INFORMATION TO CONTRIBUTORS 
The Proceedings is the ofl&cial organ of the Academy for the publica- 
tion of brief accounts of important current researches of members of the 
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American research among investigators in other countries and in all branches 
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Articles should be brief, not to exceed 2500 words or 6 printed pages. 
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Papers by members of the Academy may be sent to Edwin Bidwell Wilson, 
Managing Editor, Mass. Institute of Technology, Cambridge, Mass. Papers 
by non-members should be submitted through some member. 
Proof will be sent to authors only on their request, in order to avoid 
delay in publication. Authors are therefore requested to make final revisions 
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Copyright^ 1916, by the National Academy of Sciences 
