_The Age of Dogs._—These animals do not, like horses and cattle, present any exact criterion of their age; nevertheless, attention to the following appearances will assist us in determining the matter. At about four years, the front teeth lose their points, and each of them presents a flattened surface, which increases as the age advances; they likewise lose their whiteness. In dogs fed much on bones, and in those who “_fetch and carry_,” these teeth suffer very much, and are sometimes broken out while the dog is yet young. The holders, or tusks, are also blunted by the same causes. At seven or eight, the hair about the eyes becomes slightly grey. Gradually, likewise, a greyish tint extends over the face; but it is not till ten, eleven, or twelve years, that the eyes lose their lustre: when they become dim, general decay proceeds rapidly, though the life of some dogs is extended to fifteen, sixteen, or seventeen years; and I have seen a mother and son vigorous at twenty and twenty-one years old. Although such instances as the latter must be considered as rare, yet even these have been exceeded, if I might depend on my authority; for I once saw a small French dog, which I was assured had reached his twenty-fourth year, and which, at the time I saw him, was still vigorous and lively. I am not aware that much difference exists between the various breeds, as to the age they arrive at: spaniels, however, I have observed, are usually long lived; while terriers, on the contrary, I have seldom observed very old. The usual life of the dog may be considered as ranging between twelve and fifteen years: domestication has tended, in some degree, to curtail the period, but not so much as might have been expected, considering the powerful operation of artificial habits.—_White_—_Percival_—_Brown_—_Blaine._ AGED, _a._ Old, stricken in years. When horses pass that period of life when their age is not discoverable by the teeth marks, they are commonly termed _aged_. AGISTOR, _s._ Anciently an officer who attended upon the king’s woods and forest lands, to receive and take in cattle, &c. by agistment; that is to depasture within the forest, or to feed upon the pannage, &c. This officer was constituted by letters patent. AIM, _v._ To endeavour to strike with a missile weapon. AIM, _s._ The direction of a missile weapon; the point to which the thing thrown is directed. AIR, _v._ To expose to the air; to take the air; to warm by the fire. AIR-BLADDER, _s._ A bladder filled with air, and used in lake fishing to buoy the ends of night lines and mesh nets. AIR-CELLS OF BIRDS.