John Neville Keynes 
Studies and Exercises in Formal Logic [PDF ebook] 
Including a Generalisation of Logical Processes in Their Application to Complex Inferences

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. N. J. S. Nicholson, Professor of Political Economy in the University of Edinburgh; O. =university of Oxford r.=g. Croom Robertson, Professor of Mental Philosophy and Logic in University College, London.