There are three or four kinds of hacks in use - the road hack, cover hack, park hack, and lady's hack.
The road hack is a much rarer animal now than he was before the days of railways, telegraphs, and steamships, when much of the travelling of those days was done on his back, and when his best qualities were most fully developed. Road riding is not now very common, and journeys on horseback are seldom indulged in; consequently, the decrease in the number of road hacks has been very great, and the qualities which were so conspicuous in them are not now so much in request. This is a matter to be regretted, and especially on the score of cavalry remounts, since, owing to the greatly diminished demand for these roadsters, comparatively few are bred; and as they constituted an excellent source for the supply of cavalry, this arm is now mounted with the greatest trouble, and at a much higher rate than formerly. A good road hack was the type of a good troop horse.
Such a horse should stand from fifteen hands to fifteen hands two or three inches; he ought to be able to walk at the rate of four miles an hour, and to trot from eight to twelve, or even fourteen miles in the same time. His action should be easy, true, and level; neither too high - which would be fatiguing on long journeys, as well as damaging to legs and feet - nor yet too low, for then he would be liable to stumble, or even fall, especially in travelling over uneven roads, and particularly when tired.
In order to ensure good action, as well as to guarantee the necessary amount of strength, the road hack in make, and shape should be, like the hunter, as near perfection as possible in all those points which are necessary to this end. The requirements to be met are, therefore, somewhat numerous, if a typical animal is to be secured, and they have been enumerated as follows: - The head should be small and fine, broad between the eyes and between the branches of the lower jaw at their angles; also the distance from the eye to the angle of the lower jaw should be great. The nostrils should be large, wide, clean, and well-defined; the mouth small, with the lips thin and firm. The ears should be small, fine, and pointed, being carried firmly, with their tips inclining slightly inwards towards each other; while the eye should be large, full, and prominent, with well-developed eyebrow. The neck must be long, somewhat thin, and fit well into the space formed between the branches of the lower jaw - being longer on its upper than its under surface, as well as being convex on its superior border. The head should be well "set on" to the neck, which, if the jaws are wide and the neck of the proper conformation, will be the case, and will assist very materially in giving to the horse what is called a "good mouth." The withers must neither be too fine, thick, or low; a fine wither, well covered with muscle, and yet not loaded, is considered perfection. The mane should be fine, silky, and not too abundant. The shoulder-blade must be long and oblique, not vertical; neither must it be coarse and prominent, but should blend gradually into the withers and back. A coarse, thick shoulder should always be avoided, as should also a very fine one, which leaves the withers standing up in a thin ridge like a ploughshare; for an animal with such shoulders will soon become fatigued, owing to the insufficient muscular development of these parts. The long, oblique shoulder gives plenty of space before the rider, the saddle sits well, provided the "girth" of the chest is also deep, and the action is pleasant. But if the shoulder be straight or short, or a combination of the two, the saddle will be too forward; and when the horse stumbles, as he is almost sure to do from defective action due to this faulty conformation, he runs the chance of falling, breaking his knees, and perhaps the neck of his rider as well.
The chest should be deep and moderately wide, both conditions being essential to the full development of the functions of the heart and lungs. The fore-arm must be long in proportion to the leg, that is, the greater length in proportion must be above the knee, and the less below it the better; the muscular development of the fore-arm should be as great as possible. The elbow, in addition, should be long and prominent, not turned in, but be clear of the chest. The knee should be large, wide, and prominent, but should appear more or less broad and flat when looked at in front, while the bone behind should be long and project well backward. "Calf knees" (those which incline backwards), " buck knees " (those inclining towards each other), and those inclining forwards, should always be avoided.
The cannon or shank-bone should be as strong and short as possible, and perfectly straight, being neither curved forwards, backwards, or sideways; the tendons behind this bone should stand well out and away from it, which is the case when the bone behind the knee is well developed and prominent. The space between these tendons and the bone should be well defined, and rather depressed, but if it is filled up the leg will appear round and puffy, instead of being flat and broad laterally; such legs are designated "gummy."
The fetlock joint should be large and flat laterally, the back part being clean and prominent. The pastern bones should neither be too long, short, oblique, or vertical. If the pastern is long it is necessarily very oblique, and therefore weak; if short it is upright, and therefore predisposed to ringbones, windgalls, navicular disease, etc.; besides causing the horse to be rough and unpleasant to ride.
The pastern joint should be well developed and strong. The feet, as regards size and shape, should be neither too large nor too small; the slope in front should be between 50° and 52° angle with the ground; the sole should be moderately concave, the frog large, strong, and sound; while the whole hoof should be tough, sound, and not brittle.