CONTENTS. 



Page 



PREFATORY NOTE ON THE RECENT PROGRESS AND PRESENT 



ASPECT OF THE THEORY OF GLACIERS . xiii 



I. ON A REMARKABLE STRUCTURE OBSERVED BY THE AUTHOR 



IN THE ICE OF GLACIERS [1841] .... 1 



Obscurity of the Theory of Glacier Formation. . .Ribboned Struc- 

 ture described... Its Course traced on the Glaciers of the 

 Aar and Rhone . . . Probably perpendicular to Lines of ,^ 

 greatest Pressure... Also perpendicular to Fissures or Cre- 

 vasses... Analogy to Slaty Cleavage in Rocks ... Physical 

 Cause of both perhaps similar, 



II. FIRST LETTER ON GLACIERS. Addressed to PROFESSOR 



JAMESON [1842] ' ^ . 9 



Account of the First Experiments, undertaken in June 1842, 

 to determine the Laws of Motion of the Mer de Glace of 

 Chamouni. 



III. SECOND LETTER ON GLACIERS. Addressed to PROFESSOR 



JAMESON [1842] 13 



The Laws of Motion of the Mer de Glace farther stated. 



IV. THIRD LETTER ON GLACIERS, Addressed to PROFESSOR 



JAMESON [1842] 17 



The Laws of Structure of Glaciers generally detailed... The 

 " Dirt- Bands" described... Mechanical Theory of the Struc- 

 ture... Dirt- Bands correspond to Annual Intervals... Glaciers 

 probably move in Winter. 



