=THE BALANCING OF ENGINES.= By W. E. DALEY, M.A., B.Sc., M.Inst.C.E., M.I.M.E., Professor of Mechanical Engineering and Applied Mathematics in the City and Guilds of London Technical College, Finsbury. With 173 Illustrations. Demy 8vo., 10s. 6d. net. =THE STRENGTH AND ELASTICITY OF STRUCTURAL MEMBERS.= By R. J. WOODS, Master of Engineering, Royal University of Ireland, Fellow of the Royal Indian Engineering College, and Assistant Professor of Engineering Cooper's Hill College. Demy 8vo. 10s. 6d. net. =TRAVERSE TABLES.= With an Introductory Chapter on Coordinate Surveying. By HENRY LOUIS, M.A., A.R.S.M., F.I.C., F.G.S., etc., Professor of Mining and Lecturer on Surveying, Durham College of Science, Newcastle-on-Tyne; and G. W. CAUNT, M.A. Demy 8vo., 4s. 6d. net. =THE CALCULUS FOR ENGINEERS.= By JOHN PERRY, M.E., D.Sc., F.R.S., Professor of Mechanics and Mathematics in the Royal College of Science, etc. Crown 8vo., cloth, 7s. 6d. =ELECTRIC AND MAGNETIC CIRCUITS.= By ELLIS H. CRAPPER, M.I.E.E., Head of the Electrical Engineering Department in the University College, Sheffield, viii + 380 pages. Demy 8vo., 10s. 6d. net. =AN INTRODUCTION TO THE THEORY OF OPTICS.= By Professor ARTHUR SCHUSTER, Ph.D., F.R.S., Professor of Physics at the University of Manchester. With numerous Diagrams. Demy 8vo., 15s. net. =ASTRONOMICAL DISCOVERY.= By H. H. TURNER, Savilian Professor of Astronomy in the University of Oxford. With Diagrams. Demy 8vo., 10s. 6d. net. =VECTORS AND ROTORS.= With Applications. Being Lectures delivered at the Central Technical College By Professor O. HENRICI, F.R.S. Edited by G. C. TURNER, Goldsmith Institute. Crown 8vo., cloth. 4s. 6d. =THE PRINCIPLES OF MECHANISM.= By H. A. GARRATT, A.M.I.C.E., Head of the Engineering Department of the Northern Polytechnic Institute, Holloway. Crown 8vo., cloth, 3s. 6d. =ELEMENTARY PLANE AND SOLID MENSURATION.= By R. W. K. EDWARDS, M.A., Lecturer on Mathematics at King's College, London. For use in Schools, Colleges, and Technical Classes. 304 pages, Crown 8vo., 3s. 6d. =FIVE-FIGURE TABLES OF MATHEMATICAL FUNCTIONS.= By J. B. DALE, M.A. Camb., B.A. Lond., late Scholar St. John's College, Cambridge, Lecturer on Pure and Applied Mathematics, King's College, University of London. Demy 8vo., 3s. 6d. net. =AN ELEMENTARY TREATISE ON PRACTICAL MATHEMATICS.= By JOHN GRAHAM, B.A., Demonstrator of Mechanical Engineering and Applied Mathematics in the Technical College, Finsbury. Crown 8vo., cloth, 3s. 6d. =PRELIMINARY PRACTICAL MATHEMATICS.= BY S. G. STARLING, A.R.C.Sc., B.Sc., Head of the Mathematics and Physics Department of the West Ham Municipal Technical Institute; and F. C. CLARKE, A.R.C.Sc., B.Sc. =THE EVOLUTION THEORY.= By AUGUST WEISMANN, Professor of Zoology in the University of Freiburg-im-Breisgau. Translated by Professor J. ARTHUR THOMSON. With numerous Illustrations and Coloured Plates. Two Vols. Royal 8vo., 32s. net.