3Q0 PHILOSOPHICAL TRANSACTIONS. [aNNO 17 5Q. 



those observers. But such as were nearest, and liad a clear atmosphere, saw the 

 tail of a considerable length ; that is, the flame, the sparks, and the illuminated 

 vapour, in a train behind the head, as being lighter, and therefore meeting with 

 more resistance from the air : in the same manner as the flame, the sparks, and 

 smoke, of a torch are seen to follow it. All this is plain ; but in regard to that 

 separation of the third part of the tail from the rest, a circumstance clearly de- 

 scribed by the farmer at Ancram, and seemingly confirmed by other observa- 

 tions, there may be some difliculty. Perhaps at this period, on a greater ex- 

 plosion in the ball, most of the combustible matter was thrown out at once, 

 which falling behind, occasioned that appearance of the breaking off" a part of 

 the tail, while, for want of fuel, the remainder vanished, or, as the observer 

 expresses it, was collected into the head. This account is rendered more probable 

 by what is said of the emission of a greater light about this time, and by the 

 loud report heard by the farmer 5 minutes after, and which, on computing the 

 distance, ought to have reached him much about that time, had it been occa- 

 sioned by this extraordinaiy bursting and dispersion of the inflammable matter. 



The hissing noise, taken notice of by some while the meteor passed them, 

 was a deception of that kind, which frequently connects sound with motion ; 

 and is the case of those who fancy they hear something, when they see the 

 shootings of the aurora borealisi I say a deception, because if the meteor, during 

 its course, really made any noise, so great was the distance of that body, and so 

 short its continuance, that this sound could not have been heard till some mi- 

 nutes after the return of darkness. But the final report, so frequently men- 

 tioned, not only heard by those who saw the light, but by others who knew no- 

 thing of what had happened, was a real sound, and immensely greater than any 

 we are acquainted with. For, at the distance of 70 miles and upwards, it was 

 compared to loud thunder, the report of heavy artillery, the fall of the gable- 

 end of the house the person was in, and to a musket fired oflT in the garret. If 

 this noise was produced when the body threw out those masses of burning matter, 

 by the observers called sparks of fire, the bursting of the tail, &c. we shall find 

 that at this time the meteor, by being more than 41 miles high, was in a region 

 where the air is 3000 times rarer than on the surface of the earth: that is, about 

 6 times rarer than in a common exhausted receiver, where sonorous bodies are 

 not heard, and even where gunpowder and the pulvis fulminans take fire, and 

 are exploded, but without noise. Hence Dr. P. infers, that the separation of 

 the elastic matter must have been performed with a velocity exceeding all imagi- 

 nation, as the intensity of sound so much depends on the resistance of the air, 

 and as this elastic matter could fly off^ with so much celerity, as to find so great 

 an opposition from so thin a medium.* 



Dr. P. also concludes from the great report, that the substance of the meteor 



