120 MECHANICS. 



COMBINED DRAUGHT OF ANIMALS. 



AVTien several animals are combined together, it is 

 of great importance that they should be exactly match- 

 ed in gait. Much force is often wasted when they 

 draw unsteadily or unevenly. It is more difficult to 

 divide the draught equally among several animals when 

 placed one before the other, or ad tandem^ than when 

 arrayed abreast, for some may hang back, and others 

 do more than their share, unless a skillful driver is 

 always on the watch. It also happens, when thus 

 arranged, that the forward horses draw horizontally, 

 while the hindmost one draws in a sloping line, and 

 the line of draught between them thus being crooked, 

 more or less force is lost. This may be, however, rem- 

 edied in part by placing the taller animals forward, and 

 the smaller behind. 



For these reasons, when only three horses are used, 

 they should always be placed abreast. The force re- 

 quired for each may be rendered exactly equal by the 

 whipple-trees usually employed for this purpose, and 

 represented in Fig. 94, where two horses are attached 



Fig. 94. 



Whipple-tree for three horses. 



to the shorter end, and the third to the longer end of 

 the common bar. Another ingenious but more com- 

 plex arrangement is shown by Fig-. 95, where also the 

 central horse has only half the two others, by being 



