xvi PREFACE TO THE FOURTH EDITION. 



far, and the system of instructing the younger portion of 

 the community is one of the most effective means which the 

 Institution possesses for the diffusion of science.' 



Faraday's holding aloof was but temporary, for at 

 Christmas, 1827, we find him giving a 'Course of Six Ele- 

 mentary Lectures on Chemistry, adapted to a Juvenile Au- 

 ditory.'* 



The Easter lectures were soon abandoned ; but from the 

 date here referred to to the present time the Christmas lect- 

 ures have been a marked feature of the Royal Institution. 



In 1871 it fell to my lot to give one of these courses. 

 I had been frequently invited to write on Glaciers in ency- 

 clopaedias, journals, and magazines, but had always declined 

 to do so. I had also abstained from making them the sub- 

 ject of a course of lectures, wishing to take no advantage 

 of my position here, and indeed to avoid writing a line or 

 uttering a sentence on the subject for which I could not be 

 beld personally responsible. In view of the discussions 

 \vhich the subject had provoked, I thought this the fairest 

 course. 



But, in 1871, the time (I imagined) had come, when, 

 without risk of offence, I might tell our young people some- 

 thing about the labours of those who had unravelled for their 

 instruction the various problems of the ice- world. My 



* There is no record to show that Mr. Wallis gave the Astronomical lect- 

 ares referred to, and our librarian believes that the Christmas courses were 

 orened by Faraday. 



