52. _After the eighth year_, there is no certainty in any opinion drawn from the teeth. A guess may be hazarded, and very often that guess will prove correct, but at the same time it should be received only as a conjecture. The chance of naming the age decreases as the number of years increase. After the twelfth, the probability of hitting the exact year is very small. After the sixteenth year, all is confusion, and there remains no sign which could warrant any person in pretending he could pronounce the age by the teeth. It is true that certain tokens may induce a conviction that an animal is much older than sixteen, and this conviction may be so justified as to amount almost to a certainty; but no man, I imagine, could form any opinion with regard to the number of years by which a horse exceeded sixteen, or pronounce a decision that should have any appearance of exactitude. They who pretend to an ability of this kind, may, in a few solitary instances, strike the point; but repeated failures will show that there is no positive principle in operation to guide the judgment. Indeed the age is most correctly told during the periods of dentition, and up to the sixth year. After the sixth year, the certainty is not so great, but a very fair, if not a positive judgment can be pronounced until the eighth year is accomplished. After the eighth year, no man should give an unqualified opinion concerning the age of a horse. After the twelfth, whatever may be pronounced should be offered only as a conjecture; and, after the sixteenth, the practitioner had better be silent. When stating this the author must be understood as expressing the conviction at which almost exclusive attention to the subject, and much necessary consideration, has enabled him to arrive. It must not, however, be thought that he is arrogating a power of measuring the capabilities of genius; his wish is only to declare the truth as he perceives it. The intention to publish a work upon the teeth has not been concealed; opinions have been solicited and information sought; the author has many obligations to acknowledge; all to whom he has made application have been liberal in their communications; but from no one has he been able to obtain anything opposed to the conclusions he has here promulgated. It may be that hereafter the power of judging of the age shall be extended. Pessina and the Girards thought it could be done with exactitude up to an extreme point, and saw a principle in the latest changes which the teeth undergo. The general experience in this country, however, seems to have decided that, after the eighth year, there is no certainty. With that decision the author is reluctantly obliged to acquiesce, and even to add that certainty is not to be obtained after the sixth year. This limitation, coupled as it is with a confession of inability, may seem to be a backward movement; but truth cannot retrograde. By ascertaining how