pair, and flexibly extended at the shortest notice wherever and whenever the army

moves.

On the stroke of midnight, August 2d, 1914, all the railroads of France passed from civil into military control. Henceforth every change of time-table, every movement of rolling stock, was dictated by the need of winning the war. So the connected sketch of railway activity in 1914-18 is virtually a rapid review of the war itself. This is almost wholly from the French point of view, because only on this side are statistics, and data generally, as yet accessible for the writer.

Only a rapid glance can be thrown at one or two picturesque incidents. Thus in 1915 a fleet of fifty-two steamers arrived at Marseilles from India. It brought what, until this war, might have been considered a great foreign army of invasion: 70,000 Gourkas and Sikhs, with their peculiar personal baggage, ammunition, artillery, etc. All these had to be promptly disembarked, entrained, and transported across France to the British trenches on the Flanders front. And this was a minor task.

There was perhaps no moment when the Council of Allies was nearer to panic than when they were threatened with a debacle in Northern Italy, on the heels of Russia's collapse and withdrawal from the struggle.

On October 23, 1917, the very day when the Germans penetrated to the South of Plezzo, the (Railway) Company was called upon by the military authorities to bring together, within twenty-four hours, the means of transportation, including, of course, the train crews, sufficient to take across the Alps, by express, 120,000 British or French troops, with their artillery and military stores of every description.

This miracle was successfully wrought. In less than the required time, 500 locomotives and 12,000 cars were speeding from all parts of the national system toward the zone of embarkation. Next day the trains stood, made up, in sufficient numbers to meet the actual demand as the troops appeared.

On the 28th, the twelve thousand cars were in motion, and in four days completed the run to the Trentino from the Southern French front. When on November 8 the Italians ended their retiring movement westward, they were able to halt in security on the Piave, assured of direct union of their forces with the Anglo-French troops.

Upon this prompt and efficient action followed successively the end of the retreat, relief from imminent peril, permanent security, aggressive confidence, and decisive. victory. Probably nothing less energetic and immediate could have stopped the successful rush of the Germans across Italy to assail the French from the south and east. And we were ourselves not seriously in the field at all. The whole war might have resulted wholly otherwise.

Most marvelous of all, however, is the sudden recovery that began in July, 1918. The enemy's advance in Belgium and French territory since March had wrought wide havoc in Northern France. Entire railway lines. had been rendered useless, notably from Amiens to Arras, from Paris to Chalons via Château Thierry, etc.

Paris, however, is the heart of the whole network of French railways. Thanks to that condition, it was possible, under the shadow of a supreme crisis, for all the radiating systems to concentrate their material resources and unify all their personal efforts with reference to the final success of the military operations.

Many vitally important stations, magazines, workshops, had been destroyed or evacuated. Thus, even one at Epernay, which was not captured, was largely stripped and dismantled, as a military precaution, Thousands of carloads of tools and materials had been shipped far southward.

Before these difficulties had been at all overcome, there were issued orders from Headquarters for continuous transportation of troops, as an imperative military necessity. These two tasks the railroads were forced to carry on simultaneously. Meantime Foch's offensive, pushed without pause from July 18th onward, rapidly regained full freedom of action for the railway lines as for the armies, and the two moved onward together until the decisive triumph.

Thanks to the defensive forced upon the enemy, on the lines of the Aisne and the Vesle, they found themselves utterly unable to carry off in their retreat the great mass of stores at Soissons, Fère-en-Tardenois, etc. Wasting their energies on lines useful only in covering that retreat, they were maneuvered out of one section after another, to utter exhaustion, demoralization—and surrender. In all this marvelously rapid sweep forward the flexible organization and incessant energy of the railway system were indispensable at every step.

THE

HE lifting of the veil that enveloped so many remarkable events of the late war has revealed no more interesting episode than one described by Capt. Reginald Belknap, U. S. N., in a lecture published in the National Geographic Magazine, under the title "The North Sea Mine Barrage." Captain Belknap tells a graphic story of an exploit carried out under his command. It was stupendous in itself, and momentous in its consequences, for it opposed an almost insuperable obstacle to the operations of German submarines and thereby materially hastened the end of the war.

From the time our country entered the conflict, says Captain Belknap, the Navy advocated strong offensive measures to block the German bases, so that few submarines, if any, might get out, and those that did might be caught and destroyed in returning. Such undertakings could not, however, be carried out close to German shores.

The German forces were very strong for operations near their own coast, and although the British destroyers were constantly planting mines in the Heligoland Bight, they could not prevent the German minesweepers from keeping channels open through these mine fields.

The enemy even had special vessels called barrage-breakers, and they were also very much assisted by bad weather, fogs, and. variable currents, which handicapped the Germans much less than the British, who had to operate from a starting point farther away.

There was also the Skagerrack passage between Denmark and Norway, where no barrier could be placed without violating neutral waters. Consequently, the enemy submarines could always use this channel going to and from their bases at Kiel and Wilhelmshaven.

Any barriers that the allied navies could place near the German coast and near the Skagerrack were so close to the German bases that the enemy could at any time break through at some point by suddenly attacking there with more force than the Allies could maintain over any one section of the

whole line, so far away from the bases in Great Britain.

There were mines in plenty near the German coast, forcing all enemy craft to be very careful and now and then doing them some damage; but the submarines could still go in or out. The barrier close to the German coast could not be made effective.

The solution of the problem thus presented was made possible by the ingenuity of an American electrician, Mr. Ralph C. Browne, of Salem, Mass., who laid before the Navy Department the plan of a submarine gun. Although this invention was pronounced impractical, it embodied an idea which led to the development of a new type of submarine mine, the most important feature of which was that, by a simple automatic device, it could be moored at any desired distance below the surface of the water. This mine offered so many advantages over

previous types in economy and effectiveness, as well as the facility with which it could be planted, that the Navy was inspired with the audacious idea of closing the North Sea against submarines by laying a mine field all the way from Scotland to Norway; a distance of 230 miles, or as far as from Boston to New York. The undertaking would cost tens of millions, and might prove a failure; but it appeared to be the only hopeful solution of the submarine problem, and so, in October, 1917, it was formally approved by the Navy Department and the work went forward.

Coöperation in the fullest measure was necessary from the start. Over 500 contractors and sub-contractors were soon engaged in the manufacture of the many parts, small and large, that go into the make-up of a complete mine.

Besides being a rush order all through, the task was complicated by the necessity for keeping parts of the mine secret. Some pieces had to be made here and others there, and both kinds sent to a third place to be joined, and all of the parts were finally delivered at Norfolk, Va., for shipment to Scotland, where the complete mines were to be assembled and adjusted, ready to plant.

days, carrying mine material and stores for the northern barrage.

It was through a submarine sinking one of these ships, the Lake Moor, with forty-one of her crew, that our operation suffered its greatest, almost the only, loss of life.

Meantime the British naval authorities were preparing depots for us in Scotland. The mine material was to be unloaded on the west side of Scotland; some cargoes at Fort William, at the western terminus of the Caledonian Canal, and some at Kyle, on Loch Alsh, opposite the Isle of Skye. Thence the cargoes would be forwarded by canal barge and by rail to Inverness, and to Invergordon, on Cromarty Firth, respectively. These harbors open on Moray Firth, about eight miles apart, on the northeast coast of Scotland.

Here American naval officers established two large bases, each manned by a thousand men and together capable of preparing a thousand mines a day. As it was expected that each mine-laying trip would occupy about five days, it was decided that the minelaying squadron should have a capacity of upwards of five thousand mines. This squadron consisted of two old cruisers, the San Francisco and the Baltimore, and eight merchant ships. Each ship was equipped with from four to six elevators for raising the mines rapidly to the launching deck, thus greatly facilitating the process of planting. The squadron sailed for Scotland May 11, 1918, and on the evening of June 6 the first mine-laying cruise was begun.

Captain Belknap gives us a vivid narrative of the unlighted vessels creeping forth,

HOW A MINE IS ANCHORED AT THE DESIRED DEPTH BELOW THE SURFACE OF THE SEA

The progress of a mine after it is shown in Figures 1 to 6. When a mine

is dropped overboard, the mine proper (A) floats, while the box-like anchor (B) slowly sinks. Inside the anchor is the mooring wire (F), which unwinds from a reel as the anchor sinks. The real is unlatched (E) by the downward pull of a plummet (C) at the end of a cord (D), which is the same length as it is desired to have the mine stay below the surface. The plummet, being nearly solid metal, sinks faster than the more bulky anchor box (see Fig. 3), thus keeping the cord (D) taut. As soon as the plummet strikes bottom, however, the cord slackens and the reel in the anchor box is locked, thus preventing any more mooring wire from unwinding. The anchor continues to sink, pulling the mine case under the water until the anchor strikes bottom, as in Fig. 6.

In Arctic exploration and transatlantic flight we have three requirements to be met:

(1) A sustained flight, twice as long as the longest yet made.

(2) From ten to twenty-five hours' continuous service of the pilots on the airplane.

(3) The use of instruments for determining the course when astronomical observations, "shooting" the horizon, and ascertaining the airplane's speed and drift are, to put it mildly, difficult.

In crossing the Himalaya the cardinal requirement is to attain a sufficiently great altitude. There are three aspects of such an undertaking to be considered:

(1) Crossing the mountains by flying through the passes or gorges or by passage over the main range and avoidance of the high peaks.

(2) Flying over the highest peaks, including Mt. Everest, which is 29,002 feet, and Mt. Kanchenjunga, which is almost as high.

(3) Making a landing on the ranges. According to Dr. Kellas' the main range could be crossed at an altitude of 23,000 to 25,000 feet by avoiding the peaks that are over 24,000 feet high, of which, so far as is known, there are about eighty. Further, by utilizing passes or gorges transit could be made at a still lower elevationnot over 19,000 feet. These altitudes can be reached by present-day airplanes. There are a great many airplanes used by the British and the other Allied nations that have a "ceiling" (maximum altitude attainable by the plane) of approximately 30,000 feet with the usual military load; and the flight across the Himalaya through the gorges and passes would not be considered more difficult than the flights made daily over the enemy's barrage fire, where in addition every cloud may hide a squadron of enemy fighting planes. It certainly would not be as difficult as was the flight of the squadron of Italian S. V. A. single-motored biplanes that, under the command of Major Gabriele d'Annunzio on August 10, 1918, flew from Venice to Vienna, a trip which involved more than two hours' flying over the Alps.

The mountaineering aviator will doubtless not be satisfied, with anything short of a flight over Mt. Everest itself, and it is therefore of interest to compare the height of that mountain above sea-level (about 29,000 feet) with the greatest altitudes higherto attained by airplanes. Last September Capt. Schroeder, U. S. A., established a record of 28,900 feet at Dayton, Ohio, and on January 2 of the present year Capt. Lang, of the British Army, with a companion, rose to a height of 30,500 feet above Ipswich, England; the altitude record to date.

To carry out the project of flying over Mt.

1A. M. Kellas: The Possibility of Aerial Reconnaissance in the Himalaya, Geographical Journal, London, Vol. 51, 1918, pp. 374-389.

Everest and Mt. Kanchenjunga it will be necessary to build special airplanes. It is of little value from a military viewpoint to have a plane with a ceiling of 35,000 feet unless it can carry guns and munitions and the pilot can patrol for about two hours. In addition, the machine must have a maximum equipment of safety to enable the pilot to make vertical turns, to do the "roll," the "falling leaf," the "Immerman turn," the "nose dive," the "loop," and other similar maneuvres that may be necessary in the course of an aerial flight; the machine must also have a very high horse-power motor to insure maximum speed.

The explorer can dispense with machine guns and ammunition, although he should carry a gun for protection in case he lands away from his starting point. He can also dispense with one hour's fuel, and the construction of the machine can be lighter. But these two considerations should come last. The greatest saving in weight will be in having a smaller motor-and correspondingly less fuel and tankage.

The writer discusses the effects of the low temperatures that would be encountered over the Himalaya, and cites his reasons for believing that "the solution of the problem of flying in cold weather consists largely in providing suitable clothing for the aviator."

With regard to the physiological effects of great altitudes, concerning which so much conflicting information has been published, Mr. Woodhouse makes the important point that "the aviator has the advantage over the mountain climber that he can start out in perfect physical condition and can accomplish the entire journey in a few hours, whereas it would take the mountain climber days or weeks."

Finally comes the question of making landings on the mountains.

Landing airplanes on such surfaces as the Himalaya may be expected to present, and starting again, will be mainly a matter of skill and organization. A specially made airplane for flying at high altitudes may not have a speed of more than 75 or 80 miles an hour and would have a very low landing speed. It would also be a very light machine and, if possessing a margin of power, could rise from a flat clearance of from 400 to 500 feet. In preliminary flights the aviator could drop tents, bags of food and equipment, and spare parts on a selected spot near the place where he intended to land. Dropping these things from an airplane would not be difficult. It was done repeatedly by the British aviators at Kut. Italian aviators also dropped bread and provisions on the mountains for their forces which had been cut off from their lines of communication and had exhausted their supplies. The aviators carried sufficient food and provisions to last them many days.

Having carried and dropped all the equipment necessary, the aviator could then attempt the landing.