The sixth and final volume in Andrew Russell Forsyth's Theory of Differential Equations series, concentrating specifically on partial differential equations.Originally published in 1906, this book constitutes the sixth and final volume in Scottish mathematician Andrew Russell Forsyth's Theory of Differential Equations series, concentrating specifically on partial differential equations. The text contains detailed information on the development of this area and substantial contributions made to it.Originally published in 1906, this book constitutes the sixth and final volume in Scottish mathematician Andrew Russell Forsyth's Theory of Differential Equations series, concentrating specifically on partial differential equations. The text contains detailed information on the development of this area and substantial contributions made to it.Andrew Russell Forsyth (18581942) was an influential Scottish mathematician notable for incorporating the advances of Continental mathematics within the British tradition. Originally published in 1906, this book constitutes the sixth and final volume in Forsyth's Theory of Differential Equations series, concentrating specifically on partial differential equations. The text contains detailed information on the development of this area and substantial contributions made to it. All sources are quoted in their proper connection and a few fresh investigations are added. Examples are given, where necessary, in order to provide illustrations of various methods. This book will be of value to anyone with an interest in differential equations and the history of mathematics.12. General integrals of equations of orders higher than the first; 13. Linear equations of the second order in two independent variables: the Laplace-transformations; 14. Adjoint equations: linear equations having equal invariants; 15. Forms of equations of the second order in two independent variables having their general integrals in explicit finite form; 16. Equations of l“Y