2 44 Mi*. Scoresby Junior’s experiments and observations on the 
I. Experiments with a cylindrical bar of soft steel, for determining 
the effect of percussion , when the bar was held in a vertical 
position and resting upon a piece of metal not ferruginous. 
Length of the bar 6 % inches ; diameter a quarter of an inch ; 
weight 592 grains. 
Number of Blows. 
Weight 
lifted. 
Distance 
of Com- 
pass and 
Bar. 
Devia- 
tion. 
Hammer. 
at each 
trial. 
Total. 
1 
1 
2 
3 
8 
II. 
1 
2 
. — - 
• ♦ • • 
10 
• • • • 
5 
7 
4 
• • . • 
12 
• • • • 
10 
17 
e* 
• • • • 
12 2 
• • • • 
5 
22 
6f 
• • • • 
12jr 
I. 
This bar was next hammered upon a large mass of free- 
stone : after twenty blows with the large hammer had been 
struck upon it, the deviation it was found had not increased, 
but still remained at i2-§-°. 
Dr. Gilbert tried this experiment on iron ; but instead of 
hammering it in the direction of the dipping needle, or in a 
vertical direction, which produces almost an equal effect, he 
placed it horizontally in the magnetic meridian, which, in 
London, is a plane elevated only degrees above the 
magnetic equator. Now, as my former experiments proved 
that hammering iron in the plane of the magnetic equator 
destroys its polarity, it is evident, that a very small part only 
of the full influence of percussion must have been obtained 
by Dr. Gilbert. 
As magnetism in steel is more readily developed by the 
contact of magnetisable substances, and particularly if these 
substances be already magnetic, it occurred to me, that the 
magnetising effects of percussion might be greatly increased 
