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 poblished, wholly or in part, with Approprlations 



from tub rumpord fusd. 



