horizon and observations. . . . This is of especial value, as the aviator is often above the clouds, and even when flying at low altitudes the horizon is too dim to be seen clearly. With this new aerial sextant the curvature of the earth does not have to be taken into consideration in calculating position. The bubble is lighted at night, so that night observations may be taken.

"New methods of astronomical calculations also have been devised which enable the navigator to make his calculations in a fifth of the time that was formerly necessary. A zenithal projection-chart of the Atlantic Ocean has been specially constructed for this purpose. This chart, a new invention, does away with difficult mathematical calculations, enabling the aviator to determine his position in a few minutes.

"Another great problem of the sea-air navigator is the calculation of the speed and direction of the wind, both day and night. In spite of the reliability of the compass, it can only give the course upon which the craft heads, and in determining the true course, proper allowance must be made for the sidewise drift caused by the wind. For example, a wind blowing 30 miles an hour toward the side of the plane will blow it 30 miles an hour out of its course. This fact alone makes the navigation of the air far more difficult than the navigation of the sea.

"To overcome this difficulty, bombs have been invented which ignite upon striking the surface of the water and give a dense smoke and bright light for ten minutes.

An instrument is used in conjunction with this bomb which enables the navigator to determine the velocity and direction of the wind by sighting on the smoke in the daytime and the lights at night. This instrument has proved successful.

"When the navigator has found the speed and direction of the wind, he must then be able to calculate the course to steer toward the Azores to allow for this wind. To do this, an instrument has been designed to solve the triangle of forces, thus doing away with cumbersome mathematical calculations.

"The navigator also has instruments which show him the altitude of the plane and the time the sun keeps with the Greenwich meridian, because in going to the eastward so rapidly it is difficult to keep the correct time. In going from Newfoundland to the Azores, over two hours are lost in a period of 20 hours, so that the navigator must be very expert in order to allow for this loss in time in making his astronomical calculations.

"In aerial navigation, positions must be determined very quickly. The navigator sits down to work out his sights,' to fix his position, and by the time he arrives at results he will be far from his calculated position unless he works out his calculations very rapidly, which these instruments enable him to do."-Literary Digest, 6/28.

RIGID DIRIGIBLES AND THE U. S. NAVY.-The proposed initial outlay by the U. S. Navy of approximately $13,000,000 for rigid lighter-than-air craft, of the so-called Zeppelin type, is a move that is founded on sound principles, as it will increase the efficiency of our fleets by giving them increased and necessary facilities for spotting and scouting in battle and in convoy work during war. In considering the navy's plans it is well to keep in mind the peculiar usefulness of the rigid dirigible to the United States. The fine weather generally prevailing in the Pacific and in the Caribbean, together with the great areas over which scouting would have to be carried on in the event of war, would give to the rigid airship a value almost inconceivable. Indeed, it is difficult to see how observations over these vast regions could be covered as successfully by means other than through the agency of aircraft. They are now the eyes and ears of a fleet.-Army and Navy Journal, 7/5.

SMOTHERING A FIRE BENEATH A COMBUSTIBLE BLANKET.-Inventions of military importance which were held secret during the war are now being made public, and we may read of what American inventors have accomplished in their endeavor to bring about a victorious peace. One invention that demands particular attention is a gasoline tank which will neither leak nor explode, though it be pierced by repeated bullets.

The need of such an invention in aerial combat is obvious. When machine guns were first mounted on planes, the fighters quickly realized that the vital spot to be aimed at was not so much the pilot as the tank, which offered a much larger target. Once a hit was made here, either loss of fuel forced a premature landing, or the leaking gasoline when mixed with the current of air formed an explosive combination which ignited from the engine and set fire to the machine in mid-air.

Armor-plated tanks and compartment tanks to meet this were in turn rendered ineffective by means of armor-piercing and incendiary bullets. The tracer bullet, leaving a fine trail of smoke, guides the gunner's aim; the armor-piercer puts a hole in the tank; the fuel spills out and is ignited by the incendiary bullet. The three varieties of ammunition were fired

alternately from the one gun, the magazine of which was loaded in advance, the order and number of the three types depending upon the errand to be undertaken. The compartment tank was now also useless, because the heat in a burning or exploding compartment fired the adjoining ones; while the use of a flowing elastic compound for tank walls minimized the tear in the tank walls but gave small protection against the incendiary bullet. The latter functions through the presence of phosphorus, which when mixed with the atmospheric oxygen of the air, will ignite any explosive mixture that comes in contact with it. To get an idea of the vicious character of these bullets, cases can be cited where some of the phosphorus became imbedded in tank walls beneath the fuel level; innocuous for the moment because not exposed to the air, this charge would bring on an explosion hours or days afterwards when the fuel level fell below its hiding place.

This was the state of affairs when the United States entered the war. The problem was taken up by the Bureau of Standards, and the invention of Mr. F. Weinberg, a Detroit automotive engineer, was demonstrated in Washington in August, 1917. Through the co-operation of the Bureau and of the Science and Research Bureau of the War Department, the invention was taken up and brought to a high state of perfection.

The construction of the Weinberg tank is indicated in the diagram. Primarily it is an ordinary metal tank, having two connections and its filler cap. The suction connection is to provide a partial vacuum above the liquid, of sufficient strength to prevent its escape through any hole

that may be shot through the tank wall. As anyone knows who has seen how an inverted tumbler full of water behaves, the force that has to be added to the external atmospheric resistance to balance the gravitational pull on a fluid is a slight one. The necessary suction can be got in various ways, but probably most simply by the venturi shown, which operates by virtue of the stream of air created through the very flight of the plane. For a standing tank, of course, some mechanical means of suction would have to be employed. The fuel reaches the carburetor through the second opening by overcoming the vacuum created through the former-which may be accomplished by maintaining a greater suction, or by positive feed pumps.

To insure proper functioning at all times, the tank is enveloped in some elastic material analogous to the Zeppelin covering, which to a large extent plugs up whatever holes may be shot in the tank. Such substances are well known, possessing sufficient elasticity to return practically to their former state after being pierced, leaving a hole so small as almost to defy detection. The tank may literally be made a sieve by hostile fire and still refuse to leak.

The application of this principle to render the tank leak-proof makes it at the same time explosion-proof. To cause an explosion there must be a combustible mixture of air and fuel; but in the Weinberg tank no such mixture can be created anywhere. A bullet piercing the tank below the level of the liquid is at once surrounded by the liquid and smothered. No air is in this part of the tank, and none can get in; there is no hole for air to pour in through, no leak where air and gasoline meet. The proposition of smothering a flame with a blanket of highly combustible material is a startling one; but in the utter exclusion of oxygen it is a wholly sound one. And if on the other hand the bullet penetrates the upper portion of the tank, where there is no fuel, there is likewise here no air in sufficient quantity to give the basis for an explosion; for the venturi suction has taken care of that. So again the incendiary bullet is smothered, this time in a blanket of nothing at all.

Final tests of the Weinberg tank were made at Dayton. Two identical tanks, one made after the Weinberg plans and the other covered with elastic materials prepared by the War Department, were shot at side by side with armor-piercing and incendiary bullets. The second tank caught fire after the third shot; the Weinberg tank was penetrated by 15 piercer bullets followed by seven incendiaries, with neither leak nor explosion.

A bullet rarely goes completely through a fuel tank; ordinarily it is so checked in passage through the near wall and the fluid that it falls, spent, to the bottom of the tank. Through the Weinberg invention, which prevents it from igniting the gasoline in passage through the tank, or in repose therein, the tank that formerly possessed the greatest danger for the aviator becomes now his best protection. Moreover, a tank which eliminates danger of fire and leaks should be of value in peace as well as in war, and in many other places than on airplanes.-Scientific American, 7/12.

BRITISH AERONAUTIC LOSSES DURING THE WAR.-From the English Air Ministry it is learned that the British aeronautic losses through war were as follows:

Of these, 12,787 were officers and 3,936 privates; and this because the former were used especially in piloting machines.-Rivista Marittima, April, 1919.

MISCELLANEOUS

PEACE TERMS.-The peace_terms for Austria were presented to the Austrian delegations at St. Germain-en-Laye on June 2. In communicating the terms, M. Clemenceau said a maximum period of 15 days would be allowed the delegates in which to present their written observations, and then a date for the final answer would be announced. The terms, which are incomplete, include the following parts: Preamble, League of Nations, frontiers of Austria, political clauses-Czecho-Slovak state, political clauses relating to certain European states, protection of minorities, general provisions, Austrian interests outside Europe, naval and air clauses, prisoners of war and graves, penalties, economic clauses, aerial navigation, ports, waterways and railways, labor and miscellaneous provisions.

The following clauses will be handed over at a later period: (1) Political clauses-Italy; (2) financial clauses; (3) reparation clauses; (4) military clauses; (5) clauses relating to the Serbo-Croat-Slovene state.

The following is a summary of the clauses dealing with the navy, aircraft, prisoners of war, graves and penalties:

Naval. The naval terms provide that from the date of the coming into force of the Treaty all Austro-Hungarian warships, including submarines and all vessels of the Danube Flotilla, are declared to be finally surrendered to the principal Allied and Associated Powers. Auxiliary cruisers, etc., to the number of 21, are to be disarmed and treated as merchant ships. All warships (including submarines) now under construction in ports which belong or have belonged to Austria-Hungary are to be broken up. Articles and materials arising there from may not be used except for industrial purposes, and may not be sold to foreign countries. The construction or acquisition of any submarine, even for commercial purposes, is forbidden. All naval arms, ammunition, and other war material belonging to Austria-Hungary at the date of the armistice are to be surrendered to the Allies. The Austrian wireless station at Vienna is not to be used for naval, military, or political messages relating to Austria or her late Allies without the assent of the Allied and Associated governments during three months, but only for commercial purposes, under supervision. During the same period Austria is not to build any more high-power wireless stations.

Aircraft. The air clauses provide that the armed forces of Austria must not include any military or naval air forces. The entire personnel of the air forces in Austria is to be demobilized within two months. The aircraft of the Allied and Associated Powers are to enjoy full liberty of passage and landing over and in Austrian territory until January 1, 1923, unless prior to that date Austria is admitted to the League of Nations or is permitted to adhere to the International Air Convention. The manufacture of aircraft and parts of aircraft is forbidden for six months. All military and naval aircraft (including dirigible and aeronautical material) are to be delivered to the Allied and Associated governments within three months.

General.-General articles provide for the modification of Austrian laws in conformity with the preceding clauses.

Austria agrees not to accredit or send any military, naval or air mission to any foreign country, nor to allow Austrian nationals to enlist in the army, navy or Air Service of any foreign Power.

Prisoners of War.-The repatriation of Austrian prisoners and interned civilians is to be carried out by a commission composed of representatives of the Allies and the Austrian Government, together with local subcommissions. Austrian prisoners of war and interned civilians are to be returned without delay by the Austrian authorities at their own cost. Those under sentence for offences against discipline committed before May 1, 1919, are to be repatriated without regard to the completion of their

sentence, but this does not apply in the case of offences other than those against discipline. The Allies have the right to deal at their own discretion with Austrian nationals who do not desire to be repatriated, and all repatriation is conditional on the immediate release of any Allied subjects still in Austria. The Austrian Government is to accord facilities to Commissions of Inquiry in collecting information in regard to missing prisoners of war, and in imposing penalties on Austrian officials who have concealed Allied nationals. The Austrian Government is to restore all property belonging to Allied prisoners, and there is to be a reciprocal exchange of information as to dead prisoners and their graves.

Graves.-The Allies and the Austrian Government are to respect and maintain the graves of all soldiers and sailors buried in their territories and to recognize and assist any commissions appointed by the Allies in connection with them, agreeing also to give any practicable facilities for removal and reburial.

Penalties.-Military tribunals are to be set up by the Allies to try persons accused of acts of violation of the laws and customs of war, and the Austrian Government is to hand over all persons so accused. Similar tribunals are to be set up by any particular Allied Power against whose nationals criminal acts have been committed. The accused are to be entitled to name their own counsel, and the Austrian Government is to undertake to furnish all documents and information, the production of which may be necessary.-Army and Navy Gazette, 6/7.

WORLD'S TONNAGE LOSSES DURING WAR PERIOD.-According to an estimate made by La France Maritime, 4855 vessels aggregating 11,255,510 gross tons were lost through war's cause between August 1, 1914, and October 31, 1918. Of these, 3604 were steamers representing 10,542,925 tons and 1251 sailing vessels with a combined tonnage of 712,785 tons. Including losses suffered through ordinary marine casualties, the total tonnage destroyed during the period mentioned amounted to 14,344,082 gross tons. By years this is apportioned as follows:

According to countries, these losses grouped themselves as follows: