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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.

us with a third. It may be thought strange perhaps that he did no more during the last five years of his life towards the performance of a task, which in 1620 he talked of setting about as soon as he could find leisure', and which in 1623 he was still meditating. But the sufficient explanation of the matter is, that he never had the offer of any help in making the proposed collections, and therefore the proposed directions would have been useless.


That the suggestions contained in the paper before us, which was probably drawn up with a view to the Historia Visus et Visibilium, should retain any substantial value at the present day, was of course not to be expected.

What value they may have had in Bacon's time, I do not know. But they remain to prove (if proof were wanting) that the system of observations and experiments from which he hoped to procure a collection of the facts of nature sufficient for the purposes of philosophy, was not to be carried on altogether without help from theory. They show also in what particular way he conceived that a communication between Theory and Observation might be established; and if the points upon which in this case he asks for information were not the most critical which might have been selected, it must have been owing to his imperfect acquaintance with what was then known about Light, not from any inherent impracticability in determining what next to ask, when one has a clear idea of what one wants next to know.

In the original, the numbers are placed before the first paragraph of each section, not before the headings. But as they belong properly to the sections, and not to the paragraphs, I have in this respect preferred the arrangement of Gruter's copy, where they are prefixed to the headings.

The notes to this fragment (except those marked with my initials) are Mr. Ellis's.

J. S.

1 Enimvero cum primum huic rei vacare possimus, consilium est in singulis veluti interrogando docere, &c.- Parasceve, § 10.

2 Nos autem Topicis Particularibus tantum tribuimus ut proprium opus de ipsis, in subjectis naturalibus dignioribus et obscurioribus, conficere in animo habemus. Domini enim quæstionum sumus, rerum non item. - De Aug. v. 3.




I. Tabula Præsentiæ.

VIDENDUM primo, quæ sint ea, cujuscunque generis, quæ progignunt lucem: ut stellæ, meteora ignita, flamma, ligna, metalla et alia ignita, saccharum inter scalpendum et frangendum, cicendula, rores aquæ salsa percussæ et sparsæ, oculi quorundam animalium, ligna nonnulla putria, magna vis nivis. Aër fortasse ipse tenuem possit habere lucem, animalium visui, quæ noctu cernunt, conformem. Ferrum et stannum, cum in aquam fortem immittuntur resolvenda, ebulliunt, et sine igne ullo acrem calorem concipiunt; utrum vero lucem aliquam edant, inquiratur. Oleum lampadum magnis frigoribus scintillat: nocte suda, circa equum sudantem, conspicitur nonnunquam lux quædam tenuis: circa capillos quorundam hominum accidit, sed raro, lux etiam tenuis, tanquam flammula lambens; ut factum est Lucio Martio in Hispania. Ventrale cujusdam fœminæ nuper inventum est quod micaret, minime immotum, sed inter fricandum. Erat autem intinctum in viridi, atque tincturam illam ingreditur alumen, et crepabat nonnihil cum micabat. Utrum alumen inter scalpendum aut frangendum micet, inquiratur; sed fortiore (ut puto) indiget fractione quam saccharum, quia magis contumax est. Tibialia nonnulla inter exuendum nituerunt, sive ex sudore, sive ex tinctura aluminis. Alia.


II. Tabula Absentiæ in proximo.

Videndum etiam, quæ sint ea quæ nullam lucem edant, quæ tamen cum iis quæ edant magnam habent similitudinem.

1 Livy, xxv. 39.

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