vicinity of Buhlin. 273 



limestone afibrd some of the features which may assist in deciding on 

 the " formatioii'' of Werner, to which it is to be referred ; a point 

 of considerable interest, from the great extent which the Hmestone 

 occupies in the Counties of Dublin, Kildare, and Carlow. 



In the peninsula of Hoivth^ which forms the northern side of 

 Dublin hd^j^grcy ore of mangafiese with brown ironstone^ and brown 

 iron-ore (Museum of Dublin College, Nos. 1067-8, 887.) have been 

 obtained in considerable quantity : and a variety of the earthy black 

 cobalt ore of Werner has been found by Mr. Stephens and Dr. 

 Stokes on the southern side of the hill, forming a crust of a rich 

 blue colour lining the fissures of a rock of slate clay nearly approach- 

 ing to whetslate, (Mus. I. C. D. No. 267) : Mr. Tennant has in this 

 substance ascertained the presence of the oxides of cobalt and of 

 manganese ; and the discovery of it is important, as it indicates the 

 probability of the existence of other more valuable ores of cobalt in 

 that neighbourhood. Liignaqinlla^ which is supposed to be the 

 highest of the Wicklow mountains, is situated to the south-westward 

 of the centre of the mountainous district. I have found it, by the 

 barometer, to be 2455.1 feet above the house of Mr. Greene at 

 Kilranelagh, which is itself considerably elevated above the sea. 

 Cadeen^z. hill detached from the body of the mountains, and forming 

 a striking object from the adjacent flat country, is 1558.9 feet; 

 B a Iti nglass-bill y 6Sl,S feet; Eadestown, 1i9A feet; Brussels-town^ 

 740.1 feet ; Kilranelagb-hill, 705.5 feet above the same place.* 



Of the mountains nearest to Dublin, one of the highest, Garry- 



* The first three heights above mentioned, are each the mean of three observations, the 

 rest are from single observations, with two excellent barometers. Mr. Greene's house is 

 (by a single observation) 95.08 feet above the level of the cross roads at the bridge of 

 Tuckmill, a little village on the river Slaney ; the elevation of which above the sea will be 

 very well supplied when the line of the grand canal shall be extended in this direction, as 

 is now intended, 



2 M 



