10 



with all the parts necessary to constitute a perfect joint ; 

 it is rarely, if evei', the original seat of disease. 



The navicular joint/" the least injury to which entails such 

 disastrous consequences, is merely a sort of false jomt or bag, 

 formed between the under surface of the navicidar bone and 

 the upper surface of the tendon of the muscle, wliich bends 

 the foot by acting upon the coffin bone ; it is situated 

 beneath, and somewhat behind the coffin joint, and is 

 lined througliout by a delicate, secreting membrane for the 

 supply of the fluid, necessary to the even sliding of the 

 tendon over the bone after tlie manner of a pulley. Any 

 diminution in the quantity of fluid, either from inflammation of 

 the membrane, or other cause, will produce friction of the 

 sides of the bag upon each other, and lay the foundation for 

 that train of fatal effects, which must ensue under such 

 circumstances to a part so constantly and vigorously employed, 

 as the navicular joint ; viz. first inflammation of the membrane, 

 then ulcei'ation and absorjjtion of the gristle, and lastly disease 

 of the bone itself; a speck of which no larger, than a pin's 

 head, produces lameness, that defies all the powers of man to 

 cure, and dooms the horse to a life of pain and misery for the 

 remainder of his days. 



Before treating of the preparation of the foot for the reception 

 of a shoe it is desirable to correct the generally received, but 

 erroneous opinion, that the shape of a perfect foot is circular 

 or very ueai'ly so. It i» this opinion, that leads the generality 

 of smiths to direct their energies towards reducing the foot to 

 that shape as soon, as possible : indeed so impatient are some 



* Plate 2, fig. 4. 



