A Horse's Power

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Twenty-one and two-tent's horse power in a test of 25 feet on a cinder-surfaced road were developed by Cap and King, a pair of 10-year-old Percheron geldings, in unique pulling tests at the Iowa State Fair, Des Moines. By means of a hydraulic wagon, or dynamometer, recently invented, the "tractive pull" of horse teams was determined with scientific accuracy for the first time. This is the kind of energy required to pull a varying weight out of a hole in the ground. The winning pair exerted a maximum tractive pull of 2,300 pounds. Such a team would pull 10 loaded coal wagons on pavement. On different types of roads varying loads could be pulled, grading from concrete through brick and asphalt to dirt. The two horses weighed 1,725 and 1,905 pounds respectively. They could start heavier loads, move them faster, farther, and with less exhaustion than lighter teams, showing that weight is an important element in a draft horse. These tests proved that horses have more reserve power available than was believed. They can exert from six to ten times as much power for a short time as they ordinarily use, without injury. The horsepower was defined by James Watt, inventor of the steam engine, 150 years ago, and is a practical unit in measuring the energy that one horse can expend continuously throughout a working day; but it takes no account of the reserve power over short periods, which may amount, as the tests show, to more than 10 h.p. per animal.

Draft horses and mules can be tested by the new invention as dairy cattle or race horses are tested—on performance.