IS! E M O I R S , 



1. The Sufficiency of Tekrestriai, Kotation Fon the Deflection of Streams ; isv G. K. Gilbert. 



2. On the Temperature of the Surface of the Moon ; by Prof. S. P. Langley. 



3. On a Method of Precisely- Measuring the Vibratory Periods of Tuning-forks, and the Determina- 

 tion OF the Laws of the Vibrations of Forks ; with Special Reference of these Facts and Laws to the 

 Action of a Simple Chronoscope ; by Prof. Alfred M. Mayer. 



4. The Baum6 Hydrometers ; by Prof. C. F. Chandler. 



5. On Small Differences of Sensation; by Prof. C. S. Peirce and J. Jastrow. 



6. Description of an Articilate of Doubtful Relationshii', fro.m the Teuiiary Beds of Florissant, 

 Colorado; by- Dk. S. H. Scudder. 



7. The Structure of the Columella Auris in the Pely'cosauria : by Prof. E. D. Cope. 



8. On the Structure of the Brain;of the Sessile-eyed Crustacea. L The Brain of Asellus and the 

 Eyeless Form Cecidot.ea; by Prof. A. S. Packard. 



