At the stern of this air-ship keel I again established my propeller. I had found no advantage result from placing it in front of the "No. 4," where it was an actual hindrance to the free working of the guide rope. The propeller was now driven by a new 12 horse-power four-cylinder motor without water jacket, through the intermediary of a long, hollow steel shaft. Placing this motor in the centre of the keel I balanced its weight by taking my position in my basket well to the front, while the guide rope hung suspended from a point still farther forward (Fig. 8). To it, some distance down its length, I fastened the end of a lighter cord run up to a pulley fixed in the after part of the keel, and thence to my basket, where I fastened it convenient to my hand. Thus I made the guide rope do the work of shifting weights. Imagine, for example, that going on a straight horizontal course (as in Fig. 8) I should desire to rise. I would have but to pull in the guide rope shifter. It would pull the guide rope itself back ([Fig. 9]), and thus shift back the centre of gravity of the whole system that much. The stem of the air-ship would rise (as in [Fig. 9]), and, consequently, my propeller force would push me up along the new diagonal line.
"No. 4." FLIGHT BEFORE PROFESSOR LANGLEY
The rudder was fixed at the stern as usual, and water-ballast cylinders, accessory shifting weights, petroleum reservoir, and the other parts of the machinery, were disposed in the new keel, well balanced. For the first time in these experiments, as well as the first time in aeronautics, I used liquid ballast. Two brass reservoirs, very thin, and holding altogether 54 litres (12 gallons), were filled with water and fixed in the keel, as above stated, between motor and propeller, and their two spigots were so arranged that they could be opened and shut from my basket by means of two steel wires.
Fig. 9
Before this new keel was fitted to the enlarged balloon of my "No. 5," and in acknowledgment of the work I had done in 1900, the Scientific Commission of the Paris Aéro Club had awarded me its Encouragement prize, founded by M. Deutsch (de la Meurthe), and consisting of the yearly interest on 100,000 francs. To induce others to follow up the difficult and expensive problem of dirigible ballooning I left this 4000 francs at the disposition of the Aéro Club to found a new prize. I made the conditions of winning it very simple:
"The Santos-Dumont prize shall be awarded to the aeronaut, a member of the Paris Aéro Club, and not the founder of this prize, who between 1st May and 1st October 1901, starting from the Parc d'Aerostation of St Cloud, shall turn round the Eiffel Tower and come back to the starting-point, at the end of whatever time, without having touched ground, and by his self-contained means on board alone.
"If the Santos-Dumont prize is not won in 1901 it shall remain open the following year, always from 1st May to 1st October, and so on, until it be won."
The Aéro Club signified the importance of such a trial by deciding to give its highest reward, a gold medal, to the winner of the Santos-Dumont prize, as may be seen by its minutes of the time. Since then the 4000 francs have remained in the treasury of the Club.