Feb. 1901. Observations on Indiana Caves — Farrington. 255 



as probably the nearest correct, it can be easily calculated that 90,000 

 years would have been required for the Pillar to rise to its present 

 height had the flow of water during all this time been uniform over 

 the constantly increasing surface. I believe it safe to regard this as 

 a minimum age for the Pillar, though I am well aware that owing to 

 various factors which may give rise to fluctuations of growth, geolo- 

 gists are accustomed to believe that no satisfactory time values can 

 be assigned to measurements of stalagmitic deposits. See Dana's 

 Manual of Geology, 4th edition, p. 1024. But may not these fluctu- 

 ations be confined within limits as narrow as those affecting other 

 measurements of time, such as the rate of recession of gorges or the 

 rate of sedimentation, especially when we remember that variations 

 in the rate of deposit almost certainly find expression in the form of 

 the stalagmite? The stalagmite under discussion certainly has a 

 remarkably symmetrical form. I believe, therefore, that it must have 

 grown at a fairly uniform rate. 



Regarding the possibilities of arriving at any satisfactory value 

 of the mean age of the Pillar, I have no very lively hope of suc- 

 cess. It is hardly likely that the flow of calcareous waters over 

 the entire mass of the Pillar was constant throughout the period of 

 its growth. At the present time, growth is hardly taking place over 

 one one-hundredth part of the surface, yet a mean value can be 

 assigned to this factor only in a purely arbitrary way with nothing to 

 guide the judgment that I can think of. The data for assigning an 

 age value to the large stalagmite now in the Museum of Science and 

 Art, Edinburgh, seem to me better founded. This stalagmite is n 

 feet long and 28 inches in diameter. It was sawed from its base in a 

 cave in Bermuda in 1819. In 1863, Sir Alexander Milne in visiting 

 the cave measured the amount of matter formed on the base since the 

 removal of the stalagmite and found it to be five cubic inches. At that 

 rate it can be easily calculated that about 600,000 years were 

 required for the formation of the stalagmite.* Numerous considera- 

 tions show that it would be incorrect to apply this ratio to the forma- 

 tion of. the 20,000,000 cubic inches of matter which make up the 

 Pillar of the Constitution, and I introduce the illustration only to 

 show that a much greater age should probably be assigned the 

 Pillar than that which I have given as a minimum. In addition 

 to the time consumed in the growth of the Pillar, a large previous 

 period was required for the erosion of the chamber in which it stands. 



•My data are from the Museum label. I think the facts have been published, but I cannot 

 give the reference. 



