Meteors, or Fireballs, are bodies which do not belong to the earth, but come from other parts of space into our atmosphere, and are seen as bright balls of fire crossing the sky, with a train of light behind. Suddenly they are seen to go out, and very often a fall of stones occurs. Sometimes they are observed to break in two, and loud explosions like thunder are heard. They move very fast - ten or twelve miles per second, and are visible when between 40 and 80 miles above the earth. Other meteors dart across the sky and disappear, all in a very short time. These are known as shooting stars, and are sometimes big and bright, like planets. It is estimated that about six or eight meteors yyhich drop stones come into our atmosphere every year; but some 20,000,000 of small bodies pass through the air every day - these would all appear as shooting stars if they occurred at night. At some periods of the year there are so many shooting stars that they appear like a shower of fire. On November 14th this happens, the shower being greatest every 33 years. A stream of meteors is travelling round the sun, and every 33 years the earth just comes through them. Meteoric showers also occur about August 9th to 11th, and smaller ones in April. The luminosity of meteors is due to the intense heat caused by the resistance of the air to their passage, and in support of this theory it is found that meteoric stones are always covered, either wholly or in part, with a crust of cement that has recently been melted.