viii PREFACE. 



of what goes on in his parish, he must know something 

 about the universe ; that the pebble he kicks aside would 

 not be what it is and where it is, unless a particular chapter 

 of the earth's history, finished untold ages ago, had been 

 exactly what it was. 



It was necessary to illustrate my method by a concrete 

 case ; and, as a Londoner addressing Londoners, I selected 

 the Thames, and its basin, for my text. But any intelligent 

 teacher will have no difficulty in making use of the river 

 and river basin of the district,- in which his own school is 

 situated, for the same purpose. 



The lectures on Physiography were delivered at the 

 London Institution in 1869 ; and I repeated them, at 

 South Kensington, in 1870. Verbatim reports were taken 

 on the former occasion, as it was my intention to publish 

 the course. But I am sorry to say that, in this, as in other 

 cases, I have found a great gulf fixed between intention 

 to publish and its realization. 



Seeing a book through the press is a laborious and time- 

 wasting affair ; greatly aggravated, in cases such as the 

 present, by the necessity of superintending the execution of 

 maps and figures. And, as I never could muster up the 

 courage, or find the time, to undertake the business, the 

 manuscript remained untouched until last year. 



I then had the good fortune to be able to obtain the 

 sfervices of my friend Mr. Rudler, with whose extensive 

 knowledge of various branches of physical science, I was 

 well acquainted ; and, in whose conscientious accuracy, 

 as an editor, I knew I could place implicit confidence. 



In preparing the substance of the lectures for the press, 



