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98 DISSERTATION SECONP. [pahti. 



the test of experience. The force itself, like all other 

 forces, is not directly perceived, and its effects are not the 

 result of its mere intensity, but of that intensity combined 

 with the figure and magnitude of the body on which it 

 acts ; and, therefore, the calculus must be employed to ex- 

 press the measure of the effect, in terms of the intensity 

 and the distance only. This being done, the hypothesis 

 which gives results most nearly corresponding to the facts 

 observed, when the magnet acts on the same body, at dif- 

 ferent distances, must be taken as the nearest approxima- 

 tion to the truth. We have here an instance of the use of 

 hypothesis in inductive investigation, and, indeed, of the 

 only legitimate use to which it can ever be applied. 



It also appears that Bacon placed the ultimate object of 

 philosophy too high, and too much out of the reach of 

 man, even when his exertions are most skilfully conducted. 

 He seems to have thought, that, by giving a proper direc- 

 tion to our researches, and carrying them on according to 

 the inductive method, we should arrive at the knowledge 

 of the essences of the powers and qualities residing in 

 bodies ; that we should, for instance, become acquainted 

 with the essence of heat, of cold, of colour, of transparen- 

 cy. The fact, however, is, that, in as far as science has 

 yet advanced, no one essence has been discovered, either 

 as to matter in general, or as to any of its more extensive 

 modifications. We are yet in doubt, whether heat is a 

 peculiar motion of the minute parts of bodies, as Bacon 

 himself conceived it to be ; or something emitted or radiat- 

 ed from their surfaces ; or lastly, the vibrations of an 

 elastick medium, by which they are penetrated and sur 

 rounded. Yet whatever be the form or essence of heat, 

 we have discovered a great number of its properties and 

 its laws ; and have done so, by pursuing with more or less 

 accuracy the method of induction. We have also this con 



