6o THE ANIMAL AS A MACHINE. 



be that of Coignet ; who arranged hoists in such man- 

 ner that the men employed would go up ladders or 

 stairs to the summit of the lift and then, by their 

 weight applied to the " fall " of the tackle used, de- 

 scending to the ground thus suspended, the work of 

 their descent would be transmitted to the hoist and 

 raise the load. Tables B, C, D, are for common roads. 

 Rankine gives as the approximate relative power of 

 various animals the following : The ox draws a load 

 about equal to that of the horse, the mule one half, the 

 ass one fourth. The ox moves at two thirds the speed of 

 the horse, the mule the same velocity as the horse, the 

 ass the same ; making their respective working powers 

 as I to f, to \ and J, respectively. In all cases, the 

 practical hmit is determined by the method of applica- 

 tion, the character of the vehicle, if any, used, and the 

 adjustment of the animal to its surroundings, as well 

 as by its own physical characteristics. Animals do 

 their work mainly by draught of vehicles. Its amount 

 depends largely upon the character of the road 

 traversed. The effort required may be taken as ap- 

 proximately as follows, for total loads, including the 

 vehicle : 



Good country road . . . 

 Macadamized surfaces 

 Asphalt pavements . . , 

 Wood 



Granite tramways .... 



Granite pavement, dry, is less likely to cause falls 

 than either wood or asphalt ; when wet, wood is best 

 in this respect. Macadamized and earth roads are safer 

 than either of the pavements. 



50 lbs. per ton. 



40 " " 

 38 " " 



35 " " " 

 27 " " " 



