VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 525 



Mr. M. did not find any material difference between the old and new waters, 

 except in the convenience of drinking them. The old wells are at a distance 

 from any house, except some few huts, and exposed to the rain and land-floods, 

 by which they are often injured : the new well is a mile or two nearer to Lon- 

 don, and well secured from any injuries of the weather. 



Of the Lights seen in the Air, an Aurora Australis, on March 18, 1 738-9, at 

 London. By Cromwell Mortimer, M. D. Sec.R.S. N°4(j], p. 839. 



March 18, 1738-9, about half past 7, there appeared a bright column arising 

 about the east north-east, which reached up with its point near to the zenith, 

 but going a little south of it. This column seemed to be the boundary of the 

 clear and obscure regions of the sky. It had a uniform steady light, without 

 any dartings or shiverings ; but it sometimes vanished for a few minutes, and 

 then returned again all at once, not proceeding from the bottom, but from the 

 side next the misty part of the sky, as if it were only the border of the mist 

 illuminated. About 8 this column was become much wider, and all of a 

 breadth, extending in the same direction beyond the zenith to the west south- 

 west ; the addition to its breadth seemed to be all on its southern edge ; this 

 whole band was of a most beautiful pink-colour. A quarter after 8, the phe- 

 nomena remained the same ; but to the north north-west there appeared some 

 whitish clouds about 20° from the zenith : out of these arose 3 beautiful pyra- 

 mids of light, which extended very near the zenith ; tneir middle of a beauti- 

 ful sea-green, which went off gradually in lighter shades towards the edges, 

 which were of a bright white ; the colour of these very much resembled the 

 light of phosphorus. Half an hour after, it was all over; but it returned again 

 about 10 ; when the redness spread, almost universally, over the southern parts 

 of the heavens. 



Concerning the same Aurora Australis, seen at Chelsea, near London. By 

 Mr. John Martyn, F. R. S. N° 46l, p. 840. 



At half past 8, being informed that there was a great fire towards London, 

 Mr. M. made haste towards an upper window that looked to the north north- 

 east : he found an extraordinary redness in the air, but of too determined a 

 figure to arise from the burning of a house : a broad red band extended to the 

 northward of the east ; in the middle of which he plainly saw Arcturus, then 

 about 25° high ; and its northern edge touched Cor Caroli. It seemed to be 

 fixed and permanent ; not radiating, or fading, as in a common aurora borealis. 



