Samuel Bruce McLaren (1876–1916) was an Australian mathematician and mathematical physicist, and joint winner of the Adams Prize in 1913. Originally published in 1925, this book presents a description of the main aspects of McLaren's Adams Prize-winning essay, together with other accounts of papers and a selection of reprinted papers where necessary. The text was compiled posthumously following McLaren's early death during the Battle of the Somme. An obituary notice and a biographical appreciation of McLaren are also included. This book will be of value to anyone with an interest in mathematics, physics and the history of science.