Intelligence and Miscellaneous Articles. 389 



gave for its specific heat numbers presenting an error of at most 

 0-00061. 



I shall continue the investigation, applying the method to che- 

 mically pure substances, and determining their conductivity. — 

 Comptes Rendus de VAcademie des Sciences, April 5, 1880, t. xc. 

 pp. 814-817. , 



NOTE ON SUPERNUMERARY RAINBOWS. BY CH. MONTIGNY, 

 MEMBER OF THE ROYAL ACADEMY OF BELGIUM. 



" When a rainbow is very brilliant, there are often seen inside of 

 the interior and outside of the exterior bow coloured bands, which 

 are designated secondary, supplementary, or supernumerary bows : 

 immediately after the violet, red is distinguished, then green and 

 violet. Sometimes these colours are repeated several times in the 

 same order along the inner margin of the principal bow ; they ap- 

 pear more rarely outside of the second bow." M. Daguin, from 

 whom I borrow these statements, adds that the supernumerary 

 bows are only seen in the culminating portions of ordinary rain- 

 bows, and only when the altitude of the latter is considerable ; no 

 traces are seen of them near the horizon*. 



Kaemtz, in his Traite de Meteorologie, states the same particulars, 

 from Langwith and other observers, who have never noticed supple- 

 mentary rainbows near the parts of the principal bow in the vicinity 

 of the earth. 



Contrarily to these facts, I have recently had an opportunity of 

 observing some supernumerary rainbows which were visible only at 

 the lower extremities of the principal bow. The circumstances 

 were, perhaps, exceptional ; but it is important to make them known. 



On the 30th of August last, after a rainy day, I was with some 

 other persons in the vicinity of Eochef ort a little before sunset. A 

 few moments after a fresh shower of short duration we remarked 

 in the east, in which direction the rain continued, two ordinary 

 rainbows. The colours of the principal bow lost some of their 

 brightness in the lower regions of the air. These were sensibly 

 darkened up to a certain height by a misty tinge, forming a broad 

 zone perfectly distinct from the rain- cloud entirely above it, 

 upon which the two bows appeared brighter. Moreover, at the 

 inner side of each lower extremity of the inner bow, and conse- 

 quently near the ground, four supernumerary rainbows could be 

 distinguished, which appeared to rise on each side into the misty 

 zone of the air to about one third of the altitude of the inner bow. 

 The colours of these eight supernumerary portions possessed but 

 little brightness : the red and a dark violet were alone distinct. I 

 observed no supplementary bow outside of the large bow. 



In this observation, which took place twenty minutes before the 

 disappearance of the sun below the horizon, the production of super- 

 numerary bows at the extremities, and not at the culminating por- 

 tion, of the principal bow, constitutes a manifest exception to the 

 facts hitherto observed. This exception can be explained by the 

 circumstances which accompanied the observation, as we shall see. 

 * Traite de Physique, 3 e Edition, t. iv. pp. 284, 445. 



