AS TO SOUNDNESS. 87 
to say that you reject a horse because he is lame in his 
fore foot, than to certify that he has navicular disease ; 
because you have not in these masked cases a group of 
symptoms amounting to asign. The stiff shoulders, the 
upright pasterns, and the going on the toes, do not con- 
stitute a group of symptoms amounting to a sign, because 
tenderness and pain at the back of the foot, from any 
cause, produces the same symptoms, and your not being 
able to find any cause that could give rise to these 
symptoms is but a negative proof. Without being 
infallible, this group is found by the profession to be a 
sufficiently good working hypothesis. 
Lastly, in what class of horse have you to suspect its 
presence? Undoubtedly in the “ghter breeds, because 
we find that these have— 
1. Less feet than the heavier breeds, and therefore the 
radiation of the rays of weight is limited to a narrower 
area, and the shock is consequently the greater to the 
foot. 
2. They batter their feet more on the hard roads with 
having to go at quicker paces. 
3. They are not used for walking, but faster paces, and 
when not moving they are standing, and often sleeping 
while standing. 
Having gone somewhat at length into the mechanism 
of the fore limbs, and explained that the centre of radia- 
-tion is at the coffin joint, I have only to ask you to 
look closely at a section of this joint (see Fig. 3,'), and 
see that the navicular bone is not a hair’s-breadth from 
