Value of high speed, when combating a wind—Constructional difficulties of a hundred-mile-an-hour machine. ................. III. Variable-speed aeroplane—Plans for constructing aircraft of this type—Advantages of such a machine. ......................... IV. Power-plant of aeroplanes—Fitting two engines to obviate involuntary descents. ........................................... TENTH SECTION THE TRAINING OF ARMY AIRMEN ......................... I. French thoroughness—An expert’s tribute—Sound training all-important. .................................................. II. How the military airman is "schooled"—His course of instruction described. .......................................... III. Rules for training—Dummy aeroplanes—A pupil’s first "hops." . IV. Cross-country flights—The _vol plané_—Difficulty of first observation tests from an aeroplane. ............................ V. Finishing work at French schools—Practical tests—German thoroughness—Energy of English officers. ........................ ELEVENTH SECTION THE COST OF WAR AEROPLANES ....................... I. Why manufacturers charge high prices—Cost of experimental work—Building of trial machines. ................................ II. Economy of a large military order for machines—The incidental expenses. ....................................................... III. Question of renewals—General cheapness of an air-corps, as compared with other forms of armament. .......................... OUR AERIAL PROGRAMME FOR 1912-13 .................................. TWELFTH SECTION PROBLEM OF ARTILLERY FIRE AND THE AEROPLANE ....... I. Conflicting opinions as to an aeroplane’s vulnerability—Experiments which have been carried out. .......... II. Shrapnel shell—Question of hitting a vital part of the aeroplane—Difficulty of identifying friend or foe. .............. THIRTEENTH SECTION DESTRUCTIVE POTENTIALITIES OF WEIGHT-CARRYING AEROPLANES ........................................................ I. What a modern-type machine can raise—Load of two men, and explosives. ..................................................... II. Effect of aerial bombardment upon cities and troops—German tests. .......................................................... FOURTEENTH SECTION WAR IN THE AIR BETWEEN HOSTILE AEROPLANES ...... I. Certainty of a combat between aeroplanes in actual warfare—Air-scouts protected by aerial "cruisers." .............. II. An encounter in the air—Importance to an army of an aerial victory. ........................................................ FIFTEENTH SECTION VALUE OF THE AEROPLANE IN NAVAL WARFARE ......... I. Machines for coastal and high-seas work—Question of flying in winds. .......................................................... II.