MINERAL BASO^. 381 



fkj A small retort or vial, with a bent tube, for Improved ap- 

 ^enerating the gas which passes through the hole P^^;*^;?^'^;*^'^ ^j^^ 

 of the plates. gases. 



fmj A. small spirit lamp. 



fnj A tube, fixed so in the box, that the mercury, 

 descending from (JJ as the gas is generated, shall 

 overflow, and be received in a cup j with which 

 small jars may be filled for transferring. 



VIIT. 



Description of the Mineral Bason in the Counties of Monmonth, 

 Glamorgan, Brecon, Carmarthen, and Pembroke. By Mr. 

 Edward Martin.* 



JL he irregular oval line, delineated on the annexed Mineral basoa 

 map t shows nearly the inner edge of a limestone bason, in '" South Wale?. 

 which all the strata of coal and iron ore (commonly called 

 Iron Stone) in South Wales are deposited ; the length of this 

 buson is upwards of loo miles, and the average breadth in the 

 counties of Monmouth, Glamorgan, Carmarthen, and part of 

 Brecon, is from 18 to 20 miles, and in Pembrokeshire only 

 from 3 to 5 miles. 



a. On the north side of a line, that may be drawn in an 

 east and west direction, ranging nearly through the middle 

 of this bason, all the strata rise gradually northward ; and on 



* Phil. Trans. 1806. 



t The outline on the map given in the Tvin;)sactions(httt not copied 

 in our Journal) begins from the N. E. corner of St. Bride's Bay, and 

 proceeds by Haverford West, across a small part of Carmarthen 

 Bay whence it passes near Kidwelly more northerly till about three 

 miles south of Llandillo. From this part it inclines more southerly 

 towards Abergavenny, but within five miles of that town it rounds 

 to the south through Pontypool and thence to the S. W. (rounding\ 

 through Llantrissent, but whence it arrives at the coast of Swansea 

 Bay it spreads nearly in a line to Tenbj^, and thence V) the middle 

 of the -Western shore of St, Bride's Bay. 



2 ' the 



