A Geological Sketch of a Part of Cumberland, &c. 41 
being more distinctly visible in the clear atmospheres of France 
and Italy than in England. 
It should seem then, that in order to get a perfect knowledge 
of astronomical refraction, we ought to employ at least three 
different methods of investigation. Ist. By observations of the ~ 
fixed stars during the night, when all the prismatic colours are 
visible. 2dly. By observations of the stars during the day, 
when none but the orange-coloured rays are to be seen. And 
3dly. By observations of the sun with different coloured glasses. 
By these means we might hope to obtain such an accurate know- 
ledge of atmospheric refraction as would enable us to form tables 
adapted to every possible circumstance. 
But I must not take up the time of the Society by any addi- 
tional observations. It isin vain for me to pursue the subject 
any further, in a situation so ill-adapted to astronomical obser- 
vations as Somerset Place: I shall therefore resign the task to 
those who are more favourably placed in this respect, and who 
possess instruments better calculated for an inyestigation which 
requires so much accuracy. 
X. A Geological Sketch of a Part of Cumberland and West- 
moreland. By A CoRRESPONDENT. 
Taz geology of Great Britain has of late years become an ob- 
ject of considerable attention, and much has been done in ac- 
quiring a knowledge of the different rocks, their relative position, 
and the extent they occupy on the surface,—more especially in 
the south of England, where the different formations appear to 
have been described with as much accuracy as the present state 
of our knowledge of the subject will admit. In the northern 
counties, however, little has been done except so far as regards 
the Newcastle coal-formation, and the metalliferous rocks of the 
Cross Fell range of mountains; and although the counties of 
Cumberland and Westmoreland have been frequently visited by 
very eminent mineralogists, and some attempts have been made 
in describing their geology; yet from the multiplicity of forma- 
tions they contain, these formations occurring in such detached 
and insulated patches, and the very great difficulty in investi- 
gating and ascertaining their relative positions, we must consi- 
der our knowledge of the physical structure of these counties as 
still very imperfect. As this knowledge can only be acquired by 
the united efforts of a number of individuals, 1 take the liberty 
of offering to this Society*, the following notices of some rocks 
* The Literary and Philosophical Society, Newcastle, ’ 
which 
