OF A METEORIC FIRE-BALL. 33 



signature " G. G.," in which the writer, who was on a visit here from his residence 

 at No. 216 Walnut street, Philadelphia, thus describes the phenomena : — 



" A large ball of fire of intense brilliancy appeared in the sky, at an apparent 

 height of from twenty to twenty-five degrees above the horizon, a little to the north 

 of a due west direction, moving to the east. It was at first partially obscured by 

 the light clouds, from which in a few moments it emerged. In size it appeared 

 from eight to twelve inches in diameter. Its color was that of the most pure and 

 white flame. Its movement was so comparatively slow and regular that the idea 

 occurred to us both, while looking at it, that it might be an artificial contrivance 

 sent up from Fort Mifflin or the Gas Works, by some experimenter in rockets or 

 baUoon fire works. It appeared to be between us and the city. It quicldy sepa- 

 rated into two balls of similar appearance, one closely following the other. These 

 again soon began to throw out, at first a trail of their own white appearance, and 

 quickly after, large, distinct, and numerous fragments of the most beautiful red and 

 pink colors, the effect being like that of the bursting of an ordinary rocket, only 

 on a scale much more magnificent and grand. This continued gradually dimin- 

 ishing untU the meteor, which now had assumed a red hue, had reached a point 

 nearly due east, where it disappeared from our view at a height apparently nearly 

 the same as that at which it started. 



" The movement of this meteor appeared to be not much more rapid than the 

 flight of an eagle. I think I could have kept sight on it easily with a gun through- 

 out its course. The length of time we enjoyed this wonderful sight, it seems to 

 me, must have been considerably more than a minute. The ladies and children 

 had retired, but they all had time to go to the windows, in response to our calls, 

 and witness it." 



Wrentliam, Massachusetts, Lat. 42° 1', Lon. 71° 23'. Eeported time " about 10 

 o'clock."! 



Whatever may have been the orbit of the meteor before it became visible, it is 

 obvious that the portion of the path that was subject to observation, being so near 

 the earth, must have been controlled almost entirely by its attraction — that of the 

 sun, or of the other planets, exerting so little disturbing influence as scarcely to be 

 appreciable. The orbit about to be described is not, therefore, the path of the 

 meteor in space, but only its orbit relative to the earth, and having the centre of 

 the earth in one of its foci, according to well-known principles. 



A phenomenon of this kind being unexpected, and therefore not admitting of 

 previous preparation on the part of observers, it was not supposed, when the inves- 

 tigation was commenced, that the observations were accurate enough to warrant 

 any very refined analysis, and I proceeded to determine the path vipon the assump- 

 tion that the earth was a sphere, 7912 miles in diameter, and so did not take into 

 account its spheroidal form, nor the difference between the true and the apparent 

 zenith. The error was an unfortunate one, and has, in some degree, vitiated the 

 results ; but I shrink from the labor of cancelling all that has been done, and begin- 



» Calculated time of meridian passage at Wrentliam 9h. 58m. 39 so. 



April, 1869. 



