sippi University, and our countryman Cooke's, of two feet, to go out to Egypt, will outvie all that the Munich Optical Institute has hitherto produced, and all other similar works, of quality equal to their pretensions; for it is scarcely necessary to say that Mr. Craig's spirited undertaking at Wandsworth was a failure. Nor indeed should Munich hold up her head so high as she has done. She may no doubt boast of much that is admirable in computation and manipulation, but her material is not safe as to permanency of polish, nor is her success always on a level with her reputation. Sécrétan's fifteen-inch object-glass at Paris is, we believe, as large as anything from Munich, and must be good, since M. Laugier, Arago's nephew, told us he had with it separated the great test, y Andromedæ ; but this is no great feat for such an aperture, since Clark will do as much with eight inches, and we have seen it elongated with five and a half of his workmanship. The Germans think much of the Dialyte, a modification of the achromatic proposed some years ago by Rogers, in England, and executed about the same time from the computations of Littrow, by Plössl, in Vienna; but it does not seem likely to supersede the ordinary construction, even if it may sometimes rival it; and the fluid object-glasses of Blair, the stumbling-block of our youthful curiosity, said to be beautiful exceedingly in themselves, are too difficult of execution to be likely to be revived. No one, as far as we know, has attempted a combination of the dialyte with Blair's correcting principle, but as an experiment it would be very interesting, and would obviate the objection to the latter arising from the difficulty of construction, except on a very small scale. Nor have Steinheil's quadruple achromatics received that attention in this country which they probably deserve. But after all, the usual combination which we owe to Peter Dollond, imperfect as it is in some respects, is so practically efficient VOL. LXIII. NO. CCCLXXVI. 465 that it is likely to keep its ground. Reflectors, less manageable and less convenient, but not less perfect, are making a vigorous effort to recover the supremacy which they enjoyed in old Herschel's days. Of the Earl of Rosse's colossal tube nothing seems to have been heard of late, but Lassell's four-feet speculum is said to promise wonderful excellence, and the curious contemporaneous invention of Steinheil at Munich, and Léon Foucault at Paris, is capable, under favourable circumstances, of being very valuable. In this most ingenious contrivance, an accurately figured and highly polished concave disc of glass is coated in front, instead of at the back as a common mirror, not with the ordinary alloy of mercury and tin, reflective as it is, but with a yet more brilliant film of pure and perfect silver. The effect is beautiful, at least on terrestrial objects, to which alone we have seen one of these instruments directed. Our Astronomer Royal, who has witnessed the performance of a large speculum of this kind at the Paris Observatory, has spoken of it in terms of great admiration. In that instance the well-known ingenuity of our French neighbours is remarkably conspicuous; they employ a disc of glass so thin and flexible that its figure is completed and brought to perfection by the pressure of air blown into a cavity at its back from the mouth of the observer, and confined there at pleasure by a stop-cock. This delightful instrument has the grievous drawback of uncertain permanence, especially in a damp climate; but where the means and the skill of restoration are at hand, it is so readily repaired, that under such circumstances it promises to be of high utility; and we learn with great pleasure that it is likely to be tried on an adequate scale in the private workshop of an English clergyman. The clever contrivance of the French Colonel Porro, for viewing the sun without a darkening glass, deserves to be mentioned; in which the rays, enfeebled by reflection from an unsilvered glass mirror, are subse I I quently weakened to any required extent, by an application of the properties of polarized light. Such are the modern appliances of astronomical discovery-never so multiplied hitherto, never so adequate to the task; nor have public munificence or private liberality ever been more conspicuous in placing them in situations where they are likely to be used as they deserve. Yet while we feel a just pride in our means of attack, we may not presumptuously hope that the fortress of celestial truth will ever be yielded into our hands. We shall no doubt make further progress. Some of the outworks will fall; some whose approaching surrender may be predicted; others which perhaps at present might be deemed impregnable. But the Great Architect, while He has doubtless more than permitted the studies of astronomy-while we may rather say that He has ordered and appointed them for His own glory-has also set them their bounds which they shall not pass. Extravagant ideas may be, as they sometimes have been, entertained upon this subject; but they will never be fulfilled, and the cause of their failure is no mystery. The defects of material and workmanship increasing rapidly with every augmentation of scale, and the impediments arising from the unsteadiness of our atmosphere, which, as observers well know, are multiplied in a high ratio with every enlargement of aperture, are alone sufficient to threaten a gradual interruption of progress; and though in theory a telescope might be constructed of any assignable magnitude consistently with the strength and rigidity of materials, yet a limit would soon be reached in practice, from a cause which has been adverted to, but only in part, by Kitchener, and to which we think sufficient attention has not been paid. This is, the limited opening of the pupil of the human eye. If the aperture of the instrument is pushed beyond a certain extent, either the beam of rays emerging from the eye-piece will be too large to enter the pupil, outside the area of which all light is of course thrown away; or if diminished, as it may be by increase of magnifying power, to the necessary extent, that amount of power will become too high for any ordinary condition of atmosphere; for, as astronomers find to their cost, few are the nights or hours when they are not sensible of its prejudicial interference. For instance, since the diameters of the cylinders of rays that enter and emerge from the telescope are to each other as the magnifying power, it is evident that with an aperture of six feet, such as the Earl of Rosse attained, a power of 360 would be the lowest that could be used, since thus only would the emergent pencil be reduced to one-fifth of an inch, the customary size of the fully expanded pupil. Such is the ordinary supposition, but it is too favourable; because, under the stimulus of so powerful a light as such an instrument would collect, the pupil itself would contract to much smaller dimensions, and the power must again be raised, perhaps doubled, to compress the light into it, and would soon be forced up to an amount which would under ordinary circumstances be useless, especially with an aperture collecting so much atmospheric disturbance; and this limit would sooner be reached in the reflector than in the achromatic, in consequence of its larger aperture. But, independently of this practical difficulty, it is evident that no attainable amount of magnifying will ever sufficiently diminish our apparent distance from those remote bodies, to enable us to pronounce confidently as to their exact nature and condition. We may, and we very probably shall, gain a greater insight into the physical arrange ments of the nearer planets. We may map out the configurations of the surface of Mars and Venus, and gather full evidence of continued eruptions, and possibly trace a low-lying atmosphere and a limited vegetation in the Moon. We may yet detect the existence of planetary 1861.] Limits of Astronomical Knowledge. systems dependent upon the nearer fixed stars; and gain some data, less utterly vague than that at present, as to the cause of that wonderful phenomenon of variable light; and it is not unlikely that the proofs which are accumulating around us of the comparative proximity of many of the minuter stars may shake to the foundation some long-received speculations as to the construction of the sidereal heavens. All this may be, and some of our readers may live to see it. But as magnifying power will reach in practice an assignable limit, so the result dependent upon that power is not difficult to be assigned, at least in a general way. The nearest approach of Mars leaves him still about thirty-five millions of miles from the Earth; the distance of our own satellite is something under a quarter-of-amillion. Discarding at once what ought to have been disposed of long ago, Herschel's often-vaunted power of six thousand, as a mere experiment, which that illustrious astronomer himself considered as of no practical use, let us see what would be the result of two thousand, a power still unattained, we presume, with any degree of distinctness or perfection. Such a power would reduce the apparent distance of any objects in the same proportion, or, in other words, bring them two thousand times nearer. Then we should see Mars and the Moon as large (though by no means, from atmospherical and instrumental defects, as defined) as if he were about seventeen thousand five hundred miles distant, and she, a hundred and twenty miles from our eye. But how little should we know of the real constitution of our Earth, or its works of nature and art, at a distance of seventeen thousand five hundred miles! and how obscurely would the largest buildings or roads that could be imagined on the Moon, were it even peopled by a race of giants, be distinguished, or made out in detail, if a hundred and twenty miles intervened! What would the pros 467 pect of London or Paris at a similar distance present, beyond a speck whose real nature could only be divined from previous acquaintance? and still less hope can there be that animated beings should ever fall within our ken. We must learn to set a reasonable bound to our curiosity, and to adopt the idea of Scaliger, Nescire velle, quæ Magister Optimus This may seem but a discouraging view of the future progress of our delightful science, yet, as we have seen, it is deducible from the very nature of things. And the believer in Divine revelation at once perceives that in it which is in full accordance with the destiny of the race of man. Whatever doubts and difficulties may beset the study of unfulfilled prophecy, the duration of the present state of things may not be protracted very long. For all that we can tell a crisis may be approaching, perhaps at no very remote period, which may terminate the whole existing condition of the world; and it is consistent with this expectation that the studies and pursuits of the human race (for our remarks may be applied to other sciences) should be gradually approaching a boundary beyond which neither energy, nor ingenuity, nor perseverance, shall avail to force them; and that the increase of knowledge, which the prophet Daniel assigns as the characteristic of the last times, after a progress of unwonted velocity, should suffer gradual retardation, like the vertical ascent of a projectile as it approaches its utmost extent. Even the mind of a reflective heathen might be struck with this evident approximation to some unknown limit, the meaning of which would to him be hidden in mystery; but to the Christian that limit is not unknown, and the mystery is readily solved in the light which inspiration throws upon the future destiny of the earth and the works that are therein. IDA, with that affection which delights to ponder on every act of virtue in its object, dwelt secretly on the instances she had heard of Ernest's generosity and charity, till it seemed to her that there was no other man capable of so much goodness. She persuaded herself that she was only admiring abstract excellence. She did not believe that her approbation was influenced by personal partiality. Yet, if she had questioned her sentiments candidly, she might have convinced herself that the same benevolence reported to her of Captain Warburton, would hardly have struck her so much, and that it might not even have appeared to her as a subject either for admiration or attention. The unlooked-for meeting at Gernsdorf, the warm, undesigned praises of the schoolmistress, and the contents of D'Entzberg's letter, served to feed a thought which, it had been hoped, would dwindle and fall away from privation in the present seclusion. The perseverance of the Countess Rosenberg in her refusal to name the wedding-day, the apparent estrangement between Wertheim and his son, the delays and the difficulties that seemed to exist in the relations of all the parties concerned in this proposed alliance, were indications of some smouldering fire working its way on to open conflagration. Her heart whispered to her where that fire was first lighted, and she dreamed one night that all the flat, wide plains of Wertheimburg were filled with light and beauty, while two rejoicing lovers walked forth once again side by side, on through the dark solitude of the forest to breathe the mountain air; but as she began to climb, supported by the hand she loved, she fell from that high, happy dream, waked by the voice of Eugénie, her maid, who brought bad tidings. Her aunt Kitty was ill. Eugénie was a faithful old servant, not sparing in the way of rebuke, and she told Ida with a certain significance of manner that she believed Miss Conway had suffered from anxiety and solitude. 'Miss Conway had caught cold,” Eugénie said, 'sitting for ever in that damp garden her spirits were depressed-she had lost her strength, and now this cold was taking a bad form.' Ida's conscience told her that the solitude was the result of her own neglect; that the anxiety was the consequence of her own be haviour. She wished to repel the truth, to take refuge in unbelief; and she called Eugénie cruel, but she dressed herself with all haste, she hurried to her aunt's room. and there saw the evil as distinctly as her servant saw it. She saw it more strongly, for she saw it magnified by the force of fear and contrition. When she went to Miss Conway she found her lying down outside her bed, her face was flushed, her eyes were partially closed, her hand was pressed against her heart. Ida fell on her knees by her bedside, and threw her arms about her. Oh! was it possible that she had ever neglected her? 'Aunt Kitty, Aunt Kitty, you are ill. Why have you not told me so before? Why have you not called me to you? Why have you kept your illness a secret from me! Where is your pain-what do you feel when did it begin-where, and on what day? Oh! tell me, tell me! My Auntie-my Kitty-my own, my dear, my angel Auntie! Aunt Kitty called up her sinking strength for one soft caress as she answered with difficulty, struggling for breath. 'I did not know, my child--I thought I should get-better-do not-never mind-presently-' Ida rose, and drawing aside the heavy curtains of the bed, which were of a rich golden coloured damask, fastened on Miss Conway such a look as would let no symptom escape its hold. There was a nervous movement about the corners of the mouth, and tears made their way down the channels of the cheek; tears that, few and gentle as they were, poured down with the weight of a great deluge into Ida's soul; and yet they were grateful drops, and this moment was the only happy moment that Kitty Conway had known since her arrival at Wertheimburg; this moment, when the daughter of her heart was restored to her, and she felt that she had not doted altogether in vain. Ida was full of hurrying alarms. Her fears went in advance of the truth, and her mind foresaw a catastrophe too terrible to be endured. She concluded the importance of immediate medical assistance, but there was only the district doctor within easy reach, and his duties extended over so many miles of country that the chance of finding him at home was small. She would not trust a servant to seek for him. She would leave Eugénie with her aunt, mount her horse, and go to find him. His address was obtained from the steward, Eugénie was sent to Miss Conway, Thekla was saddled, and Ida galloped away. According to her foreboding the doctor was out, and she was referred to an assistant of small ability for her only comfort. It was better than nothing, and she urged him with energy to follow her; she would not leave the house till he did so. His long pale face looked paler and longer when he saw Miss Conway's, and after many hesitations and interjections, he indicated with a feeble attempt at decision, that it would be advisable to bleed the patient. Ida had foreseen that necessity, but Eugénie was alarmed, opposed herself to it, and alarmed Miss Conway, 'I tell you,' said Ida, with resolute authority, in answer to the servant's remonstrance, 'that it 469 must be done. I know it must, and I have brought this man here only for that. If you are afraid, leave the room, and I will undertake whatever is wanted.' Eugénie, however, was not cast in so weak a mould. She would avert the operation if possible, but if that were impossible, if the thing must be, she would stand at her post and do her duty. It was Ida's resolution alone that carried the day, for the medical adviser was prepared to give way before opposition, to shirk responsibility, and to enter upon a more timid treatment. She She The operation was performed. Miss Conway fainted under it. Eugénie was sure that she was dead. She ran confusedly hither and thither in search of restoratives, dropping the bottle she esteemed of most vital importance, smashing the glass that was to receive its contents, and, sparely as that spacious room was furnished, contriving to tumble over every piece of furniture it held before she reached the bed. Death itself could hardly have maintained its constancy in this hurly-burly, and Miss Conway opened her eyes. Half an hour afterwards she was dosing quietly, and Ida, reassured for the moment, was able to leave the room and collect her thoughts. She must write to Badheim. must have the best advice. must at once summon Dr. Enghel. He was a man of considerable skill; he was the Wertheims family physician; Baron Entzberg spoke of him as the best of men, and Aunt Kitty personally liked him. Ida wrote to him, wrote to the Baron, wrote to her father, and wrote to Emily Warburton entreating her presence, and begging her if possible to accompany the doctor; she thought her aunt dangerously ill; it was an attack of pleurisy; she could not in this anxiety bear the loneliness of her' position. Eugénie was affectionate, but she exhibited her affection by adding continually to her fears, and dwelling on and amplifying every subject of affliction. Ida implored Emily to come, im |