There is another disadvantage which will
soon be overcome--the greater liability to error in the compasses of
iron ships; an error which, however, also occurs, though perhaps to a
less extent, in every wooden ship. By a most ingenious invention,
which will shortly be made public, such errors in any ships, under any
circumstances, can at all times be at once detected.'
An important patented process for producing tapered iron, has been
explained before the Franklin Institute at Philadelphia--one by which
every variety of taper may be produced, or combinations of taper, with
flat or other forms; and seeing how much tapered iron is used on
railways, in many kinds of machinery, in ships and steamers, the
subject may be considered worthy of more than a mere passing notice.
Tapered iron is a form to which machinery has been thought
inapplicable, and only to be produced by hand-labour. The new method,
however, which has been successfully carried into practice at the
Phoenixville Ironworks, is thus described: 'The principle on which it
acts is that of hydrostatic pressure, or, more properly, _hydrostatic
resistance_. A small chamber, similar to that of the common
hydrostatic press, is set on the top of each housing; the closed end
of the press being uppermost, and a plunger entering from below; but
instead of water being forced _into_ the press, the chamber is at
first filled with water, and the pressure of the iron in passing
between the rollers, tends to lift the top one, which is held down by
the plunger.
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