THE INTEGUMENTS AND CLOTHING OF MAMMALIA. 155 



M."Monge, however, did not see the peculiarity in question: and 

 it was reserved for Mr. Youatt to demonstrate it.* The true cause of 

 the felting property of wool, and, at the same time, its distinguishing 

 character, when contrasted with hair, consists, as ascertained by micro- 

 scopical experiments, in its serrated structure externally. When viewed 

 through a microscope of great power, and as a transparent object, the 

 fibre of wool assumes a ribbon-like form, with serrated edges ; but these 

 serrations, 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 stem, the apex of the superior cone being received into the cup- 

 like base of the inferior one ; and each cup-like cone has projecting and 

 indented edges, directed from root to point, as seen in figs. 158 and 159, 

 representations of Merino wool. These conical, or cup-like circlets, 

 are farther resolvable into distinct scales, or leaves, set regularly around 



forward, in various directions ; this pressure brings the hairs against each other, and multiplies their 

 points of contact. The agitation gives to each hair a progressive motion toward the root ; but the 

 roots are disposed in different directions, in every direction ; and the lamellae of one hair will fix them - 

 selves on those of another hair, which happens to be directed a contrary way, and the hairs become 

 twisted together, and the mass assumes that compact form which it was the object of the workman to 

 produce. In proportion as the mass becomes compact, the pressure of the hands must be increased, 

 not only to make it closer, but, also, to keep up the progressive motion and twisting of the hairs, which 

 then takes place with greater difficulty." Thus near did M. Monge arrive at the truth. 



* Mr. Youatt thus announces his discovery: " On the evening of the 7th of February, 1835, Mr. 

 Thomas Flint, 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 sur- 

 geon, 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, were assembled in the parlour. 

 A fibre was taken from a Merino fleece, without selection, and placed on the frame, to be examined 

 as a transparent object. A power of 300 (linear) was used ; and, after Mr. Powell, Mr. Flint had 

 the first ocular demonstration of the irregularities in the surface of the wool, the palpable proof of the 

 cause of the most valuable of its properties, its disposition to felt. The fibre, thus looked at, assumed a 

 flattened, ribbon-like 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. These 

 were somewhat irregular in different parts of the field of 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 us 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 in each division. Having multiplied this by four, 

 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 2400 serrations in the space of an inch, all of 

 which projected in the same direction ; viz., from the root to the point." The diameter of the fibre 

 was ascertained to be 1 -750th 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." After some 

 difficulty, at length Mr. Powell succeeded; "and 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, that 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 the Bat's wool presented, but they were distinct enough ; and the apex of the 

 superior one, yet comparatively little diminished in bulk, was received in the excavated 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 root to point." 



