Professor of natural philosophy for the Royal Institution between 1853 and 1887, the physicist John Tyndall (1820-93) passionately sought to share scientific understanding with the Victorian public. Reissued here is the collected research he contributed to the Philosophical Transactions of the Royal Society and other journals. Published in 1872, it complements Tyndall's Heat Considered as a Mode of Motion (1863), which is also reissued in this series. Here each memoir is preceded by a short summary, explaining what he discovered and his reasons for embarking on the investigations in question. Accompanying the detailed descriptions of experimental methods are illustrations of the scientific apparatus used. Tyndall also shows how his work built upon previous research, acknowledging the insights of distinguished scientists such as William Herschel and Macedonio Melloni. In particular, he discusses at length his academic debates with Heinrich Gustav Magnus.