176 FRAGMENTS OF SCIENCE 



the edges of dark shafts and apertures, and squeezed our- 

 selves through narrow passages. From time to time we 

 halted, while Mr. Crookes illuminated, with ignited mag- 

 nesium wire, the roof, columns, dependent spears, and 

 graceful drapery of the stalactites. Once, coming to a 

 magnificent cluster of icicle-like spears, we helped our- 

 selves to specimens. There was some difiicultj in detach- 

 ing the more delicate ones, their fragility was so great. 

 A consciousness of vandalism, which smote me at the 

 time, haunts me still; for, though our requisitions were 

 moderate, this beauty ought not to be at all invaded. 

 Pendent from the roof, in their natural habitat, nothing 

 can exceed their delicate beauty; they live^ as it were, sur- 

 rounded by organic connections. In London they are 

 curious, but not beautiful. Of gathered shells Emerson 



writes : 



I wiped away the weeds and foam, 

 And brought my sea-born treasures home: 

 But the poor, unsightly, noisome things 

 Had left their beauty on the shore, 

 "With the sun, and the sand, and the wild uproar. 



The promontory of Gibraltar is so burrowed with cav- 

 erns that it has been called the Hill of Caves. They are 

 apparently related to the geologic disturbances which the 

 rock has undergone. The earliest of these is the tilting 

 of the once horizontal strata. Suppose a force of torsion 

 to act upon the promontory at its southern extremity near 

 Europa Point, and suppose the rock to be of a partially 

 yielding character; such a force would twist the strata 

 into screw-surfaces, the greatest amount of twisting being 

 endured near the point of application of the force. Such 

 a twisting the rock appears to have suffered; but instead 



