l894-J FAIRCHILD — THE LENGTH OF GEOLOGIC TIME. 263 



else had been friendless. His long residence in Greece gave him an 

 intimate knowledge of nearly every family and person for miles 

 around, and he was loved and honored by all who knew him. In 

 person he was rather stout, with broad shoulders and a beautiful 

 head. His forehead was broad and high, and his eyes were dark and 

 brilliant, lighting up as he became interested in conversation. His 

 whole countenance was very expressive. His manners were cordial 

 and his hospitality unbounded. Notwithstanding all his book-lore, he 

 never seemed to lack interest in even the most humble or common- 

 place person who laid claim to his attention. He was especially inter- 

 ested in the young, and was always ready to help any student. For 

 many years he taught a Bible class, or, in the absence of a pastor, 

 conducted services in the Congregational church. Cheerfulness, love 

 of humor, ready wit and quick repartee were among his prominent 

 characteristics. His intellectual life was intense and vigorous. 



In 183 1 he married Mrs. Sarah Bartlett C'rane. His three 

 children are Miss Cornelia Bradley and Mrs. Gilbert Cromwell, of 

 Ogden, and Dr. William Bradley, of Evanston, Illinois. 



The President read the following paper : 



THE LENGTH OF GEOLOGIC TIME. 

 By Herman LeRoy Fairchild. 



The problem of the Earth's age has a peculiar interest, none the 

 less from its uncertainty, and improbability of exact solution. The 

 most frequent question asked the geologist is one relating to time. 

 How many years ago was this or that event or phenomenon ? 



The problem has been approached from two directions ; by the 

 geologists, basing estimates upon the present rate of land destruction 

 and marine sedimentation, as applied to the total thickness of sedi- 

 mentary rocks ; and by the physicists, calculating from the laws of 

 matter and radiant energy the time required for cooling and condensa- 

 tion of the earth. The geological method, resting upon the theory of 

 uniformity, is simple, but the data are complex and elusive ; the 

 physical method has to make large assumptions regarding the 

 behavior of matter under conditions of heat and pressure transcending 

 all experience. 



Estimates upon the length of geologic time have been made by 

 many geologists. When the uniformitarian theory came into general 

 acceptance, a half century ago, and it was recognized that the earth, 



