EXPERIMENTS RELATIVE TO METEORITES. ^15 



presented itself was to seek tlieir ()ri>^iii in the plunet nearest to us. It was thus, as 

 will be remembered, that Laplace and JBerze I ius regarded them as bodies ejected 

 from lunar volcanoes. But the hypothesis most generally adopted is that 

 ■which Chladni ventured to enunciate in 1794 ; according to this, the stones that 

 descend from the skies are asteroids, which, entering within the sphere of the 

 earth's attraction, are precipitated to its surface. These asteroids, moreover, need 

 not pertain to our own planetary system ; there is nothing to prove that they 

 do not proceed from other regions of space. 



Thv luunber of the known falls of meteorites is not so considerable as might 

 be inferred from the great number of bolides -which have been observed and 

 which daily come to light. Those which have been well authenticated, and the 

 stones of which have been collected, do not, to our knowledge, amount to 1,000. 

 In this sort of verification we necessarily do not take account of a number of 

 falls, otherwise quite considerable, which have left us neither trace nor memento. 



But however incomplete the statistics of these falls, it is well to note how they 

 arc distributed in point of time. From monthly statements it would a|>pearthat 

 the two months which are remarkable lor showers of shooting stars have no pre- 

 eminence as regards the number of the descents of bolides. In the horary 

 distribution the variations are more marked; the falls seem to he more frequent 

 by day than by night, as is shown by the facts observed by MM. Alex. 

 Ilerschel, De Ilaidinger, and Quetelet. 



As regards the geographical apportionment of meteorites, they have been sig- 

 nalized in all parts of the globe. Nevertheless, this apportionment is far from 

 being uniform ; certain points seem distinguished for them. The abundance of 

 ferruginous meteors in certain parts of America, north and south, in Mexico, the 

 United Stales, and Chili, is well known. While some countries make no men- 

 tion of falls of stones, or mention them very rarely, as S A'itzerland, other 

 countries of the same sui"face, and which appear not better ])repared for the veri- 

 lication of phenomena of this kind, have been often their theatre. Such are 

 some of the regions of southern France, (Barbotan, Agen, Toulouse, Orgneil, 

 I^aissac, Alais, Juvinas,) the northern part of Italy and British India, the hvtter 

 having witnessed not less than 3-4 since the end of the last century. Daring 

 each of the two years 1863 and 1864, as well as in 1866, three falls of mi'teor- 

 ites have been cited in Europe. If we assume that this part of the world has 

 not been particularly favored, and remember that it represents sixteen-thou- 

 sandths of tlie total surface of the globe, we should realize for that whole surface 

 the number of ISO meteorites. If, by reason of the facility with which the phe- 

 nomenon may i)ass unperceived, this number be raised three-fold, which is doubt- 

 less far from being an exaggeration, wo find a total of from GOO to 700 for the 

 animal number of falls. 



It results from these falls of meteorites that, each year, the mass of the globe 

 is augmented by a certain cpiaulity, and, according to a principle of mechanics, 

 this augmentation would necessarily have an inlhience on the velocity of the 

 rotation of our planet. It has been sought to ascribe to this cause the secular 

 acceleration of the mean movement of the moon ; but that acceleration is very 

 far irom being completely explained by tluj phenomenon in ipiestion.* Under 

 this point of view, the very slight increase of mass jtroduced by the arrival of 

 these extra-terrestrial bodies nuiy, it woidd seem, bo wholly neglected. 



When we reflect on the number of meteorites which the earth receives from 

 year to year, wo are impelled to admit that numbers must have fallen likewise, 

 in the vast periods (jf time during which the strata of the earth were formed, on 

 land as well as in the basin of the ocean itself. Yet, often as the stratified for- 

 mations have been explored, nothing analogous to the meteoric stones has ever 

 been noticed. This renuirkable fact may be, perhajts, explained, in accordance 



* As M. Delauuuy has receatly demons truted, {Comples litndus, t. Ixi, p. WSS.) 



