on a perpetual motion machine, mentioned by authors, by means of the attraction of a loadstone.

c ardan writes183 that out of iron and the herculean stone can be made a perpetual motion machine; not that he himself had ever seen one, but only conceived the idea from an account by antonius de fantis184, of treves. such a machine he describes, book 9, de rerum varietate. but they have been little practised in magnetick experiments who forge such things as that. for no magnetick attraction can be greater (by any skill or by any kind of instrument) than the retention. things which are joined and those which are approaching near are retained with a greater force than those which are enticed and set in motion, and are moved; and that coition is, as we have shown above, a motion of both, not an attraction of one. such a machine peter peregrinus feigned many centuries before or else depicted one which he had received from others, and one which was much better fitted for the purpose. johannes taysnier published it also, spoiled by wretched figures, and copied out the whole theory of it word for word. o that the gods would at length bring to a miserable end such fictitious, crazy, deformed labours, with which the minds of the studious are blinded!