134 Mr Glover on Forms of Induction. 



individual are known to diifer.* 3. In this present division the 

 groups of facts are arranged in genera, each of which is not il- 

 limitable throughout the known universe, but confined, and find- 

 ing some similar, and many closely analogous to itself, so that the 

 law framed of one group can easily be transferred to another ; 

 while in each group, the investigation is capable of being abridged 

 by means of prerogative instances. By way of illustration, we 

 shall take the doctrine of the circulation of the blood, introduced 

 by Harvey, which at the same time will give a good example of 

 the course of inductive procedure ordinarily pursued in the physi- 

 cal sciences. If, then, we take that celebrated doctrine, and 

 spread it out, so as to display all its parts, and ask proof for 

 every assertion made in it, we should demand such a knowledge 

 of the structure of the heart and arteries as to be sure of their 

 powers and capabilities to allow of the course alleged, and to 

 perform the functions ascribed to them, — evidence that the 

 heart sends the blood into the aorta, like evidence of it being 

 sent along the arteries into the minute veins, of the return, and 

 the same kind of proof of the lesser circulation as of the greater. 

 It is believed that when Harvey announced the circulation, he 

 was not able to furnish all of those proofs, and, in particular, 

 that he had not evidence of the actual passage of the blood from 

 the small arteries into the small veins. Of the lesser circulation 

 he probably could only offer the analogy of the parts perform- 

 ing it with those concerned in the greater. Yet his doctrines, 

 founded on the proof he gave, must be acknowledged possessed 

 of such evidence, as that, if more be added, it can only amplify 

 the notion he gives of the circulation. Two grand facts are the 

 proofs of this great theory : 1, the prerogative fact of the valves 

 of the heart and veins; and, 2, the analogy of the parts engag- 



* A paper was read before the members of the Royal Medical Society, on 

 the 6th of April last ; the object of which was to prove, that in medical rea- 

 soning, the only conjtant source of uncertainty is in idiosyncracy. There 

 may be great complexity in the relations of properties — great difficulty and 

 perplexity in the investigation ; but the only constant source of uncertainty 

 arises from individual peculiarities. See Dr Abercrombie on Certain and 

 Uncertain Sciences; he classes together medicine, political economy, and 

 ethics. 



