Repository: UIHistories Project: Board of Trustees Minutes - 1886 [PAGE 232]

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tions made further than may be needed to make the results clearly understood. For the greater data we can only refer to the detailed report now in press at the Government Printing Office.

STRUCTURE OF WOOL.

If we take a tuft of woof in the hand we find it composed of a bundle of fibres similar in many respects to hairs, yet differing from these latters in several important particulars. If we separate from the tuft a single fibre and draw it between the fingers, we find that in one direction it draws very much more readily than in the other. Pull it with sufficient strain and before it will break it will stretch from one-third to one-half its length, and thus prove to be more or less elastic. If wTe cleanse a tuft of fibres, and by any convenient means mix the fibres so that they become more or less interwoven, and then pound or otherwise bring the fibres into close contact with each other, we find that the mass will soon become closely matted to a degree dependent upon the extent of manipulation, and the breed from which the wool was taken. We say it has felted. If we stretch a small bundle of fibres and then snap it while under tension, we find it will give a more or less clear ring, according to its quality. By its appearance and feel we determine whether it be line or coarse. All these means enable those engaged in the woolen industry to arrive at their appreciation of the value of any given lot of wool. The minute structure of the fibre has as a rule little value for, or at least has received but little of attention from, the practical wTool-grower, buyer, or manufacturer. And very naturally; for neither education, habits of work nor absolute necessity have intervened to lead them to such study. For proper examination and study the fibre must be suitably prepared and " m o u n t e d " upon a glass slip ordinarily used with the microscope, and because of the ''crimp ' common to it, the fibre should be subjected to sufficient tension to remove the crimp and bring the entire portion of it within the plane of the glass slip, and thus render it possible to bring a larger length within the focus at the same time, or to make examination and comparison of several fibres side by side simultaneously. For this purpose we have made use of a very simple device, which consists of supporting the slip at each end by thick blocks. Drawing a fibre at random from the tuft, which has previously been cleansed with ether, a small weight, such as an iron nail, is attached to each end, and the fibre then laid across the slip. When several fibres have been thus prepared and laid across, they are brought together as closely as possible, by means of a needle. Then a drop of a mixture of glycerine and alcohol is placed upon the fibres thus arranged, a cover glass is placed over the whole, when it soon becomes ready for examination and study. Other media than the mixture of alcohol and glycerine may be used, but we have found the refractive power of this to be about what is needed to secure the best development of the several details of minute structure, so that in our late work we have used it to the exclusion of all others.