Cows, of whatever breed, having the best developed external marks of good milkers, will very rarely disappoint the practised eye or the skilful hand; while cows of breeds in highest repute for the dairy, and which do not show these marks, will as certainly fail to answer the expectations of those who select them simply for the breed. Those who would obtain skill in judging of these marks, and by means of them be able to estimate the value of a cow, need not expect to attain this end without long study and practical observation, for which some men have far greater talent than others; being able, while examining a particular mark or favorite characteristic of a milker, to take in all others at a glance, and so, while appearing to form their opinion from one or two important points, actually to estimate the whole development of the animal, while others must examine in detail each point by itself. Long practice is required, therefore, to become an adept in the judgment and selection of milch cows; but still much assistance may, unquestionably, be derived by careful attention to the external signs which have been long observed to indicate the milking qualities. It is important, in the first place, to be able to judge of the age of the cow. Few farmers wish to purchase a cow for the dairy after she has passed her prime, which will ordinarily be at the age of nine or ten years, varying, of course, according to care, feeding, &c., in the earlier part of her life. The most usual mode of forming an estimate of the age of cattle is by an examination of the horn. At three years old, as a general rule, the horns are perfectly smooth; after this, a ring appears near the root, and annually afterward a new one is formed; so that, by adding two years to the first ring, the age is calculated. This is a very uncertain mode of judging. The rings are distinct only in the cow; and it is well known that, if a heifer goes to bull when she is two years old, or a little before or after that time, a change takes place in the horn, and the first ring appears; so that a real three-year-old would carry the mark of a four-year-old. The rings on the horns of a bull are either not seen until five, or they cannot be traced at all; while in the ox they do not appear till he is five years old, and then are often very indistinct. In addition to this, it is by no means an uncommon practice to file the horns, so as to make them smooth, and to give the animal the appearance of being much younger than it really is. This is, therefore, an exceedingly fallacious guide, and we cannot rely on it without being subject to imposition. [Illustration: Fig. 15. Teeth at birth.] [Illustration: Fig. 16. Second week.]