1 bright to dark, from red to yellow, to blue, through all the varied tints which gild the firmament, according as the interference interval is changed by the slightest elevation or depression of the plate, or change of position of the source of light, or of the eyes and yet to know that every colour is subjected to its law; that in these intervals, almost immeasurably small, we can demonstrate the same presiding principle of permanence and harmony, which, on a scale, to our weak minds as transcendently immense, governs the motions of the earth we tread, and binds together the maze of worlds within, which even from our minuteness we disappear. buk Notwithstanding the complexity of the phenomena which we have endeavoured to. describe, and the abstract nature of the speculations on which even the attempt to explain their origin must be founded, we have not arrived at the last of the wonderful discoveries recently made in optics, and in which our country has taken an elevated place.We have spoken of a ray of light as being produced by the motion of waves, almost infinitely small, but we must go deeper. Is this ray of light extended through space in a straight cylinder, like a wire or thread? That would certainly be the simplest view, but it is not the true one; the true ray of light is flat like a ribband; it has sides, as Newton said. In common light; however, there are always two of these simpler rays conjoined, the side of one corresponding to the edge of the other; and hence, if we could see the front of such a ray, it would present the form of a cross, thus In ordinary light, any effects depending on the properties of edge or flat, are neutralized by edge and flat acting together, and in opposition; but these rays may be separated by any one of a variety of methods, and then they are found to possess properties of an exceedingly interesting kind. There are crystals, such as tourmaline, which have a sort of gridiron structure, through which one ray slips, whilst the other is arrested in its course. Again, if a piece of slate be thrown obliquely on, the surface of the water, it will pass through and sink if the edge come first, but if the flat strike the water it will then be reflected upwards; so with light, a ray of light falling on water is partially, indeed, at a particular angle wholly, separated into its two component, rays; that striking with the edge being the refracted, that striking with the flat being the reflected ray, and heuce, those rays possess properties of au exactly H •{{) " opposite kind, except that they do not interfere. The two rays, thus obtained from one of common light, are said to be polarized, a word still retained, although the imperfect theory from which it rose has long since been abandoned. They are said to be polarized in opposite planes, as their sides, that is, the planes in which the vibrating particles move, are at right angles to each other. They do not interfere, for two motions at right angles cannot destroy each other; but if the planes of polarization by any means be changed, then interference, and consequent destruction of one portion of light occurs. This is now accomplished by apparatus, which has become so popular, as to have almost more of a drawing-room than of a scientific character; by transmitting white light, polarized, through thin films of doubly refracting crystals, and then changing the plane of polarization. With one thickness, the red light is lost, and an image of beautiful green appears; with another thickness the red and yellow is lost, and blue appears; and by another change of plane, the light previously destroyed is let to pass onward to the eye, whilst that portion which had previously found passage is stopped short; hence, a series of images, in colours the converse of the former: in place of red, we have green; in place of purple, yellow; the two sets being, in all cases, such as would, by mixture, produce white light and leave no trace of colour. In all the range of science, there are no phenomena so beautifully attractive to young minds as those we have noticed. We cannot conceive a disposition so inert, as not to be startled into inquiry after the secret organization of those simple films of selenite or mica, which, by the aid of two slips of blackened glass, give sights so gorgeous and so ever. varying. Light is thus polarized by reflection and refraction at the surface of every substance, and the accurate solution of the question, how much light passes in, and how much is thrown back, even in the simple case of a common singly refracting substance, formed no mean ornament, even in the brilliant crown of scientific triumphs which graced Fresnel; but to the general problem of doubly refracting crystals no adventurous philosopher had approached. In these, all simplicity or symmetry appeared completely lost-two refracted rays, polarized in opposite planes; a reflected ray, liable to be twisted out of the plane of incidence, through variable angles. It constituted the most involved, but the most important question in the higher physics, to which mathematical reasoning could be applied. In this state, our James M'Cullagh took it up. Setting out from considerations of force of an exceedingly refined kind, and correcting, in an important manner, some of the leading postulates of the theory previously received, he deduced a series of laws, expressing, with wonderful precision, all the results which experience had previously given. From his simple hypothesis, all the minute measurements and complicated changes in the direction and brilliancy of the reflected and refracted lights, at once and necessarily flowed; and thus the general problem, which, brought into shape by Newton and Huyghens, had, by experimental research, outgrown itself, until it became, even in the most powerful hands, unmanageable, was solved in Dublin. We have just reason to boast of this. Even in the favoured lands of continental Europe, such triumphs, in the most difficult investigations to which human intellect can be applied, would have been received with reverence by the public, and open manifes tation of approval by the highest authorities in the state: they would have formed an era in the scientific history of any land: how much more should they be regarded amongst us, as indicating a movement towards a position, at least in science, amongst nations, from which we have hitherto been debarred, but to which we ever should aspire. But what support does science receive in Dublin from the State? None. The Academy of Sciences for Ireland has three hundred a-year from government to defray current expenses; but if an equal sum be not raised annually by subscription, the government grant will be withdrawn. Hence, the Academy must beg for members; the title of Member of the Academy must be prostituted for forty shillings a-year. If the title were made honourable-if the name, Member of the Academy of Ireland, were made, like Member of the Institute of France, most difficult to attain and most honourable to possess, the names of Hamilton, Lloyd, M'Cullagh, Apjohn, Petrie, Crampton, Stokes, and many others, might still fix on our native land the gaze of admiring Europe; but the support of government would be withdrawn from the Academy; and, by the diminution in the number of useless members, the Academy would become extinct. Is science to be supported on the same The system, as the paupers of a parish are to be cured when sick? Is the establishment of the Royal Irish Academy to be paid upon the model of a village dispensary? It is shameful. The library of the Academy is deficient in many works of great importance; it is not well supplied with the foreign journals of science; the most valuable stores of our native ancient literature and history are, spite of the zealous care of Petrie and Todd, suffering the slow but certain injuries of time. Academy has not funds. Why has it not? Why are tens and tens of thousands of pounds annually placed at the disposal of the British Museum, whilst every halfpenny voted to an Irish purpose is snarled and kicked at ; and, to their shame be it spoken, even by Irishmen, aye, even by those who say they are liberal? But we hope that there will be an end to this. Science is rapidly acquiring in Dublin a degree of popular influence unequalled out of Paris, and may we all concur in furthering the advance in original research, as in familiar explanation, of which the last few years has given such glaring and welcome proofs. But we are not yet done. Again do we owe to Lloyd the praise of having secured for Ireland an important place in science, in a department quite distinct from optics. In every maritime nation, but, above all, to these countries, the study of the magnetic properties of the earth is of importance. It is known, that the direction in which the magnetic needle points, is always changing, and, for the purposes of navigation, a knowledge of the law of these changes is necessary. The illustrious Humboldt proposed, that, in order better to obtain a magnetic chart of the whole globe, magnetic observatories should be established in different stations, and, at his request, the European and Asiatic governments, at once, had them erected. From Pekin to Milan, Europe and part of Asia was covered with a network of magnetic houses; and the means of observation were rendered enormously more delicate, by the suggestion of Gauss, to employ very large magnets, in place of the small needles generally made. This was at once acceded to, and very soon a singular discovery was made; it was found, that so far from the earth's magnetism being the dull, steady-going force we had considered it, it is, in reality, quite variable, liable to sudden storms of great violence, succeeded by times of weakness or of repose; nay more, that these storms move not along the surface, but moment. SCIENCE IN IRELAND, come from the centre of the earth. They appear at all magnetic stations at the same Observers at Pekin, at Berlin, Dorpat, and Milan, watching their magnets at the same time, and noting every little change of power in the magnetic storm, will find, on comparing their results, that they are all alike, that at every point the But while disturbance has been the same. -- all this was doing, where was England? Independent of these services in the de partment of magnetism, Professor Lloyd has We shall pass over a crowd of papers of minor interest, although, if our space al lowed, they would all deserve notice and commendation. Those of Stevelly on the barometer, of Robinson on the longitude of the Armagh observatory, of Andrews and of Knox, on voltaic electricity, will all take place as adding new facts or principles to science, or as determining, with great precision, those numerical constants, without which the fabric of extended theory could not be built; our object, in giving this sketch of the recent progress of the physical sciences, being merely to enable ourselves and our readers to form a distinct conception, whether our country holds any place in science. And what answer can there be but one? That we can stand forward and challenge Europe to show a country where, under circumstances so unfavourable, so much has been done; where every man of talent and of ambition finds himself lured, by the most tempting prospects of gold and power, to the political and polemical arena, whilst, to the man of science, there remains but the calm satisfaction of sound good achieved, the sincere, but noiseless approbation of the few who know his value. Silent, but ceaseless, works the small worm in the eastern seas, adding in each year, a ring additional of solid rock to the isle which it creates, but, in the lapse of time, forming the ground of empires, imperishable whilst nature lasts-invisible to the millions who eat and die upon it--but found, and its power recognised by those who understand its work; whilst, in a single hour, the bright display of raging volcanoes may change the face of a whole continent, create mass of new tracts of land, , or raise into useless en destroying demon to be dis Ji oysal of volun W mind—his better nature; not by inflaming passion, or by fanning up the almost extinct flame of ignorant intolerance. The advance of science has rendered thought omnipotent over man. The printing press, the iron, furnace, the cotton mill, the steam engine, and the railway, have baffled every idea of man being ruled, or ruling by brute force. If men will be brutes, they must be power less. Every advance in knowledge, even in its most abstract, least applicable form, is se much gained in conquering prejudice-in evil; for if, guided securing harmony and mutual esteem. tion or the demands of faction, he shuts his eyes to the advances which mind calm, quiet, but mighty mind is making round him for good, if, tracing their origin in the successful progress of art and science, he foresees the changes in social and political relations, which the introduction of new modes of intercourse, personal and mental, between man and man, may render necessary ede is thus that, through the bloodstained times of conquests and dethronements, the alternations of throne and scaffold, we still see man, advancing steadily towards the grand result, of reasoning freedom. It is thus that the arts advance; that m man feels he must deal with man by speaking to his Hence do we hail Concluded from page 203.)... " 16 "The agitation of such a meeting, in all probability, hastened his death; he did not survive it many days, but his mind was thus relieved from its most pressing anxieties, and his departure was attended with a calmness and composure of spirit, of which previously there had been little hope. The very sud denness of such an event was enough tod make my uncle feel it deeply, and hel evinced such honest unaffected sorrow, as completely, to win my heart. With my wn grief shall not detain you; it wasl excessive for a time, and absorbed all other d considerations; but the buoyancy of youthdo prevailed, and I began soon, to reproach myself for being so easily consoledad bise am hose od: 1900 800 227 W SKETCH FROM THE FRENCH. Toted at sur bedug bus ridde tleroy 1 loot 8 "WHEN the returned home full on arrived, I this project, and expecting to make my next appearance at school, in the capacity of master. The head-master was now advanced in years, and desiring to secure my services, had offered me a kind of partnership in the profits, as well as in the cares of his establishment, of which the terms were too advantageous to render it likely that my wishes would meet with any opposition at a decade You home. But I had not been en returned more than a week, when my father, whose health had been for some time declining, fell sick, and was soon pronounced by the doctors to be past all hopes of recovery. He lingered, however, for a couple of months, and was saved the pain of feafing me alone and anprotected in the world, by the unexpected return of a brother of his from the Indies, of whom he had heard nothing for upwards of twenty years. As along qu was truly sorry to leave it. myself.do not re that sent, I was to remain with my uncle, but where he intended to take up his and what station he held in society I was dnable to discover. He was a self-willed, eccentric man, and had a particular dislike to talking about himself. A good deal had passed in private between him and my father, but nothing Kad transpired of the result, except that he had promised to be a father to me, and put me in of doing for I the notion of his being rich had as yet entered my head; he had come quietly in a postchaise, with little luggage or other indicationis of wealth. The only sign of luxury about him!" was a magnificent pipe, of eastern amplitude, which he smoked all the afternoon, accompanying the operation with copious libations of punch. This also was his time for talking; for in the morning he seldom opened his lips. After he had" smoked for an hour or so, a word now and then found its way amid the fragrant cloud, til, at length, a sentence of consolation or encouragement might without much difficulty be collected, at least by so attentive a listener as I was. they pinag One evening, he began lautu Mbal971 of 2290302 19 which he arrived at a scene with I had some previous acquaintance. In the midst of an extensive park, beauti fully laid out, and rich in all the usual attractions of such places, stood a handsome house, which I had often remarked on my jourmes to and from school. It ranked among my childish dreams as a kind of fairy palace, which I had been wont to see glimmering through the trees, and meeting me again and again at the different turns of the road. I had stopped, where a break in the surrounding timber afforded a full view of the mansion, and was lost in con templation of its beauty and grandeur, when my uncle called to met He was some dis tance before We'll stop here to-day, said my uncle, travelling does not agree, with me. Hesvcalled for luncheon," had our trunks brought into the inn, and dismissed the Trethe chaisely to yorsyoud snt jud nobeno After luncheon Come, my boy, said he, it is finet day, and a bit of a walk will do neither of us any harm. I want to stretch my old limbs, after being pent up in that cursed chaise. "I followed him mechanically, for I was still thinking of the farm. In about a quarI bus lode 9 of 189h any it 19tes lo viosqso on), ni, loodse was in despair, but p my uncle locked the door, put the key in his pocket, and there was no escape. I followed him at al respectful distance, but my limbs, tottered under me, my cheeks glowed, and there il was a mist before my eyes, so that I could hardly distinguish any of the objects around. My uncle marched stoutly along, till he To demarched came near the house, when he stopped. and halloged to me to make haste came I up with him, and we advanced togethers On the steps as I took,d him to be, in a splendid uniform of greenod qu and gold, with epaulettes on his shoulders, and a sword at his side. I took him for a general at least, and saluted him most respectfully; while he performed the same to homage to my uncle, who took no other |