APPLICATION OF LABOR. 171 



miles a day. He can carry in a wheel-barrow 150 

 pounds 10 miles a day. 



Well-constructed machines for saving human labor 

 by means of horse-labor, when encumbered with little 

 friction, will be found to do ahout Jive times as much 

 work for each horse as where the same work is per- 

 formed by an equal number of men. For example : an 

 active man will saw twice each stick of a cord of wood 

 in a day. Six horses, with a circular saw, driven by 

 means of a good horse-power, will saw five times six, 

 or thirty cords, working the same length of time. In 

 this case the loss by friction is about equal to the ad- 

 ditional force required for attendance on the machine. 



Again : a man will out with a cradle two and a half 

 acres of wheat in a day. A two-horse reaper should 

 therefore cut, at the same rate, ten times two and a 

 half, or twenty-five acres. This has not yet been ac- 

 comphshed. We may hence infer that the machinery 

 for reaping has been less perfected than for sawing 

 wood. It should, however, be remembered, that great 

 force is exerted, and for many hours in a day, m cut- 

 ting wheat with a cradle, and therefore a Uttle less 

 than twenty-five acres a day may be regarded as the 

 maximum attainment of good reaping-machines, when 

 they shaU become perfected. 



Applying the same mode of estimate, a horse-culti- 

 vator will do the work of five men with hoes, and a 

 two-horse plow the work of ten men with spades. A 

 horse-rake accomplishes more than five men, because 

 human force is not strongly exerted with the hand-rake. 



In using different tools, the degree of force or press- 

 ure applied to them varies greatly with the mode in 



