OUR YORKSHIRE LETTER.

Wairarapa Daily Times, Volume LV, Issue 8599, 5 November 1906, Page 2

OUR YORKSHIRE LETTER.

Why Wool Felts

( By Our Special Correspondent.) Bradford, September 21st, 1906. Many are the theories upon which writers have attempted to account for the felting of wool—the attraction of cohesion ; the elasticity of the fibres bent in every direction, and prevented from returning to their original length by the adhesion of other fibres ; the property which certain hairs and vegetable filaments have of attaching themselves more and more to each oth.er, in proportion as the fabric into which they are united is beaten, the fibres entangling each other in circles, and by their elasticity striving to return to their original condition ; these, and modifications of similar theories, were accepted as a sufficient explanation. M. Monge was the first who ventured to assert that a barbed or feathered edge must be the m structure of the surface of wool; that the l| surface is formed of lamella?, or little plates, which cover each other from the root to the point, as the scales of a fish or the back scales of a snake ; and on this theory, the truth of which M. Monge assumes, he explains the mechanism of felting as actually as though he had himself seen the serrations or scales on the surface of the fibre. It was reserved for the late eminent veterinarian, Mr Youatt, to demonstrate the peculiarity in question. Mr Youatt thus announces his discovery: —" On the evening of the 7th of February, 1835, Mr Thomas Plint, woollen manufacturer, resident at Leeds ;Mr Symonds, clothing agent, of Cateaton-street, London ; Mr T. Millington, surgeon, of London ; an esteemed friend, Mr E. Brady, veterinary surgeon, at that time assisting the author in his practice ; Mr W. H. Coates, of Leeds, veterinary pupil ; Mr Powell, the maker of the microscope ; and the author himself (Mr Youatt), were assembled in the parlour. A fibre was taken from a merino fleece without seleciion, and placed on the frame, to be examined a3 a transparent object. A power of 300 (linear) was used ; and, after Mr Powell, Mr Plint had the first ocular demonstration of the irregularities in the surface of the wool, the palpable cause of the most valuable of it«| properties., its disposition to felt. The fibre thus looked at assumed a flattened ribbonlike form ; it was of a pearly-grey colour, with faint lines across it; the edges were evidently hooked, or, more properly, serrated ; they resembled the teeth of a fine saw. Thesa were somewhat irregular in different parts of the field in view, both as to size and number. The area of the field was one-fortieth of an inch in diameter. By means of a micrometer we divided this into four, and we then counted the number of serrations in each division. Three of U9 counted all four divisions, for there was a difference in some of them. The number was set down privately, and it was found that we had all estimated it at fifteen on each division. Having multiplied this by four, in order to obtain the whole field, and that by forty, the proportionate part of an inch of which the field consisted, we obtained as a result that there were 2-iOO serrations in the space of an inch, all of which projected in the same direction, v<:... from the root to the point." The diameter of the fibre was ascertained to be l-75Oth of an inch. ' We next endeavoured to explore the cause of this serrated appearance, and the nature of the irregularities on the surface which might possibly account for the production of these tooth-like projections. We therefore took another fibre, and mounted it as an opaque object." some difficulty Mr Powell succeeded, " we were presented with a beautiful glittering column, with lines of division across it, in number and distance seemingly corresponding with the serrations that we had observed in the other fibre, which had been viewed as a transparent object. It was not at once that the eye could adapt itself to the brilliancy of the object, but by degrees these divisions developed themselves, and could be accurately traced. They are not so marked as the inverted cones which bat's wool presented, but they were distinct enough, and the apex of the superior one, yet comparatively little diminished in bulk, was received into the evacuated base of the one immediately beneath, while the edge of this base, formed into a cup-like shape, projected, and had a serrated or indented edge, bearing no indistinct resemblance to the ancient crown." All these projecting edges pointed in a direction from the point to the apex.

The true cause, then, of the felting property of wool, and at the same time its distinguishing character when contrasted with hair, consists as the microscope demonstrates, in its external serrated structure. When viewed through a microscope of great power as a transparent object, the fibre of wool assumes a ribbon-like appearance* with the edges serrated ; but these tions, when the fibre is viewed as an opaque object, are found to result from the presence of a succession of inverted cones, encircling a central stein, the apex of the superior cone being received into the cup-like base of the inferior one; each cup-like cone has projecting and indented edges, and is further resolvable into distinct scales or leaves, set regularly around the central stem, like the scaly petals of some flowers. These scales vary in number, size, and degree of projection, in the wool of different animals. In some instances these scales are pointed, in others rounded. In the wool of the bat these circlets are so decided as to produce the appearance of a series of cups placed one in another, and having indented edges. Though hair is covered with scales, it has no serrations or tooth-like projections. The hair of the tiger, for example, is covered with fine scales like those on the back of a sole, while the wool, which is beautifully fine, being only one-thousandth part of an inch in diameter, has numerous and distinct serrations, amounting to 2560 in the space of an inch. In the wool of tbe bear, and the Italian wolf dog, the serrations are distinct and numerous. The human hair, as ascertained by Mr Gill, is of a cylindrical form, and covered with scales, of rugosities, but without serrations. Dr Goring, indeed, describes ihe appearance of the hair of Uiqjl human head as being indented with teetllK somewhat resembling those of a round rasp, but extremely irregular and rugged ;he states that these all incline in one direction, like those of a file, viz:, from the origin of the hair towards its extremity. "It is singular." says Mr Youatt, " that although many years have passed, and the microscope has been singularly improved since Dr Goring observed this structure of the hair, and almost every one who possessed an instrument of much power has been eager to gaze on this new discovery, no person has been so fortunate as to detect a single eerration on its edge." A true serrated surface, according to Mr Youatt, is the character of wool only. The wool of the rabbit is

fine, with sharp angular serrations to the number of 2880 in tho inch, being 160 moie »fhan in the highly valuable and felting Saxon wcol. The fibre, however, has fewer curls. The hair of the rabbit varies from l-250th to l-300th part of an inch in diameter, and is covered with a scaly incrustation, but cannot be said to be serrated.