stereoscopic pictures were taken. Further, if the pictures represent an object which is capable of undergoing a conversion of relief,' and they be so placed in the instrument that the image of the right-hand picture reaches the left eye, and that of the left-hand picture is received by the right eye, the 'converted' instead of the real form is perceived. And the same result is brought about, by looking through a pseudoscope at the stereoscopic image on the ground-glass; its relief being converted in just the same degree as is that of the object which it represents, when seen through the same instrument.

Another very curious application of the principle of the stereoscope has lately been brought before the French Academy by M. d'Almeda, who has successfully resolved the problem of enabling several individuals to view the same stereoscopic image at once. It will be readily understood that if the two dissimilar pictures suitable for a stereoscope be projected on an enlarged scale upon the same part of a screen, the result will be somewhat of that kind of confusion which is seen when one of the pictures of a 'dissolving view' is in the act of giving place to the other. But if one of the pictures be projected by red light and the other by green, then by viewing each picture through a glass of its own colour, it alone will be seen, and the other will be extinguished, since the red rays will not pass through the green glass, nor the green through the red; and thus, if the right-hand picture be red and the left-hand be green, by placing a piece of red glass before the right eye, and a piece of green glass before the left, as each eye receives only the picture which is proper to it, and as these pictures are seen on the same part of the screen, their place is apparently taken by a stereoscopic image, which results from their combination in the mind that receives both, and this image is seen in a neutral tint.

Although there still remain several most important points to be elucidated in the theory of binocular vision, yet if we compare our present knowledge with the state of ignorance of its fundamental principles which prevailed before the publication of Professor Wheatstone's first memoir, we see how large is our debt of gratitude to that distinguished philosopher, not only for what he has actually accomplished, but for the new methods of investigation with which he has furnished those who are disposed to prosecute the inquiry. No one was more ready in the first instance to recognise the merits of these investigations, than Sir David Brewster. At successive meetings of the British Association he conferred upon them the highest praise, both for the originality of their method and the im

portance of their results. Of late years, however, he seems to have changed his opinion of them altogether, since he has done his utmost to lower Professor Wheatstone in the estimation both of the scientific and the general public, by ringing the changes upon the assertion that what is true is not new, and that what is new is not true. He has even allowed others to represent himself as the inventor of the stereoscope; when all that is really due to him is the substitution of a pair of semi-lenses for the two prisms in the refracting form of the instrument originally constructed by Professor Wheatstone,—a modification of the utmost importance, as we freely admit, in the popularisation of the instrument, but of no scientific value whatever. For the purposes of philosophical investigation, as well as for the production of the finest stereoscopic effects, the original reflecting instrument, with the subsequent modifications introduced in it by Professor Wheatstone, remains without a rival; and nothing but its want of portability, and the comparative costliness of the large photographic pictures which it is fitted to exhibit, prevent its superiority from being generally recognised. Sir David Brewster has claimed for himself to be the first to apply photography to the stereoscope, for the purpose of obtaining accurate binocular representations of living persons, sculpture, architecture, and landscape scenery. It had never been proposed,' he affirms, to apply the re'flecting stereoscope to portraiture or sculpture, or, indeed, to 'any useful purpose.' But we have before us ample evidence that Professor Wheatstone had made all these applications, long before Sir D. Brewster's invention of the lenticular form of the stereoscope; and photographic pictures adapted to the reflecting stereoscope were sold, to our own certain knowledge, by London opticians, as far back as the year 1845. Not merely, therefore, as having originated the idea on which every form of the stereoscope is based, but as having carried out that idea in the construction both of the reflecting and refracting forms of the instrument, as having developed all its most important applications, and as having furnished a theory of its operation which, if not entirely complete and satisfactory, is based, we are satisfied, on the only sure foundation- the full recognition of the share which the mind has in the interpretation of visual sensations,— we have not the slightest hesitation in affirming that Professor Wheatstone is entitled to all the honours which the scientific world can award to the discoverer of a new principle in philosophy, and to the gratitude of the general public for the large addition which has been made by his ingenuity to its sources of enjoyment.

ART. VI.-The Earls of Kildare and their Ancestors, from 1057 to 1773. By the Marquis of KILDARE. Third edition. Dublin: 1858.

IT is probable that the fasti of one of the great patrician

houses of aristocratic Rome bore some resemblance to the volume before us. Lord Kildare places us amongst the images of his gens, arranged in a series of individual figures, and has written under each of them a record of achievements without much regard to their private characters, or to their historical bearing. Properly speaking, therefore, this book is not a biography, for it does not attempt to give us a picture of its subjects, and the different phases of their chequered fortunes. Still less does it aspire to the name of a history, since it scarcely attempts to represent the drama of events in which the Earls of Kildare performed their part, or to explain their general relation to it. But it is a descriptive genealogy, enriched with many details industriously collected from original sources, and of great value to the student of Irish history. Though it is not so much a finished work as a collection of materials, it possesses the merits of research, accuracy, and modesty. To welcome a Geraldine as a contributor to literature would be a thankless office, unless Lord Kildare had widely departed from the steps of his ancestor, who laid whole districts waste with fire and sword because he had received the nickname of the Rymer.' But the manner in which the present heir of this great name has executed this pleasing task is very characteristic of the unobtrusive dignity and patriotism of the first gentleman of Ireland.

Although this book mainly consists of personal incidents, it suggests several interesting general considerations. Especially it indicates very clearly how different in England and in Ireland was the fortune of the Norman aristocracy, and how important have been the results of that difference. In England the policy of the Conqueror when he was distributing the spoils of his conquest, provided against the undue aggrandisement of any of his followers; but from the first a basis for the future government of the kingdom was formed by placing a check upon the barbarous forces of feudalism, and preventing the Bohuns, the Bigods, the Mowbrays, and the Montfichets from becoming an independent oligarchy of tyrants. And as from above, so also from below, the Norman lords were exposed to no despicable control from the sturdy nature of the English population, who, though subdued, remained unbroken in spirit, retained an

important element of power in the possession of land by freehold right, and, being not remotely alien in race from their conquerors, approached, and eventually regained, a position of natural equality.

Unfortunately the course of events in Ireland was different, and the difference in the result is still painfully apparent. In Ireland the power of the Crown was feeble from the first, and it gradually dwindled down to a nominal sovereignty, incapable of any of the functions of government. The autho

rity which it exercised over the Lacies and the De Burghs, was very different from that with which it swayed their fellows in England; and it was totally unfelt by their dependents. Thus it was unable to exact military service in Ireland; it never established there the Curia Regis; and it was a mere name both as regards the majority of the Anglo-Norman settlers, and the rude masses of the Celtic population. Occasionally, indeed, a Plantagenet king sent over a Darcy or a Talbot to Dublin, who marked his lieutenancy with some act of spasmodic rigour; but this assertion of the royal title was felt only by a few, and the recollection of it quickly faded away. Thus freed from real control, the great Anglo-Norman lords established an oligarchy of petty despots in Ireland, who kept society in a state of chronic anarchy, and checked its natural growth and development. They maintained rude armies of half-savage followers, with which they either waged a destructive war amongst each other, or harassed and oppressed the native septs. In their vast palatinates the law of England was unknown; and they substituted for it a barbarous jurisprudence which drew a fatal distinction between their English and Irish vassals. In their parliaments they legislated solely in their own interests, and endeavoured to perpetuate the severance of race from race by statutes excluding the natives from commerce and intermarriage. Occasionally, indeed, the Anglo-Norman lost his caste, and, degenerating into a Celtic chieftain, became the ruler of a barbarous sept, after 'the sluttish and unclean Irish custome;' but the Statutes of Kilkenny and Drogheda prove how odious this was to the dominant race, and how completely it held itself superior to the Irish enemy.' As regards the condition of this, the real Irish nation, it was such as naturally would appear in a people only half conquered, and kept in barbarism by the feuds of a turbulent oligarchy. It was alien in race from its AngloNorman superiors, and did not seek to obtain an equality with them. For the most part, it was debarred from their laws and institutions, but resting in swarms on the soil, it remained nominally under the rule of Anglo-Norman nobles, though really

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under that of its own customs and native princes. And, as it was only made acquainted with the English name by edicts of cruel or selfish tyranny, or by wanton invasions and spoliations, it continued in its aboriginal state, rarely mingling with the dominant race, and retaliating these acts of feudal oppression by a desultory and predatory warfare.

The natural result of this state of Ireland was the decline of the central English Government, the domination of a haughty and independent oligarchy, the separation of the people into two hostile castes, and the rule of chronic disorder and barbarism. In the time of Henry VII. the authority of the Crown in Ireland was at its lowest point; the king's writ ran in parts of four counties only; and the king's army was only the levy of a deputy, who was generally one of the great AngloNorman nobles. At this time also the Anglo-Norman oligarchy had become reduced to a small number of leading families, which, in fact, were quite independent of England, some of them having degenerated into Celtic chieftains. The native race had extended the bounds of its territory; it had almost effaced the English name in three provinces, and had spread far into the centre of Leinster; and its princes, risen in dignity and power, had been gradually connecting themselves with their conquerors. A state of war, however, continued between the two races, for they never had been allowed to coalesce into a nation; and the barren and desolate aspect of the land was a faithful witness to the barbarism of its inhabitants. The Tudor sovereigns found themselves in Ireland bereft of authority, confronted by a hostile and reckless oligarchy, the lords of immense districts and palatinates, whose power made them dangerous subjects, and menaced by an alien and barbarous nation who paid no allegiance to the English Crown. They were not slow to perceive the peril of this state of things, and resolved, with characteristic determination, to subdue these elements of opposition. The policy of every one of them was ultimately the same, to subjugate Ireland at any cost, and by any means, however unscrupulous; and it was pursued by their able instruments with steady and unrelenting vigour. Thus commenced that fierce strife between England and Ireland, which, after it had raged for about a century, and at length had assumed the shape of a war of religion, was terminated by the conquest of the weaker country. In that strife the old Anglo-Norman aristocracy, with such of the Celtic chiefs as had joined them, were overwhelmed, and with some exceptions destroyed; and, when something like peace was at last established, their place was