of rays on fubitances-for inftance, to compare either their various powers of heating, or of feparating oxygen, or of discharg ing colour, or (which equally merits notice) of affecting odour and talle, we must evidently operate upon the genuine kinds of fimple homogeneous rays contained in the fun's light decompofed by the prifm. This is the only fair, unequivocal mode of making experiments on different forts of homogeneous light; and fo excellent an optician as Professor Venturi, must have at once reforted to it, had he not entertained an unfortunate, but not unnatural, predilection for the form of procefs which he had himfelf invented, and whofe merits, in other cafes, we do not at all deny. But whatever may be our opinion as to the eligibility of this method of inquiry, we can entertain no doubt of the ingenuity with which it is made fubfervient to the author's deductions, and ftill lefs can we withhold our applaufe from the fingular modefty of the style in which he concludes this branch of his refearches. It is perhaps referved (fays he) for the induftry of the age which is now opening, to determine with certainty the true reafon of the detention of light in those coloured bodies, which owe their tints to the tranfmiffion of light alone. We must reft contented with having barely proved the fact; happy if we have only fucceeded in feparating from each other, the four great operations by which colour is produced, fo that the ftudents of this fcience may not hereafter be induced to push farther than experience juftifies, thofe laws, whofe exiftence experience has difclofed.' p. 74. IV. We now come to the last part of this valuable work, and it is inferior to none of the others, either in the ingenious originality of its combinations of facts (our author's characteristic quality), or in the clear and lucid manner of its detail. The fubject is the colours known by the names of accidental colours, imaginary colours, and ocular spectra. Thefe appearances have formerly excited much attention. Profeffor Venturi difcuffed their nature in a paper which gained the prize in the Society of Modena; and he now gives the outlines of the doctrines then advanced, with the confirmations added by his fubfequent experiments. If he has given no new information relative to the caufes of that phenomenon, we must admit, that he has at least added much to our knowledge of its circumstances, and has, by reafoning upon thofe circumstances, brought to light feveral interefting particulars regarding the law of their combinations. We prefent our readers with the propofitions, in which his theory is condensed: 1. The imaginary colour left in the retina, is always the fame from from the fame real colour, whether that real colour be fimple or mixed. 2. The imaginary colours are produced in the retina in utter darkness, after it has been impreffed with the real colours; and the real colours produce the imaginary ones in the following order: Red produces a tint between green and blue; orange an indigo; a colour between green and yellow gives a violet; a colour between green and blue gives a red; indigo gives an orange; and violet gives a tint between green and yellow. Thus, we fee that the imaginary and real colours are always oppofite to each other; and that if any imaginary colour B is produced by any real colour A, then the real colour B produces the imaginary colour A. 3. The nature of the fentient fibre of the eye is fuch, that when once excited, it continues of itself certain conceived motions or fenfations, only changing and modifying them according to peculiar and regular laws. 4. The union or fucceffion of different colours is agreeable and harmonious, provided the combined or confecutive colours are fo related to each other, that the one is the imaginary colour produced by the other, when real. Thus, red and green are often obferved to produce, when mixed, or following each other, an agreeable effect. Leonardo Da Vinci promifed to reprefent, in a general enumeration, the colours which harmonize in a picture. Unfortunately, he has not executed the plan. But others have given detached remarks on this fubject. Thus, Newton obferves, that orange and indigo agree well together. And Virgil (an authority of a very different defcription) fays, Mollia luteola pingit vaccinia caltha.' Now, it may be observ ed, that orange is the imaginary colour produced by a real indigo, and converfely. Raphael Mengs, too, fays that yellow and violet harmonize admirably together. Now, the tint of violet correfponds to a tint between green and yellow. The fame painter adds, that red, yellow, and blue do not harmonize together; but that each of these harmonizes with the intermediate colour of the other two; by which he means, that red harmonizes with green, yellow with violet, and blue with orange. A fimilar conclufion, very nearly, might have been drawn, à priori, from the above propofition, by infpecting the lift of relations formerly given (prop. 2.), between the real and Imaginary colours. Farther, it has been found in the theory of mufic, that a found leaves in the ear the fenfation of its twelfth, or the octave of its fifth; and from thence are derived the less perfect concords. Now, it is very remarkable, that if we divide the fpectrum of fimple colours according to the Newtonian rule, the tints which harmonize according to the propofition under confideration are exactly fifths to each other. Thus, it may be inferred, that the rules of harmony in founds and in colours are exactly fimilar; and we trace, in this manner, a beautiful analogy between the fenfes of hearing and fight-an analogy which future difcoveries may perhaps extend to the fenfes of fmell and taste. Our author, however, adds an ingenious fpeculation, of a more general nature, upon the barmony of ideas. He obferves, that univerfal experience in oratory, painting, architecture, poetry, as well as in the logic of fcientific claffifications, proves two diftinct points, firft, that the union of fimilar objects gives a certain pleasure to the mind, viz. the pleafure derived from order, regularity, uniformity; fecondly, that a certain pleasure is alfo derived from the appofition of extremes, viz. the pleasure of contraft. Hence, he infers that a law regulates all our mental pleasures in this particular, fimilar to the fpecial law of calorific harmony above demonftrated, viz. that thofe ideas or fenfations are harmonious together, which, by the conftitution of our minds, are mutually exchangeable. 5. If a real colour is impreffed on the retina more ftrong than one formerly impreffed, not one, but feveral different imaginary colours fucceed it. This curious propofition our author demonftrates by very decifive experiments; and he fhews that it is true of all fucceffions of the prifmatic colours. 6. The fenfations of different colours depend, not on different orders of fibres in the fenforium, but on different movements of the fame fibres. Such language is much more theoretical, than the idea contained in the affertion. Our readers will eafily perceive, that, without fpecifying the place or manner of fenfation, and without any reference to the fenforium, as our author calls it, a true propofition is couched in the above terms. 7. If the rays of any kind whatever ftrike the eye with fuffcient force, a fenfation of white is produced. This fingular propofition, that the fenfation of white depends not on the mixture, but on the intensity of the light which produces it, is proved in the following manner: If a spot of red light, feparated in whatever way from the other rays, is looked at on a white paper, no colour but red is feen. But if those red rays fall on the eye, the image of the luminous body is white, except at its outer edges, which are tinged red. And our author attempts to fhow by fome calculations on the intensity of beams, that this effect ought not to be produced, by concentrating the fame red rays on a chart, by means of a lens, but only when they fall directly on the eye. We are inclined altogether to deny this propofition; to afcribe the the event of the experiment to fome deception produced in the eye, by the mixture perhaps of imaginary with real colours; and to maintain that if the mere increased intenfity of the red rays produced the fenfation of white, that colour fhould certainly appear on the chart, provided the red rays, feparated by any means from a fufficiently large beam of light, were condenfed by a lens, and the focus received on the chart. On the contrary, the more intenfe this focus of red rays is, the deeper is the red produced. 8. An imaginary and a real colour coinciding together mutually temper and mix with each other, exactly like two real colours. This propofition is proved by feveral very ingenious and original, experiments. We have now only to return our thanks to the author for the pleasure derived from the perufal of his very valuable work; to recommend it earnestly to the attention of our fcientific readers; and to express our hopes, that his new vocation* will not interfere with the farther profecution of ftudies far more dignified and delightful to a rational creature, than the intrigues of courts, or the vulgar turmoil of republican factions. ART. III. Poems from the Portuguese of Luis de Camoens, with Reremarks on his Life and Writings. Notes, &c. &c. By Lord Viscount Strangford. Printed for J. Carpenter, London, 1803. ΤΗ THE minor poems of Camoens are held fo low in the estimation of the Portuguese themselves, that it cannot be confidered as matter of much furprife, that their merits fhould be but little known among foreigners. Vain of having produced the first, we may fay the only epic poet that has adorned their peninfula, his countrymen are too apt to neglect his fmaller compofitions, and to undervalue that originality of fentiment, and that ftrong and genuine expreffion of feeling in which they abound, and which claim for their author (as ftrongly perhaps as the boasted Lufiad itself) the character of a poet. Such being our opinion with regard to these pieces, we were much gratified at learning that a young perfon, diftinguished by his rank, and poffeffing a talte capable of difcerning their neglected beauties, poffeffed at the fame time fufficient induftry to undertake to tranfplant thefe beauties into his native foil. Under the influence of thefe confiderations, we Profeffor Venturi has lately been named ambaffador from the Italian Republic to the Helvetic Body. we had been led, fomewhat unreasonably perhaps, to form expectations of Lord Strangford's performance, which have not been completely realifed; for, however we may have been gratified in the perufal of this little volume, by the eafy verfification, and the lively, though too often licentious imagination which it exhibits, we must own that we have not, upon the whole, derived from it that fatisfaction which we were at one time inclined to anticipate. What part of our difappointment is to be attributed to the extravagance of our own ideas, and what to the infufficiency of Lord Strangford's tranflation, will beft appear from a fhort confideration of the work itself, and a comparison of it with its original. The poems, indeed, we muft obferve, in the first place, cannot honestly be termed tranflations from Camoens. The office of a tranflator requires, first, that he should exprefs, in general, faithfully the ideas of his author; and, fecondly, that his manner of expreffing them fhould approach, as nearly as the difference of the Janguages will permit, to the ftyle of the work which he tranflates. We will not fay that Lord Strangford has failed in both thefe points; he writes with too much facility to allow us to suppose that he could have been at a loss for language, had he made the attempt; but, that he has totally neglected them, no one who compares any one of thefe pieces with the original, will hefitate to admit ; and though the diffidence with which his work is offered to the public, entitles it, in other refpects, to confiderable indulgence; the confident affertion contained in his prefatory remarks (p. 31.), that, for the most part, he has clofely copied his author,' challenges, upon this ground at least, a feverer examination, more especially as the affectation of apologifing now and then, by a note, for an infignificant deviation from his original, would feem to imply, that, where fuch apologies are omitted, no deviation has been made. The fourth fonnet in Lord Strangford's tranflation will ferve to illuftrate this remark; and we shall tranfcribe the whole piece, not as being a very accurate translation, but because, fuch as it is, it is lefs disfigured by those prettineffes with which Lord Strangford has thought it neceffary to embellish his original, and is therefore better calculated to give fome idea of the style of the Portuguese poet. Slowly and heavily the time has run Which I have journey'd on this earthly ftage; And fince, compulfive, Fate and Fortune's rage In fearch of loft repofe, but finding none ! Forc'd |
