Intelligence and Miscellaneous Articles. 153 



Here are three simple colours, red, yellow, and blue; and three 

 compound colours, orange, green, and purple, each divided into 

 two species; whereas in the received enumeration, we have a con- 

 fused intermixture of genera and species in the same predicamcntal 

 line. 



Dr. W. H. Wollaston, in the Phil. Trans, for 1802, p. 878, infers 

 from some experiments, that a beam of white light is separable by 

 refraction, not into three, hutjbur simple colours, viz. red, yellowish 

 green, blue, and violet; but of these the very term "yellowish 

 green" betrays its composition, and as to violet, its components 

 h ive been already shown. R. 



Grafton Street, Dublin. 



CLAW OF THE IGUANODON. 



Among the fossil bones discovered by Mr. Mantell of Lewes, du- 

 ring the present year, in the Hastings strata of Sussex, are two spe- 

 cimens, which M. Cuvier has determined to be the ungueal bones, or 

 those which support the nails, of the Iguanodon. The largest is four 

 inches in length ; while the corresponding part in a recent Iguana 

 three feet long, is but two-fifths of an inch. 



ON LUMINOUS ARCHES OF THE AURORA BOUEALIS, SEEN AT 

 MANCHESTER ON THE IST AND 26TH OF DECEMBER 1828; 

 AND ON THAT OF THE 29tH OF SEPTEMBER, AS SEEN AT 

 DUBLIN. BY JOHN BLACKWALL, ESQ. F.L.S., &C.* 



At six o'clock on the evening of Monday, the 1st of December 1 828, 

 a luminous arch of the aurora borealis was seen at Manchester, by 

 Mr. T. Blackwall, Sen., Mr. T. Blackwall, Jun., and several gentle- 

 men of my acquaintance, from whom I obtained the following parti- 

 culars. The arch, which consisted of a belt of pale white light, be- 

 t.veen four and five degrees in breadth, was bisected by the plane of 

 the magnetic meridian, which it crossed at right angles ; its vertex 

 had an elevation of about thirty degrees above the horizon, and its 

 eastern limb passed through the body of the constellation Ursa Major. 

 At ten minutes past six the arch rapidly decreased in brilliancy, and 

 soon after entirely disappeared. 



From a horizontal light situated in the magnetic north, which had 

 accompanied the arch, and still continued very apparent, several 

 beams or streamers shot upward shortly after the arch had vanished. 

 I may add, that between the hours of nine and ten, on the same night, 

 a horizontal light of the aurora was seen at W^iiksworth, in Derby- 

 shire, but the person who made the observation had not an oppor- 

 tunity of witnessing the arch, as he was occupied within-doors at the 

 time it was visible. 



1 shall now proceed to offer a few observations, communicated to 

 me by Mr. T. IJIackwall, Jun , relative lo another well defined arch 



• Communicated l>y the Author. 

 New Series. Vol, 5. No. 2(i. Feb. 1829. X ^'f 



