Seaplanes NC-1, NC-3 and NC-4 of the U. S. Navy starting the trans-Atlantic flight from Rockaway. The NC-4 on its victorious trans-Atlantic flight, sixty miles at sea _Frontispiece_ FACING PAGE Montgolfier experiment at Versailles, 1783 10 The first cross-channel trip 11 Diagram showing the main features of the spherical balloon 16 Cocking's parachute 30 A German Zeppelin 31 Inflating a service balloon on the field 40 Army balloon ready to ascend 41 Giffard's airship 54 Santos-Dumont rounding the Eiffel Tower 55 Baldwin U. S. "Dirigible No. 1" 66 The British Army "Baby" dirigible 67 Cross section of the gas bag of the _Astra-Torres_, showing method of car suspension 70 "The Blimp," C-1, the largest dirigible of the American Navy 72 The balloon of the _U. S. S. Oklahoma_ 73 Diagram showing the essential parts of an airplane 95 Wright starting with passenger 98 An early Farman machine prior to start 99 Wright machine rising just after leaving the rail 114 An early Wright machine, showing its method of starting from a rail 114 The propeller department in one of the great Curtiss factories 115 A photograph of northern France taken at a height of three thousand feet 138 An airplane view of the city of Rheims, showing the cathedral 139 Diagram of an internal combustion engine cylinder, showing principle on which it works 157 This photograph shows the relative size of the giant Caproni bombing plane and the French baby Nieuport, used as a speed scout 170 The Spad, the pride of the French air fleet 171 A Handley-Page machine tuning up for a flight 182 The launching of a Langley, a giant bombing airplane 183 Side view of a Sopwith triplane 187 An American built Caproni airplane 188 This Curtiss triplane has a speed of one hundred and sixty miles an hour 189 A giant Gotha bombing plane brought down by the French 198