Page:Philosophical Transactions - Volume 054.pdf/242

 to you; and ask leave, for my own information, just to query, what center these bodies may most probably be supposed to revolve round? Either the Earth or the Sun seem to bid fairest for this.

1. A body revolving round the Earth in a circle, at the height of about 40 or 50 miles, would move but 7 miles in a second; and in a very eccentric orb, near a parabola, but 10 miles: which falls much short of the velocity of your Meteor, which was of 30 miles in a second.

2. The Earth's annual velocity round the Sun is near 16 miles in a second; and a body revolving in a very eccentric orb would have, at the same distance from the Sun, a velocity of 22 miles in a second. Wherefore if the Earth and such a body near it were moving in the same direction, that body would get before the Earth with a relative velocity of 6 miles in a second; but, if moving the contrary way, it would be left behind with a relative velocity of 38 miles in a second: And this is the greatest possible relative velocity. Bodies moving in oblique directions may have any relative or apparent velocity less than this maximum. This supposition therefore agrees better with a velocity of 30 miles in a second, than the former; but I shall be much obliged to you for your thoughts on this point.

As to our late Meteor of May 1759, I have not been able to come at any farther particulars than what are contained in my letter to Dr. Birch, excepting only as to the loudness of the report, at a great distance from the place of exploson. An intelligent man of this town has since informed me, that he was then ﬁshing in a boat at anchor about a Rh