98 Dr J. B. rearson, On Sympathetic Needles. [May 0, 



Litterulasque, modo banc modo et illam, cuspide tange, 

 Dum ferrum per eas iterumque iterumque rotando 

 Componas singillatim sensa omnia mentis. 

 Mira fides. Longe qui distat cernit amicus 

 Nullius impulsu trepidare volatile ferrum, 

 Nunc hue nunc illuc discurrere; conscius ha^ret, 

 Observatque styli ductum sequiturque legendo 

 Hinc atque hinc elementa, quibus in verba coactis 

 Quid sit opus sentit, ferroque interprete discit. 

 Quin etiam cum stare stylum videt, ipse vicissim 

 Si quse respondenda putat, simili ratione 

 Litterulis varie tactis, rescribit amico. 



O! utinam hgec ratio scribendi prodeat usu. 

 Cautior et citior properaret epistola, n alias 

 Latronum verita insidias, fluviosque morantes. 

 Ipse suis Princeps manibus sibi conficeret rem; 

 Nos soboles scribarum, emersi ex sequore nigro, 

 Consecraremus calamum Magnetis ad oras. 



Strada, p. 30G, (Ed. Colon. 1617). 

 It will be allowed that Addison very fairly represents Strada's mean- 

 ing. I would only observe that Strada does not say that the thing 

 ever had been done, but that if the needles are magnetized the 

 result follows with those who use them in the proper way: the 

 difference it is true is comparatively slight. 



I will now give an account of the various notices which we 

 find of the idea in successive writers down to the middle of the 

 eighteenth century. Since then, I think philosophy or common 

 sense would have precluded its reappearance, until it was either 

 re-invented or else utilized, in the construction of the electric 

 telegraph. Possibly some one conversant with the early history of 

 this instrument may be able to inform the public whether there is 

 any reason to think that our first telegraphists in the method they 

 adopted, were aware they were employing one which in a certain 

 degree is, theoretically speaking, so ancient. 



Strada's book was evidently well known, and probably much 

 used in education, during the first half of the seventeenth century. 

 In the library of my own college there are three copies, printed in 

 1617, '19, '25; and I find that there are as many in the University 

 Library, and also in that of St John's College, and probably it 

 may easily be found elsewhere. It was also reprinted at Oxford 

 in 1662; but I cannot find a copy of this edition in Cambridge. 

 Consequently the book was well known at the time, and as a con- 

 sequence, we find several references to it in writers of the period. 

 The first two references I owe to Notes and Queries. In that 

 periodical, 1st Ser. Vol. XL 459, a correspondent refers to the work 

 Recreations Matliematiques, by Denis Henrion, a French mathe- 



