Book excerpt: Although we take it for granted today, the concept of "energy" transformed nineteenth-century physics. In The Science of Energy, Crosbie Smith shows how a North British group of scientists and engineers, including James Joule, James Clerk Maxwell, William and James Thomson, Fleeming Jenkin, and P. G. Tait, developed energy physics to solve practical problems encountered by Scottish shipbuilders and marine engineers; to counter biblical revivalism and evolutionary materialism; and to rapidly enhance their own scientific credibility. Replacing the language and concepts of classical mechanics with terms such as "actual" and "potential" energy, the North British group conducted their revolution in physics so astutely and vigorously that the concept of "energy"—a valuable commodity in the early days of industrialization—became their intellectual property. Smith skillfully places this revolution in its scientific and cultural context, exploring the actual creation of scientific knowledge during one of the most significant episodes in the history of physics.