RECTOR OF SWANSCOMBE, KENT. 149 



and the Treatise on Porisms, confessedly one of the most 

 obscure and difficult enigmas of antiquity. No two opinions 

 are now held as to the merits of these restorations ; — their 

 contents, if not actually identical with those in the lost 

 treatises, are considered by the best judges to differ from 

 them only in point of excellence. About a century before 

 this period several continental geometers of eminence had 

 succeeded in restoring some of the remaining treatises, but as 

 these attempts were written in Latin, and had become very 

 scarce, Mr. Lawson determined to present them to the 

 English reader in his own language, and thereby, at least for 

 a time, rescue them from that oblivion into which they were 

 rapidly falling. His first step towards accomplishing this 

 desirable object was the publication of a translation of " The 

 Two Books of Apollonius Pergseus concerning Tangencies, 

 as they have been restored by Franciscus Vieta and Marinus 

 Ghetaldus." This work was published at Cambridge in 

 1764, and contained, besides an excellent condensation of 

 what had been effected by Vieta and Ghetaldus, several 

 additional propositions on the same subject by Mr. Lawson 

 himself, and a selection from the writings of Mr. Thomas 

 Simpson. In the second edition, London, 1771, several 

 minor oversights were corrected and a " Second Supplement" 

 added, " being M. Ferraat's Treatise on Spherical Tangencies." 



The description of a circle to touch three given circles has 

 always formed a favorite subject for the contemplation of geo- 

 meters, and the solution of the various cases, when straight 

 lines or points are substituted for one or more of the given 

 circles, has occupied the attention of many of the most able 

 mathematicians. The publication of this tract had the effect 

 of once more directing attention to different modes of treating 

 the general problem, which have since resulted in the com- 

 plete and elegant constructions of Swale, Hearn, Bobillier, 

 and Gergonne. 



It must not, however, be supposed that Mr. Lawson 



