THE MUSEUM. 



53 



Avith him when he continued, lauj^hing, 

 "But if any want to visit it now they 

 would have to wear bloomers, aud 

 they shouldn't be very baggy either. " 



^. ^ -V. J{. .If. J£. 



In threading your way carefully 

 through these underground wonder , 

 and trying with your gaze to fathom 

 the darkness which your torch-light 

 fails to penetrate, you are tempted to 

 exclaim, "What mighty convulsions 

 rent these walls asunder?" forgetting 

 foj a moment that the world is old 

 and the memory of man is but a day. 



Caves, or rather great caves, can 

 only occur in a limestone region, and 

 they result from the chemical fact 

 that the carbonates of lime snd mag- 

 nesia are soluble in water containing 

 carbonic acid. This acid abounds in 

 atmospheric air, and is one of the 

 products of the decomposition of ani- 

 mal and vegetable waters, so that rain 

 water which percolates through the 

 soil has usually been enriched with it 

 from both sources. 



With carbonic acid then, as the 

 active agent and water as the carrier, 

 we are able to account for the disap- 

 pearance of strata however thick, and 

 whether above or below ground. 

 Above ground the result is a lowering 

 of the general level, the deposition of 

 a residum stratum of clay, and the 

 formation of valleys where special 

 causes have favored the disintegration 

 of the stone. 'Hard' water flows 

 away and a clay soil is left behind. 

 Below ground, on the other hand, the 

 result is a cave — if there be a fissure 

 in the strata through which the acid- 

 ified water may make its descent. In 

 the course of time this fissure is worn 

 larger, and the entering water disolves 

 and bears away with it bit by bit 

 the stratum through which it passes, 

 flowing out at some lower level with 

 its burden of lime and magnesia, but 

 leaving the elay behind to plague the 

 adventurous cave explorer. 



Here you have cave formation in a 

 nut shell. Given the initiatory crack 

 -—common enough in lime stones — 



it only requires time and an abun- 

 dance of water to carve out the halls, 

 galleries and avenues 



("Where falls no hail, nor rain nor 



any snow 

 Nor ever wind blows loudly.") 

 which go to make up our caverns; and 

 when once this work has well begun, 

 other natural agencies contribute their 

 aid to the enlargement of the area and 

 the adornment of the interior. 



These decorations of stalactites and 

 stalagmites are usually found in all 

 caves occurring in limestone regions, 

 and their formation is simple. 



Whenever through some of the mi- 

 nute crevices in the limestone roof or 

 wall a drop of water trickles, it is sure 

 to be saturated with carbonic acid, 

 to bear along with it a solution of lime 

 and magnesia. When emerging from 

 its rocky channel it meets a current of 

 air — if the conditions of dryness and 

 ventilation are favorable — it will evap- 

 orate and leave behind it minute crys- 

 tals of carbonate of lime deposited in 

 the form of a ring, because, as the 

 drop evaporates the solid matter be- 

 comes more concentrated around its 

 edges than in the pendant center. 

 This ring now becomes the support of 

 the drop, and the process continues 

 until a tube the diameter of the drop 

 is formed. At this stage of its growth 

 it begins to fill up, and the water 

 trickling exteriorly deposits its solid 

 matter and enlarges it. So it grows — 

 the stalactites like the icicles in win- 

 ter — larger at the top because the larg- 

 er part of the lime is deposited before 

 the drop reaches the tip. 



In the majority of cases more water 

 flows down a stalactite than can be 

 evaporated and drops to the floor, de- 

 positing, particle by particle, its solid 

 matter in the same spot directly un- 

 derneath the tip of the stalactite, until 

 a corresponding column is built up; 

 forming what is called a stalagmite. 

 In time the two growths may join to- 

 gether in a single column, reaching 

 from floor to ceiling. 



RoiiT. M. Hartlkv. 



Amsterdam, N. Y. 



