N.
NAILS, in anatomy, are horny lamina or plates growing over the ends of the fingers and toes of men, as likewise over the lower extremities of the inferior animals.
The nails apparently possess similar properties with the epidermis, or outward skin, being devoid of sensation; and, if the latter membrane be separated from the true skin, by any accident, the nails are likewise in danger of being removed, or materially injured.
These excrescences are divided into three parts, namely, the root, the body, or middle, and the extremity, or end. The root is a soft, thin, white substance, which terminates in the form of a crescent, and to which the epidermis strongly adheres: from this part, the nails increase, and derive all their nourishment. The body, or middle, is considerably broader, thicker, and of a deeper red than the root; while the extremity is of still greater firmness.
The use of the nails, in animal economy, is to defend and cover the nervous warts or papillae of the toes and fingers from external injury, when they come in contact with rugged bodies. Hence, though cleanliness require them to be occasionally cut, that operation ought not to be carried too far; because the sense of feeling would thus be impaired and diminished: on the other hand, they should not be suffered to grow to a considerable length; as the impurities collecting beneath them not only present a slovenly picture, but such neglect also renders the nails liable to be split and broken by various accidents.
NAILS, in building, are small pointed spikes, generally with a flat, or convex head, made of brass, iron, or other metal; which, when driven into wood, serve to connect several pieces, such as boards and laths, or to fasten a piece of timber, &c.
Nails are divided into numerous classes: their figure and size vary according to the purpose for which they are designed; and which it would be superfluous to enumerate. As they are of such essential importance in building, the arts, and economy in general, several privileges have been granted for new inventions, or improvements, in the manner of casting, or manufacturing them. On account of their ingenuity, the following patents deserve to be mentioned; namely, Mr. Finch's, obtained in 1790; Mr. Clifford's, registered in the same year; and Mr. Spencer's, granted in 1801. But, as these processes can only be understood and practised by manufacturers, we cannot enter into any detail, but refer the curious reader to the 7th, 9th, and 15th, vols. of the Repertory of Arts, &c.; where full specifications are inserted; and Mr. Spencer's patent is illustrated with an engraving.
NAIL and BOLT-DRAWER.
In the year 1787, the Society for the Encouragement of Arts, &c. conferred a bounty of three guineas on Mr. William Rich, of Yalding, Kent, for his invention of a machine, which is represented in the following cut, in the action of drawing out a spike.
