and the heaviness, so much censured, of the northern façade, are not to be imputed to the architect alone.

The eastern tower, left uncovered, and the vast room called the Hall of the Meridian, served for setting up or sheltering telescopes, not achromatic, from 50 to 60 feet in length, such as observers used at the end of the seventeenth century, when they wished to study the physical constitution of the planets and their satellites. Excited by the remarkable discoveries with which the science was enriched by means of these great instruments, astronomers and opticians attempted to manufacture them of a still larger size; and they soon succeeded. One of these telescopes had a focal distance of over three hundred feet. As the new edifice could no longer contain or support them, it became necessary to erect masts of a prodigious height in the open air, and even to transport into the garden a colossal tower of wood, used a short time before for the water-works of Versailles. The objectglasses were fixed at the summit of these masts or of the immense tower, while the observer held the eye-glass in his hand; the telescope, confined to these two extreme pieces, had no tube. Difficulties that might have been foreseen caused the failure of these efforts, the most gigantic that are enrolled in the annals of science. It was evident, a priori, that the observer could not with sufficient precision adjust the centres of two lenses thus isolated in space, and not connected by the intervention of any rigid body. With such instruments, also, the impossibility of observing, except for a few minutes before and after the passage of stars over the meridian, was enough to prevent any continuous and prolonged labor.

But the inherent defects of Perrault's edifice became most glaring, when the necessity was perceived of applying instruments in the plane of the meridian, to the observation of stars. Thus, in 1732, no place could be found in the great building for establishing a mural quadrant of six feet radius; in an enclosure covered by roofs entirely closed, and resting upon walls of great thickness and considerable height, no continuous opening could be made in the line of the meridian, through which all the stars, from the horizon to the zenith, might be seen at the moment of their culmination. Thus compelled to give up the great edifice, the Academy caused an out-house to be built, attached to the eastern tower. On a similar occasion, in 1742, a second little building was erected by the side of the former one. About 1760, a little tower with a revolving roof was constructed to the south of the two former buildings, to facilitate the observation of equal altitudes, and thus determine the exact time of the phenomena. These three little out-buildings, erected at a trifling cost and likely to endure but a short time, formed for many years the true, the only royal observatory of Paris. The sumptuous edifice of Perrault, towered majestically over them; but, to use an expression of that day, it was only a parade observatory.

Besides, this great building, like the other monuments of the capital, felt the effects of the carelessness and indolence which characterized the later

years of the reign of Louis XV. In 1770, it was falling into ruin. It was no longer safe to enter the large halls, especially during a thaw; the walls and vaulted ceilings, undermined by the rains, were dropping piece by piece. The incessant petitions of Cassini, strengthened by reports from the Academy, were at last heeded by the minister; and it was decided that the repairs of the edifice should be immediately commenced. As the vicious arrangements of the interior had given much trouble to astronomers, Cassini proposed that the whole upper part of the building should be taken down. But Louis XVI. was unwilling to destroy an edifice erected by his grandfather, the imposing size and severe style of which placed it among the chief architectural ornaments of the metropolis. Its demolition might also have been opposed by the recollection of the brilliant scientific achievements of which it had been the theatre.

It was here, for example, that Picard, giving up the old sight vanes, applied telescopes furnished with micrometers to the graduated instruments, and thus laid a foundation for the exactness of modern observations. Here, also, was doubled, if we may so speak, the duration of an astronomer's life, by the discovery that the stars might be observed in the day-time. In this building, too, Picard and Auzout, using the hair micrometer of their invention, determined the angular diameters of the heavenly bodies, and thus overcame the difficulties with which the genius of Archimedes had striven in vain. Within these walls, now threatened with destruction, were made the trials, the minute preparations that were necessary before undertaking, with any chance of success, the celebrated measurements executed in France, in Peru, and in Lapland, to determine the dimensions and shape of the earth. Richer watched the vibrations of his pendulum here both before and after his voyage to Cayenne, and by these comparisons established the capital fact, that the weight of terrestrial bodies is diminished as they approach the equator. Under this roof, also, Cassini established the laws of the libration of the moon, discovered four of the satellites of Saturn, the rotary movement of these new bodies, and those of the satellites of Jupiter, and the zodiacal light. Finally, in these vast halls, science began to suspect that the transmission of light was not instantaneous; and it was by observing, through the large windows of the Paris observatory, the eclipses of the satellites of Jupiter, that Roemer first determined by approximation the quickness of a ray of light; after a century and a half of further inquiry, the rate has been definitively fixed at 191,000 miles in a second.

In every country where the love of science exists at all, such recollections would have sufficed to save the most defective edifice from destruction. In France they had their full weight; and, though great repairs and improvements in the observatory were made during the last quarter of the last century, the main building preserved all its chief architectural features. In 1831, the Chamber of Deputies, wishing that our national observatory should be made equal to the most celebrated observatories in Europe, voted

an appropriation for it twice as great as the minister asked for, and thus provided not only for the necessary repairs, but for the entire re-construction of the smaller buildings used by the observers. The Deputies soon afterwards furnished the establishment with its vast, convenient, and richly decorated amphitheatre, which an expert architect has happily united with the other portions of the edifice, and into which a taste for astronomy constantly draws a numerous audience. The new structures destined for meridian `observations happily unite convenience and utility with elegance, and leave absolutely nothing to be desired.

In former days, besides the dilapidation of the principal structure, another thing grieved the French visiter. The instruments in use were almost exclusively of foreign origin. The telescopes, for instance, bore the names of Campani, Borelli, Hartzæcker, Huyghens, Dollond, and Short; the mural and transit instruments, and the great repeating circles, were the productions of Sisson, Bird, Ramsden, and Reichenbach. The astronomical clocks alone came from the workshops of our own artists. But now, all the instruments in the Paris observatory are of French manufacture. We have not sacrificed scientific exactness to national pride, which would have been an act of great folly, but we still find upon the walls and the massive piers the magnificent graduated circles, the transit instruments and equatorials, of Fortin and Gambey; and in the vast halls of the old building, the great achromatic telescopes manufactured by the skilful hands of Lerebours and Cauchoix. And how was this great change effected? The answer is a very simple one. The French artists were told to pay no heed to the almost universal opinion respecting an innate superiority which the English and German workmen possessed over them. This advice was followed, and the success of the trial surpassed all our hopes. In France, to venture is almost the same thing as to succeed.

For some years, all the governments of Europe seem to have acted in concert in improving their old observatories and creating new ones. In England, Greenwich, already so justly celebrated, has been much enlarged; and the observatories of Edinburgh, Cambridge, Oxford, Dublin, and Armagh vie with that which Flamstead, Halley, Bradley, Maskelyne, and Pond have made illustrious, and which is still happily in very good hands. Similar establishments have been erected, on a great scale, at the Cape of Good Hope, at Sydney in New Holland, and at Madras. The Sicilian government, besides its renowned edifice at Palermo, to which Piazzi, at the beginning of this century, gave so much fame, has lately constructed a fine observatory near Naples, at Capo di Monte; and another, for observations in meteorology and physical science, is rising on the flanks of Vesuvius. The observatories of Florence, Milan, Padua, Turin, and Vienna might perhaps be criticised if viewed only as buildings; but the number and beauty of the instruments in them deserve all praise. All the world knows of the fine observatories, most of them new, at Brussels, Geneva, Altona, Munich, Göt

tingen, and Hamburg. In Prussia, the course of the stars is studied, under government auspices, at Bonn, Breslau, and Königsberg; and in this general rivalry in favor of the most magnificent of all sciences, Russia has placed herself in the first rank. Not content with very useful observatories at Dorpat, Abo, Kieff, Kazan, and Nicolaïeff on the Black Sea, she has just erected near Petersburg, on the hill of Pulkova, a model establishment. This central observatory of Russia has cost more than 2,000,000 of roubles; among its fine instruments is a telescope purchased at Munich for 80,000 roubles.

If some narrow minds conceive that so many observatories are useless, we can undeceive them by showing that the field of science has enlarged itself yet more rapidly than the means of investigation. Confining ourselves at first to those stars which are always visible, we find that more than 150,000 of them, formerly called fixed stars, are subject to movements which need to be continually measured with great exactness. Millions of stars, also, hitherto despised on account of their excessive smallness, now draw the attention of astronomers, and promise to unveil the most hidden wonders of the firmament. As for the comets, visible for so brief a period that we must almost steal a sight of them, protection is needed in Europe against the continuously misty atmosphere, which, at a given place, often renders any observation impossible for weeks together. Besides, is it not natural, that, in the nineteenth century, every nation should have the noble ambition to take a direct part in those astronomical victories of which men have most reason to be proud, on account of their certainty, their magnificence, and their usefulness?

Again, the vast improvements which are making in the construction of telescopes, achromatic glasses, and large graduated instruments, have contributed even more than the progress of astronomy or the ambitious eagerness of all European governments towards causing new observatories to be built, and the form and arrangement of old ones to be modified. The first spy-glasses of the poor optician of Middlebourg, who invented these wonderful instruments, had a focal distance of only one foot and a half. Those with which Galileo discovered the satellites of Jupiter, and the phases of Venus, multiplied the object hardly seven times. Huyghens and Cassini had telescopes which, with a focal distance of 24 feet, multiplied the object a hundred times. Afterwards, Auzout made an object-glass that had a multiplying power of 600, the focal distance being 300 (French) feet; but as we have already said, the use of an instrument as lofty as the dome of the Hotel of the Invalids, in spite of a thousand ingenions artifices, is obstructed by innumerable difficulties. The discouraged opticians, following the example of Newton, turned their attention to reflecting telescopes.

At length, in 1758, the son of a French refugee in England, John Dol lond, achieved that which Newton had declared to be impossible, and produced telescopes which gave the images of heavenly bodies without those colored

borders which all simple object-glasses had created. Achromatic glasses of small dimensions, which had as great a multiplying power as the instru ments 200 or 300 feet long, of Campani, Borelli, and Auzout, at once monopolized the attention of men of science. As the English alone could make flint glass without striæ, they were able to make achromatic glasses for the whole world. But they could not fabricate such lenses of more than six inches opening. The images thus created not having light enough to support the requisite multiplying power, recourse was again had to reflecting telescopes, and those colossal machines were made which have immortalized Herschel. A Swiss workman, in a glass manufactory near Munich, succeeded in making flint glass without striæ, and science then turned again to refracting telescopes. Incited by the skill with which Frauenhofer had used this glass, the English government endeavored, but in vain, to regain possession of a branch of industry which had fallen out of its hands. most powerful instruments now in use, even in the English observatories, came from the workshops of Paris and Munich. The greatest known object-glass has 15 inches opening. It seems as if the power of such an instrument ought to be equalled, if not surpassed, by reflecting telescopes of attainable magnitude. In truth, a wealthy Irish nobleman, Lord Rosse, has applied, with infinite zeal and remarkable skill, enormous sums in attempts to construct such telescopes of greater dimensions than any yet known.

The

Things were in this state, when two glass-makers, Guinand and Bontemps, presented to the Academy of Sciences masses of crown and flint glass 22 inches in diameter, which appeared free from bubbles and striæ. The same artists engaged to furnish similar masses even three feet in diameter. Opticians have, also, generously offered to scientific societies the necessary mechanical means to shape, temper, and polish these gigantic glasses. Finally, the most eminent artist of our country has offered to direct this labor. In a very short time, if the Chamber adopts the proposition now made to it by the ministry, French astronomers will perhaps turn towards the skies telescopes superior to everything of the kind which now exists, superior even to what the most glowing imaginations would have dared to hope for, a year ago. Meanwhile, the parallactic mounting and the revolving roof of the eastern tower will enable us to make good use of several telescopes, which the difficulty of managing has hitherto rendered useless.

Are the discoveries foreshadowed by such grand instruments important enough to justify so much zeal and expense. Let us cite a few facts, and the Chamber may then answer this question for itself.

Till very lately, we had not succeeded in determining the actual distance of a single star. All that astronomers could establish was a limit within which not one of these stars could be situated. Now, thanks to the great telescopes of which we shall soon have the use, the true distance of ONE star is known. The little star called 61 Cygni is so far from the earth, that it requires ten years for its light to reach us; so that, if the star were suddenly annihilated, it