Magnetical Experiments, fyc. 4 3 
ihg iron or steei completely from magnetism, but that of heat- 
ing it red-hot, and allowing it to cool in a horizontal position 
east and west. This process, however, besides spoiling the sur- 
face of the metal, is troublesome, and seldom completely effec- 
tual in its application. But the same object is accomplished, 
in a moment, and with infinitely better effect, by Mr Scoresby’s 
process, merely by a slight blow or two with a hammer, while 
the iron or steel is held in the magnetic plane, and is equally ap- 
plicable to very large and heavy bars, which could not, without 
great inconvenience, and a fire made on purpose, be heated uni- 
formly to a state of ignition. 
Another application of this discovery, is the correction of the 
magnetism usually found in the balances of chronometers, which 
produces a serious error in the rate of some instruments. Mr 
S. found, that any other mechanical action on iron was produc- 
tive of magnetism, as well as that of percussion, though not in 
an equal degree. Thus, the different actions of grinding, filing, 
polishing, drilling, turning, twisting, bending, &c. were all found 
to elicit magnetic attraction, when performed in a vertical posi- 
tion, or any position out of the magnetic plane ; but that the 
same processes were destructive of polarity, when performed on 
a bar or plate of untempered metal, when held in the plane of 
the magnetic equator. Hence, the balances of chronometers, 
which are usually formed principally of steel, become magnetic 
in turning them into form, perhaps hqa vertical plane, and po- 
lishing them in a horizontal plane; but the acquisition of mag- 
netism would no doubt be prevented, and even destroyed if 
they had previously obtained it, by performing these processes 
in the plane of the magnetic equator. 
The next branch of this science to which Mr S. seems to 
have turned his attention, was the examination of the laws of 
percussion, in developing magnetism in different kinds of ferru- 
ginous substances, the investigation of the best processes for 
carrying the magnetism elicited by this means to its highest ef- 
fect, and the application of the results obtained to useful and 
practical purposes. 
1. Mr Scoresby found that soft steel received the greatest de- 
gree of magnetic energy by permission. In soft iron the mag- 
netism was strong but evanescent. In hard steel and cast-iron 
weak, but permanent. % A bar of soft steel, inches in length. 
