|Index & Notes
Exponential improvements in steam engines
It's not the first exponential improvement of technology in history. Both trains and airplanes improved their performance on exponential curves until economic, not technical, limitations stopped progress. The Concorde was actually pulled from service for economic, not technical, reasons, and now celebrities must travel below the speed of sound. Even the original engine of the industrial revolution improved on an exponential curve. You'll note the efficiency on the Y-axis is a log scale. I took the raw data from a display by my U of Calgary professor, Grant Walker, who noted that successive steam engines, invented about 60 years apart, each took half the coal to get a horsepower-hour of work done as the previous generation. The one exception was James Watt's, whose engine doubled efficiency again only four years after the Smeaton engine came out. His was the first really economic one, kick-starting a whole industry.
© Roy Brander, P.Eng 2008