The cave is formed by regular pillars, extending to a great distance on side, which support an arch composed of the obtuse points of others, placed very close together; unfortunately the floor of this wonderful place is covered by a body of clear fresh water, several feet in depth, through which may be seen an incredible number of fragments of pillars. The co lour or the columns is grey, inclining to black, and the joints are distinguishable by the intervention of a yellow stalactic quarry- rind, that exhales, and serves to make the separations more distinct, at the same time that it produces an agreeable effect by many different gradations of co lour.
A sufficient degree of light enters the cave to illuminate it to the extremity, where the ranges of pillars are perfectly discernible, and the ebbing and flowing of the tide constantly conveying and dis charging air from within it, is at all times fit for respiration, and by no means noxi ous. This circumstance may still further originate from the passage of the water through a fissure in the rocks, rather low er than the surface, which occasions a rushing sound upon each rise of the tide, that contri butes to render the effect of the whole still more singular and impressive. A boat is certainly the most convenient for visiting Fingal's cave, but it is possible to walk into it, upon the points of some of the pillars which are higher than the level of the water.
The party already mentioned measured the dimensions of this beautiful grotto, and we acknowledge ourselves indebted to Dr. Von Troil for the following particu lars : Ft.
The length from the furthest of the basalt pillars, which from the shore formed a canal to the cave, 121 ft. 6 in.; from the commencement of the vault to the end of the cave, 250 ft. 371 6 The breadth of its entrance - 53 7 Of the interior end - - - 20 0 The height of the vault at the entrance of the cave - - - 117 6 Of ditto at the interior end - - 70 0 The height of the outermost pil lar in one corner - - . - 39 6 The height of another in the north-west corner - - 54 0 The depth of the water at entrance 18 0 Of the inside end 9 0 From the water to the foot of the pillars 36 8 Height of the pillars - 32 6 Height of the arch, or vault, above the top of the pillars - 31 4 The stratum above - - 34 4 The western corner of Fingal's cave.
From the water to the foot of the pillars 12 10 Height of the pillars - - 37 3 The stratum above them - - 66 9 Further west—the stratum be neath the pillars - - - 11 0 Height of the pillars - - - 54 0 The stratum above • - - - .61 6
Still more westward—stratum beneath the pillars - - 17 1 Height'of the pillars - - - - 50 0 The stratum above them - - 51 0 More west—stratum beneath the pillars 19 8 Height of the pillars - - - 55 1 The stratum above - • - - 54 7 The stratum beneath the pillars was considered by the party to be no other than tufa, which being heated at the peri od when this phenomenon was produced, received into its depths fragments of ba salt ; that above them tinged with red, ap pears to be lava, containing other frag ments scattered in various unequal direc tions; although it is evident the most vio lent heat must have acted upon it, yet there are not the least traces in its exteri or, the pillars having been removed by it, for the whole enormous mass rests upon them.
On the north side of the island is ano ther cave, called Corvoranti, where the stratum is raised, and the pillars conse quently appear shortened ; those are to lerably distinct, and continue so till the intervention of a bay, that extends some distance inland, and there the pillars are discontinued. The mountains in this neighbourhood are composed of dark brown stone, which may or may not be lava : but there is no sort of regularity observable in its texture. On passing further, and on the south-east side of the Island, the basalt columnar appearance commences, though almost impercepti bly ; hence they gradually assume their characteristic form, till at last the specta tor finds himself on the spot where they are in full perfection.
The shape of the columns vary from three to seven sides, though the majority have five and six ; the former are so nu merous, that a heptagonal pillar is sur rounded with seven others, which join closely to its seven sides. In some in stances inconsiderable fissures may be perceived, but those are generally filled with quartz, and in one particular place that had penetrated through several pil lars, without interrupting the regularity of their arrangement ; one of the greatest wonders attending this operation of na ture, is, the separation of each pillar into pieces, which are so closely jointed, that it is almost impossible to introduce a knife between the interstices. Upon an attentive examination of many of those pieces, it was found that the uppermost was generally concave, in some cases flat, but very rarely convex. When the upper surface was flat, the lowest joint was the same ; but when it was excavated, the lower one was rounded and reversed.