METEORITES, METEORS, AND SHOOTING-STARS. 745 



are many facts about these stones which imply that violent forces have 

 in some way acted during the meteorite's history. The brecciated ap- 

 pearance of many specimens ; the fact that the fragments in a breccia 

 are themselves a finer breccia ; the fractures, infiltrations, and apparent 

 faultings seen in microscopic sections, and by the naked eye these 

 all imply the action of force. M. Daubree supposes that the union of 

 oxygen and silicon furnishes sufficient heat for making these materials. 

 If this is possible, those transformations may have taken place in their 

 first home. Dr. Reusch argues that the repeated heating and cooling 

 of the comet as it comes down to the sun and goes back again into the 

 cold, is enough to account for all the peculiarities of structure of the 

 meteorites. These two modes of action do not, however, exclude each 

 other. 



Suppose, then, a mass containing silicon, magnesium, iron, nickel, a 

 limited supply of oxygen, and small quantities of other elements, all 

 in their primordial or nebulous state (whatever that may be), segre- 

 gated somewhere in the cold of space. As the materials consolidate 

 or crystallize, the oxygen is appropriated by the silicon and magnesium, 

 and the iron and nickel are deposited in metallic form. Possibly the 

 heat developed may, before it is radiated into space, modify and trans- 

 form the substance. The final result is a rocky mass (or possibly sev- 

 eral adjacent masses) which, sooner or later, is no doubt cooled down 

 throughout to the temperature of space. This mass in its travels comes 

 near to the sun ; powerful action is there exerted upon it. It is heated. 

 How intense is that heat upon a cold rock unprotected apparently by 

 its thin atmosphere it is not possible to say. We know that the sun's 

 action is strong enough to develop and drive off into space that im- 

 mense train, the comet's tail, that sometimes spans our heavens. It is 

 broken in pieces. We have seen the portions go away from the sun, 

 to come back probably as separate comets. Solid fragments are scat- 

 tered from it, to travel in their own independent orbits. 



What is the condition of the burned and crackled surface of a 

 cometic mass or fragment as it goes out from the sun again into the 

 cold? What changes and recrystallizations may not that surface un- 

 dergo before it comes back again to pass anew through the fiery ordeal ? 

 We have here forces that we know are acting. They are intense, and 

 act under varied conditions. The stones subject to those forces can 

 have a history full of all the scenes and actions required for growth of 

 such strange bodies as these that come down to us. Some of our me- 

 teors, those of the star-showers, certainly had that history. What good 

 reason is there for saying that all of them may not have had the like 

 birthplace and life ? 



Before I close, let me add one lesson that has been taught us by 

 recent star-showers. The pieces which come into our air in any recur- 

 ring star-shower belong to a group whose shape is only partly known. 

 It is thin, for we traverse it in a short time. It is not a uniform ring, 



