Magnetical Experiments, Sfc. 47 
to be free from magnetism before the experiment, was made* to 
lift 54 grains, or very nearly twice its own weight, by being re- 
peatedly hammered, while held vertically on the top of a kitchen 
poker. 
The quantity of magnetism developed by this process, Mr 
S. found increased by a frequent repetition of the experiment 
with the same bars. Though it was necessary to use the same 
end downward, generally in the production of the highest effect, 
it did no harm to knock the magnetism occasionally out by in- 
verting the bars. It is necessary to observe, that, in trying the 
lifting power of bars or needles after hammering, the nails, 
which are the most convenient to be used for this purpose, should 
have their points filed smooth round, and partly polished ; 
otherwise the bad contact occasioned by the oxide on the point 
or head of the nail, may cause the experiment apparently to fail 
With this precaution, there is little doubt of any one succeed- 
ing in the experiments, using only a hammer, a poker (previ- 
ously struck a few blows while held vertically), and a piece of 
steel wire not tempered. 
3. The practical application of this discovery by Mr S., is the 
formation of artificial magnets, and the ready construction of a 
compass, without the use of a magnet, at sea, 
“ Such a high degree of magnetic energy (says he) being ob- 
tained by a process so simple, it suggested a ready means of ma- 
king magnets, without the use of any magnetized substance what- 
ever, and of giving polarity to needles, so as to render them ca- 
pable of answering the purpose of compasses, in an instant. This 
application of the process induces me to be more explicit on this 
incidental subject, because of its importance to seafaring per- 
sons. There are instances on record, of the compasses of ships 
being spoiled by lightning * : The above process would enable 
* In the Philosophical Transactions (vol. xi. p. 647.), is an account of a stroke 
of lightning received on a vessel in the parallel of Bermudas, which carried away 
the foremast, split some of the sails, and damaged the rigging : and, in addition 
to these extraordinary effects, it inverted the polarity of the compass, so that the 
north point became directed towards the south. This induced the navigators, who 
were not aware of the change, to steer back again, supposing that the wind had 
shifted ; and it was not until they were accidentally set right by another ship, that 
they discovered the truth. 
Another circumstance a good deal similar to this, also mentioned in the Philo* 
3 
