A much higher power than this is necessary if the fibre in question is to be seen at its best, and for the purpose of this chapter a quarter inch objective will be used.

Underneath the stage, which is pierced by a circular aperture, is a diaphragm. This regulates the quant.i.ty of light which is to be transmitted by means of the silvered reflector shown in the ill.u.s.tration.

As a rule, two reflectors are fixed in the same holder; one a concave mirror, the other a plane one. The former brings the rays of light to a point or focus while the latter simply pa.s.ses the beam of light along just as it received it, viz., as a parallel beam of light.

In examining fibres the concave mirror will be of most use. An ordinary lamp is usually good enough for the light required, the one figured being very suitable and having a tube-like arrangement of wick. Behind the body-tube are two forms of adjustment, coa.r.s.e and fine. The latter is worked by means of the milled screw, conical in shape, which is found immediately behind the coa.r.s.e adjustment. The operator is supposed to have had some slight experience in the manipulation of the microscope.

The slide is now placed upon the stage. Fine Sea Islands cotton is mounted in Canada Balsam and protected by a small circular cover gla.s.s.

Now rack down the body-tube by means of the coa.r.s.e adjustment until within 1/16 of an inch of the cover-gla.s.s of the slide. Now see that the light from the lamp is fully on the cotton strands. Rack up or down, as the case may be, with the fine adjustment, and a wonderful sight meets the eye, for the cotton viewed through the microscope is altogether unlike what we should expect it to be.

Running completely across the field are a number of strands, varying in thickness, form and natural twist. What is meant by natural twist is very clearly shown in Fig. 7.

Most people have seen india-rubber tubing or piping such as is used in the chemical laboratory or that often found attached to feeding bottles.

Take about a foot of this and hold one end firmly. Abstract the air by means of the mouth, and it will be found that immediately the air is taken out the tube collapses. Now if the rubber be variable in thickness, here and there along these lines of least resistance will be found certain twists, and it is the same kind of twists which can be so distinctly seen as the cotton fibre is viewed through the microscope.

They are exceedingly irregular in number, on equal lengths of the same single fibre. When they run for some length, and are fairly regular, the edges appear like wavy lines or corrugations. It will now be seen by the reader why these twists are so invaluable in spinning: locking and intertwining with each other, they materially a.s.sist the spinner in building up a long and continuous thread.

Image: FIG. 7.--Transverse and longitudinal sections of cotton fibre.

Then, too, are to be seen lying close to the regularly twisted fibres a number of others which are very like ribbons, with here and there an apology for a twist, and further, a careful scrutiny will be rewarded by finding in what is reputedly the best cotton a number of filaments which do not display any twists whatever and are very much like the round tubing referred to a little while ago. Others again are quite flat, without any distinguishing twists whatever. These are said to be the half-ripe and unripe fibres, and give much trouble later on (if worked up with good cotton) to the dyer and spinner.

As the slide containing the cotton is moved laterally, it will be seen that this twisting of the fibre is continued for almost the whole length, and as many as 300 twists have been counted on a single filament. In some, the fibre tapers slightly, becoming more and more cylindrical as the end most remote from the seed is approached, until it is quite solid. These stiff ends soon disappear after the cotton has been treated in the early processes of manufacture. Thus there may be found in almost every sample of cotton what are called ripe, half-ripe and unripe cotton. The last-named kind result from--

1. Gathering the crop before the boll is properly ripened and matured.

2. Bad seasons; too much moisture and too little heat.

Then again in the same boll all fibres do not ripen together just as all apples on the same tree do not ripen together.

Immature or unripe cotton cannot be dyed, and when small white specks are seen in any dyed fabric they are often due to the fact that unripe cotton has been used in the manufacture of the cloth.

=Measurement of the Cotton Fibre.=--This is not at all a difficult matter, and the ordinary student may, by means of very simple and inexpensive apparatus, obtain fairly satisfactory results in the measurement of fibres.

There is a choice of one of three methods, viz.:--

1. By having the mechanical stage so arranged that the slightest displacement either to the left or right can be measured, and having the eye-piece so marked (generally a hair stretched across it) that when an object is to be measured, one side of it is made to coincide with this central line and the stage rack is worked left or right until the opposite side of the object is brought coincident with the central line again; the amount of displacement can then be readily obtained on referring to the graduated stage.

2. By having a stage micrometer and camera lucida.

3. By having two micrometers, a stage micrometer and eye-piece micrometer.

This latter method is certainly the least expensive, and for all practical purposes can be safely recommended.

A stage micrometer consists of a slip of gla.s.s 3" 1" on which are marked divisions of an inch, usually 1/100ths and 1/1000ths. As a rule these markings are protected by means of a small cover-gla.s.s.

Eye-piece micrometers vary much in form, size and value, but the one which is here described is of the simplest type. It consists of two circular pieces of gla.s.s carefully cemented together. On one of the inner surfaces are marked usually the 1/100ths divisions of an inch. In some 1/200ths are marked. If the top lense of the eye-piece be unscrewed, a diaphragm will be found on which the eye-piece micrometer will easily rest. Screw on the top lense again and, generally, the eye-piece will be ready for use. If the micrometer is not properly in focus after a few trials, it may easily be made right. In order, then, to measure the diameter of a single fibre of Sea Islands cotton, fit in the quarter inch objective and place the stage micrometer in position on the stage. First, focus the fine lines which are plainly to be seen, and remember the lines which are farthest apart are 1/100th of an inch; the others 1/1000th of an inch.

As a rule, these lines run from N. to S. of the field; in other words, from top to bottom across the circles of light. Now look at the divisions in the eye-piece micrometer, which are 1/100th of an inch apart.

It will be found often that an exact number of these divisions fill up one of the 1/100th divisions of the stage micrometer markings. If an exact number are not found, the draw-tube at the top end of the body-tube should be withdrawn until an exact number is found to lie within two lines of the lower micrometer.

Suppose twenty-two of the s.p.a.ces on the eye-piece micrometer just cover one of the divisions (1/100th of an inch) on the stage micrometer. Then it is clear that each division of the former represents 1/100 1/22 of an inch, or 1/2200th of an inch. For every fresh objective used, a fresh estimation of eye-piece and stage micrometer ratio is necessary. Having now got in the eye-piece micrometer a unit of measurement, it becomes a comparatively easy matter to measure the fibre.

Remove the stage-micrometer and put a slide of Sea Islands cotton in its place. Focus the fibre and observe the number of divisions or parts of a division covered by any particular fibre, and its measurement is at once known. Thus if a single filament covers two of the divisions then it is 2/2200th of an inch in diameter, or 1/1100th of an inch. Exactly the same method is adopted if it is desired to measure the diameters of sections of the same fibres.

The making of the drawing of a fibre, either transverse or horizontal section, is not at all a difficult matter.

All that is needed is what is known as a camera lucida. This consists of a bra.s.s fixing for the eye-piece end of the body-tube and a small reflecting prism. This prism receives the image of the objective, and reflects it in this case at right angles downward on to a sheet of paper, which is placed beneath for the purpose of tracing the said image.

Focus the object, first having the microscope in a horizontal position.

This will not be a difficult matter. Now remove the cap which fits on the eye-piece, and fix on the camera lucida as shown in the ill.u.s.tration (see Fig. 6). Adjust this until the image of the fibre is seen. Usually one or two smoke-coloured gla.s.ses are fixed below the prism, and these are now brought into position so as to allow the image of the fibre to pa.s.s through them. Place a sheet of drawing paper directly under the camera lucida, sitting as shown in the ill.u.s.tration. After a few trials it will not be a difficult matter to follow the outline of the image by means of a black lead on the paper as is shown in the figure. In this way many useful working drawings can be made, and a little careful calculation will give the amplification of the drawing after it is made.

CHAPTER V.

PLANTATION LIFE AND THE EARLY CLEANING PROCESSES.

After many months of anxious watching and waiting, towards the end of July or early in August, the planter may be seen to be constantly and wistfully looking for the appearance of the bursting bolls of cotton.

Daily in the early mornings he is to be seen casting his eyes down the pod-laden rows of cotton plants, to see if he can count a few ripe open bolls as he stands at the head of a row. If this be so, he knows that his harvest is close at hand, and his pickers must be ready at any moment to begin what is certainly the most tedious and difficult work of the plantation, namely, picking the raw cotton from the bursting bolls.

While the planter has been on the lookout in the fields, necessary and important operations have been going on inside in the farm outbuildings.

Sacks and baskets which can most expeditiously aid in the removal of the picked cotton from the field to the ginning factory are being got ready.

To suit the young and old, tall and small, weak and strong, different sized bags and baskets are required, and after the marking and branding of the same, they are ready for being put into use.

Now the picking of cotton is not at all an easy operation, long continuous bending, a hot sun (for it is a rule scarcely ever broken that cotton must not be plucked unless the sun is shining upon it), a constantly increasing weight round the neck or on the arm, monotonous picking of the cotton from the bolls without bringing away any of the husk or leaf--all tend to make the work of the picker very trying and tiresome. The plantation hands must be early at work, and while the day is very young they are to be seen wending their way, ready to begin when the sun makes its appearance. Often the clothes of the workers are quite wet with the early morning dews. This is specially the case in September and October. By ten o'clock a hot blazing sun streams down upon the pickers as they diligently relieve the heavy-laden bushes of the white fleecy load of cotton. As each picker fills his or her bag, it is quickly emptied into a larger receptacle, and ultimately carried away to the gin house, where it is desirable the cotton should be housed before the night dews come on and consequently damage materially the cotton which the pickers have been careful to pick while the sun was on it.

Mr. Lyman, in his book on the Cotton Culture in the States, says: "It seems like very easy work to gather a material which shows itself in such abundance as fairly to whiten the field, but let the sceptic or the grumbler take a bag on his shoulders and start in between a couple of rows. He will find upon taking hold of the first boll that the fibres are quite firmly attached to the interior lining of the pod, and if he makes a quick s.n.a.t.c.h, thinking to gather the entire lock, he will only tear it in two, or leave considerable adhering to the pod. And yet he may notice that an experienced picker will gather the cotton and lay his fingers into the middle of the open pod with a certain expertness which only practice gives, the effect of which is to clear the whole pod with one movement of the hand."

Knowing how intensely monotonous and dreary the work of cotton picking is, Mr. Lyman advises the planters to allow a very fair amount of liberty so far as merrymaking is concerned, and he says on this point that "though too much talking and singing must interfere with labour, it is earnestly recommended to every cotton grower to take care to secure cheerfulness if not hilarity in the field. Remember that it is a very severe strain upon the patience and spirits of any one, to be urged to rapid labour of precisely the same description day by day, week by week, month by month. Let there be refreshments at the baskets, a dish of hot coffee in a cool morning, or a pail of b.u.t.termilk in a hot afternoon, or a tub of sweetened water, or a basket of apples."

As a rule the cotton gathered on one farm, which has, generally speaking, had something like uniformity in method of cultivation, will produce cotton varying very little in quality and weight.

Hence on large farms there will be something like uniform quality of cotton produced. It will, however, be clear to the general reader that on the small farms of India, say where sufficient cannot be gathered on one farm, or perhaps on a few farms, to make one bale, there will not be that uniformity which is desirable, hence Indian cotton, especially of the poorer types, varies a great deal more than the American varieties.

When the hands have gathered sufficient to fill the carts drawn in America usually by mules, and in India by oxen, the cotton is taken to houses in which the seeds are separated from the fibre. This process is called "ginning."

It is astonishing to find how tenaciously the fibres cling to the seed when an attempt is made to separate them. At first much loss was occasioned because of the brutal methods employed, and now even with very much more perfect machinery a good deal of the cotton fibre is injured in the ginning process.

Image: FIG. 8.--Indian women with roller gin.

At present, most of the cotton produced in various parts of the world is ginned by machinery, though in India and China foot gins and other primitive types are still employed.

It should be stated that where a large production of cotton is desired the foot gin or even what is known as the "Churka gin" (which consists of a couple of rollers turned by hand) is never employed. Only a few pounds a day of cotton can be separated from the seeds when this method is adopted.

The following extract from a lecture by the late Sir Benjamin Dobson will be of interest here, as showing what is done at an American ginnery: