We will close our present article by mentioning two other interesting atmospheric phenomena.
Dr. Franklin proved that lightning and electricity are identical. This wonderful agent manifests itself in a variety of ways. The zigzag track of light across the darkened sky, with its accompanying crash, is one of nature’s exhibitions of tremendous power. The irregularity of its path is due to the resistance of the air, compressed by the electric motion. The beautiful illumination called heat or sheet lightning, is caused by the reflection of the electric flash, at a great distance from the observer.
A very curious form of electricity is that known as St. Elmo’s fire, which appears as a glowing ball, often poising itself on the spars of ships, to the great consternation of superstitious sailors.
Judge Dana, in his admirable book, “Two Years Before the Mast,” more than once alludes to the sensation caused by these weird visitors, as they rounded stormy Cape Horn.
The northern lights, or aurora borealis, with their throbbing, shifting, crimson and purple tints, sometimes called “the merry dancers,” are supposed to be produced by the discharge of electricity in high altitudes and in rarefied air. All around us there is slumbering this power, which science may some day awaken to do the common work of the world.
Meteors, or “shooting stars,” as they are often incorrectly called, are small bodies, often not larger than grains of sand, which rush into our atmosphere at a speed equal to the earth’s motion, eleven hundred miles a minute, and by friction are set on fire, and blaze for a moment in the sky. Lockyer[16] says that seven millions of these, visible to the naked eye, traverse our atmosphere in a single day, and that a powerful telescope would reveal in the same time not less than four hundred millions.
Once in thirty-three years an astonishing display of these celestial fireworks takes place. The last was in 1866. At that time these bodies chanced to cross the track of the earth’s orbit, and were thus brought into collision with it. The largest of them, called meteorites, sometimes pass through the atmosphere unconsumed and reach the earth. They have been known to kill both men and cattle.
In 1866 one thousand of these stones, the largest weighing six hundred pounds, fell in Hungary.
It is very incorrect to call these flashing bodies in the air shooting stars, for they are extremely minute in size, while stars are vast suns; again, in point of distance, they are different, being near at hand, while the latter are millions of miles away. It would be difficult to find an instance in which language can convey a greater error than this phrase, which constantly implies that vast worlds, by thousands, are flying hither and thither, like sky-rockets. Often a single glance at the sky on a clear night, would show how unsafe this world would be as the object of such tremendous cannonading.
End of Required Reading for January.