and the teeth of one fibre lock into those of the adjacent ones; in order no doubt to strengthen and give body to the frail morsel of transparent jelly into which they are so marvellously moulded.

In the lens of a cod four-tenths of an inch in diameter, the number of fibres is about five millions, and the number ofteeth by which the fibres are bound together is sixty-two thousand five hundred millions; and as every tooth has three surfaces, the number of touching-surfaces will be one hundred and eighty-seven thousand five hundred millions; and yet this little sphere of tender jelly is as transparent a drop of the purest water, and allows a beam of light to pass across these almost innumerable joints without obstructing or reflecting a single ray!

But the lenses of animals exhibit another structure more perplexing, though not less wonderful. While the human lens exhibits only one structure of diminishing density from the centre to the surface, the purpose of which is to correct spherical aberration, the lenses of quadrupeds display three different structures of varying densities, separated by neutral lines; in which lines a density decreasing outwards passes into a density increasing outwards. In the lens of the horse, this succession of structures is finely displayed; and when the animal has attained a great age, the densities of the inner and the outer structure have become uniform throughout, while the middle one exhibits a varying density more strongly marked than in the young lens, and exbibiting by polarized light a brilliant yellow colour, like the most perfect films of regularly crystallized bodies. That these structures are intended to correct spherical aberration, or to improve vision, cannot be doubted; but another century may pass before we discover the principles on which that correction or improvement depends.

In describing those properties of the eye which are peculiarly indicative of design, our authors have committed an oversight which it is essential to correct. In our first extract from Lord Brougham's 'Discourse,' it is stated as a truth, in both physics and theology,' that the eye is framed on the same principle as that of the compound or achromatic object glass; and that it is far more perfect than the achromatic glass of Dollond. Sir Charles Bell, though apparently aware that this statement was not perfectly correct, has yet repeated it, in substance, in his 17th note: Some modern philosophers have asserted that the

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* Phil. Transactions, 1833, p. 324,

the eye has been accurately measured; its different focal lengths for red and violet light have been determined accurately by Young and Frauenhofer; and the latter has found it necessary to correct the dispersion of the eye in the construction of his achromatic object glasses. The natural theology of the non-achromatism of the eye is given with great force and truth by Dr Blair in the paper referred to. Natura nihil agit frustra' (says he). The perfection of the contriver equally appears from a manifestation of his power, and of his economical exertion of that ¿ power.' The idea, indeed, that the eye would answer the purposes of vision more perfectly if it were achromatic, is founded on a hasty analogy. Because an achromatic telescope or microscope is superior to the same instruments when not rendered achromatic, it is supposed that an achromatic eye should have the same superiority. It is well known to opticians that an achromatic lens is not so well fitted for a camera obscura as a common lens. There is a very great difference, however, between the two cases. In a common telescope and microscope the colour, or dispersion of the object lens, is not only great in itself-increasing with its aperture and focal length; but it is greatly magnified by the eye-glass. But there is another difference between the two cases still more essential. In using a telescope or microscope, the eye views in succession every part of the image which they form, and sees the prismatic colours increasing from the centre to the circumference of the field. But there is no eye behind the retina to view in the same manner the image which is thrown upon that membrane. In fact the cannot see the colours of the lateral pencils, because it is incapable of seeing any object distinctly, unless it is situated in or near its axis; and hence it is of no importance whatever to render the image achromatic at a distance from the axis. When we wish to examine an object, or a part of an object, with minute attention, we direct to it the axis of the eye; and in order to obtain a sensibly colourless vision in or near the axis, achromatic compensation is not necessary. It is no doubt true that even in this axis there is a non-coincidence of the foci of the differently coloured rays; but owing to the shortness of the focal distance of the eye, and the low dispersive power of the humours, this non-coincidence of the different foci does no injury to our ordinary vision.

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Such is a rapid, though, we trust, a faithful analysis of a remarkable work. Its appearance at a time when the series of Bridgewater Treatises' have nearly exhausted its subject, may somewhat limit its circulation. But in its bold and spontaneous appeal to our reason, there is a moral power which the

best executed tusks are unable to develope-and a germ of activity and life which reside only in unbidden labour. He who girds himself for the forlorn hope combats under a holier spell than the readiest auxiliary or the most willing conscript. The enthusiasm of self-devotion, while it inspires courage, propagates also terror; and the moral power of one unflinching heart has often routed the physical array of thousands. The age is doubtless past when ridicule or danger are to be encountered in the defence of truths eternal and immutable; and the time, we hope, will never arrive when high and honoured names shall be again associated with all that is unsound in moral and mischievous inscepticism. A brighter era has now dawned, in which genius will fulfil its highest destiny, and all that is brilliant in talent and elevated in virtue be marshalled in the cause of our moral and religious interests. Already have the arrows from many a mighty quiver stricken the once dreaded arm of the sceptic; and among nations yetin darkness shall the magic of many a deathless name draw round our faith its mystic circle of light and of knowledge. The labours of one of the last and ablest of these defenders of the truth are now before the public; and at no former period have the principles of natural and revealed religion been more powerfully and generously supported. When Lord Broughain's eloquence in the senate shall have passed away, and his services as a statesman shall exist only in the free institutions which they have helped to secure, his 'Discourse on Natural Theology' will continue to inculcate imperishable truths, and fit the mind for that higher revelation which these truths were destined to foreshadow and confirm.

ART. II.-1. Œuvres Complètes de Ch. PAUL DE KOCK. Paris: 1834.

2. Zizine. Par Ch. PAUL DE KOCK. 4 vols. 12mo. Bruxelles: 1836.

TH HERE is a species of popularity which is often detrimental, for a time, to the reputation of an author. Some books start into favour amongst a miscellaneous and indiscriminating class, without passing the ordeal of more critical and reflective readers. The vulgar, while they approve, are not quite certain whether they ought to admire; and they contract a sort of easy familiarity with those literary acquaintances of whose rank they are not assured, which is less respectful than it might be, if they found their own opinion sanctioned by the scholastic and fastidious few. Thus, for a long time, Bunyan's Pil'grim's Progress' was one of the most popular books in our language, though it is only of late years that the very high quality of genius which characterises that remarkable allegory has been understood or appreciated. The Pilgrim's Progress would, perhaps, have attained a higher reputation had its popularity been less extensive. On the other hand, when the fame of an author is confided, as it were, to the care of a few disciples, it becomes a kind of jealous and exclusive worship; the initiated admire and extol yet the more vehemently for the indifference of the ordinary public; and they even resent as an impertinence the intrusive homage which wider circles begin at length to render to their idol. Thus Wordsworth has been claimed as a sacred monopoly by a handful of unexamining enthusiasts, who will neither allow a rival, nor listen to a critic. Warburton and St Croix never indulged wilder reveries about the Eleusinian Mysteries than a few speculative imitators and adulators have imposed upon the public with respect to the symbols and secrets which their great Hierophant of Poetry is supposed to reveal. We want no Lobeck to convince us that the konx aud ompax of their ceremonial solemnities are but the hey presto of a fanatical juggling. In fact, what is permanently popular must ever be founded upon such successful appeals to the common sense, or the universal passions of mankind, as criticism itself no sooner examines than it is compelled to approve; while, in return, what is really and lastingly admirable to a few enlightened and discerning minds, will ultimately pass into that wide and general circulation which is the proper element of true genius, and the surest test of its fidelity to the laws of nature, and the great principles of art. In litera