magnetical properties in steel and iron by percussion. 247 
III. For determining the effect of percussion on magnets properly 
tempered, a fat bar magnet of a blue temper was employed; 
it was 7-^ inches long, ~ an inch broad, and yth thick, and 
weighed 1170 grains. 
Ta. The magnet held vertically on a rod of iron; South end 
upward. 
No. of Blows. 
End of the 
Magnet 
upward. 
Distance 
of the 
Compass. 
Devia- 
tion. 
at each 
trial. 
Total. 
Inches. 
O 
O 
O 
• 
8 
45 
5 
5 
s. 
37 
5 
10 
32 
10 
20 
30 
10 
3 ° 
28 
10 
4 ° 
27 
20 
60 
26 
20 
80 
25 
20 
100 
25 
[b. North end up.j 
0 
0 
• • • 
8 
25 
1 
1 
N. 
• • 
20 
10 
11 
• • • 
• 
16 
20 
30 
• • • 
. . . 
14 
[c. Bar again magnetised and hammered upon a piece of pewter.'} 
0 
0 
• 
8 
50 
10 
10 
S. 
37 
10 
20 
33 
10 
30 
N. 
2 7 
10 
4 ° 
• • • 
2 6 
20 
60 
24 
20 
80 
• 
24 
20 
100 
S. 
24 
20 
120 
N. 
23 
20 
140 
23 
20 
160 
S. 
s Si 
