MAN'S CONQUEST OF NATURE

To most persons, reference to man's conquest over nature probably implies the perfection of chemical, physical or mechanical devices to overcome some of the obstacles to progress presented by environment. In transportation, not only the land but also the water and the air are today traversed successfully over long distances, thanks to modern inventions. Progress in these directions has involved the development of speed and safety and, in many instances, the reduction of cost. There are advances, however, that involve human physiologic adjustments. These are rarely appreciated or understood. The conquest of altitude by man is an illustration. In 1930, Lieutenant Soucek of the United States Navy climbed in an airplane to a height of 43,166 feet, an altitude at which the barometric pressure and the consequent low partial pressure of oxygen in the atmosphere would make life practically impossible under ordinary conditions. An elevation of 10,000 feet or even