OUR ORE. 1 TEST EARTHQU. I KES 



33 



Comparison with Later Earthquakes 

 In earthquake studies one of the most fascinating lines of research 

 is the investigation of the relative intensities of the different shocks. 

 Of the various evidences, that afforded by the resulting disturbances of 

 the surface conditions is most reliable. Accounts of those who have 

 felt the shocks are unreliable in determining intensities, since the 

 feelings experienced at such a time are largely dependent upon nervous 

 temperament, and upon previous experiences with earthquakes. One 

 feeling a shock for the first time is often seriously disturbed by 

 tremblings to which a resident of an earthquake country would not 

 pay the slightest attention. 



5. Old and Young Growth of Cypress in Reelfoot Lake, Tenn. The large stumps with- 

 out enlarged butts are the old trees killed by the New Madrid earthquake. The living trees 

 with enlarged butts are mainly subsequent growth. 



A comparison of the effects produced upon artificial structures and 

 upon the earth's surface by our three great earthquakes, New Madrid, 

 Charleston and San Francisco, seems to show that of the various types 

 of phenomena associated with earthquakes, nearly all were more strongly 

 developed at Xew Madrid than at either of the other localities. 



The length of the period of marked disturbance at San Francisco 

 was only a few minutes during the eighteenth of April of this year. 

 The Charleston earthquake occurred, after a preliminary tremor a day 

 or two before, but not felt in the city on August 31, 1886, the severe 

 shocks being confined to a few hours, although not entirely ceasing 

 for three months. In Xew Madrid, on the other hand, the vibrations, 



