330 Prof. Necker's Observations on some remarlcahle 



Parhelia seen the 1st of June 1830, from 5i o'clock p.m. 

 till sunset at 7j o'clock, represented in the most complete 

 state, as I saw it at 6 o'clock : — S is the sun ; EADC the inner 

 halo, which was much the brightest; C and E the two lu- 

 minous images or mock suns ; FG the outer halo, which was 



Hill ofPregny. 



Lake of Geneva. 



weak, and seen only for a few moments, as well as the inverted 

 arch H. All the various points of these arches were not 

 equally distinct at the same moment as they are represented 

 here. On the contrary, when the image or mock sun at the 

 right hand, C, was strong, the one at the left hand, E, was pale, 

 or did not appear ; such was the case at the beginning of 

 the apparition. At the end, the left image, E, was very lu- 

 minous and coloured, shining with prismatic colours; while the 

 light image C was less visible, and sometimes altogether 

 wanting. The strength of illumination of the various parts 

 of the halo was constantly variable. Often certain portions, 

 sometimes very considerable, entirely disappeared, and af- 

 terwards reappeared again. A little before the sun had set, 

 the only part visible was that between A and B, and it was 

 vividly lighted and coloured, and reflected by the lake; at the 

 same time the single point C was also shining brilliantly, 

 coloured with iridescent colours. At the moment of sunset, 

 there remained nothing but a small arch in D. The ph«- 

 nomenon ended almost immediately after the sun had disap- 

 peared behind the Jura at 7'' 20"". All this time the parts 



