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recognized it as such from the first. Planes began to carry machine guns as a matter of course; and the only drawback was the limited area in which the gun could be fired-only at right angles to the direction in which the machine was flying, in the majority of instances.

One day a pilot took a chance and fired straight ahead through the propeller. It was a risky proposition; but on landing it was found that comparatively few of the shots had hit the blade-about 4 per cent to be exact. It was, however, expensive as well as dangerous, with propellers costing $100 and more. So the next step was to armor-plate the blades so that the bullets would glance off. But this threatened to put a stop to formation flying, because the bullets, ricocheting in all directions, were as much of a menace to friend as to foe.

One summer afternoon, three years ago or thereabouts, a flight commander on the western front was surprised to hear a Hun plane overhead rattling off bursts of 40 or 50 shots with surprising ease. A pilot was sent up to bring the stranger in, and by great good luck he succeeded. When the Hun was shot down it was discovered that a novel contrivance of rods and levers had been fitted to the engine synchronizing the firing of the gun with the revolutions of the propeller, thereby making it altogether safe to fire through the rotating blades. It was at best a crude contrivance, but a vast improvement over indiscriminate fire.

This gear was turned over to a naval lieutenant who made a number of improvements, the finished product being known as the Scarff gear. The idea once in hand, numerous mechanical gears were brought out, but all were handicapped by one great drawback which it seemed impossible to overcome. The timing was a delicate operation, and the adjustments necessarily fine. The mechanical gear, constructed of metal parts, could be timed perfectly on the ground, but the intense cold of the higher altitudes caused the metal to contract, and the timing would be thrown out of adjustment. Furthermore, the very active friction of the working parts caused severe wear, and so tended to nullify the accuracy of operation.

The problem came to the attention of M. Constantinesco, a Rumanian by birth, naturalized in England, and he applied to it a principle in which he had just become greatly interested-namely, the transmission of power through a column of fluid. Because he encountered this principle while experimenting with sound waves under water, he named it the " sonic principle. He emphasizes that it is not as though the fluid were a rigid column, and imparted shock in the same way that a sledge imparts the blow of a hammer to a bar upon which it is held by a second workman. There is actually generated, by an impact upon one end of the column, pressure wave, which traverses the column at the rate of 4900 feet per second, delivering a blow at the other end, not instantaneously, but after the lapse of the infinitesimal interval called for by this velocity and the length of the tube. It was doubtless their failure to appreciate that the outfit did not constitute a rigid system that kept the Germans from learning how to operate it--for its advantages are so marked that had they been able to unravel the secret, they would surely have used it.

M. Constantinesco's apparatus consists essentially, as our drawing shows, of a copper pipe filled with oil, at one end of which is a piston and at the other a pushrod to operate the trigger. The piston is connected with the propeller shaft by a gear and a cam. At the proper instant in each rotation of the propeller, the hump on the cam drives the piston down upon the end of the oil column, which is under a pressure of 150 pounds. Through this compressed column the shock of the piston blow travels as a pressure wave; and when it reaches the other end it operates the firing mechanism. The rotation of the propeller generates 40 to 60 of these wave impulses per second, with no friction except the very slight amount to be found between the gear and the cam.

It is, of course, not desired that the gun begin firing the moment the pilot takes the air, and continue until he makes his landing and stops his engine. So some means of control must be provided, and this is made possible by the necessity of having the oil column under pressure before it will transmit an effective blow. A small chamber is provided, connected with the copper pipe, and normally the oil occupies partly this chamber and partly the pipe. When it is desired to set the gun going, the pilot throws a small lever connected with his joy-stick, and this, with the aid of the spring shown in the reservoir, expels the oil from the reservoir, forces it out into the pipe, and puts it under pressure there. Then things begin to happen in the oil column, and the gun begins to speak.–Scientific American, 5/17.

DESCRIPTION OF “C-5.".—The C-5 is a twin-engine non-rigid airship of the C class, powered with two 125-horse-power union engines. Envelope No. E 106, manufactured by the Goodyear Tire and Rubber Company, Akron, Ohio; car No. A 4126, manufactured by the Burgess Company, Marblehead, Mass. The specifications follow:

Envelope displacement, approximately 178,000 cubic feet.
Envelope length, 192 feet.
Envelope diameter, 41 feet, 9 inches.
Normal speed, 50 miles per hour.
Endurance at normal speed, 10 hours.
Useful load, 4000 pounds.
Crew, six men.
Maximum attainable height, 8600 feet.
Car length, 400.

Fuel consumption approximately ten gallons per hour, at a speed of 42 miles per hour.-N. Y. Times, 5/13.

PROMOTING AERIAL NAVIGATION.-A comprehensive program to establish air terminals in at least 32 cities and towns for military, postal and commercial purposes outlined by Major General Charles T. Menoher, director of the air service of the United States Army, to representatives of many states and municipalities at the Southern aeronautical congress, Macon, Ga., has been announced as the government's official plan for cooperating with cities wishing to promote aerial navigation.

Simultaneously it was made known that the air service hopes soon to aid in laying out municipal Aying fields wherever local conditions seem to warrant it, and where the municipality will bear expenses necessary in procuring personnel and maintaining the field and equipment, exclusive of airplanes.

At the present the army air service, primarily interested in military aviation, and the Postoffice Department, chiefly concerned with extension of aerial mail facilities, are jointly presenting the project to municipalities because the establishment of landing fields throughout the country will benefit the government as well as cities and towns.

The government has adopted the following general policy:

The air service and Postoffice Department will cooperate fully in establishing municipal landing fields.

The air service will select the landing fields in cooperation with municipal representatives.

The establishment of the field will be made in accordance with articles of agreement to be entered into between the United States Government and the municipality.

At present the government can cooperate only in the establishment of municipal flying fields at cities where the Postoffice Department has

established an aerial mail station, and where the air service cross-country routes require immediate stations. A study of the immediate requirements would indicate that the establishment of municipal flying fields will be confined at present to the following cities and towns: Boston, Mass.; New York, N. Y.; Richmond, Va.; Raleigh, N. C.; Columbia, S. C.; Augusta, Ga.; Macon, Ga.; Atlanta, Ga.; Kissimee, Fla.; Mobile, Ala.; New Orleans, La.; Baton Rouge, La.; Beaumont, Texas; Flatonia, Texas; El Paso, Texas ; Texarkana, Texas; Columbus, Ohio; Tucson, Ariz.; Phoenix, Ariz.; Yuma, Ariz.; Bakersfield, Calif.; Fresno, Calif.; Buffalo, N. Y.; Syracuse, N. Y.; Albany, N. Y.; Columbus, N. Mex.; Kansas City, Mo.; Oklahoma City, Okla.; Uniontown, Pa.; Daytona, Fla.; Cleveland, Ohio, and Chicago, Ill.—Army and Navy Register, 5/10.

DESCRIPTION OF “N-C” SEAPLANES.-Wing span from tip to tip, 126 feet.
Upper wing from tip to tip, 114 feet.
Aileron projections beyond wing tips, 6 feet on either side.
Lower wing span, 94 feet.
Width of wings, 12 feet.

Distance between wings, 14 feet at center and 12 feet at outer tips of lower wing.

Over-all length from front end to the rear end, 68 feet 3/2 inches.
Length of hull, 44 feet 9 inches.
Wing area, 2380 square feet.

Weight of flying boat (empty), including wireless installation and all navigating instruments, 15,100 pounds.

Weight full load flying condition, 28,500 pounds.

Percentage of useful load to total load, that is, load not a portion of structure or equipment, 47 per cent.

Weight carried per square foot of wing surface, 12 pounds.
Estimated speed at full load, 79 nautical miles per hour.
Estimated speed at light load, 84 nautical miles per hour.
Horse-power of four liberty engines, 1600 horse-power.

Number of gasoline tanks, nine in hull, one in upper wing above boat hull.

Capacity of gasoline tanks, 200 gallons for each hull tank and go gallons for gravity feed tank in upper wing. Weight of gasoline system, 6 pounds per gallon of gasoline. Weight of engines, 825 pounds each. Weight of boat hull (empty), 2650 pounds. Area of ailerons, 265 square feet. Area of stabilizers, 267.6 square feet. Area of elevators, 240.1 square feet. Area of rudders, 69 square feet. Displacement of wing pontoons, 1800 pounds each. Weight of wing tip pontoons, 95-pounds each.

Gasoline pumps are wind driven by small wooden propellers and are in duplicate, an auxiliary hand-operated gasoline pump is provided.

Flying control is of the dual control Deperdussin system with side-byside seating. Pilots are in hull just forward of gasoline tanks.

Complete sets of instruments provided for pilots, including one compass for each pilot.

Navigating station is in front end of bott hull. Navigator is provided with chart board, charts, and ordinary navigating instruments, including compass and sextant.

Complete wireless installation, including telegraph and telephone and wireless direction indicator, is provided. System should give a radius of approximately 300 miles while in the air and of 100 to 150 miles while on the water.

Electric current is furnished by electric generator operated by a winddriven propellor. Current is delivered to storage batteries. In addition to operating wireless set, storage batteries operate complete lighting system for interior of boat and for wing tip and tail lights as well as lights for night landing.

Wireless operator and engineer are located in main after compartment just aft of gasoline tanks. Each is provided with complete instrument board. Each of these operators has a cylindrical upholstered stool with back rest weighing 5 pounds complete, in the interior of which can be stored the small hand tools required for emergency work.

Cruising speed of boats, about 72 miles per hour.

Gasoline consumption at cruising speed, about 650 pounds average per hour.

Total gasoline carried, about 11,400 pounds.
Cruising radius without wind, about 1476 nautical miles.
Lubricating oil capacity, about 900 pounds.
Crew and provisions, about 1000 pounds.

Crew, five men-two pilots, one navigator, one wireless operator, and one engineer.

Main structure is of Western spruce.

Metal wing fittings and structural fittings in general are of crome vanadium steel of an ultimate strength of 150,000 pounds per square inch.

All flying and landing and control wires are of standard woven airplane cord wire.

Wing covering is linen treated with the ordinary airplane fabric dopes.

Gasoline tanks are of aluminum and gasoline piping is partly of aluminum and partly of copper.

Streamlining forms about wing struts are of micarta. Streamlining of flying and landing wires is of rubber covered with rubberized fabric.

Main keels of boat hulls are of oak or of rock elm. Hull structure is in general of spruce. Planking is, of spruce or of cedar. Turtle-back covering is of cedar or of cottonwood birch three-ply veneer.

Cowling around engine nacelles is aluminum.
Four liquid fire extinguishers are carried in each boat hull.

Access to any portion of the boat hull by means of wing passages or to any portion of the power plant by means of hatches in the boat hull may be had either while on the water or while in the air.

All control surfaces, such as ailerons, rudders, and elevators, are balanced by a portion of the area forward of the pivoting points in order to relieve the work of the pilots.-N. Y. Times, 5/7.

PARACHUTE DEMONSTRATION.—The first public demonstration of "Life preservers of the air” was staged as one of the special features of the Second Pan-American Aeronautical Convention on May 3.

Lieut. Jean Ors, the noted French aeronaut, whose genius is responsible for the newest aerial safety device, ascended in an aeroplane piloted by Eddie Stinson. As the machine attained a speed of 80 miles an hour and an altitude of 500 feet over the heads of the beholders, Lieut. Ors, who occupied the seat directly behind the pilot, stepped over the cowl and leaped into space, releasing the air life preserver, which is a new type of parachute, by the jerk of the main suspending rope as he went over the side.

Stinson and his aeroplane sailed on in the straightaway. Crowds below caught the flash of Lieut. Ors' body as it was catapulted from the machine by the tremendous speed of the aeroplane. In a split second the umbrellashaped top of the parachute spread out in a white canopy of safety over his head. Twenty-five feet below, suspended by the guide ropes leading down from the fringe of the “ umbrella," Lieut. Ors' plummet-like plunge

earthward was halted before he had descended fifty feet. There was no jerk. The wide spread of the parachute slowed up his descent as gradually as if brakes had been eased on slowly.-Aerial Age Weekly, 5/12.

MISCELLANEOUS Navy UNIFORM BOARD.-It is again rumored that a board of navy offcers soon will be convened to consider questions pertaining to the uniform of the naval service. For one thing, the present uniform regulations have been amended so often that the present edition is something of a patchwork affair, and there is need for a general revision of them and issue in a new edition. Moreover, a number of changes in the attire continue to be urged. Since adoption of the double-breasted open-collared coat, many officers believe that the overcoat should be of corresponding form. Changes in the cap also have been recommended, in order to make it more distinctly naval in character and less like the form of that of the army. As no collar-marks appear on the new coat, there now is no way to distinguish between line warrant officers-boatswains, gunners and machinists—as all wear the star on the sleeve, and there is need for attention to this detail. The requirement does not affect the staff warrant officers, as, under the amended regulations, they wear their respective corps marks on the sleeve.-Army and Navy Register, 4/26.

ANALYSIS OF JAPANESE SHIPPING.--The Department of Communications of Japan announces that the Japanese merchant marine to-day consists of 2578 steamers and 12,236 sailing vessels. The majority of the steamers are, however, coasting vessels not exceeding 1000 tons. Ocean-going steamers above 1000 tons number 599, their gross tonnage being 1,830,006 and their registered tonnage 1,154,377.

Of this number six are above 10,000 tons and eight between 9000 and 10,000 tons. There is only one ship between 8000 and 9000 tons. There are 123 vessels between 4000 and 8000 tons. The smaller steamers between 1000 and 4000 tons are most numerous, numbering 366. The majority of sailing vessels are between 20 and 500 tons. There are only five ships between 500 and 1000 tons, while the vessels between 1000 and 2000 tons number only two.-Shipping, 5/3.

Red Cross Home SERVICE FINDS ALLOTTEES FOR BUREAU OF WAR RISK INSURANCE.—The Bureau of War Risk Insurance has asked the Red Cross to assist it in locating 37,226 persons to whom allotment checks have been sent and which were returned to the Bureau because of incorrect address, removal from old address, or similar reasons. Up to May 1, 9204 persons were found through the efforts of Home Service workers.

The local Red Cross Home Service Section has a list of all checks misdirected to addresses in the county of

All persons who have not received their allotment checks, and who believe they may be among those missent, are advised to call at or write to the Home Service office, which is located at

and which will assist them in securing their money.


UNITED STATES AMERICAN JOURNAL OF INTERNATIONAL LAW. January.—The Lack of Uniformity in the Law and Practice of States with Regard to Merchant Vessels, by Fred K. Nielsen. Private Property on the High Seas, by Graham Bówer, Ships in Enemies' Ports as Prizes (editorial), by C. N.

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