RECORDS. 471 



The programme and catalogue of this exhibition is printed as 

 an appendix to Part I of Vol. XI of the Annals. 



Richard E. Dodge, 



Secretary. 



STATED MEETING. 



April i8, 1898. 



Academy met with Vice-President Kemp in the chair, in 

 Schermerhorn Hall, Columbia University. 



Minutes of the meeting for March were read and approved. 



Letters of thanks from Professor J. P. Iddings and Erank P. 

 Adams, accepting the honor of being elected Corresponding 

 Members were read. 



Having no further business, the Section of Geology and 

 Mineralogy then formed. 



Richard E. Dodge, 



Secretary. 



SECTION OF GEOLOGY AND MINERALOGY. 



April 18, 1898. 



Professor Kemp in the chair. Thirty-five members present. 



Professor Kemp made a few opening remarks and was fol- 

 lowed by Dr. A. A. Julien who read a paper entitled The 

 Elements of Strength and Weakness in Building Stones. 



Dr. Julien called attention to the fact that in the testing of 

 building stones little consideration is given to the causes influ- 

 encing their various properties. In judging the resistance which 

 a stone shows towards weathering, care should be taken to rec- 

 ognize the character of the forces to which it has been sub- 

 jected. The strength of a stone bears no relation to its mineral 

 components, but is dependent on the shape and arrangement of 

 the mineral grains and the character of the cementing material. 

 In considering the strength of a stone four facts have to be kept 

 in mind, viz. : interlockment of the particles ; coherence, de- 



