406 PROCEEDINGS OF THE NATIONAL MUSEUM vol.90 



For the lower cloud PF-3,896,500X2,330,000=9.3X10^l 

 For the upper cloud Py=14,950,000X2,330,000=34.8X10*2 

 Dividing each by 31,400,000 we get the amount of material whose 

 energy is required to produce each cloud. This is : 

 For the lower cloud 296,000 pounds = 148 tons. 

 For the upper cloud 1,108,000 pounds =554 tons. 

 We can now apply the temperature correction. Temperatures of 

 the air along the path of the meteor are — 51° C, or 222° abs., for the 

 upper cloud, and about 230° abs. on the average for the lower. The 

 temperature of the cloud after expansion is roughly estimated at 900° 

 abs. But the error is much greater than the difference between 222° 

 and 230°. Hence 230° is used for both, and the temperature correction 

 factor becomes 



900 



Hence the weights become, for the lower cloud : 



148X0.74 = 109 tons. 



For the upper cloud: 



554X0.74= 410 tons. 

 Total 519 tons. 



The shape of the cloud can also give us some idea as to the structure 

 of the meteor. The lower cloud appears to have been formed by a 

 single solid, about as compact as the fragments recovered, melting 

 and spalling at a fairly uniform rate. And that high extension of the 

 upper cloud, which has not been computed, may be of the same nature. 



But the shape of the upper cloud, and its "jagged-edged appearance" 

 as described b}^ Heyl, suggest that it is of a different nature. Some- 

 thing seems to have happened at the 12-mile level, which can best be 

 described as a sudden crushing of a loose outer structure surrounding 

 the more compact central core. This outer structure weighed 410 

 tons to 109 for the mner core, which probably gives the proportionate 

 size of the two, even if we could add the mass reqmred to produce 

 the sonic energy. 



What was this loose outer structm-e? 



At the Bureau of Standards is a cross section of a pot of optical 

 glass that has been allowed to cool rapidly. The whole outer portion 

 has cracked up, leaving only a few large lumps at the center. And a 

 large stony meteor, passing near the sun, would probably be similarly 

 cracked. It would have at least a slow rotation. The side toward the 

 sun would be heated, and the side away from it cooled, through tern- 



