288 Progress of Science respecting Igneous Meteors in 1823. 



witnessed the explosion, and by whom, consequently, the body 

 only of the meteor is spoken of, it is stated to have been visi- 

 ble for about one minute ; so that the time of its passage may 

 probably have been under-rated in the estimates alluded to by 

 Prof. D.: although, on the other hand, common observers of 

 such phaenomena usually attribute a greater length of time to 

 their duration than they really occupy ; and several other 

 Fire-balls on record appear to have been impelled through the 

 atmosphere with a velocity nearly equal to that assigned to 

 this one by Professor Dean. 



Professor Dean gives two measures of the apparent diameter 

 of this meteor, both obtained by comparison, at the time of 

 its passage, with stationary objects ; and which differed from 

 each other only two degrees ; Capt. Wardner's object of com- 

 parison indicating it to have subtended 10°, and Col. Page's 

 12°. Its absolute diameter, computed from these, and from 

 the mean distances of the observers respectively, " amounts," 

 he states, " to about one-third of a mile." Considering the 

 immense magnitudes which former meteors have been shown to 

 possess ; — that Montanari calculated the smaller diameter of 

 that which passed over Italy in 1676 to have been above half- 

 a-mile ; that Halley computed the diameter of the fire-ball of 

 1719 at a mile and a half; and that Cavallo and Blagden de- 

 termined that of the celebrated meteor of 1783 to have been 

 between half and three-fifths of a mile ; — the size thus ascribed 

 to the American meteor does not appear to be excessive. 



But various phaenomena displayed by this meteor, indicate, I 

 think, that we are to consider the one-third of a mile to have 

 been merely the approximate diameter of the mass of flame, in 

 which the solid matter or substance of the meteor was en- 

 veloped ; so that the latter may have been, (and no doubt it 

 was,) of much smaller dimensions. Thus Mr. Doty states, 

 that " the blazing meteor was in full view over his head, ap- 

 pearing to be twenty or thirty feet in diameter, and soon began 

 to extend itself to the north-east and south-west, increasing in 

 extension, and decreasing in its flaming appearance, until no- 

 thing was to be seen but two detached parts of it rapidly moving 

 in different directions towards the north-east and south-west." 

 Col. Page affirms, as before stated, that when it was " about 

 one-third of the way from Procyon to Sirius it suddenly broke 

 out in great splendour, and continued its course flashing and 

 sparkling east of Sirius," until it disappeared. And as neither 

 the different distances of these and other observers from the 

 meteor, nor the allowances necessary to be made in draw- 

 ing inferences from common estimates of the apparent diameter 

 of such bodies, are sufficient to reconcile the great discrepancies 



in 



