MUZZLE.—Muzzles are made of leather, and are of two sorts; the one called a _dressing_, the other a _setting_, muzzle. The first is of the same form as the last, but of different construction, having a few straps crossing each other transversely, and so united as to be about nine inches in depth, and of a shape to cover the nose of the horse so high; to which are annexed two straps; one of which passes up the cheek on each side, and buckles at the top of the head behind the ears; the use of this is to dress such horses in as are disposed to vice with the teeth, as well to prevent the MANGER from _injury_, as the GROOM from _danger_. The other is in little use, except in TRAINING STABLES; its form is not unlike the exact shape of a common water-pail, being made of the thickness of substantial leather, having a number of round holes punched in every part of it, for the free admission of air, and is brought into use on those nights _preceding_ a horse's RUNNING engagement on the following day; as well as before taking a SWEAT, or running a TRIAL. It is called a SETTING-MUZZLE, because, when put on, the horse is said "_to be set_," (that is, to fast;) and the intent is to prevent his consuming the litter, or obtaining more food than what the training-groom has a perfect knowledge of. N. NABOB—was a horse of much temporary note, and considered one of the best country plate horses of his time; he was bred by MR. SWINBURNE, and foaled in 1753; was got by _Cade_, dam by _Crab_, grand-dam by _Childers_. Although he was a known good runner, he never as a STALLION produced any racers of much celebrity. NAG—is rather a provincial than a general term, and varies a little in its signification, according to the county, or part of the kingdom, in which it is used. In the most common country acceptation, it implies a RIDING horse or ROADSTER, in contra-distinction to a _carriage_ or _cart-horse_. A "complete nag" may be considered a kind of horse beyond the line of mediocrity, and bordering upon the idea of a moderate hunter. A "smartish nag" is what the opulent farmer rides to market; and a "tightish little tit" is a well-bred galloway of SPEED and ACTION, which, in a state of purity and perfection, are always difficult to be obtained. NARROW CHESTED.—A horse is so called, whose breast is so narrow (when standing before him) that the fore-legs gradually extend wider in proportion as the eye accompanies them nearer the ground; so that, in a front view, they bear the form of two legs of a common country washing-stool, where the legs are inserted in the narrow part of the wood at the top, and are four or five inches more in width at the bottom. Horses of this description are invariably weak before; and when put into hard work, or severe exertions, are the very sort of which so many upon the roads are seen in a "CHEST-FOUNDERED" state; which see under that head, where it will be found fully explained.