Ernst Mach 
History and Root of the Principle of the Conservation of Energy [PDF ebook] 

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. But philosophers seem hardly to have done justice to Mach’s work. Mach himself, indeed, has repeatedly disclaimed for himself the name of philosopher; yet, in a sense, any man who forms a general position from which to regard, say, science, is a philosopher.10 It must be acknowledged that the least satisfactory parts of Mach’s writings are those in which he discusses mathematical conceptions, such as numbers and the continuum; and in which he implies that logic is to be founded on a psychological basis; but such things are unconnected with the greater part of his valuable work.