33(5 Scientific Intelligence. 



meteor, to which it is assumed that the crater is due, was 750 ft., 

 or 250 ft., in diameter, it should, at a reasonable depth, seriously 

 affect the magnetic field, and a difference of dip between extreme 

 stations of 30' should exist even for the smaller sized sphere. 

 " That no such difference was found argues that the meteor 

 was broken and scattered by the impact, or more probably, as 

 Mr. Barringer strongly argues in his latest paper, was a cluster 

 or swarm of small masses of iron, mostly of the shale ball variety. 

 The possible intrinsic magnetism of these masses, coupled with 

 the possibility that they have gradually oxidized in the depths of 

 the crater, would account for the absence of any observed mag- 

 netic field." 



The symmetry exhibited by the crater, both in the tilting of 

 the strata of the rim and the distribution of ejected material, is 

 such as can plausibly be referred to the impact of a body rather 

 sharply inclined to the vertical. Some experiments were tried 

 with a lead ball shot from a high-power rifle at an angle ol 30° 

 from the vertical into a level floor of smooth, densely packed 

 silica. The distribution of ejected matter on either side of the 

 surface was distinctly like that observed in the crater. 



An approximate estimate is made as follows of the energy with 

 which the meteor may have struck the earth. The work done in 

 the excavation of the crater involves the probable ejection of 

 some 330 million short tons. To lift the mass up and clear of 

 the hole would have required about 16xl0 10 foot-tons; while if 

 allowance is made also for the work of tilting back the strata and 

 lifting the unbroken rock masses around the rim, some 20X10 10 

 foot-tons in all may have been required. The larger part of the 

 energy, however, was spent in breaking up the rock and reduc- 

 ing the sandstone grains to the condition of finely pulverized 

 silica. It is estimated that over 500 million tons of rock were 

 broken up, and one-fifth of this converted into the pulverized 

 form. The work done against friction resulted in heat, but in 

 general the temperature did not rise to a point sufficient to melt 

 the quartz, as only a small amount of melted material is found. 

 Taking 2500° C as the outside limit of temperature, and suppos- 

 ing all the silica heated to that extent, the heat developed would 

 be equivalent to 9-25 X 10 13 foot-tons. If, however, a general 

 temperatiu-e of 625° is assumed, that is, below the point at which 

 the Widmanstatten figures would disappear, the heat developed 

 would be equivalent to 2-3 X 10 13 foot-tons. In addition to the 

 work on the silica, a \ajev of hard limestone, 300 feet thick, was 

 also broken up, and much of it pulverized. It is estimated finally 

 that the total amount of energy expended may easily have been 

 60 X 10 12 foot-tons. The velocity of the meteor may be put 

 somewhere between the outside limits of 3 and 48 miles per 

 second. If 18 to 20 miles per second be assumed as the most 

 probable velocity, it is found that a mass of 400,000 tons would 

 have had the amount of energy estimated as necessary for the 

 work done in connection with the formation of the crater. 



