First published in 1901, and originally delivered as lectures in the Philosophical Hall in Leeds earlier that year, this book discusses the practical and historical problems faced by those wishing to measure heat energy. Griffiths, who dealt with the problem extensively during his career, gives a brief historical survey of this problem and details various experiments performed by scientists such as Joule, Rowland and Regnault, as well as the application of such findings in both a scientific and industrial setting. This book will be of value to anyone with an interest in the history of science and scientific education.