The practice of a trade without a knowledge of the why and the wherefore of certain usages is a sad defect in any workman, but more especially in certain trades: Hatting being one of those which depends upon _second_ causes for its proficiency, we venture here an explanation with perfect confidence, hoping that the fraternity of hatters will be indulgent, and that they may profit by an experience of many years in the trade, and that for one error or omission in the writing of these sheets they will find compensation in the new ideas that will spring from their perusal, which may be an incentive to further improvements in the business resulting beneficially to all. Theory without practice, or practice without theory, is like groping in the dark, and perfection in no trade can be attained till every effect can be traced to its cause, and _vice versa_. It is much to be regretted that practical operative workmen are so diffident in writing and publishing their experience in their several trades and occupations, quietly permitting theorists ignorant of the business to glean as best they can from other parties the most intricate and complicated particulars of a trade, and hence the attempt to illustrate the most useful branches of an art often results in crude and even erroneous descriptions of things of the greatest moment, and the dissemination as correct, of that which is altogether at variance with the truth. In confirmation of the above, we may instance the manufacture of hats as described in a work of much merit, and which is accounted as worthy of all confidence, wherein the error above spoken of is but too plainly visible. Thus, in the supplement to the third edition of that most respectable work the Edinburgh "Encyclopedia Britannica," in the article Hat, an apology is made for the original treatise upon that subject, it being acknowledged as both defective and erroneous from the imperfect source of the information. Such a confession, and from such a source, sufficiently exonerates any one from egotism in an attempt to write a more perfect and correct description, coupling theory with practice; relieving the felting process from its misty obscurity by a faithful expose of the whole system: well knowing that an increase of business, like free trade, will be the result of a right understanding of a formerly supposed mystery, viz., the True cause of Felting. Felt and felted articles being already in use, in many trades in addition to that of hat-making, necessitates a general and indeed a very full and lucid description of the materials of which they are made. Descriptions of Furs, Wools, Hair, &c. Fur, properly speaking, signifies the skins of various species of animals, dressed in alum or some other preparation with the hair on, and made into articles of wearing apparel; but the term fur also signifies the stuff that is cut from the skin, for the use of the hatter, and in this sense alone it will be employed in the following pages.