DEEP-SEA DEPOSITS. 559 



vapor formed in the center of the explosion, and a trail of the same 

 vapor lasted with this cloud over the whole line followed by the 

 meteor. 



The tall at Aigle, May 20, 1803, according to the circumstantial nar- 

 rative of Biot, was announced by a flaming globe accompanied by 

 a violent explosion which lasted five or six uiinutes; it was at first 

 like four cannon shots, tlien a discharge resembling a volley of mus- 

 ketry. This noise came from a small, very high cloud of a rectangular 

 shape which seemed motionless all the time the phenomena lasted. 



Beside the fall of meteorites, properly so-called, it is certain that 

 cosmic dusts also fall. They have not attracted as much atten- 

 tion as they should, for it is difticult to distinguish them from those of 

 terrestrial origin, which are incomparably the most numerous. They 

 are recognized however, when preceded by the remarkable phenomena 

 of light and noise which we have just mentioned. The catalogue i)ub- 

 lished by Chladni in 1824 informs us of several examples, among which 

 is tlie following: In 1810, in Montreal, Canada, a black rain was 

 observed, accompanied by an extraordinary darkening of the sky, and 

 reports like those from artillery, and very brilliant lights. At first it 

 was supposed to be a tire in a neighboring forest, coinciding with a 

 violent storm. But the wliole phenomenon and the examination of the 

 matter which fell proved that it was due to the arrival in the atmos- 

 phere of substances foreign to our globe. 



There fell at Lcebau, in Saxony, January 13, 183o, a i)owder formed 

 of magnetic oxide. This fall followed the explosion of a bolide which 

 moved, it was said, with extraordinary swiftness, and the flashes from 

 which seemed to burn in }»assing tlirough the atmosphere. 



The chondritic meteorites of Orgueil, the appearance of which in the 

 atmosphere has been mentioned, and which are so interesting from 

 many points of view, were very instructive with regard to the existence 

 of meteoric dust. They are friable to such a degree that several speci- 

 mens were reduced to powder by simple pressure between the fingers. 

 It is a matter of astonishment that they reached the surface of the globe 

 whole. Perhaps this fact may be explained by presenting the two follow- 

 ing circumstances : At firsteach fragment was enveloped at themoment 

 of fall with a vitrified crust more solid than the rest of the mass. 

 Also, the various portions of the substance are cemented by alkaline 

 salts. Water in dissolving this cement brings about the complete disin- 

 tegration of the meteorite, which turns to powder of the most extreme 

 tenuity. So that if on the 14th of May, 1864, the sky, instead of being 

 perfectly clear had been rainy, or merely covered with clouds through 

 which the stones would have had to pass, nothing could have been 

 gathered up but a viscous mud, the fall of which has been observed on 

 several occasions. 



In addition to the facts derived from contemporary phenomena, a 

 second argument for ])elief in the cosmic origin of certain ferruginous 



