Many of these designs had their origin in France, but the British have not been idle. Many improvements have had their birth in England, and we know that these, as in the case of other designs here mentioned, have led to definite results. Out of persevering efforts, checked again and again by misfortune and often by disaster, have come the modern airships with which we are familiar. In their wake are many victims. Yet, as we have seen, and shall see afresh in these pages, they have called forth many heroic deeds. CHAPTER V THE BIRTH AND GROWTH OF THE AEROPLANE It is to the honour of the British nation that one of the first principles of the biplane was proposed and explained by a British subject, Mr. F. H. Wenham, as far back as 1866. He pointed out that the lifting power of a surface can be economically obtained by placing a number of smaller surfaces one above another. Indeed, flying-machines were built by Wenham on this principle, with appliances for the use of his own muscular power. He did not, however, accomplish actual flight, although valuable results were obtained as regards the driving power of superposed surfaces. After various further experiments in the same direction, it fell to H. von Helmholtz to emphasize the improbability that man could drive a flying-machine by his own muscular power. A period of stagnation followed. But interest was revived later, and fresh efforts were made, varying in importance, down to the experiments of Sir Hiram Maxim and Professor Langley. [Illustration: DISTINCTION MARKS USED BY THE BELLIGERENTS IN THE WAR. 1. British. 2. Marks on rudder of British machine. 3. French. 4. Marks on rudder of French machine. 5. Russian. 6. Italian. 7. German and Austrian. 8. Turkish. The British marks consist of circles, having a red and blue circumference, with a white or (occasionally) the natural colour of the fabric in between. The positions for these circles are:—Two on the upper surface of the top plane near the wing tips; two on the lower surface of the bottom plane, also close to the tips; one on each side of the body between the pilot’s seat and the tail. Sometimes simply a red circle is used on naval machines. The rudder is painted with three vertical stripes in the following order counting from front to back: blue, white, red. The French distinction marks are similar to the British, with the exception that the centre of the circles is blue and the circumference red. The Belgian, Serbian, and Roumanian marks are similar to the French. The Russian marks are lateral stripes on the planes in the order from the leading to the trailing edge of the wing: white, blue, red. Our Italian Allies incorporate their national colours in a rosette on their machines. The device has a red centre, then a white ring with a green circle outside.]