822 PROCEEDINGS OF THE AMERICAN ACADEMY. 



the conducting strata. It may detect electric waves with an adjustment 

 that shows no capacity by the present method of measuring capacity. 

 On the other hand, with every adjustment at which we found capacity, 

 we found also rectification and detection of electric waves. 



Acknowledgment. — The authors gratefully acknowledge their indebt- 

 edness to the National Academy for an appropriation from the Bache 

 Fund, which was employed in defraying a part of the expenses of this 

 investigation. 



Jefferson Physical Laboratory, 



Harvard University, 



Cambridge, Mass. 



