VOL. LXXIV.] 



PHILOSOPHICAL TRANSACTIONS. 



t)21 



' liant bluish white, and the tail of a dusky red, the length of which appeared to 

 extend over 15° or more, of the heavens, b. The apparent diameter of the 

 nucleus seemed i or 4 of the full moon's diameter. The greatest difficulty in 

 this estimation hence arises, that I cannot, notwithstanding all my endeavours, 

 represent in my mind the moon otherwise than as a plane or disc ; nor the 

 meteor, than as a spherical body. Its altitude, when it formed in the w. n. w. 

 was about 30°; and about 19 or 20° above the horizon, when it became extinct 

 in the s. s. e. a few sparks of the tail, nearest the nucleus, scattering themselves 

 much in the same manner as those of a sky-rocket when burnt out, c. 



It has been said, that the ball divided itself into 3 or 4 parts before its extinc- 

 tion. To me it appeared to vanish or gently die away : what confirms me in the 

 opinion, that it did not divide, is, that the 3 or 4 scattering parts above-men- 

 tioned were not of the bright colour of the ball itself, but of the dusky red 

 which the tail invariably showed. The interval of time from the meteor's 

 formation to its extinction was nearly 20 seconds, perhaps 2 or 3 seconds less. 

 The long habit I have of counting seconds in astronomical observations induces 

 me to think this quantity may be relied on ; and this I mention, because some 

 have estimated it more, some less. Nine or JO minutes after its dissipation, I 

 heard a noise, much resembling the report of a cannon at a very great distance; 

 but I would not wish to have it understood, that I speak to this last interval with 

 the same certainty as to the other ; if however it be exact, and supposing sound 

 to move 1106 feet in one second of time, and the same in the upper regions of 

 the atmosphere as here below, which however may be very different, its distance 

 from me, at its extinction, must have been about 120 miles, and its perpen- 

 dicular altitude above the earth's surface about 40 miles. 



XXXVI. Observations of the Comet of 1783. By Edw. Pigott, Esq. p. 460. 



The comet had exactly the appearance of a nebula : its light was so faint that 

 it could not be seen in a good opera glass. In the night telescope the nucleus 

 was scarcely visible, and the diameter of the surrounding coma was about 3' of 

 a degree. Between Nov. 19 and 26 it rather diminished in brightness. Dec. 

 1st and 3d it was very difficult to be seen, occasioned perhaps by its little eleva- 



