Philosophical Character of Dr. Priestley. . 33 



tive approximations to general principles might at first be deduced ; 

 to be confirmed or corrected, enlarged or circumscribed, by future 

 experience. It would have retarded the progress of science, and 

 put off, to a- far distant day, that affluence of new facts, which Priest- 

 ley so rapidly accumulated, if he had stopped to investigate, with 

 painful and rigid precision, all the minute circumstances of temper- 

 ature, of specific gravity, of absolute and relative weights, and of 

 crystalline structure, on which the more exact science of our own times 

 is firmly based, and from which its evidences must henceforward be 

 derived. Nor could such refined investigations have then been car- 

 ried on with any success, on account of the imperfection of philo- 

 sophicalinstruments. It would have been fruitless, also, at that time, 

 , to have indulged in speculations respecting the ultimate constitution 

 of bodies ; — speculations that have no solid ground-work, except in 

 a class of facts developed within the last thirty-five years, all tending 

 to establish the laws of combination in definite and in multiple pro- 

 portions, and to support the still more extensive generalization, which 

 has been reared by the genius of Dalton. 



. It was, indeed, by the activity of his intellectual faculties, rrfther 

 than by their reach or vigor, that Dr. Priestley was enabled to ren- 

 der such important services to natural science. We' should look, in 

 vain, in any thing that he has achieved, for demonstrations of that 

 powerful and sustained attention, which enables the mind to institute 

 close and accurate comparisons ; — to trace resemblances that are far 

 from obvious; — and to discriminate differences that are recondite 

 and obscure. The analogies, which caught his observation, lay 

 near the surfaeie, and were eagerly and hastily pursued ; often, m- 

 deed, beyond the boundaries, within which they ought to have been 

 circumscribed. Quick as his mind was in the perception of resem- 

 blances, it appears (probably for that reason) to have been little adapt- 

 ed for those profound and cautious abstractions, which supply the 

 only solid foundations of general laws- In sober, patient, and suc- 

 cessful induction, Priestley must yield the palm to many others, who, 

 though far less fertile than himself in new and happy combinations of 

 thought, surpassed him in the use of a searching and rigorous logic; 

 in the art of advancing, by secure steps, from phenomena to general 

 conclusions ; — and again in the employment of general axioms as the 

 instruments of farther discoveries. 



Among the defects of his philosophical habits, may be remarked, 

 that he frequently pursued an object of inquiry too exclusively, neg- 



Vol. XXIV.— No. I. 5 



