<30 THE ART OF HORSE-SHOEING. 



made macadam. With light, modern carriages and level 

 modern roads, calkins are quite unnecessary, and better 

 means of giving foot-hold may be substitued. It is a 

 fact that horses, when shoes are new and calkins prom- 

 inent, do their work without slipping, and that when the 

 calkins are worn down, the horse moves with less con- 

 fidence and security. This does not prove that calkins 

 are necessary. It must be remembered that horses 

 possess a power of adapting themselves to circum5ta,ivces, 

 but having learned to rely upon any artificial assistance, 

 they are the more helpless, for a time, on its withdrawal. 

 Calkins assist the horse for a time, but after the calkin 

 is worn down, the horse is in a worse position than if he 

 had never become accustomed to its assistance. Of 

 course, on soft ground, especially grass, calkins afford a 

 firmer grip than any other contrivance. On the other 

 hand, their constant use lifts the frog out of bearing and 

 causes it to waste, thus spoiling the action of the natural 

 provision against slipping. Level shoes on the hind feet 

 promote sound, prominent frogs, and give firm foothold 

 for all light horses. Even omnibus horses, now that the 

 vehicles are suppplied with effective foot brakes, may 

 advantageously be worked without calkins On country 

 roads, especially when the district is hilly or the load is 

 heavy, calkins may be requisite, and must then be made 

 to do as little harm as possible. 



The wear of a shoe is affected by the height of a 

 calkin. The more the heel is raised the greater the 

 amount of wear at the toe. Many shoes when worn out 

 at the toe, show very little effects of wear at other parts, 

 and the question arises how best to increase the wear of 

 the shoe without increasing its weight. In Fig. 39, three 

 diagrams are presented, in which dotted lines show the 

 effect of wear. At (a) the shoe is of even thickness 

 throughout — from heel to toe — and tUe line of wear 

 shows that when the shoe is worn out a great amount 

 of iron remains. At (&) the quarters of the shoo are 

 made thinner and the toe is made thicker, so that with 

 no increase of weight but by a better distribution of the 

 iron, increased wear is provided for at the part where 



