DEFINITION OF CORDAGE AND SOURCES OF FIBRES
The definition of cordage usually takes the form of “a quantity of cords
or ropes as the rigging of a ship, etc.,” but in commerce the word has a
more elastic meaning, and, in general, may be said to include all kinds
of continuous strands or the like which are not intended to be woven
into cloth or to be knitted into hosiery. Differentiation occurs,
however, for one often finds the phrase “Ropes, Cords and Twines” as
referring to special types of cordage, while further subdivision occurs
when one includes the many types of finer material such as lines, sewing
thread, and the like. And when one considers that the various articles
which are included in the generic term cordage have a range from ropes
of 9 or 10 in. in diameter to fine threads of not more than perhaps
1/60th of an inch, and for which a very large number of different kinds
of fibres are used, some idea of the immense variety can possibly be
formed.
From whatever source a vegetable cordage fibre is derived, it is
necessary to eliminate more or less of the substances which are closely
connected with it in the plant, in order that the comparatively pure
fibre may be spun into thread form with the maximum of strength and
production, and the minimum of difficulty and waste. In this respect it
is quite likely that an animal fibre such as wool would be more easily
separated than any other known fibre. Wool, however, is rarely used for
cordage purposes, although hair, which approximates to wool, is used for
certain types of cord. There are certainly many types of wool ropes used
for decorative purposes, but, in general, this most valuable substance
is, for obvious reasons, unsuitable for the usual kind of cordage, and
hence wool will not be discussed in this work.
The fibres from the leaves of certain tropical plants may be separated
with a little more difficulty than that which is experienced in the
operation of shearing a sheep, but these fibres are hidden, and even
when found originally, great difficulty would be experienced before a
continuous thread could be made from them. It is quite probable that a
natural process of disintegration would disclose these vegetable fibres
to primitive man, and lead to their ultimate utilization for various
purposes. Or perhaps the gradual wear and tear of the leaves used,
either loosely or bound in some crude form, as floor-covering would
result in the discovery of the fibrous layers. It is the remarkable
advance in mechanical science which has made the production of a
continuous thread from such fibres a possibility for industrial
purposes.
Long before continuous spinning was invented, however, it would be
desirable to extract the valuable fibrous material from its bed of
vegetable matter because the latter is, in general, quite unfit for the
purposes which the fibrous material has to perform. This remark applies
not only to the fibres which are extracted from leaves, but also to
those valuable fibres which are embedded in the bast layers of the stems
of certain plants.
We might now with advantage illustrate by means of photographic
reproductions of plants, and photomicrographs of sections, the three
sources from which vegetable fibres are obtained to be utilized in the
manufacture--or spinning as it is technically called--of the world’s
supply of cordage.
[Illustration: _By permission of Messrs David Bridge & Co., Ltd._
FIG. 1
TWO-YEAR-OLD SISAL PLANT]
A typical example of a leaf plant from which one type of textile or
cordage fibre is extracted is illustrated in Fig. 1. This particular
example is designated as a “Two-year-old Sisal Plant.” It is 49 in.
high, and was grown in the Voi district, British East Africa. Sisal is
the commercial name of the fibre obtained from such plants, while the
botanical name of the plant is _Agave Rigida_, variety _Sisalana_; it is
sometimes, though erroneously, termed the Americana.
[Illustration: FIG. 2
AGAVE AMERICANA]
A recently suggested nomenclature of the Agave and other plants, from
which sisal and similar fibres are extracted, is due to Professor Lyster
Dewey of the United States Department of Agriculture--
(1) Agave Fourcroydis of Yucatan; this plant yields 90 per cent. of the
sisal fibres exported from all countries. The leaves bear marginal
spines as illustrated in the _Agave Americana_ shown at A, Fig. 2: the
plant was formerly known as _Agave Rigida_, variety _Elongata_.
(2) _Agave Sisalana_ grown for use by the natives of Central America and
South Mexico, but not much exported.
(3) _Agave Cantala._ This is the “_Maguey_” plant of the Philippine
Islands, and is grown in limited quantities in Java and India.
[Illustration: FIG. 3
TRANSVERSE SECTION OF A LEAF OF AGAVE AMERICANA]
When a thin slice or fine transverse section of one of the leaves of
such a plant is mounted, and its appearance magnified by
photomicrography, the structure of the leaf is shown to be similar to
that illustrated in Fig. 3. The upper and the lower outer surfaces or
cuticle A resemble greatly the whipped edges of blankets. These
surfaces, and all the pulp-like matter lettered B, must be removed,
either by manual or mechanical means, in order to separate or extract
the groups of fibre some of which are denoted by the letter C. A still
further enlargement of a few of these groups of fibrous material appears
in Fig. 4.
[Illustration: FIG. 4
PHOTOMICROGRAPH OF A SECTION OF FIBRES OF AGAVE AMERICANA]
A photomicrograph of two fibres of a type of Agave grown in Mexico is
shown in Fig. 5; it is interesting because it depicts the formation of
crystals of Oxalate of Potash. The presence of such crystals makes the
fibre unsuitable for cordage purposes, but it may be used in the
manufacture of coarse brushes.
[Illustration: FIG. 5
PHOTOMICROGRAPH OF FIBRES OF AGAVE GROWN IN MEXICO, SHOWING OXALATE OF
POTASH CRYSTALS]
The second source from which fibre is extracted is that from the stems
of plants such as flax, hemp, jute and the like. A photographical
reproduction of a group of hemp plants grown by the Authors appears in
Fig. 6. A female plant is illustrated on the right, while the remaining
two which are taller are male plants.
[Illustration: FIG. 6
GROUP OF HEMP PLANTS]
[Illustration: FIG. 7
CROSS-SECTION OF PLANT]
A thin cross-section cut from the stem of such a plant exhibits the
characteristics in Fig. 7, in which A is the cuticle or outer bark, B is
the woody part, and C the pith. The fibrous layer is between the two
dark circles D, and a few groups of fibres in this layer are indicated
by the letter E. Here, again, a considerable amount of extraneous matter
must be separated from the bast layer, and when separated, the latter
appears in the form of long ribbons. The cuticle and bast layer were
originally stripped from the plants; the former were then placed in the
mouth so that the saliva could aid in the separation of the fibres from
the bark, and permit of a finer reduction of the fibrous layer to
produce finer threads. And although at the present time this method is
practised for thread making in many primitive communities, it need
hardly be said that much more efficient methods have long been practised
for commercial purposes, such methods being known by the technical terms
“retting,” “breaking,” and “scutching.”
[Illustration: FIG. 8
LONGITUDINAL VIEW OF COTTON FIBRES]
[Illustration: FIG. 9
CROSS-SECTIONAL VIEW OF COTTON FIBRES]
The third source of vegetable fibres is the cotton plant _Gossypium_,
the white fluffy fibres being obtained from the pods or bolls. The
operation of cotton picking which is often referred to consists of
removing this white fluffy mass from the pods in which also the seeds
are located. Cotton fibre is unlike the two previous classes of fibre
because its method of growth is different. The other textile fibres are
composed of bundles of plant cells, whereas the fibres of cotton are
individual cells; they form as it were individual hairs on the seed, and
in drying flatten and also assume a twisted and crinkled condition as
exemplified in Fig. 8, which illustrates the longitudinal
characteristics of several fibres. Fig. 9 shows the sectional
enlargements of a few fibres. This structure of the cotton fibre is a
very valuable property, since it not only assists in the binding of the
fibres into a thread, but also gives a resiliency and spring to ropes
manufactured from it which is most useful in driving; this property
makes cotton almost indispensable for the construction of the smaller
sizes of ropes for driving purposes.