1865.] BRITISH ASSOCIATION. 455 



its height well determined. The nearest approach to the earth 

 was thirty-seven miles. Startling as are the accounts of detona- 

 tions heard from such a height, it is yet more surprising that 

 the report from such a distance should be brief and momentary. 

 The sounds caused by meteors yet offer much which it is hoped 

 will be explained by further observations. Interesting matter 

 is given in the Report by Mr. Brayley and Mr. Sorby, " On the 

 Origin of Meteorites, and on the Series of Physical Processes of 

 which they are the Result." It appears, from microscopic exami- 

 nations of their structure, that aerolites resemble, in their appear- 

 ance, certain igneous terrestrial rocks ; but characteristic peculiar- 

 ities in their structure evince that this is far from being a com- 

 plete account of their previous history. M. Brayley suggests that 

 they originate in gaseous matter projected from the equator of the 

 sun, and condensed to a solid form in its passage through inter- 

 planetary space. A gradual condensation from the vaporous state 

 is said, by Mr. Sorby, to represent more nearly than any other the 

 condition under which they must have been consolidated. In this 

 view of the origin of meteorites, their source is considered to be 

 unique, and they are traced to the energetic forces whose modes 

 of action are considered in solar physics. The bodies thus arising 

 are termed " meteoritic masses," to distinguish them emphatically 

 from all other members of the solar system. In a " Memoir on 

 Sporadic Shooting Stars," Mr. Newton, basing his conclusions 

 upon a previous knowledge of their height, arrives at some interest- 

 ing results regarding the number and distribution of these bodies 

 in space. The average height of the centres of their visible tracks 

 is sixty miles above the earth. Their number in the atmosphere 

 daily is seven and a half millions, and if not intercepted in their 

 flight, there would be found in the space occupied by the earth at 

 any instant in its orbit, 13,000^ of such bodies pursuing different 

 orbits. Of shooting stars visible in telescopes, Mr. Newton cal- 

 culates that the number is at least fifty times greater than the 

 number of those visible to the naked eye. Indeed, there appears 

 to be no limit to their minuteness or to their numbers. Their 

 velocity is greater than that of the earth in its orbit, and Mr. New- 

 ton supposes they are grouped together according to some law, pro- 

 bably that of rings encompassing the sun, resembling, in their in- 

 clinations and dimensions, the orbits of the comets. Mr. Newton, 

 in conclusion, supposes that these bodies, which he terms meteor- 

 ites, are not fragments of a former world, but rather materials from 



