81 
gradual tensile strain could the true result be ascertained, 
as the bar almost immediately became heated under the 
strain, and the effects of frost at once disappeared. The 
following experiments made by Mr. William Johnson, of the 
Messrs. Johnson’s Ironworks, Bradford, near Manchester, 
will illustrate this conclusively. 
A coil of galvanised wire o f B.W. gauge was left in the 
open air for 21 hours during severe frost, December 24, 
1870; 24 pieces 1 yard in length each were then cut off. 
Of these 6 were tested for tensile strength by the direct 
application of weights, and 6 for torsion — the same tests 
were used for the remaining 12 after they had been warmed 
to about 80°. The results were as follows : 
Tension. Torsion. 
At 20° 
At 80° 
At 20° 
At 80° 
2142 lbs. 
2142 lbs. 
16* twists 
twists. 
2114 „ 
2058 „ 
15J 
14* 
V 
2114 ., 
2086 „ 
9 
13* 
>> 
2142 „ 
2086 „ 
1 H 
5 J 
141 
2114 „ 
2128 „ 
16 
12* 
55 
2114 „ 
2086 „ 
CO 
H 
14 
55 
Total 
12740 „ 
12586 „ 
90 
co 
CO 
55 
Average 
2123-3 lbs. 
2097-6 lbs. 
15 twists. 
13 - 9 twists. 
Thus, in both experiments, the iron tests worse when 
warm than when frozen. In each case the wire immediately 
became warm. Mr. F. Monks, of the Whitecross Wire 
Works, Warrington, also tested wire rods for me with 
precisely similar results. Finding these experiments to be 
unsatisfactory, I arranged for a series to be tried by the 
more rough and ready method of the striker’s hammer, 
which I judged would be more likely to show the true state 
of the iron in its frozen condition. The result either of 
gradual torsion or tension is to expel the frost there may be 
