SIMSOX. 155 



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. Simson'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 exclu- 

 sively devoted to mathematical study, had been passed 

 in these researches. He had very early become pos- 

 sessed 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 investigation. ^ 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 to make it public, and he left it unpublished among 

 his papers when he died. Nothing can be more unlike 

 those who freely boasted of having discovered the 

 secret, and promised to restore the whole of Euclid's 

 lost books. It is as certain that the secret was never 

 revealed to them as it is that neither they nor any 

 man could restore the books. But how speedily would 

 the Castillons, the Alberts, even the Feraiats, have 



