The reliability of the aëroplane depends partly on its environment, partly on its plan and structure, partly on the skill of its pilot. The pilot’s skill had been admirably developed in the tournaments and public exhibitions. The aërodynamic design conducive to stability and steadiness, the structural design conducive to maximum strength and resiliency, uniformly proportioned to the stress and work of each part of the complex machine; and above all the design of the motor, to ensure it against a thousand foibles—all these could be improved by the patient methods of theoretical and experimental science. The environment could, of course, be chosen. At first only the most favorable regions need be attempted for regular transportation, regions of level plain and farm land, or of lake and river surrounded by country not too rough and precipitous. The general cost of the aëroplane to mankind depends on its plan and structure, on the methods of manufacture, on the material running expense; but its particular cost to the passenger is determined largely by the cupidity or business acumen of those who furnish the machine and those who operate it. Naturally when the world first awoke in the morning of practical sporting aviation, with a sudden and strong relish for flying, the prices would be fabulous, not to say ridiculous. During that hour no commercial transportation could be contemplated. But without monopoly the prices must quickly abate; for neither the manufacture nor manipulation of the aëroplane demand rare ability or training. The cost of manufacture would promptly be diminished by means of specialized tools and operatives, immediately upon the assurance of large and continuous orders. The cost of pilotage would become insignificant when a single chauffeur could take a dozen passengers on one aëroplane. So much for the human and external elements in the cost of aviation. The inherent and material cost of the aëroplane could also be reduced, though perhaps less readily. It was unlikely that the machine would be built of much cheaper materials, or made much lighter per pound of cargo. Nor were such improvements of so much importance since they would affect only the first cost of the flyer. But an increase of aërodynamic efficiency in the propeller and aëroplane proper, together with increased thermodynamic efficiency in the motor, would materially lower the current cost of transportation at any given speed. These improvements would require careful research in the laboratory and patient trial in the workshop and field. The refinement and perfection of the aëroplane might therefore be looked for in those communities where men have sufficient foresight, enterprise and liberality to endow research, and to encourage the science and the art of aviation to supplement each other. PART III AËRONAUTIC METEOROLOGY CHAPTER XIII