thing for a shaft to break and expose the internal bars, showing them
to be quite separate, or only partially united. This danger has been
much lessened in late years by careful selection of the materials,
improved methods of cleaning the scrap, better furnaces, the use of
the most suitable fuels, and more powerful steam hammers. Still, with
all this care, I think I may say there is not a shaft without flaws or
defects, more or less, and when these flaws are situated in line of
the greatest strains, and though you _may not_ have a hot bearing,
they often extend until the shaft becomes unseaworthy.

[Diagrams shown illustrated the various forms of flaws.] These flaws
were not observable when the shafts were new, although carefully
inspected. They gradually increased under strain, came to the outside,
and were detected. Considerable loss fell upon the owners of these
vessels, who were in no way to blame; nor could they recover any money
from the makers of the shafts, who were alone to blame. I am pleased
to state, and some of the members here present know, that considerable
improvement has been effected in the use of better material than iron
for crank shafts, by the introduction of a special mild steel, by
Messrs. Vickers, Sons & Co., of Sheffield, and that instead of having
to record the old familiar defects found in iron shafts, I can safely
say no flaws have been observed, when new or during eight years
running, and there are now twenty-two shafts of this mild steel in the
company's service.

I may here state that steel was used for crank shafts in this service
in 1863, as then manufactured in Prussia by Messrs. Krupp, and
generally known as _Krupp's steel_, the tensile strength of which was
about 40 tons per square inch, and though free from flaws, it was
unable to stand the fatigue, and broke, giving little warning. It was