Marvels of Modern Science Part 10

Fittings in recent United States battleships are for 21-inch torpedoes.

The armor is to be 11 inch on belt and barbettes and on sides 8 inches, and each ship is to carry a complement of 1,115 officers and men. Two of the turrets will be set forward on the forecastle deck, which will have 28 feet, freeboard, the guns in the first turret being 34 feet above the water and those of the second about 40 feet. Aft of the second turret will be the conning tower, and then will come the fore fire-control tower or lattice mast, with searchlight towers carried on it. Next will come the forward funnel, on each side of which will be two small open rod towers with strong searchlights. Then will come the main fire-control tower and the after funnel and another open tower with searchlight. The two lattice steel towers are to be 120 feet high and 40 feet apart. The four remaining turrets will be abaft the main funnel, the third turret having its guns 32 feet above water; those in the other turrets about 25 feet above the water. The guns will be the new 50-calibre type. All twelve will have broadside fire over a wide arc and four can be fired right ahead and four right astern.

CHAPTER XIII

A TALK ON BIG GUNS

The First Projectiles--Introduction of Cannon--High Pressure Guns--Machine Guns--Dimensions and Cost of Big Guns.

The first arms and machines employing gunpowder as the propelling agency, came into use in the fourteenth century. Prior to this time there were machines and instruments which threw stones and catapults and large arrows by means of the reaction of a tightly twisted rope made up of hemp, catgut or hair. Slings were also much employed for hurling missiles.

The first cannons were used by the English against the Scots in 1327.

They were short and thick and wide in the bore and resembled bowls or mortars; in fact this name is still applied to this kind of ordnance.

By the end of the fifteenth century a great advancement was shown in the make of these implements of warfare. Bronze and bra.s.s as materials came into general use and cannon were turned out with twenty to twenty-five inch bore weighing twenty tons and capable of hurling to a considerable distance projectiles weighing from two hundred pounds to one thousand pounds with powder as the propelling force. In a short time these large guns were mounted and carriages were introduced to facilitate transportation with troops. Meantime stone projectiles were replaced by cast iron shot, which, owing to its greater density, necessitated a reduction in calibre, that is a narrowing of the bore, consequently lighter and smaller guns came into the field, but with a greater propelling force. When the cast iron b.a.l.l.s first came into use as projectiles, they weighed about twelve pounds, hence the cannons shooting them were known as twelve-pounders. It was soon found, however, that twelve pounds was too great a weight for long distances, so a reduction took place until the missiles were cut down to four pounds and the cannon discharging these, four pounders as they were called, weighed about one-quarter of a ton. They were very effective and handy for light field work.

The eighteenth century witnessed rapid progress in gun and ammunition manufacture. "Grape" and "canister" were introduced and the names still cling to the present day. Grape consisted of a number of tarred lead b.a.l.l.s, held together in a net. Canister consisted of a number of small shot in a tin can, the shots being dispersed by the breaking of the can on discharge. Grape now consists of cast iron b.a.l.l.s arranged in three tiers by means of circular plates, the whole secured by a pin which pa.s.ses through the centre. The number of shot in each tier varies from three to five. Grape is very destructive up to three hundred yards and effective up to six hundred yards. Canister shot as we know it at present, is made up of a number of iron b.a.l.l.s, placed in a tin cylinder with a wooden bottom, the size of the piece of ordnance for which it is intended.

Towards the close of the eighteenth century, short cast-iron guns called "carronades" were introduced by Gascoigne of the Cannon Iron Works, Scotland. They threw heavy shots at low velocity with great battery effect. They were for a long time in use in the British navy.

The sailors called them "smashers."

The entire battery of the Victory, Nelson's famous flag-ship at the battle of Trafalgar, amounting to a total of 102 guns, was composed of "carronades" varying in size from thirty-two to sixty-eight pounders. They were mounted on wooden truck carriages and were given elevation by handspikes applied under the breech, a quoin or a wedge shaped piece of wood being pushed in to hold the breech up in position.

They were trained by handspikes with the aid of side-tackle and their recoil was limited by a stout rope, called the breeching, the ends of which were secured to the sides of the ship. The slow match was used for firing, the flint lock not being applied to naval guns until 1780.

About the middle of the nineteenth century, the design of guns began to receive much scientific thought and consideration. The question of high velocities and flat trajectories without lightening the weight of the projectile was the desideratum; the minimum of weight in the cannon itself with the maximum in the projectile and the force with which it could be propelled were the ends to be attained.

In 1856 Admiral Dahlgren of the United States Navy designed the _Dahlgren_ gun with shape proportioned to the "curve of pressure,"

which is to say that the gun was heavy at the breech and light at the muzzle. This gun was well adapted to naval use at the time. From this, onward, guns of high pressure were manufactured until the pressure grew to such proportions that it exceeded the resisting power, represented by the tensile strength of cast iron. When cast, the gun cooled from the outside inwardly, thus placing the inside metal in a state of tension and the outside in a state of compression. General Rodman, Chief of Ordnance of the United States Army, came forward with a remedy for this. He suggested the casting of guns hollow and the cooling of them from the inside outwardly by circulating a stream of cold water in the bore while the outside surface was kept at a high temperature. This method placed the metal inside in a state of compression and that on the outside in a state of tension, the right condition to withstand successfully the pressure of the powder gas, which tended to expand the inner portions beyond the normal diameter and throw the strain of the supporting outer layers.

This system was universally employed and gave the best results obtainable from cast iron for many years and was only superseded by that of "built up" guns, when iron and steel were made available by improved processes of production.

The great strides made in the manufacture and forging of steel during the past quarter of a century, the improved tempering and annealing processes have resulted in the turning out of big guns solely composed of steel.

The various forms of modern ordnance are cla.s.sified and named according to size and weight, kind of projectiles used and their velocities; angle of elevation at which they are fired; use; and mode of operation.

The guns known as breechloading rifles are from three inches to fourteen inches in calibre, that is, across the bore, and in length from twelve to over sixty feet. They weigh from one ton to fifty tons.

They fire solid shot or sh.e.l.ls weighing up to eleven hundred pounds at high velocities, from twenty-three to twenty-five hundred feet per second. They can penetrate steel armor to a depth of fifteen to twenty inches at 2,000 yards distance.

Rapid fire guns are those in which the operation of opening and closing the breech is performed by a single motion of a lever actuated by the hand, and in which the explosive used is closed in a metallic case.

These guns are made in various forms and are operated by several different systems of breech mechanism generally named after their respective inventors. The Vickers-Maxim and the Nordenfeldt are the best known in America. A new type of the Vickers-Maxim was introduced in 1897 in which a quick working breech mechanism automatically ejects the primer and draws up the loading tray into position as the breech is opened. This type was quickly adopted by the United States Navy and materially increased the speed of fire in all calibres.

What are known as machine guns are rapid fire guns in which the speed of firing is such that it is practically continuous. The best known make is the famous Gatling gun invented by Dr. R. J. Gatling of Indianapolis in 1860. This gun consists of ten parallel barrels grouped around and secured firmly to a main central shaft to which is also attached the grooved cartridge carrier and the lock cylinder. Each barrel is provided with its own lock or firing mechanism, independent of the other, but all of them revolve simultaneously with the barrels, carrier and inner breech when the gun is in operation. In firing, one end of the feed case containing the cartridges is placed in the hopper on top and the operating crank is turned. The cartridges drop one by one into the grooves of the carrier and are loaded and fired by the forward motion of the locks, which also closes the breech while the backward motion extracts and expels the empty sh.e.l.ls. In its present state of efficiency the Gatling gun fires at the rate of 1,200 shots per minute, a speed, by separate discharges, not equaled by any other gun.

Much larger guns were constructed in times past than are being built now. In 1880 the English made guns weighing from 100 to 120 tons, from 18 to 20 inches bore and which fired projectiles weighing over 2,000 pounds at a velocity of almost 1,700 feet per second. At the same time the United States fashioned a monster rifle of 127 tons which had a bore of sixteen inches and fired a projectile of 2,400 pounds with a velocity of 2,300 feet per second.

The largest guns ever placed on board ship were the Armstrong one- hundred-and-ten-ton guns of the English battleships, _Sanspareil_, _Benbow_ and _Victoria_. They were sixteen and one-fourth inch calibre.

The newest battleships of England, the _Dreadnought_ and the _Temeraire_, are equipped with fourteen-inch guns, but they are not one- half so heavy as the old guns. Many experts in naval ordnance think it a mistake to have guns over twelve inch bore, basing their belief on the experience of the past which showed that guns of a less calibre carrying smaller sh.e.l.ls did more effective work than the big bore guns with larger projectiles.

The two t.i.tanic war-vessels now in course of construction for the United States Navy will each carry a battery of ten fourteen-inch rifles, which will be the most powerful weapons ever constructed and will greatly exceed in range and hitting power the twelve-inch guns of the _Delaware_ or _North Dakota_. Each of the new rifles will weigh over sixty-three tons, the projectiles will each weigh 1,400 pounds and the powder charge will be 450 pounds. At the moment of discharge each of these guns will exert a muzzle energy of 65,600 foot tons, which simply means that the energy will be so great that it could raise 65,600 tons a foot from the ground. The fourteen-hundred-pound projectiles shall be propelled through the air at the rate of half a mile a second. It will be plainly seen that the metal of the guns must be of enormous resistance to withstand such a force. The designers have taken this into full consideration and will see to it that the powder chamber in which the explosion takes place as well as the breech lock on which the shock is exerted is of steel so wrought and tempered as to withstand the terrific strain. At the moment of detonation the shock will be about equal to that of a heavy engine and a train of Pullman coaches running at seventy miles an hour, smashing into a stone wall. On leaving the muzzle of the gun the sh.e.l.l will have an energy equivalent to that of a train of cars weighing 580 tons and running at sixty miles an hour. Such energy will be sufficient to send the projectile through twenty-two and a half inches of the hardest of steel armour at the muzzle, while at a range of 3,000 yards, the projectile moving at the rate of 2,235 feet per second will pierce eighteen and a half inches of steel armor at normal impact. The velocity of the projectile leaving the gun will be 2,600 feet per second, a speed which if maintained would carry it around the world in less than fifteen hours.

Each of the mammoth guns will be a trifle over fifty-three feet in length and the estimated cost of each will be $85,000. Judging from the performance of the twelve-inch guns it is figured that these greater weapons should be able to deliver three shots a minute. If all ten guns of either of the projected _Dreadnoughts_ should be brought into action at one time and maintain the three shot rapidity for one hour, the cost of the ammunition expended in that hour would reach the enormous sum of $2,520,000.

Very few, however, of the big guns are called upon for the three shots a minute rate, for the metal would not stand the heating strain.

The big guns are expensive and even when only moderately used their "life" is short, therefore, care is taken not to put them to too great a strain. With the smaller guns it is different. Some of six-inch bore fire as high as eight aimed shots a minute, but this is only under ideal conditions.

Great care is being taken now to prolong the "life" of the big guns by using non-corrosive material for the charges. The United States has adopted a pure gun-cotton smokeless powder in which the temperature of combustion is not only lower than that of nitro-glycerine, but even lower than that of ordinary gunpowder. With the use of this there has been a very material decrease in the corrosion of the big guns.

The former smokeless powder, containing a large percentage of nitro-glycerine such as "cordite," produced such an effect that the guns were used up and practically worthless, after firing fifty to sixty rounds.

Now it is possible for a gun to be as good after two or even three hundred rounds as at the beginning, but certainly not if a three minute rate is maintained. At such a rate the "life" of the best gun made would be short indeed.

CHAPTER XV

MYSTERY OF THE STARS

Wonders of the Universe--Star Photography--The Infinity of s.p.a.ce.

In another chapter we have lightly touched upon the greatness of the Universe, in the cosmos of which our earth is but an infinitesimal speck. Even our sun, round which a system of worlds revolve and which appears so mighty and majestic to us, is but an atom, a very small one, in the infinitude of matter and as a cog, would not be missed in the ratchet wheel which fits into the grand machinery of Nature.

If our entire solar system were wiped out of being, there would be left no noticeable void among the countless systems of worlds and suns and stars; in the immensity of s.p.a.ce the sun with all his revolving planets is not even as a drop to the ocean or a grain of sand to the composition of the earth. There are millions of other suns of larger dimensions with larger attendants wheeling around them in the illimitable fields of s.p.a.ce. Those stars which we erroneously call "fixed" stars are the centers of other systems vastly greater, vastly grander than the one of which our earth forms so insignificant a part.

Of course to us numbers of them appear, even when viewed through the most powerful telescopes, only as mere luminous points, but that is owing to the immensity of distance between them and ourselves. But the number that is visible to us even with instrumental a.s.sistance can have no comparison with the number that we cannot see; there is no limit to that number; away in what to us may be called the background of s.p.a.ce are millions, billions, uncountable myriads of invisible suns regulating and illuminating countless systems of invisible worlds. And beyond those invisible suns and worlds is a region which thought cannot measure and numbers cannot span. The finite mind of man becomes dazed, dumbfounded in contemplation of magnitude so great and distance so amazing. We stand not bewildered but lost before the problem of interstellar s.p.a.ce. Its length, breadth, height and circ.u.mference are illimitable, boundless; the great eternal cosmos without beginning and without end.

In order to get some idea of the vastness of interstellar s.p.a.ce we may consider a few distances within the limits of human conception. We know that light travels at the rate of 186,000 miles a second, yet it requires light over four years to reach us from the nearest of the fixed stars, travelling at this almost inconceivable rate, and so far away are some that their light travelling at the same rate from the dawn of creation has never reached us yet or never will until our little globule of matter disintegrates and its particles, its molecules and corpuscles, float away in the boundless ether to amalgamate with the matter of other flying worlds and suns and stars.

The nearest to us of all the stars is that known as _Alpha Centauri_.

Its distance is computed at 25,000,000,000,000 miles, which in our notation reads twenty-five trillion miles. It takes light over four years to traverse this distance. It would take the "Empire State Express," never stopping night or day and going at the rate of a mile a minute, almost 50,000,000 years to travel from the earth to this star. The next of the fixed stars and the brightest in all the heavens is that which we call _Sirius_ or the Dog Star. It is double the distance of Alpha Centauri, that is, it is eight "light years" away. The distances of about seventy other stars have been ascertained ranging up to seventy or eighty "light years" away, but of the others visible to the naked eye they are too far distant to come within the range of trigonometrical calculation. They are out of reach of the mathematical eye in the depth of s.p.a.ce. But we know for certain that the distance of none of these visible stars, without a measurable parallax, is less than four million times the distance of our sun from the earth. It would be useless to express this in figures as it would be altogether incomprehensible. What then can be said of the telescopic stars, not to speak at all of those beyond the power of instruments to determine.

If a railroad could be constructed to the nearest star and the fare made one cent a mile, a single pa.s.sage would cost $250,000,000,000, that is two hundred and fifty billion dollars, which would make a 94-foot cube of pure gold. All of the coined gold in the world amounts to but $4,000,000,000 (four billion dollars), equal to a gold cube of 24 feet. Therefore it would take sixty times the world's stock of gold to pay the fare of one pa.s.senger, at a cent a mile from the earth to Alpha Centauri.

The light from numbers, probably countless numbers, of stars is so long in coming to us that they could be blotted out of existence and we would remain unconscious of the fact for years, for hundreds of years, for thousands of years, nay to infinity. Thus if _Sirius_ were to collide with some other s.p.a.ce traveler and be knocked into smithereens as an Irishman would say, we would not know about it for eight years. In fact if all the stars were blotted out and only the sun left we should still behold their light in the heavens and be unconscious of the extinction of even some of the naked-eye stars for sixty or seventy years.

It is vain to pursue farther the unthinkable vastness of the visible Universe; as for the invisible it is equally useless for even imagination to try to grapple with its never-ending immensity, to endeavor to penetrate its awful clouded mystery forever veiled from human view.

In all there are about 3,000 stars visible to the naked eye in each hemisphere. A three-inch pocket telescope brings about one million into view. The grand and scientifically perfected instruments of our great observatories show incalculable mult.i.tudes. Every improvement in light-grasping power brings millions of new stars into the range of instrumental vision and shows the "background" of the sky blazing with the light of eye-invisible suns too far away to be separately distinguished.

Great strides are daily being made in stellar photography. Plates are now being attached to the telescopic apparatus whereby luminous heavenly bodies are able to impress their own pictures. Groups of stars are being photographed on one plate. Complete sets of these star photographs are being taken every year, embracing every nook and corner of the celestial sphere and these are carefully compared with one another to find out what changes are going on in the heavens. It will not be long before every star photographically visible to the most powerful telescope will have its present position accurately defined on these photographic charts.

When, the sensitized plate is exposed for a considerable time even invisible stars photograph themselves, and in this way a great number of stars have been discovered which no telescope, however powerful, can bring within the range of vision. Tens of thousands of stars have registered themselves thus on a single plate, and on one occasion an impression was obtained on one plate of more than 400,000.

Astronomers are of the opinion that for every star visible to the naked eye there are more than 50,000 visible to the camera of the telescope.

If this is so, then the number of visible stars exceeds 300,000,000 (three hundred millions).