With the exception of encyclopædias which give detached and very abridged descriptions of felt making and of hatting generally, there has been no specific account published in either pamphlet or book-form, so far as the writer is aware, of the manner in which felt hats are made, or of the principle of felting by which they are produced. This is considered by the writer a sufficient inducement to illustrate to the best of his ability a principle entirely belonging to natural history, viz., the natural scaly clothing that is upon all hair, and hitherto but little known, and upon which several important branches of business depend. Indeed, it seems almost absurd to think that a hair, puny as it is in itself, bears upon its sides a something of such importance, so very minute as to require the utmost attention with the aid of the best microscopes to be seen at all, and yet upon that something is based the art of felting and of course of hat-making, besides several branches of other trades, some of which have already been mentioned. Hat-making was long considered a business to which machinery never could be applied, but the inventions of man have at last dispelled this illusion, and machinery is now employed in several of the most important departments of the trade. The reason why this idea obtained such general credence was, first, on account of the close attention requisite, while the hat is under the operation of sizing. Second, the known impossibility of napping or ruffing a hat by any means with machinery, also, the acknowledged failures of several attempts to substitute carding for that of bowing, and various futile attempts with the irons in the finishing department. The innovations of machinery, however, have now obtained a sure footing in all large factories, and some of them will come under observation in their proper places. In the mean time we shall confine our observations to the old system, which still prevails in most small factories and all small towns. Our honest forefathers, the manufacturers in former times, would insist upon making hats to wear not for a season, as with us, but for many years, being afraid of damaging the trade to do otherwise, but now a hat for city wear, of scarcely three ounces weight, and lasting two or it may be three months, is quite a common thing.