376 Analysis of Scientific, Books. 
1. Experiments and Observations on the Developement of Mag~ 
netical Properties in Steel and Iron, by Percussion. By Wil- 
liam Scoresby, jun., esq. 
Since the publication of Oersted’s Discovery, the magneti- 
cians have been singularly on the alert, and a great deal has 
been written upon the subject, much of which is new and curi- 
ous, and much also trifling and unimportant. The production 
of magnetism by percussion was discovered by Dr. Gilbert in 
the 16th century, but its laws and phenomena not having been 
accurately investigated, Mr. Scoresby was induced to institute 
a series of experiments, to determine them with more precision, 
and some of his results deserve attention. 
When a bar of soft-steel, six inches and a half long, and a 
quarter of an inch diameter, held vertically, and resting upon 
freestone, was struck 17 blows with a hammer *, it acquired the 
power of lifting 64 grains ? 22 blows did not augment the force. 
When the bar rested vertically upon a parlour poker (previ- 
ously deprived of magnetism), 42 blows gave it the power of 
lifting 88 grains, and 90 blows, with a larger hammer, augmented 
the lifting power to 130 grains. The poker was also rendered 
magnetic. Farther hammering rather diminished than increased 
the power. Oninverting the bar, a single blow nearly destroyed 
the magnetism; two blows changed the poles. Hammering 
the bar in the plane of the magnetic equator, also destroyed the 
polarity. The magnetism by percussion was augmented when 
the length of the bars was increased. 
Thus a quarter-inch cylindrical bar of steel, five inches Jong, after receiv- 
ing 20 smart blows, produced a deflection of the needle, at the distance of 
three inches, of 13°, and lifted 64 grains. Another piece of the same bar, 
7i inches long, after similar treatment, produced.a deviation of 24°, and 
lifted 45 grs. ; and a third bar of the same kind, 12 inches long, after twenty 
similar blows, occasioned a deviation of the compass of 339, and easily 
lifted 88 grains. The shortest bar, it was observed, received the full effect 
by the two first blows ; but the others continued to increase in energy as 
the percussion was continued. These bars did not receive a power equal 
to that first used ; the cause was probably their greater hardness. 
The strong magnetizing effect of percussion on soft steel, 
induced Mr, Scoresby to apply the property to the formation of 
magnets : 
For this purpose I procured 2 bars of soft steel, 30 inches long and an inch 
broad; also six other flat bars of soft steel, 8 inches long and half an inch 
broad, and a large bar of soft iron. The large steel and iron bars were not 
however absolutely necessary, as common pokers answer the purpose 
very well ; but I was desirous to accelerate the process by the use of 
substances capable of aiding the developement of the magnetical properties 
in steel. The large iron bar was first hammered in a vertical position. It 
was then Jaid on the ground, with its acquired south pole towards the 
south, and upen this end of it the large steel bars were rested while they 
* We do not think it necessary to specify the weight of the hammer 
used, as it had no regular effect upon the magnetism excited, and as the 
blows having been struck by the hand must have varied much in intensity. 
