VOLUMES ALREADY ISSUED 



1. THE AEROPLANE. 



By C. GRAHAME-WHITE and HARRY HARPER. 



2. THE MAN-OF-WAR. 



By Commander E. H. CURREY, R.N. 



3. MODERN INVENTIONS. By V. E. JOHNSON, M.A. 



4. ENGINEERING. By GORDON D. KNOX. 



5. ELECTRICITY. By W. H. McCoRMiCK. 



6. GEOLOGY. By A. R. DWERRYHOUSE, D.Sc. 



7. HOW ANIMALS WORK. By F. MARTIN DUNCAN. 



