Original photo by Mikayla Storms/ Unsplash
Horsepower, a common unit of power typically referring to the sustained output of an engine, was developed in the late 18th century by Scottish engineer James Watt (after whom the watt is named) as a way to demonstrate the power of steam engines. Watt calculated that in an average day’s work, a horse could turn a 24-foot mill wheel roughly 2.5 times per minute. This amount of energy worked out to 33,000 foot-pounds (approximately 746 watts) per minute, which Watt deemed a new unit of measurement called horsepower.
Logic would suggest the power of a solitary horse should equal one horsepower, but the measurement is meant to represent a horse’s continuous output over a full workday, not what horses are capable of in short bursts of extreme effort. In 1993, biologists R.D. Stevenson and R.J. Wassersug used data from the 1925 Iowa State Fair horse-pulling contest to calculate the maximum output of a horse over a short period of time, ultimately finding that one horse can exert up to 14.9 horsepower. Humans, by comparison, have a maximum output of slightly more than a single horsepower.
It's sometimes suggested that Watt deliberately underestimated the power output of a horse to help promote his new steam engine. But Watt’s calculations weren’t technically incorrect; he just presented them in such a way to make his engines seem more attractive. He emphasized sustainable rather than peak performance, underlining the fact that, unlike horses, his engines could work all day long without tiring. It’s because of this that a single horse can actually be capable of nearly 15 horsepower — at least over short periods of time.
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The offspring of a male horse and a female donkey is called a ______.
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The offspring of a male horse and a female donkey is called a hinny.
The earliest ancestor of the horse is estimated to have lived 55 million years ago.
Around 55 million years ago, the first members of the horse family were scurrying through the forests that covered much of North America. These hoofed mammals were called Hyracotherium, one of which was about as big as a medium-sized dog.
With its arched back, raised hindquarters, four functional hooves on each front foot, and three on each hind foot — unlike the unpadded, single-hoofed feet of modern equines — this early ancestor was quite unlike modern horses as we know them. Paleontologists initially thought the species entirely unrelated to equines, until fossils were found that showed a link between Hyracotherium and later extinct horses.
For more than half their history, the majority of horse species were small, forest browsers, eating leaves and twigs from trees and shrubs. Then, about 20 million years ago, new horse species began rapidly evolving when changing climate conditions allowed grasslands to expand. Some of these new grazers grew to much larger sizes, becoming more like the horses we’re familiar with today.
Tony is an English writer of nonfiction and fiction living on the edge of the Amazon jungle.
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