Synchronous Flashing of Fireflies To the Editor of the SCIENTIFIC AMERICAN: Regarding the remarks on this subject under the head of "Science" in your issue of November 17th., last, the following observations may be of interest to some of your readers. In the town of Cotabato, Island of Mindanao, P. I., a few years ago, there were two trees about the size of apple trees, and perhaps a hundred feet apart, and every evening these were filled with fireflies which flashed in synchronism, first one tree lighting up and then the other. There must have been several thousand insects in each tree, yet the synchronism was so perfect that rarely or never did a single firefly flash at the wrong time. To the best of my recollection the illuminated period lasted about two or three seconds and the dark period perhaps twice that long. I can positively vouch for the accuracy of the foregoing for it seemed so strange, and produced so beautiful an effect that I thought it one of the most remarkable things in the Philippines, and it made a deep impression on me. JOHN V. PURSSELL. Washington, D. C. Facilitating the Transportation of Coal To the Editor of the SCIENTIFIC AMERICAN: The present method of shipping coal in regular coal cars and consuming a great deal of time in switching the cars to various points of a city where the cars stand on a siding for many days before being returned to the mines, causes this method to be very inefficient. The system I wish to suggest for your consideration would be adapted to cities or other points of destination that could use at least several carloads of coal at one shipment to be discharged at one place. The plan would be to use an entire train of flat cars having hinged side boards. The entire train, or several cars, to be unloaded onto a previously prepared board floor or any place made convenient for the loading of wagons or trucks for delivery to various points throughout the city. The prepared floor having a length equal to the length of the number of cars to be unloaded. The flat cars to be unloaded by a train unloading plow the same as shown in one of your recent issues, the coal being plowed off the cars onto the ground or board floor at either side, or both sides of the track. A train of 12 cars of gravel can be unloaded in from ten to thirty minutes by this method. There is no reason why coal cannot be handled in the same way. In order to save the shoveling by hand of the coal into the trucks and wagons, they could be loaded automatically by being placed in position at the side of the flat cars. There would be very little expense for a city to prepare a place at the side of the railroad for discharging coal in this way that is located at a convenient point for a number of dealers and consumers of coal. This method would make it possible to have the coal trainon the move to and fromthe mines, or being loaded at the mines probably 9T per cent of the time, whereas under the present system the greater portion of the time is spent on the siding. The side boards being hinged at the bottom and arranged to spread outwardly at the top when released makes it possible to load the cars to any capacity desired. This method is well understood by construction engineers for handling of gravel, and it seems to me it will be a great help to relieve congestion of the railroads and to aid in solving the coal problem. Cleveland, Ohio. JOHN A. MATHES. The Aerial Torpedo To the Editor of the SCIENTIFIC AMERICAN: In the December 15th issue of the SCIENTIFIC AMERICAN, I was very much interested in the letter to you, written by Allen M. Culver, Los Angeles, Cal., regarding substituting the airplane for the large gun. It occurred to me that an aerial torpedo or a flying shell might be a modification of this idea and worked out satisfactorily. Doubtless it would be impracticable to start the aerial apparatus working immediately the shell leaves the gun. If the shell "takes wings" so to speak and has a propeller, which would be necessary, they would have to be enclosed so that there would be no resistance to the air. The internal mechanism should be arranged so that the wings and propeller open up and take effect after the force of the shell is spent. Perhaps a mechanical rudder would also be necessary to maintain properly the equilibrium of the shell. The main purpose of this would be not to replace heavy artillery but to increase the distance for possible effectiveness. IRVING F. TOOMBS. Clintonville, Wis. British Navy Defines Submarine Situation IN view of the statement made by the First Lord of the Admiralty in the House of Commons, on the submarine war, to the effect that the general curves of merchant tonnage sunk by enemy action and of German submarines sunk are satisfactory, the British Admiralty determined to make public certain diagrams showing graphically the exact conditions. By the courtesy of the London Daily Telegraph we reproduce these Admiralty diagrams which, it will be seen, cover two full years of the submarine campaign. It is explained by the Admiralty that with regard to the first diagram, the height of the curve showing enemy submarine attack upon merchantmen was reached in April 1917, which accounts for the quarter ending June showing the peak of the curve. Since that period the curve has steadily fallen, and in the last quarter of 1917 it reached the same figure as in the last quarter of 1916, which period antedated the unrestricted submarine attack. The second diagram shows that, since the quarter ending September 1916, there has been a steady rise in the number of submarines sunk; and although for the last quarter of 1917 the number sunk has not shown any further rise, it must be remembered that at the time this diagram was drawn up by the Admiralty, there were still the results of half a month to add; nevertheless, the sinkings equal the results of the quarter ending September 1917. We draw attention to the note at the foot of the diagram which states that they are statistically accurate and drawn to scale, but that obviously the scale is not the same in both, one being for tonnage of merchant vessels and the other the number of submarines.