rays, which passes from the eye-glass to the eye, must be taken into account. No optician can be considered a master of his art who does not determine the aberration of the eye, and make it disappear in the object-glass.

The consideration of the aberration of sphericity does not form any part of M. Fraunhofer's inquiry, but he has justly observed that in order to make this aberration disappear entirely, the indices of refraction for the lenses of flint and crown glass must be taken for the same coloured ray.

Although the object of our author was limited to those practical results which were necessary for the construction of a perfect achromatic telescope, yet he has favoured us, in the conclusion of his treatise, with some interesting results respecting the light of the planets, and the fixed stars. These results are, indeed, few in number, but as he has resumed the subject in another treatise, which has not yet been translated into our language; and as the results which he has there given were obtained by new instruments of singular accuracy, we are sure that our readers will be gratified with some account of them.

In examining a spectrum formed from the light of the moon, Fraunhofer observed in the lighter colours the same fixed lines which exist in solar light, and occupying the same place.

In the spectrum formed from the light of Venus, he saw distinctly the lines No. 3, 4, and 5; and two of the lines in the group of three lines in the green space. The weakness of the light, however, was such that he could not observe that the strongest of these two lines was double as in solar light; and for the same reason he could not observe the lines in the fainter colours.

In the light of the planet Mars he observed the very same lines as in that of Venus.

For the purpose of observing the lines in the light of the fixed stars, the atmosphere requires to be in a very favourable state.

In the spectrum of Sirius no fixed lines were perceived in the orange and the yellow spaces; but in the green he discovered a very strong line, and in the blue other two very strong ones; but none of these lines appear to resemble any of the lines in planetary light.

The star Castor gives a spectrum similar to that of Sirius; and notwithstanding the weakness of the light, the line in the green has so great an intensity that Fraunhofer easily determined its position, and found it to occupy the very same place as the similar one in the spectrum of Sirius. He saw also lines in the blue space, but the light was not sufficiently strong to enable him to ascertain their place.

VOL. I. NO. II.

FF

In the spectrum of Pollux Fraunhofer observed many delicate but fixed lines, which looked like those of Venus. The line No. 3, between the orange and yellow, he saw very distinctly, and it occupied exactly the same place as in the light of the planets.

In the spectrum of Capella the same fixed lines are seen as in that from the sun's light. The line No. S, and one of the lines in the group of three lines in the green space, were visible.

Betalgeus affords a spectrum containing numerous fixed lines, which are sharply defined in a clear atmosphere; and though it does not seem at first to have any resemblance to the spectrum of Venus, yet similar lines are found in it, particularly No. S, and one of the group of three lines in the green space.

In the spectrum of Procyon some lines are perceived with difficulty. Fraunhofer thought he saw the line No. 3, but he was not able to determine its place with certainty.

In order to study the spectrum produced from electrical light, our author employed the large electrical machine belonging to the Physical Cabinet of the Royal Academy of Munich. That he might obtain a continuous line of electrical light, he brought two conductors within half an inch of each other, and joined them by a fine glass fibre. One of the conductors being connected with the electrical machine, and the other with the ground, the light seemed to pass continuously along the glass fibre, and afforded a brilliant line of light. In the spectrum obtained from this light Fraunhofer observed a great number of clear lines. In the green space one of these was very brilliant, compared with the other parts of the spectrum. Another line, not quite so bright, appears in the orange, and seems to be of the same colour as that in the spectrum of lamp light. Its light, however, was much more strongly refracted, and nearly as much as the yellow rays of the light of a lamp. Near the extremity of the electrical spectrum there is a red line not very bright, yet its light has the same refrangibility as that of the clear line in the light of the lamp. In the rest of the spectrum other four lines tolerably bright may be easily distinguished.

In the spectra from the flame of hydrogen gas and alcohol, the reddish line is very bright, in relation to the rest of the spectrum. In the spectrum from burning sulphur it is seen with difficulty.

In order to ascertain if there was any difference of refrangibility in the light of different fixed stars, M. Fraunhofer prepared very expensive and delicate instruments. He used a telescope with an object-glass four inches in diameter, and his prism of flint glass was of the same breadth. The instrument required two observers, and several observations were made with it by himself and M. Soldner of Munich.. These observations, how

ever, were not considered as decisive; but he has informed us that they did not find any fixed star the light of which differed perceptibly in its refrangibility from the light of the planets. With the instrument which he used, a difference equal to

part of the whole refraction could be perceived, and it is obvious that this would not amount to the fourth part of a second in the horizontal refraction of the atmosphere. Hence we may consider it as established, that the tables of refraction will be correct for different stars, whatever be their magnitude and parallax.

Such is a brief and a general view of the brilliant optical discoveries of Fraunhofer, relative to the prismatic spectrum. To the astronomer and the optical philosopher they are of the highest interest; but when we consider them in reference to the improvement of the telescope, their importance exceeds all calculation. Nor is this value of a hypothetical nature, and one which a sanguine temperament sometimes too hastily infers. It is deduced from the splendid achromatic telescopes, which these very discoveries enabled Fraunhofer to execute; telescopes which have never been equalled on the Continent, and, we add with a pang, not even in England. Before his time the construction of an achromatic object-glass, above seven inches in diameter, was considered as beyond the reach of art; but from the perfection of his methods, and his knowledge of the art of making flint and crown glass, he has executed object-glasses of nine and even twelve inches in diameter. The first of these is that of the celebrated parallactic telescope, which was purchased by the Emperor of Russia for the observatory of Dorpat, and which has been so successfully used by M. Struve; and the second, which was made for the King of Bavaria, has, we believe, not yet been completely fitted up. But though these were the largest objectglasses which he had finished, yet he offered to execute an achromatic telescope with an object-glass eighteen inches in diameter, and he fixed the price of such an instrument at £9200. sterling, including the expense of a parallactic stand, micrometers, and other pieces of apparatus.*

In this manner has the supineness of our government, on the one hand, and the omnipotence of scientific skill on the other, transferred from England to Bavaria that sovereignty over this branch of the arts which we first established, and which we so long enjoyed. The loss of a branch of manufacture, and a source of revenue, effected by the successful rivalry of a foreign state, is

The price of the Dorpat telescope was £1300, but it was liberally given to the Emperor of Russia at prime cost, viz. £950. The price of the telescope for the King of Bavaria was £2720. The price increases nearly as the cube of the diameter of the object-glass.

an event rare in our history; but these events will increase, both in number and in magnitude, unless some effectual step is taken to elevate the condition of scientific men; to stimulate and reward their labours, and to protect the property of their inventions from the avowed robbery of pirates, and the concealed fraud of our patent laws. We are not politicians, and do not wish to mingle in their strife, or involve ourselves in their mazes; but we think that the time is now come when such objects as these imperiously demand attention, and when they are likely to meet with the support of those who are in power.

Now that British interests have been withdrawn from the safeguard of restrictive enactments, it is surely time to place them in the sunshine of national favour, and to foster them with that care which they experience in foreign states. We ask no boon which is not already enjoyed by other classes in society; no privilege which trenches upon established rights; no advantages which will not be returned tenfold into the public treasury. On the subject of our patent laws, those wretched monuments of vicious legislation, public attention has been at last roused, and we trust that the respectable individuals in this vast metropolis, who have given this impulse, will not relax their efforts till science is freed from the disabilities and fetters under which she at present groans. Popular sentiment now favours the cause which we advocate; and the knowledge and patriotism of public men entitle us to reckon upon their cordial support. Those eminent individuals who are placed at the head of the government will surely lend their high powers to uphold the intellectual glory of their country, and the distinguished member of it in the House of Commons, who with the qualities of an orator and a statesman, combines the highest attributes of a mathematician and a philosopher, can not be indifferent to a cause in which he has so zealously and successfully laboured.

From this digression, into which the subject of the achromatic telescope necessarily led us, we proceed to the conclusion of this article. The account which we have given of the discoveries of Fraunhofer must have excited in our readers a desire to know something of the history of so remarkable a man. We grieve to inform them that he was recently cut off in the very prime of life, in the middle of researches which he was anxious to complete, and in the anticipation of discoveries which he was not destined to realise. From the humble condition of a glassgrinder, the profession of his father, he rose to wealth and honours. Though placed in the most adverse circumstances, he instructed himself in mathematics and optics, and thus qualified himself for that situation in the optical establishment at Munich,

i

which was the foundation of his fortune as well as his fame. His constitution, which an early accident had shaken, was still farther weakened by the ardour of his studies, and by an imprudent exposure to the heat of the furnaces in which he carried on his experiments on glass, and a pulmonary complaint having supervened, he died on the 7th of June, 1826. In 1823 the King of Bavaria had appointed him, with a pension, Keeper of the Physical Cabinet of the Academy. In 1824 he honoured him with the rank of Chevalier of the order of Civil Merit; and such was the estimation in which he was held in foreign countries, that, a few days before his death, he received from the King of Denmark the diploma of Chevalier of the order of Dannebroga. No regular memoir of his life has yet been published, but we observe that a biographical account of him is given in the last number of the Edinburgh Journal of Science.

ART. VII-1. Deutschland; oder Briefe eines in Deutschland reisenden Deutschen.* Vol. I and II. Stuttgard, 1826, 1827. 2. Wien, wie es ist. Leipzig, 1827.

THE author of this work does not name himself; but he gives us to understand that he was born in the territories of the king of Würtemberg; that he studied at the University of Jena; that he became travelling preceptor to a person of distinction; that he at length passed into the service of the state, and attended many conferences of the diplomatic agents of different countries relative to the new distribution of the German provinces. He has pervasively visited every part of the empire, sometimes on foot, sometimes in passage-boats, sometimes on horseback, and some, times in post-waggons and post-chaises (extra-post); and he now collects his observations, not in the order in which they were made, but in a sort of geographic or political order, describing each separate sovereignty apart. A bird's eye view of the entire country is taken first; afterwards his flight swoops, and a bee's eye view succeeds of the minuter details of each particular region. The sections of the work are entitled letters, but they are impromptus à loisir, and have not the off-hand character of epistolary writing. The fresh, gay, motley colouring of autopsy has long since faded into the gray, copper-plate lines of reminiscence; still the outlines are sharp, and the delineations exact,

There are to be four volumes of this work, of which only two are before us; these relate to southern Germany, and are dedi

Germany; or Letters of a German Traveller in Germany.

Vienna, as it is.