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dary-line between the United States and that country was in part described by reference to the town of El Paso as laid down on a specified map of the United States, of which a copy was appended to the treaty. This boundary was to be surveyed and run by a joint commission of men of science. It soon appeared that errors of two or three degrees existed in the projection of the map. Its lines of latitude and longitude did not conform to the topography of the region; so that it was impossible to execute the text of the treaty. The famous Mesilla Valley was a part of the debatable ground, and the sum of ten millions of dollars paid to the Mexican government for that and for an additional strip of territory on the south-west was the smart-money which expiated the inaccuracy of the map-the necessary result, perhaps, of the want of good materials for its construction. Ten millions of dollars would have gone a good way toward the expense of a national observatory, and of a map of the continent constructed with entire accuracy.

It became my official duty in London a few years ago to apply to the British government for an authentic statement of their claim to jurisdiction over New Zealand. The official gazette of the 2d of October, 1840, was sent me from the foreign office as affording the desired information. This number of the gazette contained the proclamations issued by the lieutenant-governor of New Zealand "in pursuance of the instructions he had received from the marquess of Normanby, one of Her Majesty's principal secretaries of state," asserting the jurisdiction of his government over the islands of New Zealand, and declaring them to extend " from

thirty-four degrees thirty minutes north to forty-seven degrees ten minutes south latitude." It is scarcely necessary to say that south latitude was intended in both instances. This error of sixty-nine degrees of latitude, which would have extended the claim of British jurisdiction over the whole breadth of the Pacific, had apparently escaped the notice of that government.

It would be easy to multiply illustrations of the great practical importance of accurate scientific designations drawn from astronomical observation in various relations connected with boundaries, surveys and other geographical purposes; but I must hasten to a third important department, in which the services rendered by astronomy are equally conspicuous. I refer to commerce and navigation. It is chiefly owing to the results of astronomical observation that modern commerce has attained such a vast expansion, compared with that of the ancient world. I have already reminded you that accurate astronomical notions contributed materially to the conception in the mind of Columbus of his immortal enterprise, and to the practical success with which it was ducted. It was mainly his skill in the use of astronomical instruments, imperfect as they were, which enabled him, in spite of the bewildering variations of the compass, to find his way across the ocean.

One of the first practical applications contemplated by Galileo of his discovery of the satellites of Jupiter was the use that might be made of them in ascertaining the longitude at sea. With the progress of the true system of the universe toward general adoption, this problem was the object of universal attention. It was the avowed object of the

age since the dawn of time when men ought to be less disposed to rest satisfied with the progress already made than the age in which we live; for there never was an age more distinguished for ingenious research, for novel result and bold generalization.

foundation of the observatory at Greenwich, | side-and it seems to me there never was an and no one subject has received more of the consideration of astronomers than those investigations of the lunar theory on which the requisite tables of the navigator are founded. The pathways of the ocean are marked out in the sky above; the eternal lights of the heavens are the only Pharos whose beams. never fail, which no tempest can shake from its foundations. Within my recollecWithin my recollection it was deemed a necessary qualification for the master and the mate of a merchant-ship, and even for a prime hand, to be able to "work a lunar," as it was called. The improvements in the chronometer have in practice to a great extent superseded this laborious operation, but observation remains, and unquestionably will for ever remain, the only dependence for ascertaining the ship's time and deducing the longitude from comparison of that time with the chronometer.

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It may perhaps be thought that astronomical science is brought already to such a state of perfection that nothing more is to be desired, or at least that nothing more is attainable in reference to such practical applications as I have described. This, however, is an idea which generous minds will reject in this every other department of human knowledge. In astronomy, as in everything else, the discoveries already made, theoretical or practical, instead of exhausting the science or putting a limit to its advancement, do but furnish the means and instruments of further progress. I have no doubt we live on the verge of discoveries and inventions in every department as brilliant as any that have ever been made that there are new truths, new facts, ready to start into recognition on every

That no further improvement is desirable in the means and methods of ascertaining the ship's the ship's place at sea, no one, I think, will from experience be disposed to assert. The last time I crossed the Atlantic I walked the quarter-deck with the officer in charge of the noble vessel on one occasion when we were driving along before a leading breeze and under a head of steam, beneath a starless sky, at midnight, at the rate, certainly, of ten or eleven miles an hour. There is something sublime, but approaching the terrible, in such a scene-the rayless gloom, the midnight chill, the awful swell of the deep, the dismal moan of the wind through the rigging, the all-but volcanic fires within the hold of the ship. I scarce know an occasion in ordinary life on which a reflecting mind feels more keenly its hopeless dependence on irrational forces beyond its own control. I asked my companion how nearly he could determine his ship's place at sea under favorable circumstances. "Theoretically," he answered, "I think, within a mile; practically and usually, within three or four." My next question was, "How near do you think we may be to Cape Race?" that dangerous headland which pushes its iron-bound unlighted bastions from the shore of Newfoundland far into the Atlantic, first landfall to the homeward-bound American vessel.*

Since the voyage in question was made a lighthouse has been built on Cape Race.

"We must," said he, "by our last obser- | superable, and which to the same extent has vations and reckonings, be within three or existed in no other science—namely, that all four miles of Cape Race." A comparison A comparison the leading phenomena are in their appearof these two remarks, under the circum-ance delusive. It is indeed true that in all stances in which we were placed at the mo- sciences superficial observation can only lead, ment, brought my mind to the conclusion except by chance, to superficial knowledge; that it is greatly to be wished that the but I know of no branch in which, to the means should be discovered of finding the same degree as in astronomy, the great leadship's place more accurately, or that navi- ing phenomena are the reverse of true, while gators would give Cape Race a little wider they yet appeal so strongly to the senses that berth. Still, I do not remember that one sagacious philosophers in antiquity who could of the steam-packets between England and foretell eclipses and who discovered the preAmerica was ever lost upon that formidable cession of the equinoxes still believed that point. the earth was at rest in the centre of the

It appears to me by no means unlikely that with the improvement of instrumental power, and of the means of ascertaining the ship's time with exactness, as great an advance beyond the present state of art and science in finding a ship's place at sea may take place as was effected by the invention of the reflecting quadrant, the calculation of lunar tables and the improved construction of chronometers. In the wonderful versatility of the human mind, the improvement, when it takes place, will very probably be made by paths where it is least expected.

universe, and that all the hosts of heaven performed a daily revolution about it as a centre.

It usually happens in scientific progress that when a great fact is at length discovered it approves itself at once to all competent judges. It furnishes a solution to so many problems and harmonizes with so many other facts that all the other data as it were crystallize at once about it. In modern times we have often witnessed such an impatience, so to say, of great truths to be discovered that it has frequently happened that they have been found out simultaneously by more than one individual. A disputed question of priority is an event of very common occurrence. Not so with the true theory of the heavens. So complete is the deception practised on the senses that it failed more than once to yield to the announcement of the truth, and it was only when the visual organs were armed with an almost preternatural instrumental power that the great fact found admission to the general

Whatever advances may be made in astronomical science, theoretical or applied, I am strongly inclined to think that they will be made in connection with an increased command of instrumental power. The natural order in which the human mind proceeds in the acquisition of astronomical knowledge is minute and accurate observation of the phenomena of the heavens, the skilful discussion and analysis of these observations and sound philosophy in generalizing the results. In pursuing this course, however, a difficulty presented itself which for ages proved in-mind.

It is supposed that in the very infancy of science Pythagoras or his disciples explained the apparent motion of the heavenly bodies about the earth by the diurnal revolution of the earth on its axis. But this theory, though bearing so deeply impressed upon it the great seal of truth, simplicity, was in such glaring contrast with the evidence of the senses that it failed of acceptance in antiquity or the Middle Ages. It found no favor with minds like those of Aristotle, Archimedes, Hipparchus, Ptolemy, or any of the acute and learned Arabian or mediæval astronomers. All their ingenuity and all their mathematical skill were exhausted in the development of a wonderfully complicated and ingenious but erroneous theory. The great master-truth, rejected for its simplicity, lay disregarded at their feet.

At the second dawn of science the great fact again beamed into the mind of Copernicus. Now, at least, in that glorious age which witnessed the invention of printing, the great mechanical engine of intellectual progress, and the discovery of America, we may expect that this long-hidden revelation, a second time proclaimed, will command the assent of mankind. But the sensible phenomena were still too strong for the theory; the glorious delusion of the rising and the setting sun could not be overcome. Tycho de Brahe furnished his observatory with instruments superior in number and quality to all that had been collected before, but the great instrument of discovery which, by augmenting the optic power of the eye, enables it to penetrate beyond the apparent phenomena and to discern the true constitution of the heavenly bodies was wanting at Uranienburg. The observations of Tycho, as dis

cussed by Keppler, conducted that most fervid, powerful and sagacious mind to the discovery of some of the most important laws of the celestial motions, but it was not till Galileo, at Florence, had pointed his telescope to the sky that the Copernican system could be said to be firmly established in the scientific world.*

On this great name, my friends, assembled as we are to dedicate a temple to instrumental astronomy, we may well pause for a moment.

There is much in every way in the city of Florence to excite the curiosity, to kindle the imagination and to gratify the taste. Sheltered on the north by the vine-clad hills of Fiesole, whose Cyclopean walls carry back the antiquary to ages before the Roman, before the Etruscan, power, the flowery city (Fiorenza) covers the sunny banks of the Arno with its stately palaces. Dark and frowning piles of mediæval structure; a majestic dome the prototype of St. Peter's; basilicas which enshrine the ashes of some of the mightiest of the dead; the stone where Dante stood to gaze on the campanile; the house of Michael Angelo, still occupied by a descendant of his lineage and name, his hammer, his chisel, his dividers, his manuscript poems, all as if he had left them but yesterday; airy bridges which seem not so much to rest on the earth as to hover over the waters they span; the loveliest creations of ancient art, rescued from the grave of ages again to "enchant the world"-the breathing marbles of Michael Angelo, the glowing can

It is another interesting coincidence of events in the year 1609 that Keppler's works De Motu Martis and Astronomia Nova, in which his two first laws are propounded, appeared in this year. I am indebted for this suggestion to Dr. B. A. Gould.

vas of Raphael and Titian; museums filled | teenth century. Of all the wonders of an cient and modern art-statues and paintings, and jewels and manuscripts, the admiration and the delight of ages-there was nothing which I beheld with more affectionate awe than that poor rough tube a few feet in length, the work of his own hands-that very optic glass through which the "Tuscan artist" viewed the moon

with medals and coins of every age from Cyrus the Younger, and gems and amulets and vases from the sepulchres of Egyptian Pharaohs coeval with Joseph and Etruscan Lucumons that swayed Italy before the Romans; libraries stored with the choicest texts of ancient literature; gardens of rose and orange and pomegranate and myrtle; the very air you breathe languid with music and perfume, such is Florence. But among all its fascinations addressed to the sense, the memory and the heart there was none to which I more frequently gave a meditative hour during a year's residence than to the spot where Galileo Galilei sleeps beneath the marble floor of Santa Croce, no building on which I gazed with greater reverence than I did upon the modest mansion at Arcetri, villa at once and prison, in which that venerable sage passed the sad closing years of his life, the beloved daughter on whom he had depended to smooth his passage to the grave laid there before him, the eyes with which he had discovered worlds before unknown quenched in blindness:

"Ahime! quegli occhi si son fatti oscuri,
Che vider più di tutti i tempi antichi,
E luce fur dei secoli futuri."

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'At evening from the top of Fesolé

Or in Valdarno, to descry new lands, Rivers or mountains in her spotty globe;'

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that poor little spyglass-for it is scarcely more-through which human eye first distinctly beheld the surface of the moon, first discovered the phases of Venus, the satellites of Jupiter and the seeming handles of Saturn, first penetrated the dusky depths of the heavens, first pierced the clouds of visual error which from the creation of the world involved the system of the universe.

There are occasions in life in which a great mind lives years of rapt enjoyment in a moment. I can fancy the emotions of Galileo when, first raising the newly-constructed telescope to the heavens, he saw fulfilled the grand prophecy of Copernicus and beheld the planet Venus crescent like the moon. It was such another moment as that when the immortal printers of Mentz and Strasburg received the first copy of the Bible into their hands, the work of their divine art; like that when Columbus, through the gray dawn of the 12th of October, 1492-Copernicus, at the age of eighteen, was then a student at Cracow-beheld the shores of San Salvador; like that when the law of gravitation first revealed itself to the intellect of Newton; like that when Franklin saw by the stiffening fibres

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