pulley; this is equivalent to thirty-three thousand pounds raised
one foot in one minute, which is said to be one horse-power.

No horse, of course, could raise thirty-three thousand pounds a
foot or any portion of a foot in a minute or an hour, but the
horse can travel at the rate of two and one-half miles an hour
raising a weight of one hundred and fifty pounds, and the horse
can do more; while it cannot move so heavy a weight as
thirty-three thousand pounds, it can in an emergency and by sudden
strain move much more than one hundred and fifty pounds; with good
foothold it can pull more than its own weight along a road, out of a
hole, or up a hill. It could not lift or pull so great a weight very
far; in fact, no farther than the equivalent of approximately
thirty-three thousand pounds raised one foot in one minute; but for
the few seconds necessary a very great amount of energy is at the
command of the driver of the horse. Hence eight horses, or even
four, or two can do things on the road that an eight horse-power
gasoline machine cannot do; for the gasoline machine cannot
concentrate all its power into the exertion of a few moments. If it
is capable of lifting a given load up a given grade at a certain
speed on its lowest gear, it cannot lift twice the load up the same
grade, or the same load up a steeper grade in double the time, for
its resources are exhausted when the limit of the power developed
through the lowest gear is reached. The grade may be only a mud
hole, out of which the rear wheels have to rise only two feet to be
free, but it is as fatal to progress as a hill a mile long.

Of course it is always possible to race the engine, throw in the
clutch, and gain some power from the momentum of the fly-wheel,
and many a bad place may be surmounted step by step in this way;