Gentle motion to a heated horse is necessary, to prevent the evils likely to arise from one sot of organs doing more than another set requires. But in many cases motion after work is useful when the horse is not heated. He may come in drenched with rain, but quite cool, and there may be no one at hand to dry him, or his coat may be so long that one man can not get him dry before he begins to shiver. In such cases the horse should be walked about. Were he stabled or allowed to stand at rest in this state, he would be very likely to suffer as much injury as if he were suddenly brought to a stand-still when in a high state of per spiration. Evaporation commences the moisture with which the skin is charged is converted into vapor, and as it assumes this form it robs the horse of a large quantity of heat. If he be kept in motion while this cooling and drying process is going on, an extra quantity of heat is formed, which may very well be spared for converting the water into vapor, while sufficient is retained to keep the skin comfortably warm. Everybody must understand the difference between sitting and walking in wet clothes. If the horse be allowed to stand while wet, evaporation still goes on.

Every particle of moisture takes away so much heat, but there is no stimulus to produce the formation of an extra quantity of heat; in a little while, the skin becomes sensibly cold, the blood circulates slowly, there is no demand for it on the surface, nor among the muscles, and it accumulates upon internal organs. By-and-by the horse takes a violent shivering fit; after this has continued for a time, the system appears to become aware that it has been insidiously deprived of more heat than it can conveniently spare; then a process is set up for repairing the loss, and for meeting the increased demand. But before this calorifying process is fairly established, the demand for an extra quantity of heat has probably ceased. The skin has become dry, and there is no longer any evaporation. Hence the heat accumulates, and the horse is fevered. I do not pretend to trace events any further. The next thing of which we become aware is generally an inflammation of the feet, the throat, the lungs, or some other part. But we can not tell what is going on between the time that the body becomes hot, and the time that inflammation appears. I am not even certain that the other changes take place in the order in which they are enumerated; nor am I sure that there is no other change.

The analysis may be defective; something may take place that I have not observed, and possibly the loss of heat by evaporation may not always produce these effects without assistance. It is positively known, however, that there is danger in exposing a horse to cold when he is not in motion; and, which is the same thing, it is equally, indeed more dangerous to let him stand when he is wet. If he can not be dried by manual labor, he must be moved about till he is dried by evaporation.