492 SIMSON. 



known. The utmost care was bestowed on the revi- 

 sion of the text; no pains were spared in collating 

 editions ; all commentaries were consulted ; and the 

 elegance and perfect method of the original has been 

 so admirably preserved, that no rival has ever yet risen 

 up to dispute with Simson's Euclid the possession of 

 the schools. The time bestowed on this useful work 

 was no less than nine years. It only was published in 

 1758. To the second edition, in 1762, he added a 

 similarly correct edition of the Data, comprising 

 several very valuable original propositions of his own, 

 of Mr. Stewart, and of Lord Stanhope, together with 

 two excellent problems to illustrate the use of the 

 Data in solutions. 



We thus find Dr. Simson employed in these various 

 works which he successively gave to the world, elaborated 

 with infinite care, and of which the fame and the use 

 will remain as long as the mathematics are cultivated, 

 some of them delighting students who pursue the 

 science for the mere speculative love of contemplating 

 abstract truths, and the gratification of following the 

 rigorous proofs peculiar to that science ; some for the 

 instruction of men in the elements, which are to 

 form the foundation of their practical applications of 

 geometry. But all the while his mind never could be 

 wholly severed from the speculation which had in his 

 earliest days riveted his attention by its curious and 

 singular nature, and fired his youthful ambition by 

 its difficulty, and vanquished all his predecessors in 

 their efforts to master it. We have seen that as early 

 as 171 5 at the latest, probably much earlier, the obscure 

 subject of Porisms had engaged his thoughts ; and soon 



