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An Opinion of Our War Number To the Editor of the SCIENTIFIC AMERICAN : I am tremendously impressed with the technical value of your War Issue No. 4. I know what it means in time, toil, and expense in the mere assembling of the material you offer readers in that issue. It is a most creditable number, of a unity and harmony of design that is marvelous, even to me. New York city. THOMAS J. KEENAN. Images by Small Apertures To the Editor of the SCIENTIFIC AMERICAN : The method of observing spots on the sun by allowing its light to pass through a small hole and form an image on a piece of white paper, which is mentioned in your issue of October 31st and reported as new by the Carothers Observatory, is the familiar one known in optics under the name of "images by small apertures." While no discourtesy is intended, it is surely of interest to look at the title page of Father Scheiner's "Rosa Ursina," published about 1634, in which the method is presented in an elegant illustration. It has been frequently mentioned by the present writer in his popular essays, as for example in the Omaha Bee and World Herald on February 4th, 1905. And once, on June 28th, 1908, at Cincinnati, Ohio, having no telescope at hand, he even observed in this way, within a few seconds, the beginning and end of an eclipse. Omaha, Neb. WILLIAM F. RIGGE. Garage Fire Due to Static Electricity To the Editor of the SCIENTIFIC AMERICAN : The results of some experiments made in an attempt to explain the cause of a recent fire in a garage, appear to be worth calling to the attention of automobile owners in general. The fire in question seemed to come from no apparent cause while the tank of the car was being filled with gasoline. The gasoline was being run into the tank through a funnel with a strainer of chamois skin, and the gasoline in the funnel was suddenly noticed to be on fire. If the bottom of a metal funnel is covered with chamois skin, cotton cloth, or other material through which the gasoline develops considerable friction in passing, the funnel, if not connected with the receptacle which receives the gasoline or with the ground, becomes electrically charged.. If the gasoline is caught in a tin can which stands on a sheet of glass, and wires connected to the funnel and receiver, a spark can be obtained when the wires are brought together. The length of the spark depends upon the conductivity of the air, which is least on dry, cold days. In running gasoline into the tank of a car through a strainer of chamois or other similar material, care should be taken that the funnel is not insulated from the tank by a surface coated with varnish or other nonconductor. If metallic connection between funnel and tank" cannot be made directly, both should be grounded. Brunswick, Me. MARSHALL P. CRAM. Some Suggestions About the War To the Editor of the SCIENTIFIC AMERICAN : No doubt a great number of SCIENTIFIC AMERICAN readers must have been puzzled by the statement made in the European news that the Germans at the head of the river Seille caused an inundation below. Also a similar statement concerning the Yser, made recently. While several of the French rivers are of a fair size, quite a number are nothing but mere creeks. Nevertheless, they are navigable, having been "canalized." That is, dams provided with locks have been built across them close enough together to form ponds of slack water of sufficient depth. The river thus becomes a succession of ponds, or small lakes, separated by the dams. It is easy to see that by opening both gates of a lock the water impounded behind will rush through with tremendous force. If, after it is well started, the next one below is opened, then a little later a third, and perhaps more, an enormous quantity of water will be turned loose and flood the regions below. Another thing; after the German guns demolishe*./ several of the Belgian and French forts, every military "expert," or would-be expert, declared that the time of fortifications is passed forever. I hope it is, but I do not see any reason for taking that ground. The whole thing is simply this: the German guns were much larger and reached nwoh. farther than those of the forts. If the guns of the forts had had an equal or greater range, their fire would have made the setting of the German guns absolutely impossible. As to which can ultimately use the largest gun, I say that it is the forts, or any other kind of permanent fortification, because it is possible to secure foundations of any desired strength. With movable guns, it is not possible to establish a concrete foundation beyond a certain size, even if it could be done without being subject to the fortress' fire. Then the difficulty of transportation will limit the size of a movable gun to a point far below that of a permanent arrangement. The walls and roofs of the forts were not, calculated to resist projectiles of the size used, but their strength might be considerably increased. ADRIAN GETAZ. Knoxville, Tenn. The Optophone and Musical Pitch To the Editor of the SCIENTIFIC AMERICAN : Some time ago I wrote you about the optophone in reference to the height of the letters used. Since then I have seen a better description in which they claim the optophone will read any size of type. They do not require raised or embossed letters. There is one thing about the apparatus I do not understand, viz., why do they use a right-angle prism? Why not place the Nernst lamp and the siren disk in a vertical line with the portrait lens and save the waste of light caused by the prism? As you will see in the article, he perforates the siren disk with many holes arranged in eight concentric circles. The holes in the inner circle break the light to correspond to the note g of the musical scale. I have arranged the tuning he uses in the following table, placing g the lowest in pitch below: The figures and decimal fraction represent the double vibrations per second, according to the Standard International pitch in which a' has 435 double vibrations per second and o", the octave above middle c', has 517.3. The article about the optophone is in the Proceedings of the Royal Society, Vol. 90, No. A 619, p. 373. Do you not think that an expert in reading from the optophone in a short time would stop spelling the words letter by letter and read the characteristic sound of each word? . ?. HAWLEY, Custodian, Section of Musical Instruments, Smithsonian Institution. P.S.--I append a table of the vibrations of each letter of the musical scale from below middle C to C the octave above computed with the geometrical ratio 1.05946309435. The only whole number in the scale is a' 435. I give a the octave below to show how small the error is in the computation. I have not seen similar totals carried out much farther than three decimals. I use the above ratio to determine the positions of frets the length of horn and organ pipe the positions of lateral openings in wind instruments.-- . ?. ?. The International Standard Pitch. COMPUTED TO THE ELEVENTH DECIMAL FROM A', HAVING 435 DOUBLE VIBRATIONS PER SECOND. The international standard pitch has an equal tempered scale composed of 12 semitones, the number of vibrations of any letter, and the same letter an octave above the letter is double that of the first, and the geometrical ratio from any semitone of the scale to the next is that number which multiplied by itself and its product by the same multiplier twelve times the result should be two, in other words the 12th root of two, which I have worked out to the 11th decimal, getting the fourth letter from the bottom, is middle c, the beginning of the once marked octave which extends to & above. The letters below c' are of the unmarked octave; c" upper letter is the first of the twice marked octave, a' is the beginning of the computation of its number of double vibrations, 435 multiplied by the ratio above gives the semitone at above with 460.866 vibrations. This product again multiplied by the same ratio gives the vibrations for the next semitone V, and so on. The semitones below a' are obtained by dividing 435 by the ratio, its quotient being used as a dividend for the second semitone below, and so on, ?. ?. HAWKEY, Torpedo Attack from the Air IF the modern automobile torpedo can only thrust its nose against the side of a warship, that ship ceases to exist as a fighting unit of the fleet; instantly it is put out of action, and probably it will go to the bottom. The blow of a single modern torpedo, carrying from 200 to 300 pounds of explosive in its warhead, can send any one of the older warships to the bottom in quick time, as witness the loss of the "Aboukir," "Cressy," and "Hogue"; and it is pretty well certain that the blow of two torpedoes would do the same for the most modern dreadnought. That the torpedo will cripple or sink the enemy, if it once gets home, is an absolute certainty; but the great problem is to bring the gun-platform from which the torpedo is fired sufficiently close to the target to make sure of this overwhelmingly destructive weapon hitting the mark. As matters now stand, there are three methods of bringing the torpedo within hitting range--the hitting range in the most powerful modern torpedoes being 10,000 yards. First, they may be fired from battleship-cruisers and other large surface vessels through underwater tubes; second, they may be fired from tubes carried upon the decks of torpedo-boat destroyers; and third, they may be fired from submarines. Aimed attack from under-water tubes on large warships is not likely to be very effective, for the reason that such ships will fight at long ranges, which, in the case of armored vessels, will probably be from 8,000 to 10,000 yards. Torpedo attack from destroyers must also, usually, be carried out at considerable ranges--this for the reason that the anti-torpedo, rapid-fire battery can concentrate such an overwhelming fire that the chances of the destroyers getting within point-blank range, at least in the daytime, are very remote. Torpedo attack from submarines is not limited to distant ranges; since it is possible for a submarine to approach, undetected, within a few hundred yards of its prey. The limitations of submarine attacks are due to the slow speed, both on the surface and submerged, of the submarine as compared with the ship attacked. At the surface the submarine must keep outside of the range of torpedo-defense guns, and, if it submerges, it at once becomes blind and its slow speed renders it very improbable that it can get within striking distance of an enemy that is moving rapidly. To render torpedo attack absolutely effective, the torpedoes should be launched at a distance of between 1,500 and 2,000 yards, at which ranges the torpedo officer can estimate the speed of the ship aimed at so closely that the torpedo with its high speed of 35 to 40 knots is certain of finding its quarry. The problem of delivering torpedo attack at this close range has been worked out along novel and promising lines by Admiral Bradley A. Fiske of our Navy, who has conceived the bold idea of using a swift and powerful aeroplane for bringing the torpedo within the point-blank zone of fire and delivering the attack at distances which will make a hit inevitable. Fiske's method, as illustrated on the colored cover of this issue, is to attach the torpedo below the body of the aeroplane in such a way that its axis will coincide with the longitudinal axis of the machine. The attachment is such that the airman, by pulling a lever, can release the torpedo at the moment when it is aligned on the proper course to make a hit. Once it has dropped into the water, its automatic mechanism will submerge it to the required depth of about fifteen feet and steer it unerringly to the target. In'making the attack, the aeroplane would rise to an altitude of from 2,000 to 2,500 feet, and approach until it was within striking distance, when it would descend in a sharp spiral within a short distance of the water.' The airman would now steady his machine for an instant, until it and its torpedo were pointing on the true line of fire, when the attack would be delivered by the simple pulling of the lever above mentioned. The preferred time of attack would be on a clear night on which the dark mass of the ship to be attacked would be plainly discernible from above. The chances of discovery by the searchlights of an enemy before the aeroplane was within firing distance would be remote; and even in case of discovery, it would be difficult for the ship's guns to hit a fast-flying machine that was descending in rapid spirals of small diameter. Shackleton's Plans Upset.--When Sir Ernest Shackleton left Buenos Aires last October on his Antarctic expedition it was arranged that he would proceed in the "Endurance" and that another section of the expedition on the "Aurora" would go to the Ross Sea, on the New Zealand side of the Antarctic, where the two divisions would meet in April, 1915, or at latest in March, 1916. It appears now from reports from Sydney, N. S. W., that a strike in the dockyards has delayed the departure of the "Aurora," thus entirely upsetting all plans, and that it will not be possible for Sir Ernest to start on his transantarctje journey until next year.
