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duces a very strong magnetic flux. Concentric with the magnet is a central core having a double winding through which an alternating current of 500 alternations per second is run. Lying in the gap between the core and the magnet is a copper tube about 8 inches in diameter and about 8 inches long. When the alternating current is turned on it induces a cur- rent in the copper tube and the cop- per tube being free to move jumps. When the current in the central core is reversed the copper tube is jumped back in the opposite direction. This copper tube is attached to a large dia- phragm which is in direct contact with the water through which the sound waves are to pass. The oscillations of the copper tube give the diaphragm a vibrating motion of about one-hun- dredth of an inch amplitude at a fre- quency of 500 per second. This apparatus is used not only for sending and receiving Morse code messages, but is the same apparatus used in getting echoes from icebergs, for taking soundings and for tele- phonic work as a transmitter and as a receiver, The oscillator used: as. a receiving apparatus becomes a very sensitive magnetophone with which signals have been heard up to a distance' of 20 miles. So sensitive is this apparatus that when it is mounted with its heavy diaphragm, which is 1 inch thick and 24 inches in diameter, if a person stands in front of the diaphragm and talks, his speech will be transmitted through wires to a telephone receiver. The sensitiveness of the apparatus -can be understood when it is realized that under these conditions it is simply the energy of the sound waves of the voice deflecting the l-inch thick diaphragm. The motion of this dia- phragm causes the copper tube to be moved a very small fraction of an inch up and down through the mag- netic field, thus acting as a generator and operating the diaphragm of the receiver. ' Tests have been made with the os- cillator used for submarine telephony. Up to the present time, however, these have only been tried with an ordinary telephone transmitter which will not carry a. high. current: Using. six cells of dry battery speech has been clearly transmitted to a distance of half a mile, and from the results of our tests there is no doubt that speech can be transmitted a much greater distance if a transmitter is used which will carry a greater current. The submarine bell located at Whitefish Point, Lake Superior, was recently picked up at a. distance of 35 miles. THE MARINE REVIEW What is Contraband? There is an international list of ar- ticles which, by general agreement among the treaty nations, can never be considered as contraband. Foremost among the articles important to the United States is cotton. Of almost equal importance is the fact_that gold is a contraband of war, conditionally only. It becomes contraband absolutely if it is shipped to a nation involved in war, and is liable to seizure by ships of the -enemy of that country. Cottom was placed on the non-contfa- band list at the London Naval Confer- ence, notwithstatnding that it had been treated by Russia as contraband during the Russo-Japanese war. While the London Declaration has not been ratified by all nations it is practically certain, according to international law authori- ties, that its shipment would not be in- terfered with by any European nations in case of a general war. Absolute contraband of war, which is always liable to seizure, consists of all war material: Guns, ammunition, mili- tary vehicles of all sorts. Other articles, except those on the non-contraband list, may be treated as contraband by a belligerent after giving notice to the neutral nations of the articles it has classed as liable to seizure. "Conditional contraband is not liable to capture except. when found on board a vessel bound for territory belonging to or occupied by an. enemy or for the armed forces of the enemy, and when it is not to be discharged: at an intervening neutral port. The ship's papers are con- -clusive proof both as to the voyage in which the vessel is engaged and as to the port of discharge of the goods, un- less she is found clearly out of the course indicated by her papers and un- able to give adequate reasons to justify such deviation." Article 24 of the convention is as fol- lows: The following articles, susceptible of use in war as well as for purposes of peace, may without notice be treated as contraband of war, under the name of conditional contraband. 1. Foodstuffs. 2. Forage and grain suitable for feed- ing animals. 3. Clothing, fabrics for clothing and boots and shoes suitable for use in war. 4. Gold and. silver in coin or bullion; paper money. 5. Vehicles of all kinds available for use in war and their component parts. 6. Vessels, craft, and boats of all kinds; floating docks, parts of docks, and their component parts. 7. Railway material, both fixed and rolling stock and material for telegraphs, September, 1914 wireless telegraplis, and telephones, 8. Balloons and flying machines and their component parts, together with ac- cessories and articles recognizable ag intended for use in connection with balloons and flying machines. 9, Fuel; lubricants. 10. Powder and explosives not. es- pecially prepared for use in war. 11. Barbed wire and implements for fixing and cutting same. 12. Horseshoes and shoeing materials. 13. Harness and saddling. 14. Field glasses, telescopes, chronom- eters and all kinds of nautical instry- ments. A neutral vessel is liable to capture when more than one-half of its cargo is contraband. The war vessel making the seizure may measure her contraband by value, volume, weight, or the freight rate, and if it can bring the contraband up to more than one-half of the cargo by any of the four methods it may make a prize of the ship. The following are the articles which can never be classed as contraband, ac- cording to Article 28 of the London Declaration : 1. Raw cotton, wool, silk, jute, flax, hemp and other raw materials of the textile industries and yarns of the same. 2. Oil seeds and nuts; copra. 3. Rubber, resins, gums and lacs; hops. 4. Raw hides and horns; bones and ivory. 5. Natural and artificial manures, in- cluding nitrates and phosphates for ag- ricultural purposes. 6. Metallic ores., 7. Earths, clays, lime, chalks, stone, including marble, bricks, slates and tiles. 8. Chinaware and glass. 9. Paper and paper-making materials. 10. Soap, paint and colors, including articles exclusively used in their prepa- ration, and varnish. 11. Bleaching powder, caustic soda, salt cake, sulphate of copper. 12. Precious and semi-precious stones, pearls, mother-of-pearl and coral. 13. Clocks and watches. 14. Fashions and fancy goods. 15. Feathers of all kinds, hairs and bristles. 16. Articles of household furniture and decoration; office furniture and re- soda, ashes, ammonia, and quisites. Of course all non-contraband articles may be seized by a belligerent if they are conveyed in a ship flying an enemy's flag, or if more than half of the re- mainder of the cargo is contraband. One article enacted by the London Naval Conference which will operate to the advantage of the United States in case of a European war, according to authorities on international law, is the definition "conditional contraband."