106 Description of an Extraordinary Parhelion 



appeared to be double of the radius of SS'". The part of the 

 sky occupied by the sun was covered with small light clouds. 

 It was quite clear and blue in the Zenith. In the sky oppo- 

 site to the sun there were also very small, white, detached 

 clouds, upon which the parhelion appeared, being always in- 

 terrupted in the clear and blue sky. 



The true sun appeared at S, and was surrounded by a cir- 

 cle of shining light S' C S" S"'. M. Kreis observed that this 

 light was yellow, and the interior margin red. 



Two parhelia appeared at S' and S", a little out of the 

 circle S' C S" S'", and at the same height as the true sun S. 

 They were very bright, and shone with all the colours of the 

 rainbow. The red being nearest to the sun, and the green 

 on the opposite side, and they terminated in small tails below 

 the false suns. 



A third parhelion appeared at S"'. It was less brilliant 

 than the others, and did not appear in the horizon till be- 

 tween 7i h and 8 h . An arc of a great circle ADFB, truncated 

 on A and B, showed at D and F very lively colours of the 

 rainbow. At its extremities, A and B, and at the other part 

 DF, it was whitish ; but the whiteness could be easily distin- 

 guished from the colour of the sky. In these two arcs the 

 red colour was always next the sun, and the green on the 

 opposite side ; the centres of the two circles were, the one 

 on the side of the sun, and the other on the opposite side. 

 Dr. Buch, who observed the parhelion a quarter or half an hour 

 before M. de Hoff, saw a great portion of the circle DCF 

 turned upwards. Professor Kreis, instead of one arc, saw 

 two, which intersected in C, as shown in Fig. 15. The 

 point C appeared to him extraordinarily brilliant, but without 

 any image of the sun. 



There was also a great circle, AHGIB, concentric with 

 the small one, S' C S" S'", the upper part of which shone 

 with the most brilliant colours of the rainbow. The red was 

 still turned towards the sun. The rest of that circle appear- 

 ed to M. de HofF white, but M. Kreis remarked, near the 

 horizon, the colours of the rainbow. A part of the circle 

 dipped under the horizon, cutting the two circles ADFB and 

 AS'SS"B at the same point A and B. Its radius appeared 

 to be double that of the circle S'CS"S'". 



