Intelligence and Miscellaneous Articles. 237 



quartziferous syenite ; the rest are syenites ; and one contains so 

 much plagioclase as to be almost a diorite. One of the above, near 

 Enderby, is seen to be distinctly intrusive in an altered slaty rock, 

 which the authors have no doubt belongs to the Forest series. This 

 discovery proves the igneous character of these rocks also, and 

 extends the area of the slaty series 5 miles further south than was 

 previously known. A section was devoted to the faults of the Forest 

 region. Here the principal fault runs along the anticlinal axis, 

 with a downthrow on its eastern side which diminishes from 

 2500 feet at the north end to 500 feet at the south end. East of this 

 the beds seem undisturbed ; but on the west they are shattered by 

 many faults, whose course cannot be traced. These are most 

 numerous near Whitwick. The anticlinal fault is Precarboniferous. 

 In conclusion, the age of the clastic and of the igneous rocks was 

 discussed. The authors inclined to the opinion that the former are 

 of the same age as the Borrowdale series of the Lake district 

 (Lower Silurian), but admitted that the recent discovery of agglo- 

 merates in the Precambrian rocks of Wales, and in the probably 

 Precambrian ridges of the Wrekin district, weakens the argu- 

 ments for this correlation. They do not think that there is any 

 reason for supposing them Cambrian. If the Charnwood series 

 is Lower Silurian, they think it most probable that the syenites and 

 the Quornden granite were intruded in some part of the Old-Red- 

 Sandstone period, and that the later dykes were very probably 

 Postcarboniferous but Pretriassic. 



XXXV. Intelligence and Miscellaneous Articles. 



ON SOME MEASUREMENTS OF THE POLARIZATION OF THE LIGHT 

 COMING FROM THE MOON AND FROM THE PLANET VENUS. BY 

 THE EARL OF ROSSE, F.R.S.* 



SEVERAL years ago, at the suggestion of a friend, having ex- 

 amined some portions of the lunar surface with a Nicol's prism 

 with a view to the detection of small sheets of standing water, if any 

 such chanced to exist, I was led on to make a rather extended ex- 

 amination of particular portions of the surface with the polarimeter, 

 under the idea that if the precise position of elongation from the 

 sun where the polarization of a point of the lunar surface attains a 

 maximum could be accurately determined, it might be possible to 

 obtain an approximate value of the refractive index of the material 

 composing that surface, and so to distinguish between material of 

 a vitreous nature, ejected from volcanoes, and a surface of ice and 

 snow. 



The subject has been invested with the greater interest from 

 the fact that Arago, having found the maximum of polarization 

 of the whole of the moon's light to occur at or near quadrature, 



* From the Proceedings of the Royal Dublin Society, May 21, 1877. 

 Communicated by the Author. 



