PLATE XXIX.—DRIVING A PAIR
If you will examine a pair of two-horse reins, you will notice that they are just like the two reins for one horse—one rein goes on the outside of the bit of one horse, and one goes on the outside of the bit of the other horse. These are called the draught-reins. But there is a marked difference, for on each of these reins is buckled another rein, called the coupling-rein; the one on the left rein goes over and is buckled on the inside of the bit of the right-hand horse, and the coupling-rein of the right rein goes over and is buckled on the inside of the bit of the left-hand or near horse. In buckling these coupling-reins to the bits, if one horse is more up-headed than the other, let his coupling-rein be on top, so that he will not annoy the other horse by jerking up the other's coupling-rein. The adjustment of these reins should be suited to the conformation and disposition of the horses, and it is in this adjustment that the experienced whip makes himself and his horses comfortable, by making them go together, and go level. No two horses suit each other exactly as to length of body or neck, or the way of carrying the head, and yet you may see dozens of pairs of reins where the coupling-rein buckles have apparently never been changed! The buckles of the coupling-reins should be near enough to the hand in pair or four driving—say eighteen inches—to enable one to change the couplings from the driving-cushion. In most harnesses there are two or three holes in the billet that buckles to the bit, so that the length may be changed also at the bit. There are arguments for and against this practice of having holes in the billet. It is said that this makes it easy to change a coupling from the ground; on the other hand, an ignorant groom may make the change there unknown to the coachman, and thus cause confusion. Take your choice!
The object of these two inside, or coupling, reins is to hold the horses together, at the head, of course, and they should be so adjusted that an even pressure is brought to bear on both sides of the horses' mouths, so that they will go straight, and do each his share of the work. If horses were all alike, it would be easy enough to buckle these coupling-reins in the same hole on each draught-rein, and your horses would be level. But suppose we have two horses, one of which, the near horse, carries his head higher than the other and out farther than the other. If these two are to go level, the near horse must have his reins longer than those of his mate. Up and down the draught-reins are punched some fifteen holes in four-in-hand harness, fewer in pair-horse harness, and an inch apart, and the coupling-reins can be buckled longer or shorter by buckling up and down these reins. In the case we are describing, we must of course let out the coupling-rein of the up-headed, near side horse, say three holes, and (remember that the near side coupling-rein is the one buckled on to the off side draught-rein and vice versa) take up the near side coupling-rein the same number.
It must be remembered in this operation, however, that the shortening of the coupling-rein brings the horses' heads nearer together, and if they were going properly, parallel to the pole, and at the right distance apart, before one coupling-rein was shortened, then, if this relative position to one another is to be maintained, the other coupling-rein must be let out an equal number of holes.
"When the horses are working exactly alike, the reins are as shown by the heavy lines; A and B are the two sides of the off horse's bit, and C and D the two sides of the near horse's bit. The two outside or draught reins run straight to the coachman's hand, viz. AM and DN. The coupling-reins are CM and BN, buckled to the draught-reins M and N. If the off horse bends his neck so as to bring his head nearer to his body, both the reins which run to his bit will be too slack, and he will run forward and do more than his share of the work, while the near horse is held back. To prevent this the off horse's coupling-rein to BN is shortened by running it up the draught-rein to N', the last hole, until it comes just tight to the bit; but this obviously leaves the off draught-rein AM as slack as it was before, so that the coachman has to draw his hand back to bring it to bear upon the bit at A'. In so doing he draws back the coupling-rein CM and pulls the head of the near horse to the inside. To prevent this the coupling-rein CM must be let out on its draught-rein exactly as much as the other coupling-rein has been taken up, which is equivalent to pulling back the draught-rein, whereupon the coupling-reins will have the positions shown by the dotted lines with the buckle of C rein in the first hole, and all the reins will act evenly upon both horses, notwithstanding that the mouth and bit of the off horse is nearer to the coachman's hand than that of the near horse."—Fairman Rogers, "A Manual of Coaching."
The most common fault in adjusting coupling-reins, next to that of having one horse in advance of the other, is that of having the horses coupled too closely, or too loosely, together; in the first case the horses must go awkwardly, with their heads too close together, with a tendency to make them stumble, and in the other, with their heads yawing apart, and not under proper control. Some horses are greatly irritated by being made to go on one side of the bit only, and often enough a pair going all sorts of ways will settle down and go well enough where their coupling-reins are so adjusted that they can go level, with an equal pressure of the bit on both sides of the mouth.