THE SCREW-SHOE. 131 



of the frog upon the ground. Now, the stem of the 

 toe-piece passes under the frog, and consequently 

 prevents it from touching the ground. 



A fair idea of the appearance of the screw- shoe 

 may be obtained by comparing it to the ecclesiastic 

 capital letter CD, the central perpendicular line 

 representing the stem of the toe -piece. 



The special object of the screw- shoe was, however, 

 to be a corrective of contraction of the hoof, one of 

 the ailments to which that much-enduring organ is 

 subject. ' What is the practical working of the screw 

 is well pointed out by Lieut. Douglas : 



6 The foot was kept in water to soften the horn (!), 

 and every day the screw was slightly turned by a key, 

 the hoof apparently opening wider at the heels by 

 the interior lengthening of the screw. But it was 

 soon found that no proper expansion took place, it 

 being either the nails that- gave or the crust that 

 split. 



' So ended the theory of the screw-shoes, which 

 could never have been looked into properly, as they 

 would not have stood the test of common-sense in- 

 vestigation an hour. 



' We have only to imagine that if the nails did 

 not give, nor the crust split while the shoe was forced 

 wider apart, this result must follow viz. the wall of 

 the foot would be torn away at the heels from the 



K 2 



