Outlines of Meteoric Astronomy. 209 



down the smoke and gas when a lighted match is approached to 

 the wick of a smouldering taper. Other vapours again are too 

 heavy to he lifted completely to the summit of the atmosphere, 

 which is the native region of heat. The " phlogiston " then 

 escapes upwards, and projects downwards the ponderating 

 vapours, as a cherry-stone is jerked from between the finger and 

 the thumb. These are the shooting- stars. Aristotle regarded 

 aerolites as having been carried up into the air by whirl- 

 winds, and thence let fall. Anaxagoras, on the contrary, 

 believed them to be pieces of the heavenly bodies. 



(2.) A century after the time of Cornelius Gemma, whose 

 work illustrates the views of Aristotle, Copernicus and Galileo 

 flourished at the end of the 16th, and Kepler at the beginning 

 of the 1 7th century. These astronomers combined to raise the 

 science of astronomy to a new point of perfection by their ob- 

 servations, and Kepler was the first to publish an " Epheme- 

 rides/ - ' or yearly journal of his observations, in one of which 

 there is described a fire-ball that passed over the whole of 

 Austria from east to west with a terrific explosion, on the 1 7th 

 of November, 1623. On the 31st of March, 1667, a similar 

 detonating fire-ball was observed in Italy, and described by 

 Montanari. A meteor was seen at twilight in England on the 

 20th of September, 1676, and taken by Wallis to have been a 

 comet. A detonating meteor that visited England on the 19th 

 of March, 1719, was described by Halley, and attributed to the 

 combustible gases imagined by Aristotle. This meteor was, 

 he thought, seventy miles high, and, therefore, at the very 

 summit of the atmosphere, and the great explosions were ex- 

 plained by remarking that they might very well be caused by 

 gas, which often produces in coal mines frightful catastrophes. 

 These meteors he recommended for the future to be carefully 

 observed, in order thereby to determine the longitudes of dis- 

 tant places. These recommendations, Lynn, a few years later, 

 extended to shooting- stars, for he observed that they were never 

 noticed on cloudy nights, and must therefore always stay a con- 

 siderable height above the clouds. Saussure and Spallanzani, 

 also, at the end of the last century, on the Alps and Ap- 

 penines, remarked that they appeared to be quite as high 

 above their heads from the tops of mountains, as they usually 

 appear from the level of the plains below. Two students at 

 Gottingen, Brandes and Benzenberg, determined, in 1798, to 

 sift this question to the bottom. An opinion had sprung up 

 in Germany, of which a short outline may very well serve as 

 an introduction to the third period, or that of explanation, in 

 the history of shooting stars. 



(3.) In the choir of the cathedral at Ensisheim (Alsace) 

 there was preserved, until recently, a dark-looking stone 



