magnetical properties in steel and iron by percussion. 24,5 
by hammering the steel bar, with its lower end resting on 
the 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 on 
the bar would probably be augmented. The following ex- 
periments prove that these opinions were not incorrect. 
II. Experiments for determining the effect of percussion on a 
soft steel bar , when the bar was held in a vertical position and 
resting upon a parlour poker. 
[a. Both the bar and the poker were first deprived of magnetism .' ] 
Number of Blows. 
Weight 
lifted. 
Distance 
of Com- 
pass and 
Bar. 
Devia- 
tion. 
No. of the 
Hammer. 
at each 
trial. 
Total. 
Grains. 
Inches. 
O 
1 
1 
6 i 
3 
13 
II- 
1 
2 
14 
16 
Q 
18 
6 
• * • 
IO 
4 
7 
37 
21 
5 
\ 12 
45 
25 
10 
22 
88 
27 
20 
42 
88 
SO 
J 
3° 
72 
• • . 
3 1 
10 
82 
• • • 
sH 
I . . . 
The effect seemed now to be at a maximum, for more blows 
with the same hammer produced no alteration ; but on sub- 
stituting a larger hammer, the deviation was augmented. 
[b. Change of Hammer.'] 
3 
85 
• • . 
33 
I. 
5 
90 
130 
34 
3 
93 
• • • 
• • • 
30 ! 
The bar was now inverted, so that the north pole was upward. 
Change of the ends of the Bar.] 
o 
o 
3 
5 
2 
11. 1 
Poles changed. 
