many as would enable them, were the country open and free from obstacles, to form their line of battle in half an hour. It may indeed be said that they move in order of battle, perfectly well aware that an adherence to the old rule of covering each separate column of march with its own advanced-guard and its own flankers would expose them at any moment to be cut asunder by an enemy falling upon them in force. But the Prussians do not adhere to this rule. They have their advanced-guards covering every column, and the flankers too; but in front of their advanced-guards, properly so called, and far wide of either flank, they send out swarms of light cavalry well mounted, led by intelligent officers, and made up of men all of them more or less educated, and carefully prepared in peace for the parts that will be assigned to them in war. These cover the entire army as with a zone, within which the columns pursue their way comparatively at ease, well knowing that any such force as would give serious cause of alarm to any one of them, could not approach within miles of their front or flank without due notice given of the danger. Nor is this all. These swarms of intelligent horsemen find out where the enemy are-not where the main force is exclusively, but where every detachment is stationed, every picket placed, every sentry and vedette planted. The intelligence thus acquired they carry back to the headquarters of the corps or division to which they belong; while the enemy, who have taken no such precautions, remain profoundly ignorant, either that their dispositions have been looked into, or that they are about to be assailed where, perhaps, they least expected danger. Just observe how the campaign opened, and judge from that whether or no we attribute more praise than is due either to the Prussian tactics or to their strategy.

However surely the Prussian Government might count on being sooner or later en prise with France, it is certain that the declaration of war last July took them very much by surprise. So far, the French had a great advantage over them; and had they known how to use it, and been in strength enough to do so, as the great Napoleon would have been, the first serious collision between the two armies would have occurred on German soil.

We now know what the Emperor's

plans and expectations were. Crossing the Rhine at Axau, and penetrating between Rastadt on his right, and Germersheim on his left, he would have interposed between southern and northern Germany, given an opportunity to such of the States as were discontented with the present condition of affairs to turn against Prussia, and, as he tells us in his very remarkable manifesto, induced Italy and Austria to make common cause with him. Even for this Moltke was not unprepared. It is evident, indeed, from the dispositions which he made of his corps, as one by one they became mobilized and recruited up to the proper war strength, that had the plan been carried into execution, the invaders would have been struck simultaneously both in front and on the flank. The plan was not, however, carried into execution. Be the causes what they might, the French army, which was to have made its first halt at Berlin, never got beyond the French frontier, where it waited in an ill-chosen position, apparently without the most remote notion on the part of its commanders that the enemy they had to deal with might take the initiative.

The fortnight's pause was an enormous gain to the Germans. It enabled them to mass their troops at the exact points which long before had been selected as most suitable for the emergency. And now came up the fruit of all that careful study of which we have been speaking. This very war had been for years foreseen and provided against. Two plans of campaign were settled, the first defensive, the second offensive; and seeing that the French did not constrain them to act upon the former, the Prussians proceeded at once to execute the latter. Now if we, or the French, or the Austrians, or any other Power than Prussia, had been placed in this situation, we should have acted thus: Providing ourselves with the best maps that we could find of the east of France, we should have begun our advance by the roads marked out on those maps; and, covering our columns with advanced guards and outflankers, sent out staff officers to reconnoitre and find out by degrees where the enemy were, and how we might best hope to engage and beat him. The Prussians did nothing of the sort. They knew beforehand perfectly where the enemy were likely to be, and how

they could be approached, every road, lane, and track being put down in their charts; and they had among them scores of officers who, from personal observation and inspection, had the sweep of these tracks and the lie of the country through which they passed distinct in their maps. Accordingly, the entire force was so disposed in separate armies, as that, moving in order of battle, it should be capable of falling upon the French in detail ere the order was given for concentration of their scattered corps; while clouds of cavalry at once protected each of the advancing columns from the danger of being taken in delictu, and served as guides to the infantry and artillery when the moment drew near for bringing them into play. It was thus that on the 4th of August the Crown Prince was able to fall upon General Douay at Wissembourg with overwhelming numbers, the French general being in ignorance till the attack began that an enemy was within several days' march of him. It was then that M'Mahon, hastening to retrieve the disaster which had come upon his lieutenant, found himself, on the 6th, assailed in front and flank, and his rear threatened. While the same day General Froissard, executing, as he believed, a perfectly safe movement to the rear, was overtaken at Spicheren, and defeated with great loss. The results of these first operations were completely to disperse the French armies: M'Mahon went off in one direction; Failly, who endeavored but failed to reinforce him before the battle of the 6th, went off in another; and the remains of Douay's corps got together, its leader being killed, as they best could at Belfort, quite out of the theatre of the war. Meanwhile Bazaine fell back upon Metz, where the arrival of Canrobert's corps from Chalons raised his effective to 140,000 or 150,

ooo men, hoping that the opportunity would be presented to him of engaging

one or other of the Prussian armies before it could be sustained by the rest. The hope proved utterly vain, for reasons which cannot be better given than in the words of the Emperor's pamphlet: "The Prussians concealed every movement so effectually behind a formidable belt of cavalry, which spread out before them in all directions, that we could never, notwithstanding the most anxious researches, make out in reality where the masses of their troops were placed, nor in what direction it behooved us to strike hard. Nobody imagined, either on the 14th or the 16th of August, that we had the bulk of the Prussian army to deal with; nobody doubted, after the battle of Gravelotte, that to reach Verdun on the morrow would be the easiest thing in the world."

One great cause, then, of the astounding success of the Germans in this war is to be found in this, that, superadded to the excellency of their system of recruitment, they have the best-instructed staff in the world, which have revolutionized for them the tactics, or practical portion, of the art of war as completely as their own Frederick did a century or more ago; and even more than was done, not so much by Napoleon himself as by the course of events during the first days of the French Revolution, and the skill with which he seized the result and improved upon it. Another is to be found in the perfection of their equipment in every arm, and the admirable order which prevails in their intendance or department of supply. Upon these points, however, we cannot enter now, having already, it is feared, trespassed more upon the attention of our non-military readers than, under any other circumstances than the present, they would probably thank us for doing.

It is to be presumed that all well-informed persons are aware that the system of linear measurement used in France and most continental nations is based upon the mètre, which has been extended to measures and weights in general, and carried into practice by a decimal system of computation. At the same time, few are con

versant with the circumstances under which the metrical system was established at the commencement of the present century, and the difficulties encountered by the savants of the period in prosecuting their scientific operations for that purpose. During the time the system was being perfected, and promulgated as one of in

ternational importance, this country was at war with France-where it originated --and political feeling ran so strong against anything French, that, on being submitted for our adoption, it was rejected by the government and parliament of the day. Happily, a more friendly feeling now subsists between both the people and governments of the two nations, and committees of our learned societies are zealously endeavoring to promote the introduction of this system, in order to simplify our commercial relations with the continent.

As regards the adoption of the system in this country, or its practical working on the continent, we do not intend to direct the reader's attention in the present article. Neither do we intend to discuss the scientific problem upon which the system was based. The subject of our notice relates to the remarkable incidents of travel that befell the operators in determining their observations at different stations in Spain, France, England, and Scotland. Not only had they to encounter privations and dangers by sea and land, but, in the then disturbed state of Europe, some of them suffered captivity, and others died from fatigue and exposure. The narratives are contained in the Reports read before the French Institute between 1810 and 1817, from which we condense a brief account of the most salient points of observation and the attendant circumstances.

In order to understand the operations of these scientific expeditions, it is necessary to premise that their main object was to determine a standard linear measure by the admeasurement of a great arc of the earth's circumference as near as possible at a fixed parallel of latitude, from which a fractional section would be taken as an unalterable basis. It is well known that the circumference of the earth is greatest at the equator, and gradually decreases towards the poles. As a medium between those two extremes, it was determined that the parallel of latitude forty-five degrees north should be the basis, especially as it intersected a part of Europe where a great arc of the meridian could be measured by a trigonometrical survey.

The first sets of observations were made by Mechain and Delambre, between Dunkirk, at the extreme northern frontier of France, and Barcelona, in Spain, compris ing a terrestrial arc of more than ten degrees of latitude. This operation was the

greatest of the kind that had been made up to that period, and was considered most perfect in its execution. But the improvements that were at that time being made in the astronomical and other scientific instruments employed in the work, rendered it necessary to correct the observations. The result was, that some errors were discovered, which caused great uncertainty regarding the correctness of the whole. Notwithstanding the indefatigable labors of these men of science, the whole operations must be repeated with new instruments, to arrive at a definite conclusion. Meanwhile, M. Mechain died in Spain, a victim to the excessive fatigue and labor he had undergone in prosecuting his part of the work, which put a stop to further operations for some years,

In 1806, when the first Empire in France was in the ascendency, and Napoleon I. in the plenitude of his power, the question. was resumed by the French Institute, and two of its members recommended to continue the operations. This was acceded to by the Emperor, who gave orders to fit out the expedition, and accorded liberally the funds necessary for its execution. Application was also made to the Spanish government for assistance in a work that was of international benefit. This was freely acquiesced in, by the appointment of Signors Chaix and Rodriguez, men of eminence in astronomy; while a vessel was placed at their disposal for conveying the expedition in Spanish waters. Éngland being apprised of the expedition, the British government granted letters of safeconduct to its members, should they be challenged by the officers of the Mediterranean fleet. The two savants to whom this important scientific mission was intrusted were M. Arago-then a young man. but who, during a long life, arrived at the greatest eminence as a profound and practical astronomer-and M. Biot, at that time in the prime of life, with a European reputation as one of the most learned physicists of the age, to whom the chief command of the expedition was given.

OPERATIONS IN FRANCE AND SPAIN.

On arriving in Spain, the attention of the expedition was first bestowed upon visiting the mountain chains where Mechain had established his stations during the survey. Of the trigonometrical base

line thus formed, one angle measured about one hundred and twenty-five miles over the sea, extending to the Isle of Iviza, off the Spanish coast, in the Mediterranean. On the mainland, the previous observations were found perfect; but doubts were entertained of those connected with the island, in consequence of atmospheric difficulties which prevented the signallights being seen at night, when it was desirable they should be observed, while the stars were visible in the firmament. was absolutely necessary that they should wait for at least one favorable night, when the weather was calm, and the heavens perfectly serene, in order to fix the exact distance between the mainland and one of the Spanish isles. They were resolved not to be baffled, should it require a nightly watch for months, in all weathers, and at the dreary summits of mountains, to seize the favorable opportunity.

It

Accordingly, it was arranged that M. Arago should establish himself and instruments in a rude cabin on the summit of a mountain in the Desierto de las Palmas, which Mechain had chosen for one of the stations of his great triangle, formed on the islands of Majorca and Iviza with the coast of Valencia. A favorable site in the Mediterranean was obtained on the small isle of Formentera, which, with Iviza and several rocky islets, forms the group of Pithyusa Isles, and their most southern point. The only accommodation to be got here was in the hut of a poor peasant, who was astonished to see strangers looking for such a habitation. Here they carried their reflectors and other instruments up to the summit of the rocky isle, and constructed a temporary observatory of planks. The party consisted of M. Biot, the French savant, and M. Rodriguez, the Spanish astronomer, with four sailors; the latter being stationed there to see the lamps supplied with oil, and the reflectors polished and adjusted every night. By the time these arrangements were completed, winter had set in, the weather became tempestuous, and the land covered with snow. The inclemency of the weather, together with the difficulty of obtaining warmth and food, soon took effect on M. Rodriguez, so that he left the island for Spain, and M. Biot had to take his arduous watch by night. It was a dreary and try ing situation, at the summit of that rocky isle, with the sailors only as companions, NEW SERIES.-VOL. XIII., No. 2.

nothing but coarse food to eat,.,no place for exercise, except among the débris of the rocks, and surrounded by a monotonous prospect of the sea.

Having fixed upon two mountain summits, a third station was necessary to determine the great triangle. This was fixed at the extremity of Cape San Antonio, on the mainland of Spain, almost due west of Formentera Isle, and about twenty leagues distant. The highest point of this cape is a mountain named Mongo, well adapted for a trigonometrical station, but much exposed-especially in winter-to the storms that visit that part of the coast. Consequently, an observatory had to be constructed of rock-work, to protect the instruments from the violent gusts of wind, with rain and snow. In this work the party was assisted by some Spanish peasants, who volunteered their services; but the sailors attached to the expedition had the most arduous task to perform in keeping the lamps alight, and the reflectors fixed every night during a rigorous and stormy season.

At the various points of observation, the indefatigable members of the expedition kept watch day and night from the middle of October to the middle of December. M. Biot, in his Report, describes feelingly the trying position of his party, and the aspect of nature from the isle of Formentera. While all around him presented a dreary scene of snow-covered peaks and valleys, yet, when the days were fine and clear, he could see the fertile plains of Valencia covered with groves of citron, olive, and orange trees, their verdant aspect presenting a pleasing contrast to the eye. But those delightful days were rare. More frequently the tempest raged over the sea around, while the winds threatened at times to drive his observatory and instruments down the rocks into the surge beneath. To prevent a catastrophe of this kind, they had to fasten the wooden erection to strong cables fixed into the rocks. In this manner, and suffering great privation, this learned savant continued at his post.

At length, after two months' sojourn on that solitary mountain, his perseverance was rewarded by a favorable state of the weather, when the signal-lights from the different stations were visible. The night was perfectly serene and clear, and the absence of the moon rendered the_hea

15

vens profoundly dark. Having adjusted the telescope of his circle in the direction of the isle of Iviza, he saw in the field of the glass a small luminous point, just perceptible, resembling a star of the fifteenth or sixteenth magnitude. Find ing that it was perfectly stationary, he knew that it was not a heavenly body. heavenly body. After looking long and anxiously at the light, he was satisfied that it came from the signal-lights on Mount Campvey, in the island of Iviza, ten leagues distant. Subsequent observations fixed the exact distance by the survey to the mainland, and connected the new triangle with those previously ascertained. It is not necessary to enter into any detail on this head; suffice it to say that all uncertainty regarding the correctness of previous observations was removed. The base line of the grand triangle was calculated by three combinations of observations, absolutely independent of each other, furnishing results the value of which scarcely differed two mètres in a hundred and fourteen thousand, or about one fathom in thirtyfive leagues. Then followed a set of observations by M. Arago on the island of Iviza, from whence he saw the island of Majorca on the east, and the coast of Spain on the west, and thus determined an arc of parallels of latitude, measuring three degrees of longitude. This arc, situated at the southern extremity of the meridian, determined also most completely the curvature of that part of the terrestrial spheroid of revolution, at the level of the sea, from which the measurement of the mètre was to be taken. These results were again compared with the first observations of M. Delambre on land at Dunkirk, from which the value of the mètre was fixed according to the French laws. The difference was infinitesimal-amounting to the ten-thousandth part of a line, or about four-tenths of a mètre upon the total length of the arc between the parallels of Dunkirk and Formentera-approximating to one and a half feet in 865 English statute miles. So small an error was deemed of no account, and this part of the operations was satisfactorily concluded.

Meanwhile, the members of the expedition prepared to leave the isles of Formentera and Iviza, and remove their astronomical instruments to the mainland of Spain. Before doing so, the curate of the district where M. Biot was situated

requested permission for himself and some of the inhabitants to see their instrumen's. Though one of the inferior clergy of Spain, yet he took considerable interest in scientific operations, and appreciated the instruments in the observatory. On the other hand, those islanders permitted to enter the building gazed on them with the astonishment of savages. It was a Sunday and a fête day, when a troop of them came in the evening, with the alcalde at their head, dancing and singing in a most extraordinary manner, both men and women. The men clattered with their feet in a kind of half-African, half European dance; while the women, having their hair plaited into long pendent queues, turned and pirouetted on their naked feet, without raising them off the ground, like puppets on springs. The music that accompanied these strange postures was quite as barbarous in character: one played on a species of flute, another struck a tambourine, and some had wooden clappers, while the alcalde kept measured time by striking a large metal plate with a piece of iron. As each one, however, entered the observatory, he made his observations in silence; presenting a contrast between civilization and barbarism, a contrast of the most sublime science and the most profound ignorance. It must be admitted, however, that though ignorant of the instruments and objects of the expedition to their solitary isles, these people in no way interfered with the mission, but assisted its members in their simple way when they could be of use.

Not so with the inhabitants of the island of Majorca, where M. Arago was stationed with Senor Rodriguez, on the summit of Mount Galatzo, making his final observations, which he successfully accomplished. While on the eve of departure, the rumor suddenly spread amongst the inhabitants that these operations, these instruments, these fires, these signal lights, were for the purpose of guiding the enemies of Spain to conquer the island. It must be remembered that the fears of the ignorant islanders were excited by the accounts from the mainland. Napoleon was at that time preparing for his Peninsular campaign, and as the leader of the scientific expedition was a Frenchman, they concluded that he and his companions were emissaries of Bonaparte come to spy the land. Galatzo was