CONTENTS 



i 



PAGE 

 ON A PIECE OF CHALK [1868] 1 



(A Lecture delivered to the working men of 

 Norwich during the meeting of the British 

 Association. ) 



II 



THE PROBLEMS OF THE DEEP SEA [1873] 37 



III 



ON SOME OF THE RESULTS OF THE EXPEDITION OF H. M. 8. 



"CHALLENGER" [1875] 69 



IV 



YEAST [1871] . . . 11C 



