Mr. Halliwell on the Mathematical Collections ofPajipus, 85 



In order to see whether this projierty of complete polariza- 

 tion was proper to mercury, or common to all metals in a state 

 effusion, I caused two currents, one proceeding from a voltaic 

 pair consisting of zinc and a fused globule of Darcet's alloy, 

 the other from zinc and mercury kept at the same temperature, 

 to pass in contrary directions through the wire of a galvano- 

 meter; the current proceeding from the first pair was much 

 more energetic than that from the second, and kept the needle 

 constantly at 85 degrees. I could not repeat the experiment 

 with other metals, from the impossibility of keeping them 

 fused without volatilizing the electrolyte. As far as this case 

 goes, it would seem that metals possess different polarizing 

 capacities. I have before remarked a difference in the propor- 

 tionate diminution of tlie current by polarization with solid 

 metals, and think the subject merits an experimental exami- 

 nation : it is of some importance to the arts, as likely to lead 

 to effectual means of preserving metals from oxidation. 

 July 1, 183D. 



XVIII. Notice of a lost Manuscript of the Seventh Book of 

 the Mathematical Collections of Pappus Alexandrinus. By 

 J. O. Halliwell, Esq., F.R.S,, F.S.A., 4-c* 



IN the Advocates' Library at Edinburgh is preserved a very 

 valuable and beautiful manuscript of five books of the 

 Mathematical Collections of Pappus, viz. the 3rd, 4th, 5th, 

 6th, and 8th. To supply the deficiency of the seventh book, 

 the most valuable one in the series, Dr. Moor, of Glasgow, 

 procured a transcript of that part to be made from one of 

 the Paris manuscripts by the celebrated Greek scholar Cape- 

 ronier, at the commencement of the last century. This tran- 

 script was for some time in the hands of Dr. Robert Simson, 

 who enriched it with MS. notes. In the dispersion of Dr. 

 Moor's library the transcript was lost, and Dr. Trail in his 

 Life of Simson regrets not having been able to discover its 

 situation. About a year ago I accidentally found this identical 

 MS. in a bundle of waste paper at a bookseller's shop in 

 London, and, though unbound, quite perfect : my late la- 

 mented friend Professor Rigaud, who had it for some time, 

 thus writes concerning it: " There cannot be the slightest 

 doubt of its being Dr. Moor's transcript, for I have com- 

 pared the hand-writing with Caperonier's other transcript in 

 the Savilian Library, and find them agree. I congratulate 

 you on having obtained a curious relic of Dr.Simson's favourite 



♦ Communicated by the Author. 



