Reciprocating Magnetic Attraction. 341 
as a new effect produced by one of the most mysterious agents of 
nature, you will not, perhaps, think the following account of it un- 
worthy of a place in the Journal of Science. 
It is well known that an attractive or repulsive force is exerted 
between ‘two magnets, according as poles of different names, or poles 
of the same name, are presented to each other. 
In order to understand how this principle can be applied to pro- 
duce a reciprocating motion, let us suppose a bar magnet to be sup- 
ported horizontally on an axis passing through the center of g vity, 
in precisely the same manner as a dipping needle is poise 3 and 
Suppose two other magnets to be placed perpendicularly, one stile 
each pole of the horizontal magnet, and a little below it, with their 
north poles uppermost; then it is evident that the south pole of the 
horizontal magnet will be attracted by the north pole of one of the 
perpendicular magnets, and its north pole repelled by the north pole 
of the other : in this state it will remain at rest, but if, by any means, 
we reverse the polarity of the horizontal magnet, its position will be 
changed and the extremity, which was before attracted, will now be re- 
pelled ; if the polarity be again reversed, the position will again be 
changed, and so on indefinitely: ) produce, therefore, a continued 
vibration, it is only necessary to “introduce, into this arrangement, 
some means by which the polarity of the horizontal magnet can be 
instantaneously changed, and that too by a cause which shall be put 
M Operation by the motion of the magnet itself; how this can be 
effected, will not be difficult to conceive, when I mention that, instead 
of a permanent steel magnet, i in the moveable part of the apparatus, 
4 soft iron galvanic magnet is used.* 
The change of polarity i is produced simply by soldering to the — 
€xtremities of the wires which surround the galvanic magnet, two 
small galvanic batteries in such a manner that the vibrations of the 
magnet itself may immerse these alternately into vessels of on 
acid; care being taken that the batteries are so attached that 
Current of galvanism from each shall pass around the magnet in an 
Opposite direction. 
Thstead of soldering the batteries to the ends of the wires, and 
_ thus causing them at each vibration to be lifted from the acid by the 
Power of the machine ; they may be permanently fixed in the vessels, 
ps See 
* For a method of constructing difeitcnnlc magnet on an improved plan, see my 
Paper in Vol. XIX, p: 329 of this — 
Vou. XX.—No. 2 
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