from this and other reasons, that the transmission is straight through the earth. Do you understand?” "You mean that these waves come to us along the chord of the arc instead of along the arc itself," I ventured, recalling my geometry. "Exactly, and now I come to the most important thing: we find that all these waves from distant earthquakes reach Shide in practically the same number of minutes, no matter where the earthquakes occur. They come from Japan in sixteen minutes, from South America in sixteen minutes, from Java in sixteen minutes, and so on as far as our data extend. When all the stations are working, we shall be able to verify this conclusion; but it certainly looks already as if the period of wave transmission through the earth was uniform." "I don't see, Professor, if all these different earthquake waves get here in the same time, how you can tell one from the other, or know that this one started in South America and that one in South Africa, and so on ?" "I may say in a general way," he replied, "that we know them by their signatures, just as you know the handwriting of your friends; that is, an earthquake wave which has traveled 3,000 miles makes a different record in the instruments from one that has traveled 5,000 miles, and that again a different record from one that has traveled 7,000 miles, and so on. Each one writes its name in its own way, as you have seen on the bands. It's a fine thing, isn't it, to have the earth's crust harnessed up so that it is forced to mark down for us on paper a diagram of its own movements!" "Are these differences in the wave signatures due to differences in the distance traveled?" "Exactly. See here, I can make it plain to you in a moment." He took pencil and paper again, and dashed off an earthquake wave like this: vire "You see the difference at a glance; the second seismogram (that is what we call these records) is very much more stretched out than the first, and a seismogram taken at 12,000 kilometers from the start would be more stretched out still. This is because the waves of transmission grow longer and longer, and slower and slower, the further they spread from the source of disturbance. In both figures, the point A, where the straight line begins to waver, marks the beginning of the earthquake; the rippling line AB shows the preliminary tremors which always precede the heavy shocks, marked C; and D shows the dying away of the earthquake in tremors similar to AB. "Now it is chiefly in the preliminary tremors (we call them the P.T.'s) that the various earthquakes reveal their identity. The slower waves come, the longer it takes to. record them, and the more stretched out they become in the seismograms. And by carefully noting these differences, especially those in time, we get our information. Suppose we have an earthquake in Japan. If you were there in person you would feel the preliminary tremors very fast, five or ten in a second, and their whole duration before the heavy shocks would not exceed ten or twenty seconds. But these preliminary tremors, transmitted to the Isle of Wight, would keep the pendulums swinging from thirty to thirty-two minutes before the heavy shocks, and each vibration would occupy five seconds. "There would be similar differences in the duration of the heavy vibrations; in Japan they would come at the rate of about one a second, here at the rate of about one in twenty or forty seconds. It is the time, then, occupied by the preliminary tremors that tells us the distance of the earthquake. Earthquakes in Borneo, for instance, give P. T.'s occupying about forty-one minutes, in Japan about half an hour, in the earthquake region east of Newfoundland about eight minutes, in the disturbed region of the West Indies about nineteen or twenty minutes, and so on." since the other stations working with us have similar information. So many miles from Shide, and so many miles from Batavia, and so many miles from Argentina, and we must, with the help of a pair of compasses on the map, fix the place beyond question. And that is why it is desirable to have as many observatories as possible in different parts of the earth. Who can say, for instance, what great sums might be saved cable companies if they knew the precise boundaries of danger regions in the ocean's bed?" "Are such regions well marked?" "So well marked that a blind man could pick them out by running his fingers over a map of the ocean's bottom made in relief. Wherever he found sudden slopes going down from hundreds to thou sands of fathoms, he could say with confidence 'There is one. We know in a general way some of these dangerous regions there is one off the west coast of South America from Ecuador down; there is one in the mid-Atlantic, about the in a moment. And the great majority of breaks in the North Atlantic cables have occurred at the place just indicated, where there are two slopes, one from 708 to 2,400 fathoms in a distance of sixty miles, and the other from 275 to 1,946 fathoms within. thirty miles. On October 4, 1884, three cables, lying about ten miles apart, broke simultaneously at the spot. The significance of such breaks is greater when you bear in mind that cables frequently lie uninjured for many years on the great level plains of the ocean bed, where seismic disturbances are infrequent." Then the Professor went on to explain in PROFESSOR JOHN MILNE. From a photograph by S. Suzuki, Kudanzaka, Tokio. equator, between twenty degrees and forty degrees west longitude; there is one at the Grecian end of the Mediterranean; one in the Bay of Bengal; and one bordering the Alps; there is the famous Tuscarora Deep,' from the Phillippine Islands down to Java; and there is the North Atlantic region, about 300 miles east of Newfoundland. In the Tuscarora Deep' the slope increases 1,000 fathoms in twenty-five miles, until it reaches a depth of 4,000 fathoms. "There have been submarine earthquakes here, like that of June 15, 1896, that have shaken the earth from pole to pole; and more than once different cables from Java have been broken simultaneously, as in 1890, when the three cables to Australia snapped detail how the cables are broken by these submarine earthquakes, the two chief causes being landslides, where enormous masses of earth plunge from a higher to a lower level, and in so doing crush down upon the cable and "faults," that is, subsidences of great areas, which occur on land as well as at the bottom of the sea, and which in the latter case may drag down imbedded cables with them. Sta tistics show that fifteen breaks in Atlantic cables between 1884 and 1894 cost the companies about $3,000,000, and it is estimated that if the whole coast line of the world was looped with cables, as may be the case some day, there would be not less than three hundred interruptions annually from seismic disturbances. It is evident, then, that as the laying of ocean cables increases, it is of the first importance that cable companies be in possession of the best available knowledge as to the more dangerous regions in the ocean's bed and the safer regions. This knowledge can come only through the study of such phenomena as are being investigated now at the earthquake observatories of the world. REMINISCENCES OF MEN AND EVENTS OF THE CIVIL WAR. BY CHARLES A. DANA, Assistant Secretary of War from 1863 to 1865. ILLUSTRATED WITH PORTRAITS FROM THE WAR DEPARTMENT COLLECTION OF CIVIL WAR PHOTOGRAPHS. VII. WITH GRANT AND HIS GENERALS IN THE MARCH TO PETERSBURG. -IN THE PANIC AT WASHINGTON RAISED BY EARLY. THE Army of the Potomac, to which I went in May, 1864, at Mr. Lincoln's request, was composed of the Second, Fifth, Sixth, and Ninth Army Corps, and of one cavalry corps. In command of the army was Major-General George G. Meade. He was a tall, thin man, rather dyspeptic, I should suppose, from the fits of nervous irritation to which he was subject. He was totally lacking in cordiality with those with whom he had business, and, as a consequence, was generally disliked by his subordinates. With General Grant, Meade got along perfectly, because he had the first virtue of a soldierthat is, obedience to orders. He was an intellectual man, agreeable to talk to when his mind was free; but silent and indifferent to everybody when he was occupied with that which interested him. As a commander, Meade seemed to me to lack the boldness that was necessary to bring the war to a close; he lacked self-confidence and tenacity of purpose; and he had not the moral authority that Grant had attained from his grand successes in other fields. As soon as Meade had a commander, he was all right; but when he himself was the commander, he began to hesitate. Meade had entirely separate headquarters and a separate staff, and Grant sent his orders to him. THE CORPS COMMANDERS. spirit than almost anybody else in that army. Major-General G. K. Warren, who commanded the Fifth Army Corps, was an accomplished engineer. Major-General John Sedgwick, who commanded the Sixth Army Corps, I had known for over twenty years. Sedgwick graduated at West Point in 1837, and was appointed a second lieutenant in the Second Artillery. At the time of the Mackenzie rebellion in Canada, Sedgwick's company was stationed at Buffalo, New York, a considerable length of time. I was living at Buffalo then, and in this rebellion the young men of the town organized a regiment of city guards, and I was a sergeant in one of those companies; so that I became quite familiar with all the military movements then going on. Then it was that I got acquainted with Sedgwick. He was a very solid man; no flummery about him; you could always tell where he was to be found, and in a battle that was apt to be where the hardest fighting was. He was not an ardent, impetuous man, like Hancock, but was steady and sure. Two days after I reached the army, on May 9th, not far from Spotsylvania Court House, Sedgwick was killed. He had gone out in the morning to inspect his lines, and, getting beyond the point of safety, was struck in the forehead by a sharpshooter and instantly killed. The command of the Sixth Corps was given to General H. G. Wright. Wright In command of the Second Army Corps was another engineer officer, well educated, was Major-General W. S. Hancock. He was of good, solid intellect, with capacity for a splendid fellow, a brilliant man, as brave command, but no special predilection for as Julius Cæsar, and always ready to obey fighting. From the moment Meade assumed orders, especially if they were fighting command of the army, two days before orders. He had more of the aggressive Gettysburg, the engineers rapidly came to 1 the front; for Meade had the pride of corps strongly implanted in his heart. Major-General A. E. Burnside, whom I had last seen at Knoxville, in December, was in command of the Ninth Army Corps. Immediately after the siege of Knoxville, at his own request, Burnside had been relieved of the command in East Tennessee by MajorGeneral John G. Foster. The President, somehow, always showed Burnside great respect and good will. After Grant's plans for the spring campaign were made known, the Ninth Corps was moved by rail to Annapolis, where it was recruited up to about 25,000 men. As the time for action neared, it was set in motion, and by easy marches reached and reinforced the Army of the Potomac on the morning of the 6th of May, in the midst of the battle of the Wilderness. It was not formally incorporated with that army until later; but, by a sort of fiction, was held as a distinct army, Burnside acting in concert with Grant, and receiving his orders directly from him, as did Meade. These two armies were the excuse for Grant's personal presence without actually superseding Meade. In my opinion, the great soldier of the Army of the Potomac was General Humphreys. He was the chief of staff to General Meade, and was a strategist, a tactician, and an engineer. Humphreys was a fighter, too, and in this an exception to most engineers. He was a very interesting figure. He used to ride about in a black felt hat, the brim of which was turned down all around, making him look like a Quaker. He was very pleasant to deal with, unless you were fighting against him, and then he was not so pleasant. He was one of the loudest swearers that I ever knew. The men of distinguished and brilliant profanity in the war were General Sherman and General Humphreys I could not mention any others to be classed with them. General Logan was a strong swearer, but he was not a West Pointer: he was a civilian. Sherman and Humphreys would swear to make everything blue, when some despatch had not been delivered correctly, or they were provoked. GENERAL GEORGE GORDON MEADE, COMMANDER OF THE ARMY OF THE POTOMAC FROM JUNE 28, 1863, UNTIL THE CLOSE OF THE WAR. BORN, 1815; DIED, 1872. Humphreys was a very charming man, and morning; for when our advance reached quite destitute of vanity. I think he had con- Spotsylvania Court House, it found Lee's sented to go and serve with Meade as chief troops there, ready to dispute the right of of staff out of pure patriotism. He pre- way with us, and two days later Grant was ferred an active command, and, eventually, obliged to fight the battle of Spotsylvania on the eve of the end, succeeded to the before we could make another move south. command of the Second Corps, and bore a It is no part of my present plan to go into conspicuous part in the Appomattox cam- detailed description of the battles of this paign. campaign, but rather to recall incidents and deeds which impressed me most deeply at the moment. In the battle of Spotsylvania, a terrific struggle, with many dramatic features, there is nothing I remember more distinctly than a little scene in General Grant's tent between him and a captured GRANT'S PLAN OF CAMPAIGN IN 1864. son. The battle had begun on the morning of May 10th, and had continued all day. On the 11th the armies had rested, but at halfpast four on the morning of the 12th, fighting had been begun by an attack by Hancock on a rebel salient. Hancock attacked with his accustomed impetuosity, storming and capturing the enemy's fortified line, with some 4,000 prisoners and twenty cannon. The captures included nearly all of Major-General Edward Johnson's division, together with Johnson himself and General George H. Steuart. Meade was in command of the Army of the Potomac, but it was Grant, the Lieutenant-General of the Armies of the United States, who was really directing its move- Confederate officer, General Edward Johnments. The central idea of the campaign had not developed to the army when I reached headquarters, but it was soon clear to everybody. Grant's great operation was the endeavor to interpose the Federal army between Lee's army and Richmond, so as to cut Lee off from his base of supplies. He meant to get considerably in advance of Lee -between him and Richmond--thus compelling Lee to leave his intrenchments and hasten southward. If in the collision thus forced Grant found that he could not smash Lee, he meant to make another move to get behind his army. That was to be the strategy of the campaign of 1864. That was CURIOUS MEETING OF GRANT AND JOHNSON. what Lee thwarted, though he had a narrow escape more than once. The previous history of the Army of the Potomac had been to advance and fight a battle, then either to retreat or lie still, and finally to go into winter quarters. The men had become so accustomed to this that few, if any, of them believed that the new commander-in-chief would be able to do differently from his predecessors. I remember distinctly the sensation in the ranks when the rumor first went around that our position was south of Lee's. It was the morning of May 8th. The night before, the army had made a forced march on Spotsylvania Court House. There was no indication the next morning that Lee had moved in any direction. As the army began to realize that we were really moving south, and at that moment were probably much nearer Richmond than was our enemy, the spirits of men and officers rose to the highest pitch of animation. On every hand I heard the cry, "On to Richmond.” But there were to be a great many more obstacles to our reaching Richmond than General Grant himself, I presume, realized on May 8, 1864. We met one that very I was at Grant's headquarters when General Johnson was brought in a prisoner. He was a West Pointer, had been a captain in the old army before secession, and was an important officer in the Confederate service, having distinguished himself in the Valley in 1863, and at Gettysburg. Grant had not seen him since they had been in Mexico together. The two men shook hands cordially, and at once began a brisk conversation, which was very interesting to me, because nothing was said in it on the subject in which they were both most interested just then, that is, the fight that was going on and the surprise that Hancock had effected. It was the past alone of which they talked. It was quite early in the morning when Hancock's prisoners were brought in. The battle raged without cessation throughout the day. The results of the struggle were that we crowded the enemy out of some of his most important positions and weakened him by losses of between 6,000 and 7,000 men killed, wounded, and captured, besides taking many battle flags and much artillery, and that our troops rested upon the ground they had fought for. |