He was more interested in what he could do with 

 the magnet than in explaining these efTects. However, 

 he discussed it at sufhcient length for one to find that 

 his explanation of magnetic phenomena was basically 

 similar to that of his contemporary, St. Thomas. 



Peregrinus based his discussion of the loadstone 

 upon its nature and analyzed magnetic phenomena 

 in terms of the change of alteration. In magnetic 

 attraction, the nature of the iron is altered by having 

 a new cjuality impressed upon it,-" and the loadstone 

 is the agent that makes the iron the same species as 

 the stone. ^' 



. . . Oportet enim quod illud quod lam conversum est ex 

 duobus in unum, sit in cadcm specie cum agente; quod 

 non esset, si natura istud impo.ssible cligerct. 



This impressed similarity to the agent, Peregrinus 

 realized, is not a pole of the same polarity but one 

 opposite to that of the inducing pole. To produce 

 this effect, the \irtue of the stronger agent dominates 

 the weaker patient and impresses the virtue of the 

 stronger on the weaker so that they are made similar.** 



... In cuius attractionc, lapis foriioris vinulis agens est; 

 debilioris vero patiens. 



.\ further instance of alteration occurs in the reversal 

 of polarity of magnetized iron when one brings two 

 similar poles together. Again, the stronger agent 

 dominates the weaker patient and the iron is left 

 with a similarity to the last agent.-* 



. . . Causa huis est imprcssio uliimi agcniis. confuiideiuis et 

 alterantis virtutem primi. 



In this assimilation of the agent to the patient, 

 another effect is produced: the agent not only desires 

 to assimilate the patient to itself, but to unite with 

 it to become one and the same. Speaking of the 

 motion to come together, he says: '" 



Huius aulem rei causam per hanc viam fieri exislimo: 

 agens cnim intendit suum patiens non solum sibi assimilare, 

 sed unirc, ut ex agente et patiente fiat unum, per numerum. 

 Et hoc potes e.xperiri in isto lapidc mirabili in hunc modum. 

 . . . Agens ergo, ut vides experimenlo, inlendit suum paciens 

 sibi unirc; hoc autem fit rationc similiiudinis inter ea. 



^' Ilcllmann, op. cit. (footnote 6), Peregrinus, pt. 1, ch. 8. 

 The magnet attracts the iron ".secundum naturalem appetitum 

 lapidis . . . sine resistentia." There is no natural resistcnce 

 to this motion since it is no longer contrary to the nature of 

 the iron. The nature of the iron has changed. 



2' Ibid., pt. 1, ch. 9. 



28 Ibid., pt. 1, ch. 9. 



2» Ibid., pt. 1, ch. 8. 



^ Ibid., pt, 1, ch. 9. 



Oportet ergo . . . virtute altractionis. fiat una linea, ex 

 agente et patiente, secundum hunc ordinem . . . 



The nature cjf the magnet, as an active cause, tends 

 to enact, and since it acts in the best manner in which 

 it is able, it acts so as to preserve the similarities of 

 opposite poles." 



Natura autem, que lendcl ad esse, agit meliori modo quo 

 potest, eligit primum ordinem actionis, in qucj melius 

 salvatur idemiilitas, quani in sccundo . . . 



Tims unlike poles tend to come together when a 

 dissected magnet is reassembled. 



Like St. Thomas, Peregrinus argued that the magnet 

 receives its powers from the heavens. But he further 

 specified this by declaring that different virtues from 

 the different parts of the heavens flow into their 

 counterpart in the loadstone — from the poles of the 

 heavens the \irtue flows into the poles of the magnet,^^ 



Praeterea cum ferrum, vel lapis, vertatur tam ad partem 

 meridionalem cjuam ad partem septemtrionalem . . . 

 existima cogimur, non solum a partem septemtrionali, 

 verum etiam a meridionali virtutem influi in polos lapidis, 

 magis quam a locis minere . . . Omnes autem orbes 

 meridian! in polls mundi concurrunt; quare, a polls mundi, 

 poll magnetis virtutem recipiunt. Et ex hoc apparet 

 manifeste quod non ad slellam iiauticam movetur, cum 

 ibi non concurrant orbes mcridiani, sed in polls; Stella enim 

 nautica, extra orbem meridianum cuiuslibet rcgionis semper 

 invenitur, nisi bis, in completa firmanenti revolutionc. Ex 

 hiis ergo manifestum est quod a partibus cell, partes 

 magnetis virtutem recipiunt. 



and similarly for the other parts of the heavens and 

 the other parts of the loadstone.''' 



Ceteras autem partes lapidis nierito estimarc potes, 

 influcntiam a reliquis cell partibus retinere, ut non sic 

 solum polos lapidis a polls mundi, sed totum lapidem a toto 

 celo, recipere influcntiam et virtutem, estimes. 



Physical proof for sucii influences was adduced by 

 Peregrinus from the motions of the loadstone. That 

 the poles of the loadstone receive their \irtue from 

 the poles of the heavens follows experimentally from 

 north-south alignment of a loadstone. That not 

 only the poles but the entire loadstone receives power 

 from corresponding portions of the heavens follows 

 from the fact that a spherical loadstone, when 

 "properly balanced," would follow the motion of 

 the heavens.'* 



'' Ihid., pt. 1, ch. 9. See also footnote 27. 



32 Ibid., pt. 1, ch. 10. See also ch. 4. 



23 Ibid., pt. 1, ch. 10. See also ch. 4. 



3* Ibid., pt. 1, ch. 10. 



128 



BULLETIN 218: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY .\ND TECHNOLOGY 



