This book provides a chronological introduction to modern atomic theory, which represented an attempt to reconcile the ancient doctrine of atomism with careful experimentsâperformed during the 19th centuryâon the flow of heat through substances and across empty space. Included herein are selections from classic texts such as Carnotâs Reflection on the Motive Power of Fire, Clausiusâ Mechanical Theory of Heat, Rutherfordâs Nuclear Constitution of Atoms, Planckâs Atomic Theory of Matter and Heisenbergâs Copenhagen Interpretation of Quantum Theory. Each chapter begins with a short introduction followed by a reading selection. Carefully crafted study questions draw out key points in the text and focus the readerâs attention on the authorâs methods, analysis and conclusions. Numerical and laboratory exercises at the end of each chapter test the readerâs ability to understand and apply key concepts from the text. Heat, Radiation and Quanta is the last of four volumes in A Studentâs Guide through the Great Physics Texts. The book comes from a four-semester undergraduate physics curriculum designed to encourage a critical and circumspect approach to natural science while at the same time preparing students for advanced coursework in physics. This book is particularly suitable as a college-level textbook for students of the natural sciences, history or philosophy. It might also serve as a textbook for advanced high-school or home-schooled students, or as a thematically-organized source-book for scholars and motivated lay-readers. In studying the classic scientific texts included herein, the reader will be drawn toward a lifetime of contemplation.