' HY SICS TO NATURAL THEOLOGY.

of poor unemployed people, who have heretofore obtained their THE late Earl of BRIDGEWATER bequeathed eight thousand pounds livelihood by trading in foreign merchandise : if, in one day, they sterling to procure to be written and published a work on the should lose the means of gaining a livelihood, the evil consequences Power, Wisdom, and Goodness of God, as manifested in the Crea- te the place would be great." Governor LE was a sensible fellow, tion. Whether it was thought that no single man could write and had more wit than the four-and-twenty Directors. He clearly such a work single-handed, or that eight thousand pounds in these apprehends insurrection ; and if the stoppage of a trade of fifteen times was too great a prize for one individual master of natural millions per annum will not drive an industrious and commercial science, it seemed good to the parties to whom the task was corn- people to rebellion, we know not what will. Then the Governor, mitted to divide the labour, and eke the money, into eight parts. and all the Governor's friends, are in the enjoyment of very large Mr. DAVIES GILBERT, the then President of the Royal Society, perquisites, derived solely from the foreign trade; for Canton is was the person to whom, by the will, was committed the task of the only place where the public officers of China can make a great selecting the writer : one person, however, was not deemed equal . fortune in. Moreover, the Emperor himself derives from the fo- to the charge of choosing the learned man or men, and he asso- reign trade a yearly revenue, which, as the duties on imports alone ciated with himself the Archbishop of CANTERBURY and the Bishop amount to 300,000/. per annum, we suppose cannot be short of of LONDON. It was agreed, as we have here stated, to divide both, half a million, or one twenty-fourth of the revenue of the Em- money and duty into eight parts. The eight gentlemen selected to pire. To part with such a source of income, would be the perform the work Lord PRIDGEWA.TER bad vainly imposed on one, same thine. as parting in this country with a couple of millions a were Dr. CHALMERS, Dr. KIDD, Mr. WHEWELL, Sir CHARLES year : and wesee that the good Lord ALTHORP, with all his eager- BELL, Dr. ROGET, Dr. BUCKL AND, Mr. KIRBY, Dr. PROUT. We ness to lower the taxes and please the people, finds a reduction of will not presume to condemn this arrangement,—first, because all two millions a year impossible. these individuals are men of unexceptionable ability ; and next, be- . With respect to the second question—the probability of extending cause we respect the judgment of the three authorities who decided our commerce to other ports than Canton—we think it very con- on this course. Nevertheless, we cannot help thinking, that the tes- siderable. The feeble Tartar dynasty which first excluded Euro- tator's intentions would have been more fully carried into effect by peans from a general intercourse with the ports of China, is totter- making it worth the while of a man of acknowledged power to de- ing to its fall. During the last seven years, a number of English vote a few years to the completion of the whole task. In that case, ships have visited the Northern parts of China, and traded with he might have bestowed his whole and undivided abilities upon the them to some extent. In the last summer, one of these vessels subject, and thus struck out some novelty, and at any rate brought posted a Chinese placardin the streets of Ningpo, a port in the great to bear the entire weight of modern science on the. labour. This. silk province of Chekian, which was headed "A brief Account of the will now be done, it may be said, by eight minds instead of one. English Character," and was signed " A Friend to China and Each of these eight minds may not, however, collectively feel the . England." Placards of a similar character, inviting to trade, it great interest and responsibility in the undertaking that one would: appears, have been posted as far north as the maritime and rich the theme may not be so powerfully urged when divided into eight. province of Shantong, in the 28th degree of latitude. In reference channels, as it might have been had the whole matter descended to this particular ship, one of the Canton journals (for there are two in one grand stream of argument. There must now be consider- English newspapers, and about 140 British residents at the place) able repetition; some interference with each other; the same con- observes—" The merchants were found everywhere eager to put- elusions must be drawn continually from different arguments,. chase British manufactures ; but, owing to the opposition of the which might as well have been urged with the united force of va- Mandarins, we believe that sales were effected only at the port of rims illustrations.

fourth of what 'We give to our Governor-General in India, with The subject assigned to the Tutor of Trinity College is the most. about the same number of souls to govern. The Companion to the mathematical, or, in common parlance, the most abstract of the Kalendar, we-should add, although containing no more than 160 whole eight: it is yet, however, managed with so much mastery duodecimo..pages, embraces almost every kind of local information of its whole range, and with such evidence of a habit of scientific . which a merchant resorting to China would desire to possess. We exposition, that it is not merely intelligible, but deeply interesting . recommend it to.our readers ; and we would recommend to some of to the reader of any ordinary education. Its grand object is to ourenterprishig publishers . to reprint it, before. the opening of the. exhibit the evidences of design in the Earth and its productions,

_. .. .. . . that evidences of design and the most elaborate • contrivance are everywhere evident, and force themselves upon the least observant and the most unreflecting : and in this view the Bridgewater Treatises may be held as unnecessary. It was, however, impor- tant to be shown thatithe extensive modern discoveries of science —the nearer view our philosophers had got into its arcana—did not militate against the conclusions obtained in former times. The still more important view which may be taken of these treatises, is not the light they cast upon Natural Theology—which, truly, wants none—but the light they reflect on natural science: its rela- tions, its mutual adaptations, its curious phenomena, the initiation into its secrets, the reward of a sincere love of truth, and a severe mental discipline, are all exhibited in this treatise under so beauti- ful an aspect, that the student can hardly fail, though his resolution may be but transient, to abjure the grovelling intrigues, the selfish passions, the degrading influences of the world, and dedicate him- self, or aspire to dedicate himself, to the ennobling pursuit of knowledge.

Such a work as this, close, lucid, connected, and equal, is ill adapted for extract in a newspaper. Ours is scarcely the diapha- nous light in which the minuter and more delicate organization of this description of reasoning can be beneficially exhibited. The experiment, may, however, be tried by quoting the chapter on

Light.

Besides the hearing and sound, there is another mode by which we become sensible of the impressions of external objects, namely, sight and light. This subject also offers some observations bearing on_our present purpose.

It has been declared by writers on natural theology, that the human eye ex- hibits such evidence of design and skill in its construction, that no one who coLl siders it attentively can resist this impression : nor does this appear to be saving 'ton much. It must, at the same time, he obvious that this construction of the

eye could not answer its purposes, except the constitution of light corresponded In it. Light is an element of the most peculiar kind and properties ; and such an element can hardly be conceived to have been placed in the universe without a regard to its operation and functions. As the eye is made-for light, so light .must have been made, at least among other ends, for the eye. I. We must expect to comprehend imperfectly only the mechanism of the elements. Still, we have endeavoured to show that in some instances the ar- rangements by which their purposes are effected, are, to ii certain extent, intelli- gible. In order to explain, however, in what manner light answers those ends which appear to us its principal ones, we must know something of the nature of light. There have, hitherto, been, among men of science, two prevailing opinions upon this subject : some considering light as consisting in the emission of luminous particles ; others accounting for its phenomena by the propagation of vibrations thraugh a highly subtile and elastic ether. The former opinion has, till lately, been most generally entertained in this country, having been the hypo- thesis on which Newton made his calculations ; the latter is the one to which most of those persons have been led, who, in recent times, have endeavoured to deduce general conclusions from the newly-discovered phenomena of light. Among these persons, the theory of undulations is conceived to be established in nearly the same manner, and almost as certainly, as the doctrine of universal

gravitation; naruelv, by a series of laws inferred from numerous facts, which, proceeding from different sets of phenomena, are found to converge to one coin- anon view ;' and by calculations founded upon the theory, which, indicating new and untried facts, are found to agree exactly with experiment.

We Cannot here introduce a sketch of the progress by which the phenomena have thus led to the acceptance of the theory of undulations. But this theory appears to have such claims to our assent, that the views which we have to offer with regard to the design exercised in the adoption of light to its purposes, will depend on the undulatory theory, so far as they depend on theory at all. 2. The impressions of sight, like those of hearing, differ in intensity and in kind. Brightness and colour are the principal differences among visible things, as loudness and pitch are among sounds. But there is a singular distinction .between these senses in one respect : every object and part of an object seen, is necessarily and inevitably referred to some position in the space before us ; and hence visible things have place, magnitude, form, as well as light, shade, and colour. There is nothing analogous to this in the sense of hearing ; for though we can, in some approximate degree, guess the situation of the point from which

&sound proceeds, this is a secondary process, distinguishable from the percep- tion of the sound itself; whereas we cannot conceive visible things without form and place.

The law according to which the sense of vision is thus effected, appears to be this. By the properties of light, the external scene produces, through the trans- parent parts of the eye, an image or picture exactly resembling the reality, upon

the back part of the retina: and each point which we see is seen in the direction of a line passing from its image on the retina, through the centre of the pupil of the eye. In this manner we perceive by the eye the situation of every point, at the same time that we perceive its existence; and by combining the situations of many points, we have forms and outlines of every sort. That we should receive from the eye this notice of the position of the object as well as of its other visible qualities, appears to be absolutely necessary for our intercourse with the external world; and the faculty of doing so is so intimate a part of our constitution, that we cannot conceive ourselves divested of it. Yet, in order to imagine ourselves destitute of this faculty, we have only to sup- pose that the eve should receive its impressions as the ear does, and should ap- prehend red arid green, bright and dark, without placing them aide by side; as the ear takes in the different sounds which compose a concert without attribut- ing them to different parts of space.

The peculiar property thus belonging to vision, of perceiving position, is so essential to us, that we may readily believe that some particular provision has

been made for its existence. The remarkable mechanism 'of the eye (precilely resembling that of a camera obscura), by which it produces an image on the nervous web forming its binder part, seems to have this effect for its main ob- ject. And this mechanism necessaily supposes certain corresponding properties in light itself, by means of which such an effect becomes possible. The main properties of light which are concerned in this arrangement; are re- flexion and refraction : reflexion, by which light is *fleeted and scattered .by. an objects, and thus comes to the eye from all; and refraction, by which hs, course is .bent, when it passes obliquely out of one transparent Medium into another ; and by which, consequently, convex transparent substances, such as the cornea and humours of the eye, possess the power of making the light con- verge to a focus or point ; an assemblage of such points forming the images on the retina, which we have mentioned.

Reflexion and refraction are, therefore, the essential and indispensable proper- ties of light; and so far as we can understand, it appears that it was necessary that light should possess such properties, in order that it might form a medium

of communication between man and the external world. We may consider its power of passing through transparent media (as air) to be given in order that it away enfighten the earth ; its affection of refiezion, fur the purpose of malsiiag

eidours visible; and its refraction to be bestowed, that it may enable us to dis- criminate figure and position, by means of the krises of the eye.

In this manner light may be considered as constituted with a peculiar reference to the eyes of animals, and its leading properties may be looked upon as contriv- ances or adaptations to fit it for its visual office. And in such a point of view, the perfection of the contrivance or adaptation must be allowed to be very re- markable.

3. But besides the properties of reflection and refraction—the most obvious laws of light—an extraordinary variety of phenomena have lately been discovered, regulated by other laws of the most curious kind, uniting great complexity with great symmetry. We refer to the phenomena of diffraction, polarization, and periodical colours, produced by crystals and by thin plates. We have, in these facts, a vast mass of properties and laws, offering a subject of study which has been pursued with eminent skill and intelligence. Bat these properties and laws, so far as has yet been discovered, exert no agency whatever, and have no purpose, in the general economy of nature. Beams of light polarized in con- trary.directions exhibit the most remarkable differences when they pass through certain crystals, but manifest no discoverable difference in their immediate im- pression on the eye. We have, therefore, here, a number of laws of light, which we cannot perceive to be established with any design which has a reference to the other parts of the universe. Undoubtedly, it is exceedingly possible that these differences of light may Operate in some quarter, and in some way, which we cannot detect ; and that these laws may have purposes and may answer ends of which we have no sus- picion. All the analogy of nature teaches us a lesson of humility, with regard to the reliance we are to place on our discernment and judgment as to such matters. But with our present knowledge, we may observe, that this curious system of phenomena appears to be a collateral result of the mechanism, by which the effects of light are produced; and therefore a necessary consequence of the existence of that element of which the offices are so numerous and so beneficent.

The new properties of light, and the speculations founded upon them, have many persons to the belief of the undulatory theory ; which' as we have sa, is considered by some philosophers as demonstrated. If we adopt this theoryy we consider the luminiferous ether to have no local motion ; and to produce re- fraction and reflexion by the operation of its elasticity alone. We must neces- sarily suppose the tenuity of the ether to be extreme ; and if we moreover sup- pose its tension to be very great, which the vast velocity of light requires us to. suppose, the vibrations by which light is propagated will be transverse vibra- tions, that is, the motion to and fro will be athwart the line along which the undulation travels ; and from this circumstance all the laws of polarization ne- cessarily follow. And the properties of transverse vibrations, combined with

i the properties of vibrations n general, give rise to all the curious and numerous phenomena of colours of which we have spoken. If the vibrations be transverse, they may be resolved into two different planes; this is polarization : if they fall on a medium which has different elasticity in different directions, they will he divided into two sets of vibrations ; this is double refraction; and so on. Some of the new properties, however, as the fringes of shadows and the colours of thin plates, follow from the undulatory theory, whether the vibrations be transverse or not. It would appear, therefore, that the propagation of light by means of a subtile medium, leads necessarily to the extraordinary collection of properties which have recently been discovered ; and, at any rate, its propagation by the trans- verse vibrations of such a medium does lead inevitably to these results.

Leaving it, therefore, to future times to point out the other reasons (or uses if they exist) of these newly-discovered properties of light, in their bearing on other parts of the world, we may venture to say, that if light was to be propa- gated through transparent media by the undulations of a subtile fluid, these pro- perties must result, as necessarily as the rainbow results from the unequal re- frangibility of different colours. This phenomenon and those, appear alike to be the collateral consequences of the laws impressed on light with a view to its principal offices.

Thus the exquisitely beautiful and symmetrical phenomena and laws ofpolar- ization, and of crystalline and other effects, may be looked upon as indications of the delicacy and subtilty of the mechanism by which man, through his visual organs, is put in communication with the external world; is made acquainted with the forms and qualities of objects in the most remote regions of space ; and is enabled, in some measure, to determine his position and relation in a universe in which he is but an atom.

• 4. If we suppose it clearly established that light is produced by the vibrations of an ether, we find considerations offer themselves similar to those which oc- curred in the case of sound. The vibrations of this ether affect our organs with the sense of light Ind colour. Why, or how do they do this? It is only within certain limits that the effect is Produced, and these limits are comparatively nal-tower here than in the case of sound. The whole scale of colour, from violet to crimson, lies between vibrations which are 458 million millions, and '727 million millions in a second ; a proportion much smaller than the corresponding ratio for perceptible sounds. Why should such vibrations produce perception in the eye, and no other? There must be here some peculiar adaptation of the sensitive powers to these wonderfully minute and condensed mechanical motions. What happens when the vibrations are slower than the red, or quicker than the blue? They do not produce vision : do they produce any effect? Have they any thing to do with heat or electricity? We cannot tell. The ether must be as susceptible of these vibrations, as of those which produce vision. But the mechanism' of the eye is adjusted to this latter kind only ; and this precise kind (whether alone or mixed with others), proceeds from the Sun and from other luminaries, and thus communicates to us the state of the visible universe. The mere material elements, then, are full of properties which we can understand no otherwise, than as the results of a refined contrivance.