576 PHILOSOPHICAL TRANSACTIONS. [aNNO 1775. 



to the south of it. This view particularly represents a natural range of prismatic 

 columns, of different shapes and sizes, placed in a direction nearly perpendicular 

 to the horizon, and parallel to each other, much resembling that part of the 

 famous Giant's Causeway in Ireland, called The Organs. The next is a similar 

 representation of the west side of another basaltine hill, called II Monte Del 

 Diavolo, or the Devil's Hill, near San Giovanni lUarione, also in the Venetian 

 State, and Veronese district, about 10 miles nearly north west of Vicenza. The 

 prismatic columns appear to be ranged in an oblique position, along the side of 

 the hill. This drawing however represents only a part of the Cause- 

 way of San Giovanni, which continues along the side of a valley, nearly in the 

 same manner, to a considerable distance. Though the columns of both these 

 hills are of the simple, or unjointed species, yet they differ very remarkably 

 from each other in many respects, but principally in their forms, and the tex- 

 ture and quality of their parts. Those of San Giovanni commonly approach a 

 circular form, as nearly as their angles will permit ; which is also observable in 

 the columns of the Giants Causeway, and of most other basaltine groups. On 

 the contrary, those of Monte Rosso rather affect an oblong or oval figure. The 

 columns of San Giovanni measure, one with the other, near a foot in diameter ; 

 nor do they vary much in their size ; though this is often the case in similar 

 groups, and is particularly observable in that of Monte Rosso, whose columns 

 sometimes equal nearly a foot in diameter, while others scarcely exceed 3 inches : 

 their common width is about 6 or 8 inches. They differ therefore very con- 

 siderably, in size, from those of the Giants Causeway ; some of which, it is 

 well known, measure 2 feet in width. Nothing certain can be said concerning 

 the length of the columns of San Giovanni, as they present only their tops to 

 view ; the remaining parts of them being deeply buried in the hill, and in some 

 places entirely covered. The columns of Monte Rosso, as far as they are 

 visible, measure only from 6 to 8 or 10 feet in height ; which is also a small size, 

 when compared with the height of those of the Giants Causeway, some of 

 which measure near 40 feet. The columns of the Venetian groups manifest 

 however all the varieties of prismatic forms, that are observable in those of the 

 Giants Causeway, and other similar groups. But they are commonly either of 

 5 6 or 7 sides ; but the hexagonal form seems mostly to prevail, which is also 

 remarkable in the Giants Causeway, and probably in most others. Nor is there 

 less difference in the texture and qualiti>-3 of these columns, than in their forms. 

 Those of San Giovanni present a smooth surface, and, when broken, appear 

 within of a dark iron grey colour, manifesting also a very solid and uniform tex- 

 ture ; in which characters they correspond with the columns of the Giants 

 Causeway, and those of most other basaltine groups. But the columns of 

 Monte Rosso are very different in all these respects. For they have not only a 



