INQUISITIO DE MAGNETE. MAGNES trahit pulverem chalybis præparati, quali utuntur ad medicinam, etiam chalybem calcinatum in tenuissimum pulverem nigrum, æque fortiter ac limaturam ferri crudam: crocum autem Martis, qui est rubigo ferri artificiosa, hebetius et debilius. Si vero ferrum dissolvatur in aqua forti, et guttæ aliquæ dissolutionis ponantur super vitrum planum, non extrahit magnes ferrum, nec trahit aquam ipsam ferratam. Magnes scobem suum trahit, quemadmodum limaturam ferri: parvaque admodum magnetis frustula, alterum alterum trahit, ut pensilia fiant, et capillata, quemadmodum acus. Pone magnetem in tali distantia a ferro, ut non trahat: interpone pileum ferri, servata distantia, et trahet; virtute magnetis per ferrum melius diffusa, quam per medium aëris solius. Magnes immissus intra aquam fortem, ibique per plures horas manens, virtute non minuitur. Magnes fricatione contra pannum (ut utimur in electro), aut contra alium magnetem, aut calefactus ad ignem, virtute non augetur. Magnes alius alio est longe virtuosior: quinetiam virtutem suam, pro modo ejus, ferro tactum transmittit: virtutem, inquam, non solum verticitatis, sed etiam attractionis simplicis. Nam si accipias magnetem fortiorem, eoque ferrum (puta cultellum) tangas, deinde magnete debiliore similiter alium cultellum, videbis cultellum fortiore magnete tactum majus trahere pondus ferri, quam qui debiliore tactus est. Magnes ad æque distans ferrum trahit per aërem, aquam, vinum, oleum. Magnete, aut pulvere ejus, in aqua forti immerso, nihil omnino dissolvitur, sicut in ferro fit; licet magnes videatur esse corpus ferro consubstantiale. Pulvis magnetis ferrum intactum non trahit, nec tactum etiam: attamen ipse pulvis a ferro tacto trahitur, et adhæret ; ab intacto autem minime: adeo ut pulvis magnetis videatur passivam virtutem aliquo modo retinere, activam autem non omnino. Acus super planum posita, quæ magnete non trahitur propter pondus, eadem superimposita fundo vitri elevato, ut utrinque propendeat, trahetur; quod eo magis relatu dignum puto, quia hujusmodi quiddam fortasse occasionem dedit frivolæ illi narrationi, quod adamas magnetis virtutem impediat. Pone enim acum super adamantem parvum, in tabulam sectum, magnete præsente ad distans majus quam in quo trahere posset, tamen trepidabit: illa autem trepidatio, non prohibitio motus est, sed motus ipse. Magnes ferrum tactum longe vivacius trahit, quam intactum; adeo ut ferrum, quod intactum in data distantia non trahit, id in triplici distantia tactum trahat. Nihil extrahitur ferri aut metallicæ materiæ ex magnete per ignem, et nota separationis. Magnes non solvitur in aqua regis plus quam in aqua forti. Magnes in crucibulo positus, citra tamen quam ut flammam immittat, minuitur multum pondere, et immensum virtute, ut vix ferrum attrahat. Magnes ægre liquefit, sed tamen figuram nonnihil immutat, et rubescit ut ferrum. Magnes combustus integer, virtutem passivam, ut se applicet alteri magneti, retinet; activam ad ferrum trahendum fere perdit. Magnes in crucibulo combustus emittit fumum, vix tamen visibilem, qui laminam æris superimpositam nonnihil albicare facit: ut solent etiam metalla. Magnes in comburendo penetrat per crucibulum, idque tam extra quam intra fracto, quod a splendore splendescere facit. Consentiunt omnes, magnetem, si comburatur, ita ut flammam quandam luridam et sulphuream jaciat, prorsus fieri virtute evanidum; eamque nunquam postea recuperare; licet refrigeretur in positura australi, et septentrionali: id quod lateribus virtutem indit, et in magnetibus non prorsus combustis vires renovat. Experimentum factum est, de ferro magnete tacto, ac etiam de magnete ipso, collocatis super fastigium templi S. Pauli Londini, quod est ex altissimis templis Europe; annon minuerentur virtute attractiva, propter distantiam a terra? sed nihil prorsus variatum est. PREFACE ΤΟ TOPICA INQUISITIONIS DE LUCE ET LUMINE. THE following paper of directions for an experimental inquiry concerning Light was first published by Gruter in 1653, among the pieces which he entitles Impetus Philosophici; afterwards (from another copy) by Dr. Rawley in 1658; and since a work with the same title is mentioned in Rawley's list of Bacon's later writings, where it stands last but one', I presume that this is it, and that it was meant to be preserved. If so, this is its proper place. In my preface to the Parasceve, I have noticed Bacon's intention to draw up, with reference to the Natural and Experimental History which was to be the basis of the new philosophy, certain heads of inquiry showing what points in each subject were more particularly to be observed; and I have pointed out the importance of this part of his scheme, as bearing upon the question whether it were possible or not to procure a collection of the facts of nature in the manner he proposed. One example of the thing we have already seen, in the Topica Particularis sive Articuli Inquisitionis de Gravi et Levi, given in the fifth book of the De Augmentis. This is another; and though it does not profess to contain more than a few instances by way of example, it serves to show how he proposed to set about the work. If the enclosure transmitted in his letter to Father Baranzan, which related to a history of Comets (de qua conficienda ecce tibi articulos quosdam et quasi topica particularia), had been preserved, it would have supplied 1 See Vol. I. p. 10. Mr. Ellis however infers from the allusion (infra, p. 317.) to specula perspectiva, that this tract must have been written before 1612. See his note. -J. S. |