1895.] on the Structure and Function of the Horses Foot. 561 



The expansion of the foot has been known for many years, but has 

 always found more opponents than supporters ; it was not until the 

 introduction of foot apparatus which was capable of making delicate 

 measurements that it was possible to convince the incredulous. 

 Lungwitz in Germany has made some valuable observations on the 

 expansion of the foot. Independently and unknown to each other we 

 were both reinvestigating the phenomenon with improved apparatus, 

 and obtained results which were practically identical. I show you on 

 the screen the apparatus employed by Lungwitz, which consists chiefly 

 of a shoe to which can be fitted an arm carrying a screw. To this 

 arm one pole of the battery of an electric bell is attached ; the wall of 

 the foot is covered with tinfoil carefully secured in its place, and to 

 it is attached the other pole of the battery ; the contact screw is so 

 adjusted that if the foot widens when the weight is placed on it, 

 the tinfoil touches the screw and so closes the circuit, of which the 

 bell gives the indication. With this and other apparatus Lungwitz 

 investigated the movements of the foot not only at rest, but during 

 work. 



I have been unable to investigate the movements of the foot during 

 work, but on the table may be seen a piece of apparatus constructed 

 on the same lines as that employed by Lungwitz, and with it I shall be 

 able to show you, even on the dead foot, that there is marked lateral 

 expansion. There is another piece of apparatus which I have 

 employed, not only to indicate lateral movement in the foot, but to 

 register the amount. The apparatus is constructed on the lines of a 

 well-known form of steam gauge ; a pin is connected with a series 

 of wheels which multiply its movement, and convey this for the 

 purpose of registration to a hand working on a dial ; a very small 

 amount of movement in the pin gives rise to a considerable excursion 

 of the hand on the dial ; by dividing the dial into a certain number 

 of parts and carefully estimating their value by means of a vernier, 

 an apparatus capable of registering the y^- of an inch is readily 

 obtained. I have this instrument on the table ; it is placed against 

 the wall of the foot at any desired spot, and, by lifting up the opposite 

 leg, and so throwing extra weight on its fellow, the foot expands. A 

 large number of observations carried out on these lines, demonstrated 

 that during rest simply imposing extra weight on one fore-foot by 

 lifting up its fellow, caused it to expand 03- of an inch. 



It may be asked what is the value of this trifling increase ? My 

 answer is that this " give " makes all the difference between a rigid and 

 a yielding mass, the slight yielding saves the foot from jar and con- 

 cussion. 3 1 is obvious that the amount of " give" depends upon the force 

 with which the foot comes to the ground, viz. on the pace, but under 

 no circumstance is it likely to be more than -} of an inch. The only 

 part of the foot which expands is that portion of the wall situated 

 towards the heels. 



On this large model I have shown you in section the arrangement 

 of the bones within the foot, and I pointed out the existence of a 



