240 Murchisoris Silurian System, 



tinct formations between the old red sandstone and non-fos- 

 siliferous slates, and the two groups, which he named the 

 older and newer transition rocks, would appear to refer to 

 those divisions of Silurian strata the peculiarities of which 

 have been so well illustrated by Mr. Murchison in the great 

 work before us. In the Plinlimon, or dark and indurated 

 slaty sandstone, which forms the intermediate beds between 

 the Silurian rocks of Murchison and the Cambrian system of 

 Professor Sedgwicke, no fossils have been found, while 

 nearly all those of the i Bala' or dark limestone overlying the 

 Cambrian or primary rocks, contain fossils identical with 

 those of the lower strata of the Silurian system. Perhaps 

 these beds, as well as the grauwacke of foreign geologists, 

 should still be included in the same system with Silurian 

 rocks. Mr. Murchison and Professor Sedgwicke, however, 

 think otherwise, and while the former has given positive 

 characters to Silurian rocks, the investigations of the latter, 

 when fully before the public, will go far, no doubt, to cast as 

 much light upon the Cambrian system, as the nature of the 

 beds composing it will admit of. 



Experiments on the Magnetic Influence of Solar Light. 

 By Lieut. R. Baird Smith, Bengal Engineers. 



The repeated ebb and flow of opinion among scientific 

 men, as to the existence of a magnetic influence in solar 

 light, gives a curious degree of interest to the history of the 

 question. The discovery was originally announced in 1813, 

 by Prof. Morenchini of Rome, who asserted, that by expos- 

 ing steel needles in a particular manner to the violet ray 

 of the solar spectrum, he had succeeded in imparting to 

 them a perceptible magnetic polarity. These experiments 

 were repeated in the presence, and apparently to the entire 

 satisfaction of Sir Humphrey Davy, Professor Playfair, and 

 certain other English philosophers, who happened, at the 



