46 MAGIE— PHYSICAL NOTES ON [April 22, 



it to powder. On either side of the plane of incidence, making 

 angles with it of about 40°, were many fine marks or scratches in 

 the smooth floor, showing where small particles had been driven 

 ahead with great violence. The hole had sloping walls and an 

 inner level floor. A sketch map made from the bullet hole and a 

 map of the crater in which only those details are preserved which 

 the bullet hole can show, are remarkably similar. 



The theory of the strains which would end in such a distri- 

 bution of the broken material ejected by an impact cannot be given; 

 but the observations direct attention to some interesting peculiarities. 

 The piling up of most of the ejecta ahead of the projectile is what 

 might be expected, but it is less obvious that the stresses should 

 be so distributed as to break up the material on either side of the 

 line of flight into separate blocks and arrange them on either side 

 of the hole along the rim. The two spurts of small fragments, 

 thrown out forward diagonally from the line of flight, are also 

 remarkable. 



The lead bullet used was torn to fragments, and much of it was 

 flung out of the hole. The other bullets tried, of other material, 

 were generally badly deformed and torn ; and were thrown back- 

 wards out of the hole, either whole or in fragments. The steel 

 bullets were the only ones which retained their shape, and they 

 remained buried in the holes made by them. It does not seem prob- 

 able that much, if any, of the meteor which made the crater was 

 thrown out of it in a similar way. 



4. Energy. — The data from which to determine the energy with 

 which the meteor struck the earth are not precise ; but an estimate 

 can be made of the energy with some degree of plausibility. 



The work done in excavating the crater is insignificant in com- 

 parison with that done in crushing the rock. The mass ejected 

 may be estimated at 330 million tons (of 2,000 lbs.). This is con- 

 siderably more than the mass excavated in the construction of the 

 Panama Canal. The bottom of this mass was 500 ft. below the 

 original surface. To lift the mass up and clear of the hole would 

 probably use 16 X lo^'^ ft. tons. Something more must be added 

 for the work of tilting back the strata and lifting the unbroken 



