218 Drv BuaGpen’s Account of i 
velocity. As at the heizht of 50 .miles above, the furface of 
the earth, it. might be vifible from the fame flation; for artrack * 
of more than 12090 miles,.and the longeft- continuance of its. 
illumination. fearcely. exceeded a minute, we have hence fomie 
prefumption that it moved not lefs than 20 miles:in a feconds 
The rey. Mr. Warson, in his letter to Lord |MuLtGRave, 
fhys, that the arc defcribed by it whilft in his view could not be 
le/s than 70° or 80°, and yet the time could not exceed 4!’ or 5!’ at 
mof. ‘This, with an altitude of 60°, and height of 50‘ miles, 
gives for its velocity about 21 miles in a fecond. ‘The obferver 
at Newton Ardes eftimated its motion to be 10° zm a fecond, at 
the altitude of 16°; this would make its velocity 30 miles in a 
fecond. Mr. Herscuet found it defcribe am arch of 167° 
during the 40 or 45 feconds he obferved it, which gives a velo-' 

oa ee 
city. of more ‘than 20 miles in a fecond. Finally, Mr. 
Ausert F.R.S. thought it defcribed an arch of 136° of azi- 
muth in 10 or 12 feconds, which would make its velocity above’ 
40 miles in a fecond. Iam fenfible of the objeCtions that may 
be made to all thefe computations; undoubtedly they are too 
vague; and yet, all taken together, perhaps they may have 
fome weight, efpecially as they correfpond fo well with the 
different phenomena of the meteor’s duration, and other fire- 
balls have been computed to move as faft*. Stating the velo- 
city at the loweft computation of 20 miles a fecond, it exceeds 
that of found above go times, and begins to approach toward 
that of the earth in her annual orbit. At fuch a rate, it muft 
have paffled over the whole ifland of Great Britain in lefs than 
half a minute, and might have reached Rome within a minute 
¥* See Mem. de l’Acad. des Scienc, 1771, pe 678. Phil. Tranf. Ww 341. and 
360. and vol. LI. p. 263, &c, 
5 afterwards, - 

