Page:The National Geographic Magazine Vol 16 1905.djvu/155

of the particles are caught by the outer walls of the atom and their energy of motion converted into heat. "The radium, in consequence, is heated by its self-bombardment."

The emanations of radium and of other radioactive substances are present everywhere in the atmosphere. Every falling raindrop and snowflake carries some of this radioactive matter to the earth, while every leaf and blade of grass is covered with an invisible film of this radioactive material. These emanations are not produced in the air itself, but are exhaled from the earth's crust, which is impregnated with radioactive matter.

The question, then, arises, Is the amount of radioactive matter present in the earth sufficient to heat it to an appreciable extent? Prof. Rutherford believes that it is. The present loss of heat from the earth is equivalent, he says, to that supplied by the presence of about 270,000 tons of radium, which, if distributed uniformly throughout the earth's crust, corresponds to only five parts in one hundred million million per unit mass. The radioactivity observed in soils corresponds to the presence of about this proportion of radium.

According to Prof. Rutherford's view, the present internal heat of the earth tends to be maintained by the constant evolution of heat by the radioactive matter contained in it. The calculations of the age of the earth made by Lord Kelvin, which were based on the theory that the earth was a simple cooling body, in which there was no further generation of heat, cannot, then, apply, for the present temperature gradient of the earth may have been nearly the same for a long interval of time.

The new knowledge which the discovery of radium and of its properties has given inclines the author to the theory that there is available in the sun a vast store of atomic energy. "If ordinary matter in breaking up emits as much heat as radium, then it can be deduced that the duration of the sun's heat would be prolonged for about one hundred times the estimate founded on the condensation theory. . . . If this heat of atomic disintegration is available, it would suffice to keep up the present output of energy from the sun for about five thousand million years, a period of time which probably both geologists and biologists would consider sufficient for the processes of organic evolution, while the duration of the sun's heat in the future may possibly be extended for a hundred times the estimate made by Kelvin."

The Batavia quadrangle, situated in western New York, in Genesee and Wyoming counties. It embraces an area of about 220 square miles. In addition to Batavia, a town of about 10,000 inhabitants, the smaller villages of Bethany, Pavilion, Wyoming, Dale, Linden, Lagrange, and Warsaw are shown on the map.

The Greene quadrangle of New York, including a portion of Chenango, Broome, and Cortland Counties. The area represented includes the thriving village of Greene, in Greenetown; portions of the towns of Smithville, German, and McDonough, in Chenango County; the village of Whitney Point, in the town of Triangle; portions of the towns of Barker, Nanticoke, and Lisle, in Broome County; the town of Willet and portions of the towns of Cincinnati, Freetown, and Marathon, in