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Page 13
Attention was turned in 1876 to silk raising, and it was found that
all the conditions for producing cocoons of good quality and at low
cost were most favorable. It was, however, useless to raise cocoons
unless they could be utilized; in a word, it was seen that the country
needed silk-reeling machinery in 1876, as it had needed cotton-ginning
machinery in 1790. Under these conditions, Mr. Edward W. Serrell, Jr.,
an engineer of New York, undertook the study of the matter, and soon
became convinced that the production of such machinery was feasible.
He devoted his time to this work, and by 1880 had pushed his
investigations as far as was possible in a country where silk reeling
was not commercially carried on. He then went to France, where he has
since been incessantly engaged in the heart of the silk-reeling
district in perfecting, reducing to practice, and applying his
improvements and inventions. The success obtained was such that Mr.
Serrell has been enabled to interest many of the principal silk
producers of the Continent in his work, and a revolution in silk
reeling is being gradually brought about, for, strangely enough, he
found that the work which he had undertaken solely for America was of
equal importance for all silk-producing countries.
We have described the processes by which cocoons are ordinarily cooked
and brushed, these being the first processes of the filature. Instead
of first softening the gum of the cocoons and then attacking the floss
with the points of a brush, Mr. Serrell places the cocoons in a
receptacle full of boiling water, in which by various means violent
reciprocating or vortex currents are produced. The result is that by
the action of the water itself and the rubbing of the cocoons one
against the other the floss is removed, carrying with it the end of
the continuous filament without unduly softening the cocoon or
exposing any of the more delicate filament to the rough action of the
brush, as has hitherto been the case. The advantages of this process
will be readily understood. In brushing after the ordinary manner, the
point of the brush is almost sure to come into contact with and to
break some of the filament forming the body of the cocoon. When this
occurs, and the cocoon is sent to be reeled, it naturally becomes
detached when the unwinding reaches the point at which the break
exists. It then has to be sent back, and the end of the filament
detached by brushing over again, when several layers of filament are
inevitably caught by the brush and wasted, and very probably some
other part of the filament is cut. This accounts for the enormous
waste which occurs in silk reeling, and to which we have referred. Its
importance will be appreciated when it is remembered that every pound
of fiber thus dragged off by the brush represents a net loss of about
19s. at the present low prices.
The mechanical details by which Mr. Serrell carries out this process
vary somewhat according to the nature of the different cocoons to be
treated. In one type of machine the water is caused to surge in and
out of a metal vessel with perforated sides; in another a vertical
brush is rapidly raised and lowered, agitating the water in a basin,
without, however, actually touching the cocoons. After a certain
number of strokes the brush is automatically raised, when the ends of
the filaments are found to adhere to it, having been swept against it
by the scouring action of the water. The cleaning of the cocoons is
performed by means of a mechanism also entirely new. In the brushing
machinery the floss is loosened and partially detached from the
cocoon. The object of the cleaning machine is to thoroughly complete
the operation. To this end the cocoons are floated under a plate, and
the floss passed up through a slot in the latter. A rapid to and fro
horizontal movement is given to the plate, and those cocoons from
which the floss has been entirely removed easily give off a few inches
of their filament, and allow themselves to be pushed on one side,
which is accomplished by the cocoons which still have some floss
adhering to them; because these latter, not being free to pay off, are
drawn up to the slot in the plate, and by its motion are rapidly
washed backward and forward in the water. This washing soon causes all
the cocoons to be freed from the last vestiges of floss without
breaking the filament, and after about twenty seconds of movement they
are all free and clean, ready for reeling.
We have now to explain the operation of the machine by which the
thread is formed from the prepared cocoon. At the risk of some
repetition, however, it seems necessary to call attention to the
character of the work itself. In each prepared cocoon are about a
thousand yards of filament ready to pay off, but this filament is
nearly as fine as a cobweb and is tapering. The object is to form a
thread by laying these filaments side by side in sufficient number to
obtain the desired size. For the threads of raw silk used in commerce,
the sizes vary, so that while some require but an average of three
filaments, the coarsest sizes require twenty-five or thirty. It being
necessary keep the thread at as near the same size as possible, the
work required is, in effect, to add an additional cocoon filament to
the thread which is being wound whenever this latter has tapered down
to a given size, or whenever one of the filaments going to form it has
become detached. Those familiar with cotton spinning will understand
what is meant when it is said that the reeling is effectively a
"doubling" operation, but performed with a variable number of ends, so
as to compensate for the taper of the filaments. In reeling by hand,
as has been said, the size of the silk is judged, as nearly as
possible, by a complex mental operation, taking into account the
number, size, and state of unwinding of the cocoons. It is impossible
to do this mechanically, if for no other reason than this, that the
cocoons must be left free to float and roll about in the water in
order to give off their ends without breaking, and any mechanical
device which touched them would defeat the object of the machine. The
only way in which the thread can be mechanically regulated in silk
reeling is by some kind of actual measurement performed after the
thread has left the cocoons. The conditions are such that no direct
measurement of size can be made, even with very delicate and expensive
apparatus; but Mr. Serrell discovered that, owing to the great
tenacity of the thread in proportion to its size, its almost absolute
elastic uniformity, and from the fact that it could be stretched, two
or three per cent. without injury, it was possible to measure its size
indirectly, but as accurately as could be desired. As this fact is the
starting point of an entirely new and important class of machinery, we
may explain with considerable detail the method in which this
measurement is performed. Bearing in mind that the thread is of
uniform quality, it is evident that it will require more force to
stretch a coarse thread by a given percentage of its length than it
will to stretch one that is finer. Supposing the thread is uniform in
quality but varying in size, the force required to stretch it varies
directly with the size or sectional area of the thread itself. In the
automatic reeling machine this stretch is obtained by causing the
thread to take a turn round a pulley of a given winding speed, and
then, after leaving this pulley, to take a turn around a second pulley
having a somewhat greater winding speed.
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