the Philosophical Character ofDr Priestley. 5 



science. But, in other cases, his analogies were fanciful and un- 

 founded, and led him far astray from the path which might 

 have conducted him directly to truth. It is curious, however, 

 as he himself observes, that in missing one thing, of which he 

 was in search, he often found another of greater value. In such 

 cases, his vigilance seldom failed to put him in full possession of 

 the treasure upon which he had stumbled. Finding by experi- 

 ence, how much chance had to do with the success of his inves- 

 tigations, he resolved to multiply experiments, with the view of 

 increasing the numerical probabilities of discovery. We find 

 him confessing, on one occasion, that he " was led on, by a ran- 

 dom expectation of some change or other taking place." In 

 other instances, he was influenced by theoretical views of so 

 flimsy a texture, that they were dispersed by the first appeal to 

 experiment. " These mistakes," he observes, " it was in my 

 power to have concealed ; but I was determined to show how 

 little mystery there is in the business of experimental philosophy; 

 and with how little sagacity, discoveries, which some persons are 

 pleased to consider great and wonderful, have been made." 

 Candid acknowledgments of this kind were, however, turned 

 against him by persons envious of his growing fame ; and it was 

 asserted that all his discoveries, when not the fruits of plagiarism, 

 were " lucky guesses," or owing to mere chance*. Such de- 

 tractors, however, could not have been aware of the great 

 amount of credit that is due to the philosopher, who at once 

 perceives the value of a casual observation, or of an unexpected 

 result ; who discriminates what facts are trivial, and what are 

 important ; and selects the latter, to guide him through difficult 

 and perplexed mazes of investigation. In the words of D''Alem- 

 bert, " Ces hazards ne sont que pour ceux quijouent bien."" 



The talents and qualifications which are here represented as 

 having characterized the mind of .Dr Priestley, though not of 

 the rarest kind, or of the highest dignity, were yet such as ad- 

 mirably adapted him for improving chemical science at the time 

 when he lived. What was then wanted, was a wider field of 



• These charges, especially that of plagiarism, which had heen unjustly 

 advanced by some friends of Dr Higgins, were triumphantly repelled by T)r 

 Priestley, in a pamphlet entitled, " Philosophical Empiricism," published in 

 1775. 



