Intelligence and Miscellaneous Articles. 331 



first known appearance in the Nummulitic formation of Egypt to 

 the present day. He also inferred, from its presence in the Num- 

 mulitic limestone, that this rock had been deposited not far from a 

 shore. 



2. " On the Geology of North-west Lincolnshire." By the llev. 

 J". E. Cross, M.A., F.G.S. 



The district treated of is that lying between the three rivers 

 Humber, Trent, and Ancholme. The Liassic and Oolitic beds were 

 described, from the Kenper (found in the bed of the Trent) to the 

 Cornbrash (the highest Oolitic stratum existing on this line). The 

 existence of the Rhastic beds was held to be doubtful ; the bone-bed 

 and the shell Avicida contorta have not been found. On the other 

 hand, the Lower Lias has a large development ; and the recently dis- 

 covered Ironstones of Frodingham and Sennthorpe were shown to 

 lie in this formation, the zone being that of Amm. semicostatus. 

 Higher up the series the zone of Amm. margaritatus seems to be 

 wholly wanting, and the Alarlstone series has dwindled to a bed of 

 8 feet thickness, locally termed the Rhynchonella-hed. The Upper 

 Lias is represented by clays not much explored. 



As regards the Oolites, the " Lincolnshire Oolite'' is the prevail- 

 ing rock ; but a lower band, called " Santon Oolite," was distin- 

 guished from it, containing a different fauna. Above the Lincoln- 

 shire Oolite a greenish clay, capped by Cornbrash, represents the 

 great Oolite formation ; and beyond" this the alluvium of the Ancholme 

 valley covers every thing, till the Chalk rubble and the Chalk wold 

 rise above it to the eastward. 



XXXIX. Intelligence and Miscellaneous Articles. 



ON THE COLD BANDS OF DARK SPECTRA. 

 BY MM. P. DESAINS AND AYMONET. 



WHEN a thin pencil of rays from a Drummond lamp is dispersed 

 by a rock-salt prism, and the distribution of the heat in the 

 spectrum thus obtained is studied, cold bands like those o£ the solar 

 spectrum are not detected ; and yet those bands can be developed. 

 For this purpose it is sufficient if the rays, previous to their inci- 

 dence on the prism, be compelled to pass through suitable absorb- 

 ents. This statement was proved by one of us several years since. 

 Water and saline solutions were the absorbents most frequently 

 made use of. 



AVe have resumed this investigation, and ask permission to sub- 

 mit to the Academy a few of the results we have obtained. 



The source of heat in all our experiments has been the lamp of 

 MIL Bourbouze and Wiesnegg ; its use is more convenient and 

 trustworthy than that of the Drummond lamp. 



In a first series of experiments we studied the development of the 

 lines in a spectrum formed by means of a rock-salt prism, of 60°, 



