It seems just as if it had been formed by cutting away the middle of some of the pillars, since you can see that many parts of the pillars now remaining on the roof, are placed as if they were continuations of the stumps on which you walk at the bottom.
We went into it in a boat, and when we were at the farther end, we got out upon the broken pillars and surveyed everything at our leisure.
The length of the cave is two hundred and fifty feet, the breadth about forty, and the height above one hundred feet at the entrance, and seventy at the inner end.
Along the middle of the roof, is a deep cleft, or fissure, which makes it something like a pointed arch, resembling the roof of a cathedral. The sides of the fissure are variegated, yellow, red, brown, and white, in consequence of water containing various substances, soaking through from the surface above; and on each side of it, there are several rows of the top of the broken pillars, which look quite black.
On the sides at the bottom, the stumps form a sort of pavement like this, which is an exact copy of a small portion of it, and will show you the forms of the pillars; some stand higher than others; but there is not generally sufficient difference to prevent you from walking over them.
Between these pavements the water is very deep, and as it flows direct from the Atlantic Ocean without any dirty shore or shallows, it looks very beautiful,—of a clear emerald green, showing at the bottom the black basaltic pillars in ruins, and a very few long luxuriant sea-weeds gracefully waving with the undulations of the water.
The exposed surfaces of the pillars, between high and low water-marks, are covered with the little shell-fish called balanus, or BARNACLE, of colours varying from pink, which is the hue of those that are placed deepest, to yellow and white, which are those that are least covered by the water.
The walls of the cave above these shells, are of a deep slate colour. The pillars which compose them, are on the average about three feet in diameter, and they are fitted so close together that you cannot get a penknife in between them. If separated at certain intervals, they break short off, and leave a remarkably level surface without the least splinter. Between these joints they break roughly and irregularly.