"Yes, they are curious; but now you may see why, when hairs are worked together, they may be made to stick to each other. These rough parts catch into each other, and hook themselves; and the more you press them or move them, the more closely you work them into one solid mass, which you cannot easily pull to pieces. Besides, you must remember that the hairs will work only one way, as you found out just now when your finger ends caught upon the little joints and moved them along. Now, suppose that a very large heap of hairs, or wool, or fur, after it is made ready, should be put upon a table, and covered with a linen cloth, and pressed down in different directions. Each hair would begin to move in the direction of its root, just as it did between your fingers, and so all would be joined together at last into one solid piece." "We understand you, Uncle Philip." "Then you understand, boys, the way in which a hat is made. These hairs are all worked together by the hands of the hat-maker, and to make them work more easily (for curled hair, such as wool, does not move easily) the hatter uses hot water, and dips his hat in it while he is working it. After it is done, it is died, and then put upon a wooden block to give it shape, and is ironed smooth." "And this is the way, then, Uncle Philip, to make hats: it is curious, is it not?" "Yes, boys; but plain enough when you come to examine into it. And the best stuff for the hatters is such hair as has most joints ready to catch into each other: the rabbit's hair is very good, and for that reason." "And is it possible, Uncle Philip, that any bird can do such work as this?" "Not only possible, boys, but true. There are several birds very expert at making felt, and their nest appears like a piece of hatter's felt, or double-milled woollen cloth. I do not mean to say that it is as close and solid as the hat or cloth; it would feel in your fingers looser than either, still it is quite close; and when you examine it, you will find it put together in the same way; it is all carded into one mass, and not woven together thread by thread, or hair by hair." "And are there many birds able to do such work, Uncle Philip?" "I told you, boys, that there were several. The chief article which they use is wool, but with this many other things will be found mixed--sometimes, upon the outside, fine moss--sometimes pieces of a spider's web rolled up into a little bundle--sometimes, when cotton can be had, they will use small bunches of cotton-wool; but sheep's wool they must have, and by means of that, they contrive to make, with the other things I have mentioned, a felt wonderfully smooth." "Is it smooth on the outside, Uncle Philip?"