be a pressure of air greater on one side than
on the other of the permeated medium. Mr.
Goodyear thought of this; and the result of
his thoughts was that he devised a machine
for piercing thin sheets of India-rubber with
innumerable holes of very small size: holes
so small that, while they will allow an exit
for perspiration, they allow no entrance for
water: for this additional reason, that when
the perspiration (which is always transuding,
even when we are not conscious of it,) has
risen, it fills these little holes, and being
oleaginous, has the power, equally with the
India-rubber material, of resisting wet. Not
only shoes, therefore, but every other
garment to which the Macintosh process has
been hitherto applied, will doubtless soon be
brought into the range of this ingenious discovery.

It is worthy of notice, that the employment
of India-rubber in its uncombined state is not
very varied or extensive. In most cases the gum
is kneaded with sulphur, or magnesia, or
carbonate of lead, or some other mineral substance;
or else is applied to some other woven material.
Of each of these two large groups of applications
we have mentioned instances, and it
would not be difficult to add largely to the
list. The "doctored," or vulcanised, or
mineralized India-rubber is used for tubes, hose-
pipes, decanter and bottle stoppers, surgical
and veterinary apparatus, chemical apparatus,
buffers for locomotives, buffer and bearing
springs for carriages, tires for noiseless wheels,
sewer and sink valves, elastic tackle and
pulleys, pistons and washers and packings for
machinery, moulded articles for various purposes
of use or ornament, valves and taps
for various hydraulic and chemical purposes,
air-pump valves, inking rollers for printers,
cushions for billiard-tables, joints for pipes;
indeed, an ever-widening circle of useful purposes.
Some of the results are most valuable,
some curious; some are both valuable
and curious. We all know that to keep a pipe
so closed that a liquid shall pass through it
only in one direction, requires a complex
arrangement of valvular apparatus; but our
India-rubber manufacturers (there ought to
be some short name devised here, equivalent
to these three words), effect this object
by simply compressing one end of an India-
rubber pipe so as to form a kind of mouth
or pair of lips: the lips close resolutely
except when water forces them apart to obtain
a passage in one direction. When the
mineralised gum is prepared in moulds, it assumes
and preserves the form of those moulds; and
thus, among other things, are produced the
dolls' heads, and animals, and toys, which are
now finding their way into the. nursery and
the play-ground, and which, from their sturdy,
unbreakable disposition, are so justly valued
by mammas and nursemaids.

Among the other applications of, and experiments
with, vulcanized India-rubber, its use
for street pavements must not be forgotten.
The enormous thoroughfare through the
streets of London has given rise to a vast
number of inventions to combine hardness
and durability with sufficient roughness or
elasticity to form an easy and effectual "foothold"
for horses and passengers. It was at first
thought that all these conditions could be
combined by the application of India-rubber
submitted to a hardening process something
similar to vulcanizing. But experience proved
that a due amount of proficiency in that art had
not been attained in order to pave our streets
with so pleasant a material as "doctored"
India-rubber. The only relic left of this
contrivance is the court-yard of the Admiralty.

The second important application of this
most valuable substance is, as we have said,
in the form of a liquid cement, or an unctuous
varnish, on a surface of woven, or, at any rate,
fibrous material. And the great magnitude
of this application, we have by this time
already computed. Who is not familiar with
the cloaks and capes, the wrappers and overalls,
the sou'westers and leggings, the gloves
and gaiters, the air-beds and air-cushions, the
neat little India-rubber bands or rings, the
maps and prints, the bags and balloons?
What with our elasticity and our impermeability,
we are certainly becoming a redoubtable
race in this nineteenth century.

But one class of applications of India-
rubber we have left wholly unnoticed in the
above paragraphs; applications, too, which
curiously enough, depend on the very quality
which was for many years a stumbling-block
in other ways. India-rubber loses nearly all
its elasticity at a temperature a little above
that of freezing; and this property has been
made available in the manufacture of braids,
and braces, and cords, in infinite variety.
The hosiers, tailors, haberdashers, and
milliners, now make use of these little trifles
to a remarkable extent; and very pretty
trifles they are, in the mode of production.
There are here threads of India-rubber
combined with threads of silk, cotton, wool, or
flax. The gum is cut into threads by very
ingeniously arranged knife-points, or cutters;
they are stretched by a wheel, and kept
extended till nearly deprived of their elasticity;
they are next put into the braiding machine
—a beautiful piece of machinery and have
a sheathing of silk, wool, hair, flax, or cotton,
braided around them; and when thus
sheathed, the threads are used as warp or
weft, or both, in various kinds of weaving
processes. Thus are made the elastic stay-
laces, braid, upholsterer's cord, and other
articles of a similar character; but it has
yet to be explained in what way the elasticity
of the material is restored. If threads
of India-rubber were woven in their ordinary
state, either with or without other threads,
they would be so yielding as to be unfitted
for the object in view; but by being kept
stretched for some time at a low temperature,
they acquire a rigidity as if stiffened by cold,