406 PHILOSOPHICAL TRANSACTIONS. [aNNO I7I9. 



and did no more in 64. — 5. A piece of Pompey's pillar at Alexandria was vitri- 

 fied in the black part in 50 seconds, and in the white part in 54. — 6. Copper 

 ore, which had no metal in it visible, vitrified in 8 seconds. — 7. Slag, or cinder 

 of the ancient iron-work said to have been wrought by the Saxons, was ready 

 to run in 294- seconds. 



Here the glass, growing hot, burned with much less force. 



8. Iron-ore fled at first, but melted in 24 seconds. — 9. Talk began to calcine 

 at 40 seconds, and held in the focus 64. — 10. Calculus humanus in 2 seconds 

 was calcined, and only dropped off in 60. — 11. An anonymous fish's tooth 

 melted in 324- seconds. — 12. The asbestos seemed condensed a little in 28 

 seconds ; but it was now something cloudy ; Mons. Villette says, that the glass 

 usually calcines it. — 13. A golden marchasite broke in pieces, and began to 

 melt in about 30 seconds. — 14. A silver sixpence melted in 74- seconds. — 15. 

 A King William's copper halfpenny melted in 20 seconds, and ran with a hole 

 in it in 31. — 16. A King George's halfpenny melted in 16 seconds, and ran in 

 34. — 17. Tin melted in 3 seconds. — 18. Cast iron in 16 seconds. — 19. Slate 

 melted in 3 seconds, and had a hole in 6. — 20. Thin tile melted in 4 seconds, 

 and had a hole and was vitrified through in 80. — 21 . Bone calcined in 4 seconds, 

 and vitrified in 33. — 22. An emerald was melted into a substance like a turquois 

 stone. — 23. A diamond, weighing 4 grains, lost -|- of its weight. 



An Account of the extraordinary Meteor seen all over England, on the I9M of 



March, 1 7 1 8-9. By Edm. Halley, LL.D. and Sec. to the R. S. N*' 36o, 



p. 978. 



This wonderful luminous meteor, which was seen in the heavens on the 19th 

 of March, as it was matter of surprise and astonishment to the vulgar spectator, 

 so it afforded no less subject of inquiry and entertainment to the speculative and 

 curious in physical matters ; some of its phasnomena being exceedingly hard to 

 account for, according to the notions hitherto received by our naturalists; 

 such are its very great height thereof above the earth, the vast quantity of its 

 matter, the extreme velocity with which it moved, and the prodigious explo- 

 sions heard at so great a distance, whose sound, attended with a very sensible 

 tremour of the subject air, was certainly propagated through a medium ex- 

 tremely rare, and next to a vacuum. 



In N° 341 of these Transactions,* I have collected what I could find of such 

 meteors, and since, turning over the Ephemerides of Kepler, I accidentally hit 

 upon another, prior to all those there described, and which was seen all over 



* See p. 99, &c. of this volume. 



