122 fingal's cave. 



The entrance to this splendid cavern is 50 feet 

 broad and 100 feet high, and its length 250 feet. 

 On each side, as well as at the base, these columns 

 are thickly studded ; the whole presenting a singu- 

 larly rich and varied effect. The basalt of which 

 the columns are composed is of a dark, greenish- 

 black hue, highly coloured by iron. The columns 

 consist generally of five or six sides, though they 

 may range from 3 to 12 : and they are made up of 

 numerous joints or separate pieces, united by a thin 

 layer of silicious cement. The whole island of 

 Staffa, which is two miles in circumference, is sur- 

 rounded on every side by steep cliffs about 70 feet 

 high, formed of clusters* of the same angular col- 

 umns. Sometimes they are curved. 



* Mr. Gregory Watt, in ] 804, melted 700 weight of basalt, 

 and kept it in the furnace several days after the fire was redu 

 ced. It fused into a dark-coloured vitreous mass with less heat 

 than was necessary to melt pig-iron ; as the mass cooled, it 

 changed into a hard, stony substance, and globules appeared; 

 these enlarged till they pressed laterally against each other, and 

 became cemented into regular prisms. It is, therefore, clearly 

 established by this experiment, that the articulated structure 



