Mr Menteath on the Geology of Nithsdale. 323 



Inigo Jones, but is in a decayed state compared with that 

 building. 



Not far from the Gateley Bridge, red sandstone quarry, a 

 mile up the Cample, basalt occurs in pentagonal columns. It 

 appears to form a narrow ridge or dike, traceable from Mor- 

 ton-Mains Hill on the north-east of this spot, and it seems to 

 take the direction of the Linburn Hill on the southeast*. 



The white and grey sandstones, under the red sandstone, are 

 not found in any considerable quantity. The white, which oc- 

 curs very seldom, is hard and compact in its texture, and well fit- 

 ted to resist the effects of the weather. Of the grey more is 

 found, and it partakes much of the characters and qualities of 

 the white. 



The limestone is found only at the south end of the basin of 

 Closeburn on both sides of the Nith, as at Closeburn and Bar- 

 jarg, but at the latter in much less quantity 



{To be conduced in our next Number.) 



A Proposition for carrying on a Course of Experiments, with 

 a view to constructing, as a National Instrument, a large 

 Refracting Telescope, with a fluid concave Lens, instead of 

 the usual Lens of Flint Glass. Addressed to his Royal High. 

 ness the Lord High Admiral, and the Right Honourable and 

 Honourable Members of the Board of Longitude. By Petee 

 Barlow, F.R.S. Mem. Imp. Ac. Petrop., S^c. S^e, 



[This Memoir has been presented to the Board of Longitude ; and we 

 are gratified to add that the members have ordered the experiments to 

 be pursued. Mr Barlow is accordingly, as another step, attempting aa 

 eight inch aperture, of ten feet in length, but with a focal power of 

 about sixteen feet.] 



In a memoir I had the honour to present to the Royal Society 

 in the early part of the year 1827, which was published in the 



* In this valley there are no fixed rocks of granite, and indeed none nearer 

 than perhaps thirty miles. It is very curious, however, that there are round- 

 ed blocks of it found in many places on the siuface, some of them exceedinf^ 

 a ton in weight. The same occurs in other districts, where the distance from 

 the granite formation is still greater, aa in Cheshire. The existence of these 

 masses in such situations, has never yet perhaps been satisfactorily accounted 

 for. Two explanations have been offered ; according to the one, they are of 

 lacustrine origin-.while the other connects them with the Mosaic deluge. 



