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. 



Investigations on Light and Heat made or published, wnoLi/r or dj part, with Appropriations 



FROM THE RUMF0RD FdND. 



