Proceedings of the American Academy of Arts and Sciences. 

 Vol. XXXVIII. No. 23. — May, 1903. 



CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 



HARVARD COLLEGE. 



ON THE THERMAL CONDUCTIVITIES OF CERTAIN 



PIECES OF ROCK FROM THE CALUMET 



AND HECLA MINE. 



By B. O. Peirce. 



Investioations on Light and Heat biade or published, wholly or in part, with Appropriations 



FROM THB RDUFORD FUND. 



