By CHARLES F. HOLDER.
A thin stratum of air, an invisible armor of great tenuity, lies between man and the menace of possible annihilation.
The regions of space beyond our planet are filled with flying fragments. Some meet the earth in its onward rush; others, having attained inconceivable velocity, overtake and crash into the whirling sphere with loud detonation and ominous glare, finding destruction in its molecular armor, or perhaps ricocheting from it again into the unknown. Some come singly, vagrant fragments from the infinity of space; others fall in showers like golden rain; all constituting a bombardment appalling in its magnitude. It has been estimated that every twenty-four hours the earth or its atmosphere is struck by four hundred million missiles of iron or stone, ranging from an ounce up to tons in weight. Every month there rushes upon the flying globe at least twelve billion iron and stone fragments, which, with lurid accompaniment, crash into the circumambient atmosphere. Owing to the resistance offered by the air, few of these solid shots strike the earth. They move out of space with a possible velocity of thirty or forty miles per second, and, like moths, plunge into the revolving globe, lured to their destruction by its fatal attraction. The moment they enter our atmosphere they ignite; the air is piled up and compressed ahead of them with inconceivable force, the resultant friction producing an immediate rise in temperature, and the shooting star, the meteor of popular parlance, is the result.
Ideal View of the Earth as it is Bombarded by the Estimated Four Hundred Million Meteorites every Twenty-four Hours.[20]
A simple experiment, made by Joule and Thomson, well illustrates the possibility of this rise in temperature by atmospheric friction. If a wire is whirled through the air at a rate of one hundred and seventy-five feet per second, a rise of one degree, centigrade, will be noticed. If the revolutions are increased to three hundred and seventy-two feet per second, the elevation will be 5.3° C. If the temperature increases as the square of the velocity, a rate of speed of twenty miles per second would develop a temperature not far from 360,000° C., which is probably far less than that at the surface of the ordinary meteor as it is seen blazing through our atmosphere. If the meteor is small it is often consumed by the intense heat generated; but larger fragments, owing to their velocity and the fact that they are poor conductors of heat and burn slowly, reach the surface and bury themselves in the sea or earth. But few escape the inevitable consequences of the contact, and of the untold millions which have struck the earth within the memory of man but five hundred and thirty have been seen to fall. The phenomena associated with the plunging meteor is most interesting. A blaze of light, as the terrific heat ignites the iron, announces its entrance into our atmosphere. It may be red, yellow, white, green, or blue, all these hues having been observed. Then follows the explosion, caused by the contact with the air piled up ahead, and in certain instances a loud detonation or a series of noises is heard, which may be repeated indefinitely until the meteoric mass is completely destroyed, and drops, a shower of disintegrated particles, which fall rattling to the ground.
The blaze of light does not continue to the earth, nor does the meteor, should it survive, strike the ground with the velocity with which it entered the atmosphere, as the latter often arrests its motion so completely that it drops upon the earth by its own weight, well illustrated by the meteorites of the Hesslefall, which dropped upon ice but a few inches thick, rebounding as they fell. Thus the atmosphere protects the inhabitants of the globe from a terrific bombardment by destroying many of the largest meteorites, reducing the size of others before they reach the surface and arresting the velocity so that few bury themselves deeply in the soil.
The writer observed a remarkable meteor in 1894. It entered our atmosphere, apparently, over the Mojave Desert, in California, and exploded over the San Gabriel Valley, though without any appreciable sound, and after the first flash disappeared, leaving in the air a large balloon-shaped object of yellow light which lasted some moments, presenting a remarkable spectacle. In this instance the meteor had probably exploded or been consumed, leaving only the light to tell the story, the atmospheric armor of the earth having successfully warded off the blow.
Viewing the facts as they exist, the earth, a seeming fugitive mass flying through space, vainly endeavoring to break the bonds which bind it to the sun, hunted, bombarded with strange missiles hurled from unseen hands or forces from the infinity of space, it is little wonder that the ancients and some savage races of later times invested the phenomena with strange meanings. It requires but little imagination to see in the flying earth a living monster followed by shadowy furies which hurl themselves upon it, now vainly attempting to reach the air-protected body or again striking it with terrific force, lodging deep in its sides amid loud reverberation and dazzling blaze of light.
Meteorites have been known from the very earliest times, and have often been regarded as miraculous creatures to be worshiped and handed down from family to family. The famous meteorite which fell in Phrygia, centuries ago, was worshiped as Cybele, "the mother of the gods," and about the year 204 B.C. was carried to Rome with much display and ceremony, when people of all classes fell down before it, deeming it a messenger from the gods. Diana of Ephesus and the famous Cyprian Venus were, in all probability, meteoric stones which were seen to fall, and were worshiped for the same reason as above. Livy describes a shower of meteorites which fell about the Alban Mount 652 B.C. The senate was demoralized, and certain prophets announced it a warning from heaven, so impressing the lawmakers that they declared a nine-days' festival with which to propitiate the gods. The visitor to Mecca will find enshrined in a place of honor a meteorite which can be traced back beyond 600 A.D., and which is worshiped by pilgrims. The Tartars pointed out a meteorite to Pallas, in 1772, which had fallen at Krasnojarsk, and which they considered a holy messenger from heaven. A large body of meteoric iron found in Wichita County, Texas, was regarded by the Indians as a fetich. They told strangers that it came from the sky as a messenger from the Great Spirit. This meteorite was stationed at a point where two Indian trails met, and was observed and worshiped as a shrine.