James Joule was perhaps the greatest amateur scientist of all time. He was the proprietor of a successful brewery who never held an academic post--in fact, he never completed an undergraduate degree. Today he is recognized as an important contributor to the field of thermodynamics.

Joule was born in Manchester, England, in 1818. He was a sickly child who suffered from a chronic spinal injury. His father, a wealthy brewer, was eager to please his young son; he provided as many books as the child could read and eventually built for him a home laboratory. Joule was entirely self-educated, taking from his books only the information that interested him. He quickly gained a working knowledge of physics and chemistry. At the age of seventeen he briefly attended Manchester University but left shortly thereafter to pursue his own studies.

During his early years, Joule had developed a passion for measurement...