[268] Andrès, ii. 92, gives on the whole the best account of the progress of numerals. The article by Leslie in the Encyclopædia Britannica is too dogmatical in denying their antiquity. That in the Encyclopædia Metropolitana, by Mr. Peacock, is more learned. Montucla is as superficial as usual; and Kästner has confined himself to the claims of Gerbert, admitting which, he is too indifferent about subsequent evidence.
Mathematical treatises. 31. Adelard of Bath, in the twelfth century, translated the elements of Euclid from the Arabic, and another version was made by Campanus in the next age. The first printed editions are of the latter. The writings of Ptolemy became known through the same channel; and the once celebrated treatise on the Sphere by John de Sacro Bosco (Holywood, or, according to Leland, Halifax) about the beginning of the thirteenth century, is said to be but an abridgment of the Alexandrian geometer.[269] It has been frequently printed, and was even thought worthy of a commentary by Clavius. Jordan of Namur (Nemorarius) near the same time, shows a considerable insight into the properties of numbers.[270] Vitello, a native of Poland, not long afterwards, first made known the principles of optics in a treatise in ten books, several times printed in the sixteenth century, and indicating an extensive acquaintance with the Greek and Arabian geometers. Montucla has charged Vitello with having done no more than compress and arrange a work on the same subject by Alhazen; which Andrès, always partial to the Arabian writers, has not failed to repeat. But the author of an article on Vitello in the Biographie Universelle repels this imputation, which could not, he says, have proceeded from any one who had compared the two writers. A more definite judgment is pronounced by the laborious German historian of mathematics, Kästner. “Vitello,” he says, “has with diligence and judgment collected, as far as lay in his power, what had been previously known; and, avoiding the tediousness of Arabian verbosity, is far more readable, perspicuous, and methodical than Alhazen; he has also gone much farther in the science.”[271]
[269] Montucla, i. 506. Biogr. Univ., Kästner.
[270] Montucla. Kästner.
[271] Gesch. der Mathem. ii. 263. The true name is Vitello, as Playfair has remarked (Dissertat. in Encycl. Brit.), but Vitello is much more common. Kästner is correct, always copying the old editions.
Roger Bacon. 32. It seems hard to determine whether or not Roger Bacon be entitled to the honours of a discoverer in science; that he has not described any instrument analogous to the telescope, is now generally admitted; but he paid much attention to optics, and has some new and important notions on that subject. That he was acquainted with the explosive powers of gunpowder, it seems unreasonable to deny: the mere detonation of nitre in contact with an inflammable substance, which of course might be casually observed, is by no means adequate to his expressions in the well-known passage on that subject.[272] But there is no ground for doubting that the Saracens were already conversant with gunpowder.
[272] This has been suggested by Professor Leslie, in the article on arithmetic above quoted; a great chemical authority, but who had not taken the trouble to look at Bacon, and forgot that he mentions charcoal and sulphur as well as nitre.
His resemblance to Lord Bacon. 33. The mind of Roger Bacon was strangely compounded of almost prophetic gleams of the future course of science, and the best principles of the inductive philosophy, with a more than usual credulity in the superstitions of his own time. Some have deemed him overrated by the nationality of the English.[273] But if we may have sometimes given him credit for discoveries to which he has only borne testimony, there can be no doubt of the originality of his genius. I have in another place remarked the singular resemblance he bears to Lord Bacon, not only in the character of his philosophy, but in several coincidences of expression. This has since been followed up by a later writer,[274] (with no knowledge, probably, of what I had written, since he does not allude to it), who plainly charges Lord Bacon with having borrowed much, and with having concealed his obligations. The Opus Majus of Roger Bacon was not published till 1733, but the manuscripts were not uncommon, and Selden had thoughts of printing the work. The quotations from the Franciscan and the Chancellor, printed in parallel columns by Mr. Forster, are sometimes very curiously similar; but he presses the resemblance too far; and certainly the celebrated distinction, in the Novum Organum, of four classes of Idola which mislead the judgment, does not correspond in meaning, as he supposes, with the causes of error assigned by Roger Bacon.
[273] Meiners, of all modern historians of literature, is the least favourable to Bacon, on account of his superstition and credulity in the occult sciences. Vergleichung der Sitten, ii. 710, and iii. 232. Heeren, p. 244, speaks more candidly of him. It is impossible, I think, to deny that credulity is one of the points of resemblance between him and his namesake.
[274] Hist. of Middle Ages, iii. 539. Forster’s Mahometanism Unveiled, ii. 312.