448 THE POPULAR SCIENCE MONTHLY. 



tude toward such criticisms as had then appeared, to be as follows : 

 ^* I had been frequently invited to write on Glaciers in encyclopaedias, 

 journals, and magazines, but had always declined to do so. I had also 

 abstained from making them the subject of a course of lectures at the 

 Royal Institution, wishing to take no advantage of my position there, 

 and indeed to avoid writing a line or uttering a sentence on the subject 

 for which I could not be held personally responsible. In view of the 

 discussions which the subject had provoked, I thought this the fairest 

 course. 



" But, in 1871, the time (I imagined) had come when, without risk 

 of offense, I might tell our young people something about the labors of 

 those who had unraveled for their instruction the various problems of 

 the ice-world. My lamented friend and ever-helpful counselor, Dr. 

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

 chosen. Strong in my sympathy with youth, and remembering 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, thor- 

 oughness, and life. 



"I aimed, indeed, at nothing less than presenting to my youthful 

 audience, in a concentrated but perfectly digestible form, every essen- 

 tial 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 this subject contained. But my 

 theory of education agrees with that of Emerson, according to which 

 instruction is only half the battle: what he q^W^ 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 ramblings, in 

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

 here dealing with what might be called the abstract idea of a boy, I 

 realized his presence so fully as to entertain for him, before our excur- 

 sions ended, an affection consciously warm and real. 



"A German critic, whom I have no reason to regard as specially 

 favorable to me or it, makes the following remark on the style of the 

 book : * This passion ' (for the mountains) ' tempts him frequently to re- 

 veal more of his Alpine wanderings than is necessary for his demonstra- 

 tions. The reader, however, will not find this a disagreeable interrup- 

 tion of the course of thought ; for tlie book thereby gains wonderfully 

 in vividness.' This, I would say, was the express aim of the breaks 

 referred to. I desire to keep my companion fresh as well as instructed, 

 and these interruptions were so many breathing-places where the intel- 

 lectual tension was purposely relaxed and the mind of the pupil braced 

 to fresh action. 



