SIMSON. 505 



This is erroneous, and contrary to the rules of logic 

 from its generality ; it is, as the lawyers say, void for 

 uncertainty. The modern one objected to by Pappus 

 is not uncertain ; it is quite accurate as far as it goes ; 

 but it is too confined, and errs against the rules of 

 logic by not being coextensive with the thing proposed 

 to be defined. 



The difficulty of the subject has been sufficiently 

 shown from the extreme conciseness and the many 

 omissions, the almost studied obscurity, of the only 

 account of it which remains, and to this must cer- 

 tainly be added the corruption of the Greek text. 

 The success which attended Dr. Siinson's labours in 

 restoring the lost work, as far as that was possible, and, 

 at any rate, in giving a full elucidation of the nature of 

 porisms, now, for the first time, disclosed to mathe- 

 maticians, is, on account of those great difficulties by 

 which his predecessors had been baffled, the more to 

 be admired. But there is one thing yet more justly 

 a matter of wonder, when we contrast his proceedings 

 with theirs. The greater part of his life, a life ex- 

 clusively devoted to mathematical study, had been 

 passed in these researches. He had very early become 

 possessed of the whole mystery, from other eyes so 

 long concealed. He had obtained a number of the 

 most curious solutions of problems connected with 

 porisms, and was constantly adding to his store of 

 porisms and of lemmas subservient to their investi- 

 gation. For many years before his death, his work 

 had attained, certainly the form, if not the size, in 

 which we now possess it. Yet he never could so far 

 satisfy himself with what has abundantly satisfied 

 every one else, as to make it public, and he left it un- 



