PREFACE TO THE FOURTH EDITION. xvii 



lamented friend and ever -helpful counsellor, Dr. Bence 

 Jones, thought the subject a good one, and accordingly it 

 was chosen. Strong in my sympathy with youth, and re- 

 membering the damage done by defective exposition to my 

 own young mind, I sought, to the best of my ability, to 

 confer upon these lectures clearness, thoroughness, and life. 



Wishing, moreover, to render them of permanent value, 

 I wrote out copious Notes of the course, and had them dis- 

 tributed among the boys and girls. In preparing these 

 Notes I aimed at nothing less than presenting to my youth- 

 ful audience, in a concentrated but perfectly digestible 

 form, every essential point embraced in the literature of the 

 glaciers, and some things in addition, which, derived as they 

 were from my own recent researches, no book previously 

 published on the subject contained. 



But my theory cf education agrees with that of Emer- 

 son, according to which instruction is only half the battle, 

 what he calls provocation being the other half. By this he 

 means that power of the teacher, through the force of his 

 character and the vitality of his thought, to bring out all 

 the latent strength of his pupil, and to invest with interest 

 even the driest matters of detail. In the present instance I 

 was determined to shirk nothing essential, however dry; 

 and, to keep my mind alive to the requirements of my 

 pupil, I proposed a series of ideal rambles, in which he 

 should be always at my side. Oddly enough, though I 

 was here dealing with what might be called the abstract 



