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of manipulation were completed, experiments were commenced to determine the difference of longitude between the Observatories of Greenwich and Cambridge. This was the first application of the method in England. In operations of this kind two persons are required at each station. One is the signal giver, who, while observing the transit of stars over the wires of the transit circle with his eye applied to the telescope, completes the voltaic circuit with his finger. The other is the signal observer, and his duty is to watch the motion of the needles and record the time; and at Greenwich this may be done with the greatest accuracy, for the galvanic needle is carried by the transit clock. The order of operation is described by the Astronomer Royal in the following passage:
•At 11 P.M. Greenwich mean solar time, Greenwich commenced by giving five signals at intervals of about 2" each. The turnplates were changed, and Cambridge responded by five similar signals. These were merely to say “ all is right.” Then Greenwich gave batches of signals in numbers of from three to nine (some of them being transits of stars) to 11h 15". Then Cambridge gave similar batches to 11h 30". Then Greenwich gave signals to 11h 45", and Cambridge to 12h 0". This closed the night's signals. From one hundred and thirty-five to one hundred and fifty efficient signals were given, and as the observation of a signal is perhaps rather less accurate than the observation of a transit wire, the probable error of the mean of these will be fairly comparable with that of the determination of clock error in an evening's transits.'
The long disputed question of the origin of the spots on the sun is again revived, and we may now hope to have it settled at no very distant period; or if this cannot be at once done, we shall at least ascertain if any, and what, connexion exists between their changed form and place and certain physical phenomena with which they are supposed to have some unknown relation. The Kew committee purpose to take a daily image of the sun by the aid of photography, and arrangements are being made for that purpose at the Meteorological Observatory under the advice of Sir John Herschel. Speaking generally of the arrangement, it may be said to consist of a telescope mounted equatorially with a clock motion in parallel ; but Herschel himself will describe, in the following passage, the object proposed, and the means by which it is to be obtained
* The image to be impressed on the paper (or collodionized glass) should be formed not in the focus of the object lens, but in that of the eye lens drawn out somewhat beyond the proper situation for distinct vision, and always to the same invariable distance, to insure an equally magnified image on each day. By this arrangement a considerably magnified image of the sun, and also of any system of wires in the
focus of the object glass, may be thrown upon the focusing glass of a camera box, adjusted to the eye end of the telescope. By employing a system of spider lines parallel and perpendicular to the diurnal motion, and so disposed as to divide the field of view into squares, say of five minutes in the side, the central one crossing the sun's centre (or rather as liable to no uncertainty, one of them being a tangent to its lower or upper limb), the place of each spot on the surface is, ipso facto, mapped down in reference to the parallel and declination circle, and its distance from the border, and its size, measurable on a fixed scale. If large spots are to be photographed, specially with a view to the delineation of their forms and changes, a pretty large object glass will be required, and the whole affair will become a matter of much greater nicety; but for reading the daily history of the sun I should imagine a three-inch object glass would be ample. The representations should, if possible, be taken daily, and time carefully noted.'
It must not be supposed that this is a novel experiment. It has no claim to originality except as a continuous experiment. In 1842 Dr. Draper took a beautiful photographic impression of the solar spectrum in the south of Virginia, from which he deduced that negative rays exist on both ends of the spectrum, and do not depend on refrangibility. Whether he attempted at that time to take a portrait of the sun we are not certain, but believe that he did so. It matters however but little who may have been the first to succeed in the bold design of taking the sun's photographic likeness; it has now been done so often that by this time it must have been stereotyped, and many indications of the results to be anticipated from a consecutive course of observations have been already indicated. According to M. Wolf, the director of the observatory at Berne, the number of spots visible upon the disc of the sun return periodically, and the years in which the spots have been most numerous have been the driest and most fertile. In 1852 Professor Secchi, of Rome, took a daguerreotype view of the sun during an eclipse. This experiment seems to have been made, principally, for the purpose of testing the accuracy of M. Fizeau's statement that the chemical energy of solar light is more active in the rays which proceed from its centre than those which come from the edge of its disc. Having, as it would appear, confirmed this report, he extended his inquiries, and proved that the heat of the solar rays is twice as great at the centre as at the border of the sun's image, and that the maximum of heat is on the solar equator. If this be the fact, the equatorial regions of the sun are hotter than the polar, and we must not only reject the old theory of the sun being a globe of fire, but calculate what effect the newly discovered condition of the sun would have on the climatology of the earth, not forgetting the supposition, already confidently expressed, that the two solar hemispheres have different temperatures, and con
sequently, that in estimating seasons, we must take into consideration which pole of the sun is turned to the earth.
The committee appointed by the British Association in 1852 to report on the physical character of the moon's surface, as compared with that of the earth, have a task which will probably occupy more time, if a thorough investigation be intended, than is expected. To collect and arrange the materials for the proposed report, if it is to be in any respect historical, will be a work of labour, but one of so much interest, that any man suited to the task must derive more pleasure from the investigation than from the anticipation of the credit to follow, although that will not be meagre if the execution be satisfactory. But in all probability this is no part of the design. The object is to obtain a series of photographic views of the moon, and to deduce from them, and from such observations as may be made, a theory of the physical constitution of that satellite. Dr. Robinson of Armagh made an attempt to take an image of the moon. For this purpose he took, as he supposed, a favourable opportunity, but failed; for after exposing a prepared surface for twenty minutes, no image was impressed. From this he deduced that lunar light has no chemical action upon the ioduret of silver ; but this generalization has not been supported by succeeding experiments. Sharp edged and well developed pictures of the moon have been since obtained by many astronomers, and there can be no doubt that other still more perfect pictures will be procured. We cannot now, from the want of time and space, even state, not to say investigate, the results obtained by Professor Ponzi, a geologist well acquainted with the volcanic districts of Italy, but the opinions of this observer will be carefully considered by Professor Phillips, who has in many particulars deduced the same conclusions from independent observation.
We must say one word about the progress of geology; that universally popular science which gains admirers everywhere, and students and co-operators from all classes ---some to satisfy their curiosity, some their wonder, but others (and they are the larger number) to satisfy their love of inductive reasoning. To describe, and estimate the labours of the geologists during twelve months, would occupy more pages than we are giving to all the reported doings of the British Association ; but there are always subjects of peculiar periodical interest, and these were last year the classification of the Silurian formations and the distribution of gold. Upon the former we have a few words to say.
Sir Roderick Murchison is fairly entitled to great honour for his investigation of the so-called, Silurian formations. The most enthusiastic of his admirers cannot, in this respect, award him a
larger meed of honour than we are willing to grant. He has 'made out,' or, in less technical phraseology, he has investigated, arranged, classified, and, if the term were admissible, he has fossil-hunted an immense deposit of Palæozoic rocks, which all the world had before disregarded, literally passed by as worthless, not deserving investigation. As this honour is his own, out of the reach of envy though enviable, he must diminish his fame by appropriating that which belongs to another. When those inquiries commenced which have led to these satisfactory results, Sir Roderick, then Mr. Murchison, had a companion, friend, tutor,-What name shall we give him? any will be appropriate which recognises friendship without competition; for the existence of any such feeling between the two men would be absurd, and might verge into the ridiculous. But they appear to have been agreed upon the necessity of studying by observation the doubtful rocks lying between the well-known primitive and secondary formations. Sedgwick undertook what might then have been spoken of without much exaggeration as the impossible task, or, at least, the forlorn hope, of depicting the geological history of Cumberland, Westmoreland, and North Wales; while Murchison devoted himself to Hereford, Shropshire, and the neighbouring counties of South Wales. Fortune did not, in this instance, favour the braver; but both earned honours; and if the louder praise came to one, the most valued were offered to the other. But by some chance or the other, Sedgwick's diggings have gone to Murchison's profits, and the loser very properly complains that by some unfortunate circumstance he has been deprived of the reward of his labour. Now, Sedgwick happens to be a man possessing a profound knowledge of geology, bringing to every research in which he is engaged, a keen observation, a logical mind, and that broad perception of cause and effect which, in science, is genius. He is, too, a man of lively wit, and of earnestness of purpose, and he has an appropriate facility of expression which make him a most agreeable and esteemed companion, whether he comes in page or person. Such a man cannot imagine himself injured without securing listeners to his complaints, if he chose to make them. He believes himself to have been deprived, by his coadjutor, of the right which every discoverer possesses of naming and retaining, till sovereign authority bas decided otherwise, the conquests he has made. An amicable misunderstanding has thereupon arisen between him and the author of the Silurian system, which involves the question of scientific accuracy and judicious classification, as well as the rights of scientific conquest.
To illustrate these remarks, we must state the facts :-Beneath the new red sandstone and above the metamorphic rocks there is a series of rocks appropriately named by Sedgwick, the Palæozoic.
This series is as distinctly marked as the Tertiary and Secondary systems. The propriety of the division and of the name has been acknowledged by geologists in all parts of the world, and the designation will probably remain when the conventional phraseology of the science, too much cherished, has been forgotten. This system of rocks was divided into groups, commonly known as the Permian, Carboniferous, Devonian, Silurian, and Cambrian. These divisions are supposed to be established by the necessity of order; but some adventurous Silurian chief attacked and annexed Cambria, invading it, as its chieftain says, without a declaration of war. But if, as Sedgwick seems to have proved, the upper Caradoc or May-hill sandstone possesses fossils belonging to the Silurian series, and the Caradoc is connected by all its characters with the Cambrian, the old land-marks must be restored, and the veteran conqueror must be re-established in the possession of that which he has so honourably won.
There are many other subjects, theoretical and practical, which we might be expected to mention, but both time and space are exhausted. Enough has been said to prove the value of the scientific labours of the past year, and the character of future research is indicated in the fact that the men of science in our day are devoted to that knowledge which ministers to the public good.
Art. V.-The Annotated Edition of the English Poets. By Robert
Bell. ‘Dryden.' 3 vols. London: John W. Parker & Son. 1854. THE successive vicissitudes of rise, fashion, and decay, which pass upon the materials of language, have been gracefully compared by Horace to the analogous changes which annually take place in the foliage of trees ; the poet ascribing to custom that dominion over words which Nature exercises over the vegetable creation. The image is as true as it is beautiful, except that it reverses chronology--inasmuch as we are the ancients, and look back to our far distant ancestors as the infants of the race. So the Romans saw in Ennius, and we in Chaucer and Spenser, not the blossoms of spring, but the decayed foliage of winter, while summer blossoms and autumnal fruits enrich the later eras of national literature.
There must necessarily be a period at which these seasons meet. That is not when summer mellows into autumn, but when winter is regenerated into spring; in other words, the best language of a nation only decays with the decease of national individuality, in which event it, like those who spoke and wrote it, puts on