46 
Account of Captain Scoresby’s. 
J inch in diameter, weight 392 grains, hammered in a vertical 
position, while held on a surface of metal not ferruginous, or 
even upon iron or steel, if placed horizontally, like the surface 
of an anvil, or upon a mass of stone, acquired, after seventeen 
blows, a lifting power of 6J grains ; but a repetition of the blows 
was productive of no higher energy. 
“ As magnetism in steel is more readily developed by the 
contact of magnetizable substances, and particularly if these 
substances be already magnetic,"” it occurred to Mr S., “ that 
the magnetizing effects of percussion might be greatly increa- 
sed, by hammering the steel-bar with its lower end resting on 
tlie upper end of a large rod of iron or soft steel, both the 
masses being held in a vertical position ; and that, if the rod 
were first rendered magnetic by hammering, the effect oh the 
bar would probably be augmented The experiments insti- 
tuted to ascertain the effect of such treatment fully proved that 
these opinions were correct. 
The same soft steel-bar that could only be made to lift 6f 
grains when hammered while resting upon a surface of stone or 
metal not ferruginous, when hammered vertically upon a par- 
lour poker, also held erect, lifted a nail of 88 grains weight, 
after twenty-two blows. u When the poker had been pre- 
viously hammered in a vertical position, an increase of magneti 
effect on the bar was obtained, a single blow being now suffi- 
cient to enable the bar to lift about 20 grains and, in one in- 
stance, ten blows produced a lifting power of 188 grains in the 
bar, being nearly one-third of its own weight. 
A single blow struck upon the bar when held with the other 
end up, almost destroyed its magnetism, and two additional 
blows changed its poles. 
A difference of power was found to be obtained by using bars 
of different lengths ; that is, there was an increase of attraction 
in bars of the same diameters, when the lengths were increased. 
2. In another series of experiments, Mr S. found, that small or 
slender bars acquired a much greater lifting power, in proportion 
to their weight, than large bars. Thus, a piece of a knitting 
needle, 3 inches long, and weighing 28 grains, which was found 
Phil. Trans. 18 22, p. 2U. 
