APPENDIX A. 



Reply to Professor TyndaWs Remarks, in his work ' On the 

 Glaciers of the Alps,' relating to RendiCs ' Thforie des Glaciers! 

 By JAMES- DAVID FORBES, D.C.L., LL.D., F.RS., &c., Corre- 

 sponding Member of the Institute of France, Principal of the 

 United College in the University of St. Andrews, and late 

 Professor of Natural Philosophy in the University of 

 Edinburgh. (A. and C. Black, 1860.) 



CONTENTS. 1. Introduction. 2. Professor Tyndall's General Account of 

 Rendu's Theorie des Glaciers. 3. My first references to Rendu's Theorie. 

 4. References to Rendu in my Travels in the Alps (1843), and in my 

 later Publications. 5. Professor Tyndall's Extracts from Rendu examined. 

 The first Extract. 6. Value of the Estimates of Glacier Motion previous to 

 1842 discussed. 7. Professor Tyndall's Second Extract from Rendu examined. 

 8. Reception of Rendu's Theorie at Home and Abroad. Conclusion. 



1. Introduction. 



PROFESSOR TYNDALL informs us, in the introductory chapter of 

 his recent work On the Glaciers of tlie Alps of the circumstances 

 which, in 1856, first directed his attention to the structure of the 

 ice of glaciers, and subsequently to all their other phenomena. 

 Mr. Sorby's ingenious experiments on the production of clea 

 in soft substances by pressure, led him to vary those experiments; 

 and a reference by Professor Huxley to the laminated structure 

 of glaciers, as described by me, induced him first to look into my 

 Travels in the Alps of Savoy and afterwards (still in 1856) to 

 some of the Swiss glaciers. A series of papers suggested by 

 these and subsequent experiments and o\< -\irsiniis, have been 

 successively] l>y Professor Tyndall in the Proceedings of 



the TJnyjil I: I, and in tlir i in^s and Transactions 



; "ii. 



