Experience teaches us that horses in the open keep their health better, especially as regards their organs of breathing, and possess greater immunity from infective diseases, than stabled horses, other things being equal. Mr. Miller tells us (p. 390) that when polo ponies are turned out during the winter in England, they prefer to sleep outside at night, even when snow is on the ground, than to seek the shelter of a comfortable hovel provided for them. The ponies to which he alludes were well-bred and well-fed animals. I have noted at Mr. Miller's place that the judiciousness of their choice was amply justified by their robust health and good condition.

The horses reared on the steppes of Little Russia for the Russian dragoon regiments have a strong dash of Arab and thoroughbred blood; yet they show no ill effects, as far as their health is concerned, from having lived in the open during the extreme cold (often below - 300 F.) of their winter, provided they get a sufficiency of food. In England, a temperature of 50 F. would be regarded as extreme cold. In almost all cases, before these intended remounts are taken up and finally selected for cavalry purposes, they have much difficulty in obtaining grass in winter, and consequently they are stunted in growth. In fact, the minimum dragoon height for remounts, which are "taken up" when they are either three off or four off, is only 15 h. 3/4 in. During an official tour I made to the Dragoon Remount Depots in 1898, I learned that when these young animals are well supplied during winter with hay, the effect of cold on their growth is not apparent. Even those which are not thus artificially fed, show excellent "bone," and are compact and very useful saddle animals. All the remounts for the fifty-four Russian Dragoon regiments and for all the Cossack cavalry regiments, are taken from horses reared in the open, and the bigger horses required for the twelve cavalry Guard regiments, are brought up in ordinary horse-breeding studs. From the principles already discussed, we know that as the internal temperature of horses has to be sustained by the combustion of food in the body, the severer the cold to which they are exposed, the better should they be fed. The lowest temperature which has been recorded in Arctic regions is -58.70 C. (-73.6° F.). We may regard -350 R. (-470 F.) as an extreme degree of cold in Russia.

Mr. T. B. Drybrough, in Polo, tells us that "Montana has a perfect climate for eight months of the year, but the weather of January, February and March is sometimes intensely severe, - 400 F. being not uncommon and - 6o° F. being occasionally recorded. At these times, horses can paw away the frozen snow and so reach the grass underneath, but cattle have not this instinct; they merely plough with their noses, which become so painfully lacerated where there is a hard crust on the snow, that the poor brutes lose heart, give up the vain attempt, and stand miserably awaiting death. In the winter of 1886-7, 90 per cent. of the whole cattle stock perished in this way." As this instinct of scraping away the snow when in search of grass, is, as far as I can learn, possessed by all horses; it does not seem unreasonable to regard them as animals which have been evolved under conditions of severe cold.

Even groomed horses which are picketed outside at night, and which are consequently deprived of the means of keeping themselves more or less warm by exercise, show great tolerance of cold. I have never seen the slightest harm result to Arabs and well-bred Australasian army horses which were picketed in the open, as the custom is, with only the protection of a rug over their backs and loins, during the cold weather of Northern India, where sharp frosts are not unfrequent towards the end and beginning of the year. These artillery and cavalry animals appeared to be in about the same working condition as the stabled chargers and hacks of the officers, with the exception that the greater length of their coats during the cold weather lessened to a small extent their capacity for performing fast work. The experience gained from military cam-paigns - for instance, that of the Crimea, during the winter of which the cold was intense - proves still more strongly that exposure to frost and snow will very slightly, if at all, impair the efficiency of well-fed horses. It is true that the mortality among the army horses of Napoleon I. during the retreat from Moscow was appalling: but these unfortunate animals were in a more or less starving condition. The comparative immunity from the effects of cold shown by the more or less well-bred horses we have been considering, is of course surpassed by that possessed by animals which have no Eastern blood, and which have been inured from their birth to very low temperatures, like the Kirgis, Himalaya and Manchuria ponies.

A form of cold which the skin of a horse can badly withstand, is that which is produced by using common salt to melt snow, as is sometimes done during winter, in order to clear snow from streets, so as to save the trouble and expense of carting it away. A combination of snow and common salt acts as a freezing mixture, which with, say, equal weights of these two substances, has at the time of melting a temperature of about o° F. Consequently, if such a fluid comes in contact with the feet and pasterns of a horse, it will be liable to produce frost-bite by the direct application of great cold to the skin of the part. In ordinary circumstances, water cannot be colder than 32° F. Hence, when a horse is travelling over ground covered with snow, its particles will be prevented from coming in contact with the skin, by the hairs of the part forming an obstacle to the entrance of these solid bodies. Also, the air imprisoned between these hairs will greatly aid in the defence of the skin, by the fact of air being an extremely bad conductor of heat. Besides, the air contained in the snow, as we have already seen (p. 32), renders snow a far worse conductor of heat than water, or than ice which is more or less free from air. Therefore, horses which travel through a solution of snow and salt, will be much more liable to frost-bite of their extremities, than if, under similar conditions, they were to go through snow, say, of a temperature of - 200 F., which is a degree of cold far below that ever experienced in England. I have found in Northern Europe during winter, that when the temperature of the air falls below, say, 50 F., snow which had been subjected to traffic, assumes more or less the form of dry dust, and will neither penetrate through nor adhere to the hairs of the pasterns. It is evident that the greater the length of these hairs, the more effectively will they protect the skin which is covered by them. Horses of all breeds suffer little from extreme climatic heat, provided that they are protected from the direct rays of the sun (by, for instance, the shade of trees or by a thick roof overhead), and that they are in an airy situation void of adjacent objects which might impede the free circulation of the surrounding atmosphere. By the expression extreme heat I mean anything over 110° F. in the shade. The highest atmospheric temperature I have felt was 1250 F. in the shade in Sindh. I have known the temperature of the air to be 1090 F. at nine o'clock at night in Mian Mir in the Punjab. In England, the temperature of the atmosphere very rarely exceeds 900 F. in the shade. In confined positions or when unprotected from the direct rays of the sun, and especially if put to hard work, horses which are exposed to great climatic heat are very susceptible to fever and even to sunstroke.