

Proceedings of the American Academy of Arts and Sciences. 

 Vol. XXXIX. No. 18. — Fkbkuaky, 1904. 



CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 



HARVARD UNIVERSITY. 



ON THE COOPER HEWITT MERCURY INTERRUPTER. 



By Geokge W. Pierce. 



With TuiiEE Plates. 



