CONTENTS 



Original Papers 



Page 



Physics. — A mechanical differential telethermograph and some of its ap- 

 plications. Lyman J. Briggs • 33 



Physics. — ^Media of high refraction for refractive index determinations with 

 the microscope; also a permanent standard media of lower refraction. 

 H. E. Merwin 35 



Electrochemistry. — ^The silver voltameter. E. B. Rosa, G. W. Vinal and 

 A. S. McDaniel 40 



Proceedings 



The Philosophical Society of Washington 46 



The Geological Society of Washington 49 



Programs and Announcements 



The Washington Academy of Sciences 52 



The Botanical Society of Washington 52 



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