474 PROCEEDINGS OF THE ACADEMY OF [August, 



This is only a theory, but the inference seems to be justified. 

 The rounded shape common to this kind of meteorites is a fact 

 which must be explained, and the only reasonable explanation 

 is that it has been due to mutual abrasion. The largest mass of 

 meteoric iron of this description so far found by us weighed over 

 100* pounds. I have no doubt, however, that many of them com- 

 posing the cluster which formed the head of the very small comet, 

 which produced by its impact with the earth what we know as Meteor 

 Crater, were much larger. Evidence that many others fell upon 

 the earth around the crater is to be found in the fact that the plain 

 round about is strewn with what is locally known as " iron-shale," 

 certainly due to the decomposition of these "shale-balls," it being 

 merely oxidized meteoric iron. A great many thousand pieces of 

 this "iron-shale" have been found around the crater, on all sides of 

 it, but most abundantly to the N.N.E., the direction from which the 

 cluster is supposed by those of us who now recognize the true origin 

 of the crater to have approached the earth. This variety of meteoric 

 iron, as I have previously stated, decomposes very much more 

 rapidly than any other meteoric iron ever discovered, owing to 

 the fact that it contains appreciable quantities of chlorine. That 

 thousands of "shale-balls" were strewn about the crater a moment 

 after the impact there can now be no reasonable doubt. It is 

 a remarkable fact, however, that no piece of the so-called "iron- 

 shale" has ever been found which is not slightly curved, similarly 

 to the "iron-shale," found on the outside of the slowly decomposing 

 "shale-ball" meteorites which lie deeply imbedded in the silicious' 

 dust forming a great portion of the rim of the crater. Most of the 

 latter have iron centres and the "iron-shale" surrounding them are 

 merely the layers of iron oxide still adhering to the central iron mass. 

 When we compare the two, the pieces of "iron-shale" found on the 

 surrounding plain show conclusively by their shape that the so-called 

 "shale-ball" meteorites from which they were derived were originally 

 more or less globular in shape. 



Saturn's rings are now believed to be composed of meteorites, but 

 upon the theory which I have advanced there is possibly no milling 

 or grinding action taking place between them such as may take place 

 for some unknown reason in the head of a comet. I may, however, 

 easily be in error as to this. 



If the lunar craters and the Arizona crater have had a common origin, 

 as now seems very probable, there can be no doubt that our knowl- 

 edge of cosmogony has been greatly advanced by the discovery of the 



