PHILOSOPHICAL SOCIETY OP WASHINGTON. ' 143 



was heard, which was 145 or 150 seconds, corresponding to a 

 distance of thirty or thirty-one miles. We are disposed to con- 

 sider the so-called " explosion" and subsequent " rumbling" not 

 as due to a definite explosion of the meteor, but as the result of 

 the concentration at the observer's ear of the vast volume of 

 sound emanating, almost simultaneously, from a large part of 

 the meteor's path, being, in that respect, not dissimilar to ordi- 

 nary thunder. 



It is evident that the waves of sound starting from that por- 

 tion of the meteor's path nearest to the observer would reach his 

 ear first; thustheobserver 

 at G would hear a violent 

 sound due to the com- 

 bined noises of the slight 

 explosions, whirring, rush- 

 ing, and snapping, ema- 

 nating within a portion 

 of a second from the whole 

 of the line x y. Sub- 

 sequently he would hear 



the sounds from x x^ and Ji^2 



y y^, then those from x^ x^ 



and y, y^, etc. The absorption and refraction of sound by the 

 atmosphere and the progression of the meteor materially affect 

 this phenomenon. 



The dimensions of the cone-shaped meteor were estimated by 

 Washington observers at about 45' broad by Y5' long, from 

 which some allowance is to be made for irradiation ; but which 

 correspond to 2000 and 3400 feet respectively. 



By these figures, however, we are not to understand that there 

 necessarily was any solid body of this size. The actual quan- 

 tity of solid luminous matter producing the appearance of so 

 large a meteor, as is well known, may have been extremely 

 small ; since the same visible effect would be produced by a 

 cloud of very small and very bright meteoric particles moving 

 very rapidly. 



Of the actual velocity of the meteor there does not appear to 

 be any means of forming a reliable determination. It probably 

 described its entire visible path (of possibly about 120 miles) in 

 three to five seconds. 



For the convenience of those members who may desire to sub- 

 mit to further study the data we have collected, we submit, in 

 Appendix No. II, some convenient abstracts of the more import- 

 ant reports. 



In Appendix No. ill we nave collected the data relating to 

 the position of the meteor at its disappearance. 



In Appendix No IV will be found whatever seemed valuable 

 with reference to the sounds heard during or after its passage. 



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