ESSAY ON SHOEING HORSES. 133 



thinner the crust is, the more heat becomes transmitted to the inter- 

 nal parts. 



Having thus assured himself of the hoof's conducting power, his 

 next object was to ascertain the amount of heat transmitted to the 

 sensitive tissues. The facts are as follows : 



From twelve experiments made on feet, in view of throwing light 

 on a subject hitherto considered as dark^ the following are the re- 

 sults : 



First. That the ordinary shoe, heated to cherry redness, and 

 applied to a horny sole of an inch in thickness, and kept burning for 

 one minute, the carbonized portion not being obliterated in " paring 

 out the foot," has transmitted from three to four degrees of caloric 

 to the villo-papillary and reticular tissue. 



Second. That the greatest amount of caloric transmitted in these 

 experiments, was felt, according to the thermometer, between the 

 fourth and sixth minute from the application of the heated shoe. 



Third. That the sole, pared to the thickness of one-third of an 

 inch, giving under the pressure of the thumb, and the iron kept burn- 

 ing upon it for half a minute, exhibited the villo-papillae destroyed 

 by the caloric. 



Fourth. That when the sole had but one-eighth of an inch in 

 thickness, and readily bent under the thumb, when the heated shoe 

 was held upon it, burning for half a minute, both its villo-papillae 

 and the surface of the reticular tissues were destroyed by the caloric. 



From other twelve experiments, performed with the shoe heated 

 to black redness, the following facts were gleaned : 



First. The shoe being applied to the sole upon which the burnt 

 mark still remained, it was found to transmit in the same time more 

 caloric to the living tissues than the iron at a cherry red heat. 



Second. The dull heated iron, the thickness of the sole being the 

 same, caused a more lively and deeper burn than the bright heated 

 one. 



Third. These experiments confirm what was said by the elder 

 Lafosse, in 1858, viz., that it was not the bright heated iron which 

 oftenest occasioned the burning of the fleshy sole, but rather the 

 iron brought to a dull or obscure heat. 



" A notion has generally passed current among persons engaged 

 in the art of shoeing, that if the burnt part of the sole be pared 

 away, by means of the ordinary tools (knife and butteris), immedi- 

 ately after the application of the hot shoe, the burn is obliterated, 

 with its effects at the same time. I found this, however, by placing 

 my hand upon the burnt spot, and by testing it with a thermometer, 

 not to be correct ; and I further demonstrated its fallacy by direct 

 experiment." 



The reader will now perceive that the danger apprehended as the 

 result of hot shoeing, is not entirely gromidless ; neither do the 

 efiects of the same exist only in a fertile imagination, as some writers 

 have asserted, but there is often more truth than poetry in the matter. 



Unfortunately we have a vast amount of book knowledge on shoe- 

 ing., which often passes current as the result of scientific investiga- 

 tion ; yet, in my opinion, the horse and its owner would have been 

 better off had such works never been written. 



Some smiths contend that it is necessary to apply hot shoes in 



