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 a sign. 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 

 infaUible, 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 lighter 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 Hmbs, 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 



