18 JUNE 1927, Page 30

Ordinary Differential Equations, by E. C. Ince (Longmans, 36s.), is

research of high quality. To say that the theories of Lie and Klein receive full treatment is to mention only a very small part of its scope. Appendix A, discussing the history of " Formal Methods of Integration " from the seventeenth century onwards, is a useful addendum. Mathe- matical tutors and masters will find H. G. Forder's Foundations bf Euclidean Geometry (Cambridge, 25s.) solid reading, and it should not be neglected by those who have interest in the historical aspects of mathematical study. Elementary Trigo- nometry, by Mr. C. V. Durrell and Mr. R. M. Wright, both Winchester masters (Bell, 5s.), is excellent for the intelligent boy. Longman's Elementary Algebra (2 vols., 6s.), by Mr. F. Bowman, is much fuller than similar textbooks. Its special appeal is to technological students.