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seventeenth century, under the title of his collected Works, in twenty-one volumes folio. A large portion of these consists of Commentaries on Aristotle, whose works, however, he knew only through the medium of the wretched Latin translations then existing. Attached as Friar Bacon was to those vain speculations, known under the names of the sciences of astrology and alchemy, he was so far from ever pretending to operate by supernatural means, that one of his works, his Treatise on the Miracles of Art and Nature,' to which we have already referred, is written principally for the purpose of proving the nullity or absurdity of what was called the Art of Magic, and exposing the tricks of its professors. In the beginning of this little work, after enumerating the various methods by which these impostors pretended to perform their wonders, he affirms, that no true philosopher did ever regard to work by any of these ways. And immediately after, nothing can be more sensible than the manner in which he expresses himself on the subject of charms, spells, &c. "Without doubt," says he, "there is nothing in these days of this kind, but what is either deceitful, dubious, or irrational, which philosophers formerly invented to hide their secret operations of nature and art from the eyes of an unworthy generation." The domination which he imagined the heavenly bodies to possess over human affairs, was certainly an absurd dream; and so was his other favourite fancy about the tincture which possessed the power of curing all diseases, and turning everything into gold: but neither of them proceeded upon the idea of anything like supernatural or magical agency. The moral influence which he attributed to the stars, he conceived to be as truly a law of nature as that which directed their motions, or retained them in their orbits; and one, the operation and effects of which equally admitted of being made

matter of calculation and science. In the same manner, his universal solvent was merely one of the yet undiscovered essences or compounds of natural chemistry, the expectation of ever finding which might be wild and unwarrantable enough, and the properties ascribed to it such, in fact, as nothing existing did actually possess: but still there was not necessarily anything magical, either about the supposed nature of the substance itself, or the manner in which it was to be applied, or even the processes and experiments by which it was sought to be discovered. It is quite true that some of the other cultivators of these visionary sciences professed to avail themselves of the aid of spells or spirits, or other supernatural means, in prosecuting their researches; but Bacon never did. The worst that can be said of him is, that his language, when he is speaking of the subject, is occasionally somewhat mystical-which arises, in a great part, it is but fair to observe, merely from his employment of the peculiar and technical phraseology of which the sciences in question, as well as all others, have their share. Nothing, therefore, could be more undeserved than the opprobrium to which he was exposed as a student of necromancy, or as one who ever even professed to work enchantments. It has been said that this calumny only arose many years after his death, and that he himself never was annoyed by it; but both his history and his writings, we cannot help thinking, prove the contrary. In his book on Old Age, he distinctly complains of being hindered from making such experiments as he would have wished, by "the rumours of the vulgar." And in various other passages we find him alluding to the difficulties and dangers which philosophy had to encounter from the same cause. is gratifying, however, to observe, that in whatever spirit this accusation may have been originally

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brought against him, and with however much affected horror his name may have long been regarded by his brother churchmen, who used to nail his books, we are told, to the shelves of their libraries, and to allow them to remain in that state covered with dust, and a prey to the moths and worms, he seems even, in his character of a magician, to have been a favourite with the people in general. In "The Famous History of Friar Bacon," instead of being represented as in league with the powers of evil, we find him, on various occasions, opposing and foiling them in a style that would do honour to any legendary saint in the calendar; and when his fellow conjurers, Bungey and Vandermast, are consigned, at the close of their career, to the usual fate of persons of their craft, he is, by an extraordinary piece of indulgence on the part of the chronicler, released from the dreadful penalty by being made, in a fit of repentance, to burn his books of magic, to turn anchorite, and to study divinity. Everything that is told of him, too, speaks in favour of the kind and generous manner in which he used to dispense his enchantments; and, upon the whole, he is represented to us, in point of moral character, very much in the same light in which his own writings, so evidently the produce of a simple, benevolent, and philosophic spirit, would lead us to regard him. He was, indeed, a genuine lover of knowledge and philosophy, for which he was ever ready to suffer all things,-preferring them infinitely to all things. He unfolds to us, in short, very clearly, what manner of man he must have been, by a single remark: when speaking of one of his projects or contrivances, he calls it, with delightful enthusiasm, an invention of more satisfaction to a discreet head, than a king's crown."

CHAPTER XII,

Professors of Optical Discovery.-Dollond; Ramsden; Herschel; Thomas Phelps and John Bartlett; Fraunhofer; Palitzch.

THE truth, as we have already remarked, with regard to many of the inventions mentioned by Friar Bacon, probably is, that he had rather deduced them as possibilities from the philosophical principles in which he believed, than actually realised them experimentally. Among others, certain optical instruments to which he attributes very wonderful powers existed merely, there can be little doubt, as conceptions of his mind, and had never been either fashioned or handled by him.

The invention of spectacles, however, may be considered as having been traced, on evidence of unusual clearness in such matters, to about the time of the death of Bacon. By the testimony of more than one contemporary writer this useful contrivance is assigned to a Florentine named Salvini degl' Armati; although he, it is said, would have kept the secret to himself, had it not been for another subject of the same state, Father Alexander de Spina, who, having found it out by the exertion of his own ingenuity and penetration, was too generous to withhold from the world so useful a discovery. This was about the close of the twelfth century. From this time magnifying, or burning, lenses continued to be made of various sizes. But nearly three hundred years more elapsed before any additional discovery of much importance was made in optical science; although in the early part of the sixteenth century Mamolicus of Messina, and, soon after him, Baptista Porta, began once more

to direct attention to its principles by their writings and experiments. The latter is said to have first performed the experiment of producing a picture of external objects on the wall of a darkened chamber, by the admission of the light through a lens fixed in a small circular aperture of the window-shutter, the origin of the modern Camera Obscura; and the former made an imperfect attempt to explain the phenomenon of the rainbow. The fortune of ascertaining the true principles of this phenomenon, however, was reserved for Antonio de Dominis, Archbishop of Spalatro, who published his exposition of them in the year 1611.

It appears to have been about this time, also, or not long before, that the telescope was invented; although the accounts that have come down to us regarding this matter are extremely contradictory. As magnifying lenses had been long known, and were commonly in use, nothing is more probable than that, as has been suggested, more than one person may, ere this, have accidentally placed two lenses in such a position as to form a sort of rude telescope; and this may account for various evidence that has been adduced of something resembling this invention having been in use at an earlier period. But what is certain is, that the discovery of the telescope which made it generally known took place only about the close of the sixteenth century. It seems also to be generally agreed, that it was in the town of Middleburg, in the Netherlands, that the discovery in question was made; and moreover, that it was made by chance, although the accounts vary as to who was the fortunate author of it. The story commonly told is, that the children of a spectaclemaker, while playing in their father's shop, having got possession of two lenses, happened accidentally to hold them up at the proper distance from each