56 THE NAVICULAR DISEASE, OR CHRONIC 
horny box have changed their position and character, from the 
deprivation of this natural pressure and motion conjointly. The 
particulars of this I shall presently explain • and I firmly believe, 
that, if every valuable horse in this kingdom were to be forthwith 
turned loose into a large box night and day, besides the continu¬ 
ance at his ordinary work, it would prove the worst event for vete¬ 
rinary surgeons that has ever yet happened in the horse world; 
because it would tend more to cut off our supply of groggy lame¬ 
ness, and its attendants, than any circumstance, or single cause, 
that has ever yet been published, or even named. 
3dly, The frog is doubtless an important organ in preserving the 
natural form of the hoof; but I differ from those eminent veterinary 
authors who have urged, in opposition to our distinguished Pre¬ 
sident, Professor Coleman, that the frog cannot bear pressure: 
my experience has shewn me that it can; and I have convinced 
myself, by repeated experiments, that it can endure an extraor¬ 
dinary degree of protected pressure without inj ury to itself or other 
parts of the foot. I believe, however, I am now at issue with the 
Professor, when I state my conviction that one of its uses is to 
serve as a cushion or elastic bed for the navicular joint to rest 
upon, not merely for the purpose of protecting the insensible 
flexor tendon, as Mr. Freeman states, but especially for the pro¬ 
tection of the fine delicate synovial membrane lining the navicu¬ 
lar joint, a web as exquisitely sensible, when inflamed, as the i 
outer coat or conjunctiva of the human eye. 
There is another important function that the frog is intended by 
nature to perform, which, in the hands of art, it is seldom allowed 
to do,—which is, to act as an elastic prop of support both when 
the animal is in action and stationary. It had its bold prominent 
figure for that purpose. Every unshod colt’s foot (foals excepted), 
free from thrush, evinces this clearly. When all parts of the foot 
are in their natural state, this organ is pressed upon from above 
fearlessly, including all that anterior portion of it which is influ¬ 
enced by the navicular bone, whilst its posterior part, by touching 
the ground, ascends at the same instant, and acts as a spring, i 
which not only gives the animal confidence in his action, but, 
when standing still, emboldens him to convey a due proportion of 
his weight on his navicular bones, and to stand on his heels 
instead of his toes. This is the real characteristic of a valuable 
horse ; viz. standing firmly on his flexor muscles, thus giving the 
leg, particularly the back sinew, that fibrous, tense appearance 
which is the inducement to the judge to purchase him. The 
dealers in these valuable animals don’t forget to lay the charges 
on when they possess such an one; and this they have a right to 
do, for, all other things concurring, he is invaluable. 
