This book contains a series of dedicated introductory essays, lectures, and reviews covering a wide range of topics. Written with the desire to 'extend sympathy for science beyond the limits of the scientific public, these pieces have been written with the layperson in mind and, although most of the essays are of a purely scientific nature, the author has endeavoured to exclude every word which may have caused needless irritation. Conveyed in an engaging and accessible manner, this fascinating text is a must-have for any aspiring student of science. John Tyndall was an influential 19th century physicist. Originally published in 1871, this text is republished now with an introductory biography of the author.