I N · T H I S · I S S U E
"On the Edge of Nowhere" by James Lawrence is an easy read that left a deep impression about the profound pace of evolution of our society. "Nowhere" takes you into the life of a trapper and his family in the Alaskan outback, only 50 years ago. How self-reliant these people were; building shelter, hunting for sustenance, and trekking miles across frozen tundra to trade and enjoy "modern" amenities like soap and shoes.
Our civilization is flourishing at a break-neck pace: From one to six billion people in our parents' generation: moon landings, telecom, mobile phones, the Internet. Remarkable advances in materials, biotechnologies, and synthetics of all kinds. There are few reminders for just how fast this has all taken place.
"Horsepower" is a vestige of a time not long ago. Motors are rated using this metric, the motors in cars (which really did take over for horses) to the electric motors in our clothes dryers. A "half a horse" weighs about 20 pounds, a remarkable technological feat. A typical horse - whose height is measured in "hands" not "feet" - weighs 700 pounds. (Englishmen I know still weigh themselves in "stones," about 12 pounds each.)
So where did horsepower come from? Is it what a horse can do? The term was developed by James Watt whose name we all know as the most basic unit of power, "the watt." Working with ponies in coal mines, Watt developed a unit of work over time. The horsepower, he decided, is the amount of material that a horse can lift one foot in a minute. He set a standard: A horsepower lifts 33,000 pounds one foot in one minute.
That's a lot of coal. And it's 745.699872 watts and 2,545 BTUs, or 1,055 joules, or about 600 calories. That defines how much you have to feed the horse to sustain that level of activity, assuming 100% efficiency. This can be taken full circle: A 20-watt lightbulb consumes 0.0268 horsepower.
Later the auto industry glommed onto the term. An automotive horsepower - versus mechanical horsepower -- is derived by taking the square of the diameter of the engine's cylinder and dividing it by 2.5. A 2001 Corvette "with 385 horses under the hood" is propelled by the equivalent of about 49 horses, still a lot of horses, hay, and oats at work.
Other Historical Units of Measurement
A Leonardo Da Vinci illustration shows nine historical units of measurement, including the span, cubit, various ells, fathom, yard, hand, and foot. And then there are rods, and chains, and yards. Some think the latter may have related to a man's single stride, or a person's girth. Barrels are also somewhat antiquated: Beer barrels are 31 gallons; barrels of oil are 42. Anyone heard of a "hogshead?" It's a 63-gallon cask of fluid.