The stiffness of
the framing in a machine produces an important advantage. If the
bearings of the axis (those places at which they are supported)
are once placed in a straight line, they will remain so, if the
framing be immovable; whereas if the framework changes its form,
though ever so slightly, considerable friction is immediately
produced. This effect is so well understood in the districts
where spinning factories are numerous, that, in estimating the
expense of working a new factory, it is allowed that five per
cent on the power of the steam-engine will be saved if the
building is fireproof: for the greater strength and rigidity of a
fireproof building prevents the movement of the long shafts or
axes which drive the machinery, from being impeded by the
friction that would arise from the slightest deviation in any of
the bearings.
323. In conducting experiments upon machinery, it is quite a
mistake to suppose that any imperfect mechanical work is good
enough for such a purpose. If the experiment is worth making, it
ought to be tried with all the advantages of which the state of
mechanical art admits; for an imperfect trial may cause an idea
to be given up, which better workmanship might have proved to be
practicable.
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