42 ESSAYS BIOGRAPHICAL AND CHEMICAL 



ancients ideas which have their origin rather in our 

 own brains than in their works. Objects in the middle 

 distance are perhaps most truthfully interpreted. They 

 are not obscured by the haze of perspective nor by the 

 multitudinous aggregations of propinquity. So it is with 

 Boyle and with Cavendish. But with Davy, and with 

 Graham, whose lives and works are to form the subject 

 of this essay, it is difficult to select from their writings 

 those salient features which will, in the course of another 

 half-century, stand out clearly and luminously among 

 the labours of their contemporaries. In chemical and 

 physical work, as in life, safety lies in a happy mean ; and 

 it shall be my endeavour to avoid unimportant details, 

 while presenting the main characteristics of the work of 

 these two remarkable men. The difficulty is to know 

 what to omit ; for that which appears unimportant to-day 

 may to-morrow turn out to be essential to the fundamental 

 doctrines of our science. 



At the time when Cavendish was beginning his splendid 

 series of experiments on gases, Humphry Davy, an infant 

 of two, was beginning to show signs of that ability which 

 so remarkably distinguished him in after life. At that 

 age, he could speak fluently ; a year or two later, he was 

 sent to school, where he learned to read and write before 

 he was six ; and in his seventh year he was sent to the 

 Grammar School at Truro, his native place. Looking 

 back on his experiences there, from the standpoint of a 

 young man of twenty-two, he wrote : ' I consider it fortu- 

 nate that I was left much to myself when a child, and 

 put upon no particular plan of study, and that I enjoyed 

 much idleness at Mr. Coryton's school.' Do not we err 

 in insisting too much on the systematic employment of 

 time by the boys of our modern schools ? For, be it re- 

 membered, the compulsory cricket and football, so com- 

 mon in our schools, is to some boys the hardest task 



