88 Mr Coldstream on the Rarer Atmospherical Phenomena 



ing the whole time of the existence of the arch, the aurora 

 sent forth no coruscations, although the diffused light in the 

 north was very intense. But about 20 minutes from 12, 

 beams again arose, and continued to play with considerable 

 brilliancy for more than an hour. The mean temperature of 

 the next day was 41°.25. Pressure 30.62. Wind S.W., 

 gentle. 



At Paris, " on the 19th of March, at half-past one p. m., 

 the horizontal magnetic needle went suddenly, and, after 

 many oscillations from its usual position, nearly 5'. These 

 irregular movements led the observer - ' 1 (M. Arago, we pre- 

 sume) " to suppose, that, in the evening, there would be an 

 Aurora Borealis, but no trace of such a phenomenon was dis- 

 covered, although the sky was perfectly serene. At six and 

 eight o'clock the needle did not oscillate ; it did not pass its 

 ordinary limits ; but at half-past eleven, the declination sud- 

 denly diminished more than 8', and the needle oscillated in 

 great arcs. 1 '' * 



On the 7th of June, several large and dense nimbi passed 

 from S. W., discharging at intervals heavy showers of rain. 

 At 5 P. m., a primary rainbow was seen, within the interior 

 circumference of which were two perfect supernumeraries of 

 great brilliancy. They were of unequal breadth : the second 

 was narrower than the first ; and both taken together, scarce- 

 ly equalled in breadth the primary. In each, all the spectral 

 tints were distinguishable. Now and then, as the cloud mov- 

 ed on, a third set of colours was perceived, in detached por- 

 tions ; but a third bow was never completed. At the same 

 time, a very distinct convergence of the solar rays was observ- 

 ed. The beams filled the whole space included by the rain- 

 bow, and passed beyond its circumference to a considerable dis- 



" " Au reste, les zones, les arcs, les jets lumineux dc-nt les aurores 

 boreales se composent, alors meme qu'ils ne sont pas visibles dans un lieu 

 donne, y exercent une influence manifeste sur la position de 1'aiguille ai- 

 mantee. Cette singuliere connexion merite certainement d'etre etudie'e 

 sous toutes ses faces; mais il faudta peut-etre des recherches assidues, 

 continues pendant un grand noinbre d'anne'es, avant qu'on puisse en saisir 

 tous les details." — (Annates de Chimie, T. xxx. p. 423. ) 



