132 L] Crj/stallized Bodies on Homogeneous Light, WV" 



intensity of illumination any point in the screen being, eateris 

 paribus, as the square of the focal length; consequently, when- 

 the rings lie within a very small angular compass, a greater illu*'' 

 mination of every part of them may be obtained by using a lens{ 

 of a longer focus. 



The dimensions of the figure, fig. 6, are nearly of the actual 

 «ize. 



Article II. ^ 



Observations on a Memoir " On the Theory of Franklin ^ accord''^ 

 ing to which Electrical Phenomena are explained by a singhi 

 Fluid" read at the Royal Institution of the Sciences at Amster^ . 

 dam, by M. Martin Van Marum, Knight of the Order of the 

 JBelgic Lion, Secretary of the Dutch Scientific Society, Director, 

 of the Teylerian Museum, ^c.S^c.^ (With a Plate.) 



(To the Editor of the Annals of Philosophy.) ^ 



SIR, Dec. 13, 1820. ; 



It has been repeated so often as almost to require an apology : 

 for its introduction, that the Baconian philosophy proceeds by ^ 

 discovering and establishing facts, holding that upon such a- 

 foundation alone, can be raised any structure deserving the name- 

 of science. The philosophy which has happily been almost^ 

 exploded by Bacon and his successors, lays its foundation iat 

 hypotheses ; and the labours of its adherents are spent in inge-; 

 nious conjectures, or in efforts to bend the various facts disco- ^ 

 vered, to give those conjectures an apparent truth. A Baconian^ 

 philosopher gathers his maxims and principles from the united ; 

 rays of numerous observations and experiments, and as they are . 

 received in all the simplicity with which the facts themselves 

 express them, they yield to the mind all that satisfaction and: 

 confidence which spring from the clear perception of truth. On^ 

 the contrary, an hypothesis is incapable of teaching any truth at 

 all, and ought, under no circumstances, to be received as "a 

 confirmed truth ; " the observation being certainly well-founded, ^ 

 *' that an hypothesis, however satisfactory as far as concerns the,, 

 explanation of all the phenomena for which it has been proposed, 

 cannot nevertheless, for this reason, be considered as incon-> 



testibly proved.'' t ♦ 



Unfortunately the worthlessness of hypotheses is not their* 

 greatest evil ; they invariably tend either to mislead the mind • 

 from those conclusions naturally deducible from experiments, or 



* Ann. Phil. No. 96, p. 440. | 



t Aim Phil. No. 96, p 441. I conceive this must be the meaning of the sentence 



which it is apprehended (though without an examina ion of the original paper), must 



be mistranslated. 



