human
What is this doughty question which is to puzzle science? To this I can only answer that if science has or can solve it satisfactorily, I humbly beg its pardon for doubting its powers. Well, the subject I am raising is expressed by the word _Traction_. Traction, I mean, as connected with pace. What is the difference in power required to move a given load at ten miles an hour and at five miles an hour? I have somewhere seen it argued as if it was the same, and that therefore the horses must suffer greatly over the latter part of a stage, supposing that their powers were less and the weight to be drawn remained the same. Of course, the weight does in one sense continue the same, but every coachman who has had any experience in driving will have observed how much longer time it requires to pull up a coach going at a high speed than one at a slow pace; which of itself proves that after the coach is once set in motion and has acquired a fast pace, the exertion required to keep it going is considerably reduced. Without for a moment forgetting the cardinal truth that