PREFACE 



IT seemed desirable to the committee in charge of the arrange- 

 ments for the Semi-Centennial Meeting of the National 

 Academy of Sciences, held at the Smithsonian Institution in 

 Washington on April 22, 23, and 24, 1913, to include in the plans 

 some provision for a permanent record of its proceedings. 



Accordingly, a contract was entered into with a local report- 

 ing bureau to make duplicate stenographic reports of the scien- 

 tific papers, the presentation addresses, and of the after-dinner 

 speaking at the formal dinner of the members and their guests on 

 the closing day of the meeting. 



This record, after careful comparison of the two sets of 

 stenographic notes and, in the case of certain of the scientific 

 papers, with the author's manuscript, was thought to be a true 

 and complete record of the proceedings of the Semi-Centennial 

 Meeting, and in this form, without editing of any kind, it was 

 presented to the Council of the Academy on May 21, 1913. 



The Council directed that this record be printed. 



In the closing pages of the volume there has been added a 

 record of the attendance in the form of a reproduction of the 

 signatures of all the members and guests registered at the 

 meeting. 



The Secretary offers this brief preface partly in explanation 

 of the origin of this volume, and partly in certification of the 

 correctness of the record in so far as it has proved possible to 

 establish it. 



ARTHUR L. DAY, 



Home Secretary. 



Washington, November 18, 



