THE PACK WAX. 229 



at the end of a steelyard beam, so that like it, it requires a hundred 

 times more power to support it than it would do if the weight 

 were close to the shoulder. The leverage of the neck is so great 

 that it would demand muscles at the withers equal to lifting 

 several thousand pounds to support tlie horse's head at the end 

 of his long neck. But instead of such heavy muscles that would 

 greatly retard the horse's speed, nature has made provision to 

 sustain this great weight with a strong animal cord, or a very 

 powerful and slightly elastic ligament. This provides for bearing 

 the weight without fatigue, but only for bearing it at a certain 

 height. With this provision the horse can even go to sleep 

 whilst standing, and this strong ligament, called the pack wax, 

 will support his head at the exact height for which its length is 

 adapted, without any muscular effort, or any nervous supervision. 

 When the head is wanted lower, as for grazing, there are 

 muscles in the neck which pull it down, and stretch the strong- 

 elastic cord enough to let the horse's mouth reach the ground. 

 When it is wanted higher, there are other muscles strong enough 

 to lift the head for a little while. But the higher the head goes 

 the less the pack wax takes of the weight, and the muscles are 

 by no means strong enough to sustain the weight, without the 

 assistance of that cord for any length of time. 



543. — We can soon form an idea of the pain that results if 

 we try to hold our arm straight out from our body for ten 

 minutes. We can lift that arm to a horizontal position with 

 considerable force, but nature never intended it to be kept there, 

 and has supplied no muscles strong enough to support it long in 

 that position. We can lift it up and down for twelve hours a 

 day, but we cannot keep it in an unchanged, horizontal position 

 for a quarter of an hour without absolute torture ; torture so great 

 that we should gladly rest our hand on the point of a needle, or on 

 a bed of thorns or nettles, rather than not rest it at all. So it is 

 with the horse. His small neck muscles cannot support the 

 weight so far above the natural angle as to get no assistance from 

 the pack wax, and he is therefore when tightly reined up obliged 

 to let the weight of his head rest on his sensitive, tender, foaming, 

 or bleeding mouth. Xature in time will make that mouth less 



