On the Convergence of the Solar Beams. 137 



bridge who observes, that he once saw it upon Lincolnheath.* 

 He describes it as " an apparent convergence, of long whitish 

 beams, towards a point diametrically opposite to the sun. 

 For as near as I could estimate, it was situated as much be- 

 low the horizon as the sun was then elevated above the op- 

 posite point of it." " In the unusual phenomenon," Dr. 

 Smith afterwards adds, " I well remember, that the con- 

 verging sun-beams towards the point below the horizon, were 

 not quite so bright and shining as those usually are which 

 diverge from him, and that the sky beyond them appeared 

 very black, which certainly contributed to the evidence of this 

 appearance." Smith's Optics, vol. ii. Remarks, p. 57, 58. 



On Saturday, the 9th October, 1824, Dr. Brewster had 

 the pleasure to observe this curious phenomenon when tra- 

 velling from Melrose to Edinburgh, and of pointing it out to 

 two friends who accompanied him. It was first seen at that 

 part of the road opposite to the avenue to Ki'rkhUI, the seat of 

 John Tod, Esq. at about a quarter past four o'clock. The 

 sun was then considerably elevated above the Pentland range 

 of hills, and was throwing out his diverging beams in great 

 beauty through the interstices of the broken masses of clouds 

 which floated in the west. The eastern part of the horizon, 

 where the converging lines were seen, was occupied with a dark 

 black cloud, as described by Dr. Smith, and which seems ne- 

 cessary as a gi'ound for rendering visible such faint radia- 

 tions. The converging beams were very much fainter than 

 the diverging ones, and the point to which they converged 

 was as near as could be estimated, as far below the horizon 

 as the sun was above it. About ten minutes after the phe- 

 nomenon was first seen, the convergent lines were black or 

 very dark. This arose from the real beams having become 

 broad, and of irregular intensity, so that the eye took up, as 

 it were, the spaces between the beams more readily than the 

 beams themselves. 



In order to explain the cause of this phenomenon minutely, 

 several diagrams would be necessary, for which we cannot at 



• A similar phenomenon has, we understand, been observed near Freiberg, 

 by Professor Mohs and Mr. Haidinger. There were clouds in the west be- 

 tween the observers and the sun. 



