Mechanics are aware, that, from the time of James Watt to the
year 1850, the grand desideratum of the engine builder was a perfect
joint,--a joint that would not admit the escape of steam. A
steam-engine is all over joints and valves, from most of which some
steam sooner or later would escape, since an engine in motion produces
a continual jar that finally impaired the best joint that art could
make. The old joint-making process was exceedingly expensive. The two
surfaces of iron had to be most carefully ground and polished, then
screwed together, and the edges closed with white lead. By the use of
a thin sheet of vulcanized India-rubber, placed between the iron
surfaces, not only is all this expense saved, but a joint is produced
that is absolutely and permanently perfect. It is not even necessary
to rub off the roughness of the casting, for the rougher the surface,
the better the joint. Goodyear's invention supplies an article that
Watt and Fulton sought in vain, and which would seem to put the
finishing touch to the steam-engine,--if, in these days of
improvement, anything whatever could be considered finished.
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