82 DISCOVERY CH. 



fascinations of science. At the outset he planned out his life, and 

 resolved that there should be no interruption to his geological 

 work. The hours at his disposal he allotted, as before, to the 

 identification of fossils and to the analysis of minerals. Time 

 for that work, and for practical chemistry, as well as for his 

 mathematics and reading, had to be found in the early morning 

 before breakfast and after his return from the City at six or 

 seven in the evening, when each hour had its appointed subject. 

 . . . The youth seemed to have an intuitive consciousness 

 that there was something for him to do, that he himself might 

 aspire to demonstrate some truth in God's nature ; and hence- 

 forward every hour he could call his own was set apart to train 

 and gird himself for the task." 



This devotion to truth and knowledge remained with 

 Prestwich to the end of his long life, and led to results 

 of the highest value both to the nation and to science. 

 He was the first to insist upon the importance of geo- 

 logical knowledge in dealing with questions of water- 

 supply, and he became the leading authority upon this 

 subject in England. Water-diviners suggest that some 

 occult influence enables them to locate underground 

 springs or water-courses ; but without expressing any 

 opinion upon their claims we can assert that geological 

 conditions alone determine the presence or absence of 

 underground water, and when these conditions are 

 precisely known the geologist can state without hesitation 

 what the possibility is of finding water. 



A striking instance of the application of geological 

 knowledge to the subject of water supply is given in 

 Prestwich's Life. Having acquired a site for a house 

 overlooking the valley of the Darent above the village 

 of Shoreham, Kent, Prestwich engaged two well-diggers 

 to sink a well 168 feet deep. The boring proceeded, 

 but when a depth of 166 feet was reached, the well- 

 diggers went to the city and sought an interview with 

 their employer, whom they found at his desk. They 



