H = 29.3 30 p. c. Good 66 90 12
I = 28.9 28.9 p. c. Good 53 68 12

I think all of the above tests show that this material, when carefully
made and treated with sufficient mechanical work on forging down from
the ingot, is suitable up to 34 tons for crank shafts; how much higher
it would be desirable to go is a question of superior excellence in
material and manufacture resting with the makers. I would, however,
remark that no allowance has been made by the Board of Trade or Lloyds
for the excellence of this material above that of iron. I was
interested to know how the material in the best iron shafts would
stand this fatigue test compared with steel, and had some specimens of
same dimensions cut out of iron shafts. The following are the results:
Best iron, three good qualities, rolled into flat bars, cut and made
into 4½ cwt. blooms.

J = 18.6 24.3 p. c. Good 17 18 12

Made of best double rolled scrap, 4½ cwt. blooms.

K = 22 32½ p. c. Good 21 32 12

You will see from these results that steel stood this fatigue test,
Vickers' 73 per cent. and Steel Co.'s 68 per cent., better than iron
of the best quality for crank shafts; and I am of opinion that so long
as we use such material as these for crank shafts, along with the
present rules, and give ample _bearing surface_, there will be few
broken shafts to record.

I omitted to mention that built shafts, both of steel and iron, of