the application of electro-magnets for somewhat analogous 

 objects in various manufactures. He particularly mentions needle 

 and other dry grinding. 



An Inquiry into the Possibility and Advantage of the Application of 

 Magnetism as a Moving Power, with Remarks on the Nature of 

 Magnetism. By the Rev. James William M'Gauley. 



To consider with advantage the possibility of applying magnetism 

 as a moving power, we must examine its nature and peculiar pro- 

 perties, because otherwise we cannot pronounce with accuracy on the 

 quantity at our command, or the probable cheapness of its produc- 

 tion. In this inquiry the author does not contemplate such a power 

 as that attained in magnetic rotations and. similar mechanism ; it could 

 never be advantageous ; for the force of the magnet is not directly 

 applied, or is applied at such a distance as to be almost annihilated. 



The quantity of magnetism we may produce seems to have no 

 limit, since we can combine any number of powerful magnets. 



The ceconomy of magnetism. A very small electrical power, which 

 may be produced if necessary by the agency of sea-water, will 

 abundantly suffice. 



The obstacles likely to prevent the application of magnetism as 

 a moving power. Of these the principal seems to consist in the 

 disturbing influence which magnets of any power exercise over 

 each other. This prevents the necessary reversion of the poles. 



Experiment 1st. The author tried to reverse the poles of one 

 electro-magnet in contact with another : the sudden rush of elec- 

 tricity evidently caused a magnetic needle near the magnet to be af- 

 fected, but there was no separation or repulsion of the magnets, nor 

 any permanent change of polarity. — Experiment 2nd. The similar 

 poles of two electro-magnets of very different power were brought 

 together : they attracted each other ; the poles of the smaller magnet 

 were reversed by the larger, and a counter-current was formed 

 through its battery, and indicated by a galvanometer placed in the 

 circuit. — Experiment 3rd. Only one of the magnets was excited, 

 then its poles reversed ; the other, acting as a keeper, was thrown 

 off, and attracted with great violence. — Experiment 4th. Between 

 two semicircular magnets A and B, a bar of soft 

 -jf \ iron, C, was suspended, and their poles reversed in 



IA C b J such a manner alternately as to throw off the bar from 

 V*_ ^ / one magnet and cause it to be attracted by the other. 



— Experiment 5th. A bar of magnetized steel was 

 placed between the magnets ; but the effect was not so powerful, 



