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Field Columbian Museum — Geology, Vol. i. 



would take their origin from the larger current trickling down 

 the side of the stalactite and from the drop of water at the 

 end. That currents rise from the drop of water at the end of a stalac- 

 tite may be proved by the clumsy and not-recommended-often-to-be- 

 tried experiment of holding a lighted candle for a moment close 

 under the drop. The particles of soot thus left in the water will be 

 seen to whirl about for a long time, much longer than any convection 

 currents produced by the heat of the candle would account for. 

 This motion continued in one stalactite which I watched for a period 

 of five minutes, and it, may be, is still kept up. The deposit formed 

 under the conditions of the above experiment with salt may be con- 

 sidered illustrative of one produced by rapid evaporation from a con- 

 centrated solution. The subject evidently admits of much further 

 treatment experimentally by way of determining what variations, if 

 any, would be produced in the nature and amount of the deposit by 

 employing solutions of different strengths, by varying if possible the 

 rate of evaporation and by the use of different salts. 



The " Pillar of the Constitution." — Fig. 3. The shape and 

 size of this huge stalagmite have often been described. It is located 

 in the hall known as the " Senate Chamber," which is accurately 



Fig 3— The "Pillar of the Constitution," Wyandotte Cave. 



