290 Progress of Science respecting Igneous Meteors in 1823. 



paper on the origin of meteoric stones. A sphere of this 

 diameter, seen at the distance of the meteor from Wenham, 

 would hardly be visible without the assistance of a telescope, 

 since its apparent diameter would not exceed two-thirds of a 

 second. These reasons seem strongly to favour the opinion, 

 that by far the greater part of the mass continued on its course 

 without falling to the Earth, and the gradual disappearance 

 of the meteor, as observed by Judge Wheeler, is agreeable to 

 this hypothesis*." — But how different an aspect will these cir- 

 cumstances assume, and how different will be their bearing on 

 theoretical inquiries, if it can be shown that we must consider 

 the visible meteor to have been principally a mass of flame, 

 proceeding from a solid nucleus comparatively small ? I do 

 not intend, in this place, to enter into the subject of the theory 

 of these meteors ; but shall merely endeavour to prove that it 

 cannot be investigated, without the application of a correction 

 for the probable difference between their size, as computed 

 from their apparent diameter, and that of the mass of solid 

 matter which they may respectively contain. 



The chief phaenomena of Bolides from which I am disposed 

 to infer that they consist, essentially, of a nucleus of com- 

 bustible solid matter, from which arises a body of flame of 

 vastly superior magnitude, are the following : First, the cha- 

 racteristic appearances of inflammation which some of these 

 meteors are said to have presented ; particularly those, which, 

 by descending comparatively low in the atmosphere, have ap- 

 proached the nearest to the spectators: secondly, the fre- 

 quently ovate figure of their disk, indicating their spheroidal 

 form, with the longest axis in the direction of their motion : 

 thirdly, the change of form which many have been seen to un- 

 dergo during their progress through the heavens ; a change, 

 which in various instances cannot have been merely an optical 

 deception, produced by the different aspects under which the 

 meteors were successively viewed : fourthly, the tails which by 

 far the greater number of fire-balls have been seen to draw 

 after them, and from which, by some observers among the 

 ancients, and by the uninformed in modern times, they have 

 been occasionally 'confounded with comets: and fifthly, the 

 luminous traces, often in a continuous band, or track, as it 

 has been termed, and sometimes remaining for many minutes 

 after the meteors' disappearance, by which their path in the 

 heavens has in a variety of cases been marked ; and which, in 

 conjunction with their caudate appen ranee, have caused many 

 observers to compare them to immense sky-rockets. — I pro- 



* Nicholson's Philosophical Journal, vol. xxviii. p. 218: from the Memoirs 

 of the American Academy. 



ceed 



