54 
GREENLAND VOYAGE. 
duction of magnetism, is in a great‘measure owing 
to the use of the rod of iron, the polarity of which, 
after hammering, greatly aids the development of 
magnetism in the steel; for the highest effect 
obtained by hammering the larger steel-bar, when 
held verticaUy upon stone, pewter, brass, &c. in¬ 
stead of iron, was only a lifting power of di¬ 
grams *. 
Such a high degree of magnetic energy being 
obtained by a process so simple, it suggested a 
ready means of making magnets, without the use 
of any magnetized substance whatever, and of 
* Dr Gilbert, who was the first person that investigate^ 
the phenomenaof magnetism in a scientific way, found, among 
many other valuable discoveries, that iron, hammered in 
the magnetic meridian, acquired a slight degree of polarity, 
and that when a piece of iron was heated to incandescence, 
and drawn out in this direction, it became sufficiently mag¬ 
netic for adjusting itself north and south, when carefully 
balanced afloat in water, by being thrust through a piece 
of cork. This is the only experiment with which I am r ac¬ 
quainted that bears any analogy to the one that is detailed 
above ; blit this was not known to me at the time the dis¬ 
covery of this property was made. The effect, however, of 
Dr Gilbert’s process, is inconsiderable, iron acquiring there¬ 
by little or no lifting power, with a directive force that is 
extremely small. By one blow with a small hammer, on a 
cold rod of soft steel held upon a poker, fifty times more 
magnetic virtue can be induced than the method of Dr Gil¬ 
bert is capable of developing. 
