ANIMAL - MECHANICAL TILLAGE 235 



connected by a universal joint, operates the binder under the 

 most severe conditions. Two horses easily pull the entire 

 outfit, yet three to five horses are ordinarily used when the 

 cutting and binding mechanisms are driven by the bull-wheel. 



A combination tillage machine might be built light enough so 

 that on a smooth piece of laud two horses would pull it for ten 

 to twelve hours per day without being abnormally fatigued. 

 A 2-h.p. gasoline motor for traction could not replace these 

 two horses, even on s uooth ground. Taking into account emer- 

 gencies, the losses by internal friction and slippage of tractor 

 wheels, probably 6 h.p. would be necessary, and much more 

 on grades. Animals may be allowed to rest from time to time 

 for a fresh start on tiling land, and thus will negotiate steep 

 grades without assistance. The gasoline motor gains nothing 

 by resting, except a certain amount of momentum in the fly- 

 wheel. The steam tractor, by using a surplus of steam and 

 waiting now and then to replenish it, may mount surprising 

 grades, but it is not so well adapted to use in small units. 

 It is this difference which makes the animate motor really valu- 

 able for traction, because it has at its command, at a given 

 moment, a motor power two to five times greater than the 

 effort normally necessary. If the propulsion of the machine 

 requires ordinarily 2 h.p. and at times 6 or even 15 h.p., then a 

 mechanical tractor must be chosen with reference to the maxi- 

 mum requirements. A motor cultivator requiring at all times 

 10 h.p. for its effective work and 6 h.p. at the outside for 

 traction, would work advantageously with a 16-h.p. motor, 

 but one requiring a 25-h.p. motor where most of the time only 

 12 to 16 h.p. is necessary is not an economical proposition. 



The inventors claim that a combined machine will as surely 

 replace the four-horse plow as the band saw has replaced the 

 back-and-forth motion of the band saw as the grindstone 

 has, in factories, displaced the whetstone and the file. They 

 overlook the vital fact that, in the plow, the harrow and the 

 ordinary hay rake, there is no lost stroke as with the saw, and 



