RETROSPECT AND PROSPECT IN TRANSPORTATION—THE DE WITT CLINTON TRAIN AND THE GYRO-CAR.The De Witt Clinton engine, with its archaic coaches, represents the earliest type of railway transportation in America. The Gyro-car, two views of which are given, is the working model of a single-rail vehicle exhibited in England by Mr. Louis Brennan in 1907. It is balanced by an ingenious gyroscopic mechanism, which its inventor believes will prove equally successful when applied to vehicles on a commercial scale.
RETROSPECT AND PROSPECT IN TRANSPORTATION—THE DE WITT CLINTON TRAIN AND THE GYRO-CAR.The De Witt Clinton engine, with its archaic coaches, represents the earliest type of railway transportation in America. The Gyro-car, two views of which are given, is the working model of a single-rail vehicle exhibited in England by Mr. Louis Brennan in 1907. It is balanced by an ingenious gyroscopic mechanism, which its inventor believes will prove equally successful when applied to vehicles on a commercial scale.
RETROSPECT AND PROSPECT IN TRANSPORTATION—THE DE WITT CLINTON TRAIN AND THE GYRO-CAR.
The De Witt Clinton engine, with its archaic coaches, represents the earliest type of railway transportation in America. The Gyro-car, two views of which are given, is the working model of a single-rail vehicle exhibited in England by Mr. Louis Brennan in 1907. It is balanced by an ingenious gyroscopic mechanism, which its inventor believes will prove equally successful when applied to vehicles on a commercial scale.
The Brennan car as at first exhibited was only a working-model about six feet in length, and the gyroscopesthat balanced it were about five inches in diameter. It seems almost incredible that wheels so small should be able to balance a car six feet in length, but it must be understood that these small gyroscopes whirl at the rate of about seven thousand revolutions per minute, and, of course, the gyroscopic force is proportionate to the rate of revolution. If we recall that a light hoop making perhaps fifty or a hundred revolutions per minute acquires a considerable stability, we shall cease to wonder at the rigidity of the axles of the wheels revolving at such enormous speed.
The model car accomplished the feat of carrying a passenger weighing about one hundred and forty pounds across a little valley on a wire cable, a voyage in some respects the most remarkable that any man has thus far been privileged to make. The car has shown that it can go up or down a sharp incline; but this, as a moment's reflection will show, does not involve any change of direction of the gyroscopic axle, and therefore involves only the ordinary laws of mechanics. It is all one to the gyroscope whether the car moves on the level or up or down hill, so long as it moves straight ahead.
Nor do the gyroscopes interfere in the least with the turning of the car in passing round a curve, when the two of them are linked together, as Mr. Brennan links them, so that any lateral change in the axis of one is balanced by an opposite change of the axis of the other. With the single gyroscope, such as Mr. Brennan used when he first began his experiments, the car encounters difficulties at curves in the track.
But before we can understand how the two gyroscopesbalance each other in such a way as to make the Brennan car lean in while passing about a curve, we must investigate more fully the action of the individual gyroscopes. I have already said that there is another principle involved as supplementary to the principle of the fixed axis; this we must now investigate.
Perhaps it would be fairer to say that what we have to consider is not a new principle but a complication as to the application of the principle of gyroscopic action already put forward. In any event there is an elementary fact about the gyroscope that I have not yet stated. It is this: in order that the gyroscope may exercise its fundamental property of holding its axis fixed, it must have that axis so adjusted that it is free to oscillate or wabble. That sounds distinctly paradoxical, but it is a very essential fact. If Mr. Brennan had merely fixed two wheels rigidly in the frame of his car, they would have had no appreciable effect in balancing it. Had nothing more than that been necessary, some one would have invented a gyrocar long ago. But very much more than that was necessary, as we shall see.
The complication of which I am speaking is illustrated by the action of the simplest top, which likewise owes its stability to its wabble. Your top does not rise merely because it spins, but because it wabbles as it spins—wabbling being the familiar word for what the machinist calls "precession." A freely spinning top, if in equilibrium, has no inherency to rise up against gravitation, as your top may have led you to suppose. Your top rises because it is not spinning freely in equilibrium, its action being interfered with by the friction of thepoint on which it rests; it is seeking a position of equilibrium, which, owing to the location of its centre of gravity, will be found when its spindle is erect. But a top supported at both ends and properly balanced, does not tend to rise but only to maintain its position.
It is such a balanced top as this that we must call to our aid in explaining the action of Mr. Brennan's gyroscopes. The explanation will involve the use of a diagram perhaps rather unpleasantly suggestive of the days when you studied geometry, and I fear I cannot hope to make interesting reading of the explanation. But it will be worth your while to follow it, that you may understand the action of one of the most remarkable and ingenious of inventions. Figure 1 represents a kind of top called a Foucault gyrostat. It is merely a top or gyroscope in gimbal frames, such as I have already referred to. With certain slight modifications, the diagram that represents it might also be a diagram of one of the gyroscopes in Mr. Brennan's car. Indeed, it was such a top as this that led Mr. Brennan to his discovery. Once while on a visit to Cannes, he purchased a top like this of a street vender—and the gyrocar is the outcome of the studies he made with it. This is also the kind of top with which Foucault, after whom it is named, proved that the earth revolves; but we shall come to that story in another connection.
Fig. 1.
Fig. 1.
Reverting to the diagram, the gyroscope or top proper is at the centre, revolving on the axisO A. It ispivoted on the frameB A C, which frame is in turn pivoted so that it can rotate on the axisB C. Lastly, the outer frameB D C Eis pivoted on the axisD E. Thus the apparatus as a whole is capable of revolving on each of its three principal axes. But under ordinary conditions it is only the inner wheel that is spinning. As this wheel is perfectly balanced, it will maintain steadily any position that it chances to have when it isset spinning, and the outer frames will remain stationary unless a disturbing force is applied to them.
Suppose, now, that the wheel has been set spinning on its axisO Ain the direction indicated by the arrow, while its axis is horizontal, as represented in the diagram. The wheel will then tend to maintain its position and resist any attempt to displace it. But its resistance will be shown in a very peculiar way—whereby hangs our tale. If you apply a steady downward pressure to the frameB A Cat pointA, attempting thus to deflect the axis of the spinning wheel of the gyroscope, the frame will not tip down as you expect it to do (and as it would do if the top were not spinning) but instead, it will move in a horizontal plane along the arcC A B, the entire mechanism rotating on the axisD E. This motion is equivalent to the wabble of the top, and it is called "precession."
Please remember the word and its meaning, for we must use it repeatedly.
But now, curiously enough, if you were to apply a sidewise pressure atA, pushing to the left (as we view the diagram) to help on the motion of precession, the obstinate apparatus will cease altogether to move in that direction and the pointAwill begin to rise instead, the frameB A Crotating on its axisB C. This rise of the axisO Awill take place even though the downward pressure is continued. You have disturbed the equilibrium of the top—unbalanced it—and it must seek a new position. Contrariwise, if you would have the point A moved to the right, you must push it upward; if you would have it go down, you must push it to the right.
This seems rather weird behavior, but if you will note the direction of the arrow on the wheel you will see a certain method in it. It will appear that in each case the force you apply has been carried round a corner, as it were, by the whirling disc, and made to act at right angles to the direction of its application. This change of direction of a force applied is strictly comparable to the change effected by the familiar device known as a pulley. With that device, to be sure, a pull instead of a push is used, but this is a distinction without a difference, for pushing and pulling are only opposite views of the same thing.
Possibly this suggested explanation of the action of the gyrostat may not seem very satisfactory, but the facts are perfectly clear, and if you will bear them steadily in mind you will readily be able to understand the Brennan gyroscope, as you otherwise cannot possibly hope to do. You have only to recall that pushing down atAcauses motion (called "precession") to the left, and pushing up atA, motion to the right; and that in order to makeAeither rise or fall, you must "accelerate precession" by pushing to the left or to the right, respectively. But you must understand further, that when, through the application of any of these disturbing forces, you have forced the axisO Ainto a new position, it will tend to maintain that new position, having no propensity whatever to return to its original position. It is quite as stably in equilibrium with its axis pointing upward as when in the position shown in the diagram. One position is quite like another to it; but having accepted a position it resents any change whatsoever.
Now we are prepared to understand the Brennan gyroscope, which consists essentially of two such gyrostats as that shown in our diagramA, set into the frame of the car on the axisD E, their wheels revolving in opposite directions and their outer frames so linked together that when one turns in one direction on its axisD E, the other must turn in the opposite direction. As the sole object of having two of the gyroscopes is to facilitate the going around curves, we may for the moment neglect the second one, and consider the action of only one of the pair.
Our diagram 2, then, will represent one of Mr. Brennan's gyroscopes in action. It is pivoted into the framework of the car on the axisD E. If you examine it you will see that it is essentially the Foucault gyrostat of our other diagram, with the axisO Aprojected beyond the frame to the pointF.
In practice, the frameB A Cis made to carry the field-magnet of an electric motor for spinning the wheel. But this in no wise affects the principles of action. Mr. Brennan's invention consists of the exceedingly ingenious way in which he applies these principles; and to understand this we must follow our diagram closely. Looking at it, you will see that the spindleO Fcarries two rollersR1andR2which may come in contact under certain circumstances with the curved segment markedG1,G2,G3,G4, which are strong segments of the car-frame itself—the segments, indeed, upon which the force of the gyroscope is expended in holding the car in equilibrium. It must be understood further that the rollerR1is loosely fitted to the spindleO Fand hence can whirl with it when pressed against the segmentG1orG3; whereas the rollerR2is fitted about a non-revolving extension of the frameB A C, and not to the spindle itself. Bearing in mind that the gyroscope itself is perfectly balanced and hence tends to maintain its axisO Fin a fixed direction, we shall be able to understand what must happen when the car is tipped from any cause whatever—as the shifting of its load, the pressure of the wind, or the centrifugal action due to rounding a curve.
Fig. 2.
Fig. 2.
Suppose, for example, that the car tips to the right. This will bring the segmentG1in contact with the rollerR1, and the roller will instantly tend to run along it, as a car-wheel runs along the track, because friction with the spindle causes it to revolve. But this, it will be evident, is equivalent to pushing the spindleF(or the frameA) towardB—"accelerating the precession"—and we know that the effect of such a push will be to cause the spindle (thanks to that round-the-corner action) to rise, thus pushing up the segmentG1, and with it the car itself.
The thrust will cause the car to topple to the left and this will free the rollerR2, but a moment later it will bring the segmentG2in contact with rollerR2which thus receives an upward thrust. But an upward thrust, we recall, will not cause the spindle to move upward, but off to the right towardC; and so, a moment later still the rollerR2will pass beyond the end of the segmentG2and the rollerR1will come in contact with the segmentG3, along which it will tend to roll, thus accelerating the precession to the right, and so causing the spindle to push downward, bringing the car back to its old position or beyond it; whereupon the segmentG4will be brought in contact withR2, retarding the further oscillation of the car and causing the spindle to move back again to the left.
This sequence of oscillations will be repeated over and over so long as any disturbing force tends to throw the car out of equilibrium. In other words, the gyroscope, when its balance is disturbed by a thrust due to any unbalancing of the car, will begin to wabble and continue to wabble until it finds a position where it is no longer disturbed, and this new position will be attained only when the car as a whole is perfectly balanced again.
In this new position of balance, the car (owing to a shift of its load or to the force of the wind) may be tipped far over to one side, as a man leans in carrying a weight on one shoulder, to get the centre of gravity over the rail, and in that event the axis of the gyroscope will be no longer horizontal. But that is quite immaterial. There is no more merit in the horizontal position than in any other, as regards the tendency to keep a fixed axis. If it is usually horizontal, this is only because under normal conditions the car will be balanced at its physical centre, just as ordinarily a man stands erect and does not lean to one side in walking.
Reverting for a moment to our diagram and the explanation just given, it will be understood that the two rollers R1and R2are never in action at the same time, and that it is only the roller R1that gives the sidewise push that accelerates the precession (since R2is not in contact with the axle itself).
The function of R2is to retard the precession and bring the axis to its normal position at right angles to the rail on which the car runs. There is nothing of mystery about the action of either which the action of our gyrostat does not explain, but the mechanism by which the different segments of the car are made to push against the spindle, and so force it to balance the car in order that it may maintain its own balance, is exceedingly ingenious. Mr. Brennan himself tells me that he has improved methods of accomplishing these results, which are not yet to be made public. The principle, however, is the same as that outlined in the earlier patents which I have just described.
If you have taken the trouble to follow carefully the description just given, you will be prepared to understand the anomalies of action of the gyrocar; for example, why its side rises when a weight is placed on it; why it leans toward the wind, and why it leans to the inner and not to the outer side of the track in rounding a curve. The substance of the explanation is that the greater the force brought to bear on the roller R1by the segment of the car that strikes against it, the stronger its precession, and hence the more powerful its lift. The oscillations and counter-oscillations thus brought about continue to operate powerfully on the roller R1so long as the weight of the car is out of balance; and balance is restored only when the heavier side of the car rises, bringing the centre of gravity over the track, just as a man carrying a weight on the right shoulder leans toward the left, and vice-versa. Thus, when the gyrocar has a heavy weight on one side, or encounters a strong wind, it may lean far over, but still be perfectly and securely balanced, the gyroscopes finally remaining quiescent in their new position until some new disturbance is applied.
It remains to be said, however, that there is another element introduced when the car rounds a curve. To understand this, we must revert to the action of the Foucault gyrostat, as illustrated in diagram 1. If you held such a gyrostat in your hand in the upright position in which it is shown in the diagram, and whirled it about, the axisO Awould of course maintain a fixed direction so long as the gyrostat was free to revolve on the axisD E. But if you prevented such revolution, as by clutchingthe spindleEfirmly, and then whirled the gyrostat about at arm's length, the axisO Awould at once be forced to take an upright position. If your hand whirled to the right, the pointAwould rise; if your hand whirled to the left, the pointAwould go down; the principle determining this motion in either case being that the direction of whirl of the gyroscope must correspond to the direction of curve given to the apparatus as a whole by the motion of your arm.
Exactly the same principle applies to the Brennan gyroscope when the car to which it is attached goes about a curve. The frame pivoted atD Erevolves only within a limited arc, and then becomes fixed, and so the axisO Ftends to tip upward when the car rounds a curve. If only a single gyroscope were used, this would tend to make the car tip in opposite directions, according to whether the car is going forward or backward, and the tip might be dangerous in going about a curve, as Mr. Brennan found to his cost in his earlier experiments. But when the two gyroscopes, revolving in opposite directions, are linked together, the action of one balances that of the other, and their joint effect is always to make the car lean in at a curve, which is precisely what it should do to ensure safety. Moreover, the two linked gyroscopes keep their planes of revolution parallel to the rail, as is essential to their proper action, and as a single gyroscope would not do.
The balancing action of the gyroscope seems no whit less remarkable after it is explained. It should be said, however, that the force exerted by the mechanism is notso tremendous as might at first thought appear, for the gyroscopes are by no means called upon to counteract the entire force of gravity brought to bear on the car. They do not in any senseliftthe car; they only balance its two sides, which when left to themselves are approximately of equal weight. The car, as a whole, weighs down on the track just as heavily with the gyroscopes in action as when they are still. Balancing is a very different feat from lifting, as everyone is aware from personal experience. Two men pushing against the opposite sides of a monorail car could keep it balanced on the central rail though its weight vastly exceeded anything they could lift.
It goes without saying that so elaborate a mechanism as Mr. Brennan's gyroscope was not perfected in a day. Neither was it hit upon by accident. It belongs in the category of inventions that were thought out to meet a mechanical need. Mr. Brennan is an Irishman by birth, but he was taken by his parents to Australia at the age of nine and remained there throughout the years of his early manhood. Observation of the condition of the roads in Australia, and of the enormous retardation of development due to inadequate transportation facilities led him to ponder over the possibilities of improvement in this direction, as he was jolted about the country in a coach with leather straps in lieu of springs. It became clear to him that a way must be found to build railroads more cheaply. Furthermore, it wasbrought to his attention through observation of the condition of the cattle that were shipped from North Australia across the continent, that a railway car that would enable the cattle to make the journey in comfort, and thus arrive in marketable condition, would have enormous value for this purpose alone.
For years, Mr. Brennan tells me, the problem haunted him, of how to make a monorail car balance itself. He studied the action of rope-walkers, and he attempted various crude methods of balancing a car, which all came to nothing. He thought about the possibility of using the gyroscope, and even purchased several elaborate gyrostats in order to study gyroscopic action. As a friend of Sir Henry Bessemer, he knew of that gentleman's experiments with the gyroscope in attempting to make a steady room in a ship, but these also availed him nothing. It was not until he purchased the toy top at Cannes, as already mentioned, that he got hold of a really viable idea; and then, of course, almost numberless experiments were necessary before an apparatus was devised that could meet all the requirements.
At last, however, a model car, more than fulfilling all his fondest hopes, was in actual operation. It remained to build a car of commercial size. To aid him in thus completing his experiments, Mr. Brennan received a grant of $30,000 from the India Society. He believed that a car one hundred feet long and sixteen feet wide would be balanced by gyroscopes three and a half feet in diameter, so effectively that it would stand erect and rigid though fifty passengers were clustered on one side of its spacious room.
The accuracy of this prediction was put to the test in November, 1909, when Mr. Brennan exhibited the first gyrocar of commercial size. The result was demonstrative and convincing. The large car, carrying forty or fifty passengers, operated exactly as its inventor had foretold, and the doubts of the most skeptical were set at rest. Photographs of the car in actual operation, with its load of passengers, were sent broadcast, and it became apparent that the introduction of the gyrocar in competition with railway, trolley, and motor cars of the old type would be only a matter of time.
When we come thus to consider the gyrocar as a vehicle in which all of us may soon have an opportunity to ride, there is one practical question that is sure to present itself to the mind of almost every reader. What will be the effect should the electrical power that drives the gyroscopes give out at a critical moment, as, for instance, when the car is just crossing a gorge or river on a cable? Mr. Brennan's ingenuity has anticipated this emergency. The gyroscopes that balance his cars operate in a vacuum, and all the bearings are so well devised as to give very little friction. The wheels will continue running for a considerable time after the power is shut off. The large gyroscopes of the commercial car, it is estimated, will perhaps require two hours to attain the highest rate of rotation, but they will then continue revolving at an effective speed for some hours, even if no further power is applied to them.
It may be said, too, that the gyrocar is provided with lateral legs that may be let down in case of emergency or when the car is not in use, to avoid waste of energyin needless running of the gyroscope. All in all, it would appear that the dangers of travel in a gyrocar should be fewer than those that attend an ordinary double-track car; and Mr. Brennan believes that it will be possible, with the aid of the new mechanism, to attain a speed of one hundred and fifty, perhaps even two hundred miles an hour with safety.
TWO VIEWS OF MR. LOUIS BRENNAN'S MONO-RAIL GYRO-CAR.The gyroscopic mechanism for automatically balancing the car is contained in the cab-like anterior portion. The platform of the car maintains its equilibrium even when the forty passengers are crowded on one side, as shown in the upper picture.
TWO VIEWS OF MR. LOUIS BRENNAN'S MONO-RAIL GYRO-CAR.The gyroscopic mechanism for automatically balancing the car is contained in the cab-like anterior portion. The platform of the car maintains its equilibrium even when the forty passengers are crowded on one side, as shown in the upper picture.
TWO VIEWS OF MR. LOUIS BRENNAN'S MONO-RAIL GYRO-CAR.
The gyroscopic mechanism for automatically balancing the car is contained in the cab-like anterior portion. The platform of the car maintains its equilibrium even when the forty passengers are crowded on one side, as shown in the upper picture.
ITmust not be supposed that Mr. Louis Brennan's remarkable monorail car affords the first illustration of an attempt to make practical use of the principles of gyroscopic action. The fact is quite otherwise. The idea of giving steadiness to such instruments as telescopes and compasses on shipboard with the aid of gyroscopes originated half a century ago, and was put into fairly successful operation by Professor Piazzi Smyth (in 1856). More than a century earlier than that (in 1744), an effort was made to aid the navigator, by the use of a spinning-top with a polished upper surface, to give an artificial horizon at sea, that observations might be made when the actual horizon was hidden by clouds or fog. The inventor himself, Serson by name, was sent out by the British Admiralty to test the apparatus, and was lost in the wreck of the shipVictory. His top seemed not to have commended itself to his compatriots, but it has been in use more or less ever since, particularly among French navigators.
These first attempts to use the gyroscope at sea were of a technical character, and could have no great popularinterest. But about twenty-five years ago an attempt was made to utilize the principle of the spinning-top in a way that would directly concern the personal comfort of a large number of voyagers. It was nothing less than the effort to give stability to a room on a steamship, in order that the fortunate occupant might avoid the evils of seasickness. The man who stood sponsor for the idea, and who expended sums variously estimated at from fifty thousand to more than a million dollars in the futile attempt to carry it into execution, was the famous Sir Henry Bessemer, famed for his revolutionary innovations in the steel industry. It would appear that Bessemer's first intention was to make a movable room to be balanced by mechanisms worked by hand. But after his project was under way his attention was called to the possibility of utilizing gyroscopic forces to the same end. As the story goes, he chanced to purchase a top for sixpence, and that small beginning led him ultimately to expend more than a million dollars in playing with larger tops. His expensive toy passed into history as the "Bessemer chamber." It was actually constructed on a Channel steamer; but the would-be inventor, practical engineer though he was, did not find a way properly to apply the principle, and his experiment ended in utter failure.
With this, the idea that the gyroscope-wheel could ever aid in steadying a ship at sea seemed to be proved a mere vagary unworthy the attention of engineers. But not all experimenters were disheartened, and since the day of Sir Henry Bessemer's fiasco a number of workers have given thought to the problem—with the object,however, of applying the powers of the revolving wheel not merely to a single room but to an entire ship. I have personal knowledge of at least one inventor, quite unknown to fame, who believed that he had solved the problem, but who died before he could put his invention to a practical test. It remained for a German engineer, Dr. Otto Schlick, to put before the world, first as a theory and then as a demonstration, the practical utility of the revolving wheel in preventing a ship from rolling.
In the year 1904 Dr. Schlick elaborated his theory before the Society of Naval Architects in London. His paper aroused much interest in technical circles, but most of his hearers believed that it represented a theory that would never be made a tangible reality. Fortunately, however, Dr. Schlick was enabled to make a practical test, by constructing a wheel and installing it on a small ship—a torpedo-boat called theSea-bar, discarded from the German navy. The vessel is one hundred and sixteen feet in length and of a little over fifty-six tons' displacement. The device employed consists of a fly-wheel one meter in diameter, weighing just over eleven hundred pounds and operated by a turbine mechanism capable of giving it a maximum velocity of sixteen hundred revolutions per minute. This powerful fly-wheel was installed in the hull of theSea-baron a vertical axis, whereas the Brennan gyroscope operates on a horizontal axis. So installed, the Schlick gyroscope does not interfere in the least with the steering or withthe ordinary progression of the ship. Its sole design is to prevent the ship from rolling.
The expectations of its inventor were fully realized. On a certain day in July, 1906, with a sea so rough that the ship rolled through an arc of thirty degrees, when the balance-wheel was not in revolution, the arc of rolling was reduced to one degree when the great top was set spinning and its secondary bearings released. In other words, it practically abolished the rolling motion of the craft, causing its decks to remain substantially level, while the ship as a whole heaved up and down with the waves. These remarkable results, with more in kind, were recorded in the paper which Sir William White read before the Institution of Naval Architects in London in April, 1907. He himself had witnessed tests of the Schlick gyroscope, and, in common with his colleagues, he accepted the demonstrations as unequivocal.
Fully to understand the action of Dr. Schlick's invention, one must know that it is not a mere wheel on the single pivot, but a wheel adjusted in such a fashion that it can oscillate longitudinally while revolving on its vertical axis. In other words, it is precisely as if one of the two gyroscope-wheels used in the Brennan car (greatly enlarged) were so placed that its main axis was vertical, its secondary axis, or axis of oscillation, being horizontal and at right angles to the ship's length. Thus, while spinning on its vertical axis the body of the top is able to oscillate, pendulum-like, lengthwise of the ship.
In principle the action of this wheel is not different from that of an ordinary top on your table which wabblesto the right or to the left when you push its axis straight away from you. Yet to the untechnical observer it seems as if the Schlick gyroscope were a living thing, governed by almost human motives. If you apply a brake to prevent the longitudinal oscillations of the gyroscope, the effect, even though the fly-wheel still revolves at full speed, is precisely as if you pinioned the arms of a strong man, so that he saw the futility of resistance and made no struggle to free himself. Under such circumstances the gyroscope—though it continues to spin as hard as ever—has no effect whatever in preventing the rolling of the ship; it stands there, like the strong man bound, expressing its discontent with an angry groan.
But if you release the brake so that the entire mechanism is free to oscillate lengthwise of the ship, all is changed. It is as if you cut the cords that bound the strong man's arms. Instantly the mechanism springs into action. It will no longer allow itself to be swung with each roll of the ship; it will resist and prove which is master. Its mighty mass, pivoted on the lateral trunnions, lunges forward and backward with terrific force, as if it would tear loose from its bearings and dash the entire ship into pieces. It causes the ship to pitch a trifle fore and aft as it does so; but meantime its axis stands rigidly erect in the lateral plane, though the waves push against the sides of the ship as before. The decks of the vessel, that were tipping from side to side, so that loose objects slid from one rail to the other, are now held rigidly at a level, scarcely permitted to deviate to the extent of a violent tremor. The gyroscope haswon the contest. To maintain its victory it must continue its backward and forward plunging; but from side to side its axis will not swerve.
It was the failure to understand that a gyroscope-wheel, to work effectively, must be given opportunity to oscillate in this secondary fashion that led Sir Henry Bessemer to spend an enormous sum in a vain effort to accomplish on a small scale what Dr. Schlick's gyroscope accomplishes for the entire ship. Now it is clearly understood that a marine gyroscope on an absolutely fixed shaft cannot exercise its full action; but there is still a good deal of difference of opinion among engineers as to just how much a spinning body must be permitted to oscillate in order to make its gyroscopic effects noticeable. The discussion that has taken place over the loss of the torpedo-boatViperfurnishes a case in point.
Some critics contend that the loss of the boat was due to the gyroscopic action of its turbine engines. They believed that the turbine at the stern of the little ship held that portion of the craft in a rigid plane, while the anterior portion of the ship, caught in the trough of a wave, broke away. That the ship broke in two is certain; but competent engineers have denied that gyroscopic turbines could have had any share in its destruction. According to their view, the turbines of a ship are powerless to exert the gyroscopic action in question, because their axes are fixed and they thus have not the opportunity for secondary oscillation to which Ihave referred. Meanwhile there are other equally competent mechanicians who believe that the vibration or oscillation of the body of the ship itself may suffice, under certain circumstances, to give the turbine precisely such freedom of motion as will enable it to exercise a powerful gyroscopic effect. Dr. Schlick himself contends, and seems with the aid of models to demonstrate, that such a gyroscopic action is exercised by the wheels of a side-wheel steamer, which revolve on a shaft no less fixed than that of a turbine. If such is the case, there would seem to be no reason why a turbine-engine may not at times exercise the power of a tremendous gyroscope, such as it obviously constitutes. The question must find practical solution at the hands of the naval architects of the immediate future, as turbine engines are now in use in several of the largest steamships afloat, and others are being installed in craft of all descriptions.
It should be said that engineers disagree as to the practical utility of the Schlick gyroscope. No one questions that it steadies the ship, but some critics think that its use may not be unattended with danger. It has been suggested that under certain circumstances—for example, the sudden disturbance of equilibrium due to a tremendous wave—the gyroscope might increase the oscillation of the ship to a dangerous extent, though ordinarily having the opposite effect.
The danger from this source is probably remote.There is, however, another danger that cannot be overlooked, and which marine architects must take into constant account. What we have already seen has made it clear that the revolving wheel of the Schlick gyroscope, to be effective, must bear an appreciable relation to the mass of the entire ship. Such a weight, revolving at a terrific speed and oscillating like a tremendous pendulum, obviously represents an enormous store of energy. It was estimated by Professor Lambert that a gyroscope of sufficient size to render even a Channel steamer stable would represent energy equal to fifty thousand foot-pounds—making it comparable, therefore, to an enormous projectile. Should such a gyroscope in action break loose from its trunnions, it would go through the ship with all the devastating effect of a monster cannon ball.
The possibility of such a catastrophe is perhaps the one thing that will cause naval architects to go slowly in the adoption of the new device. We can hardly suppose that the difficulties represented are insuperable, but undoubtedly a long series of experiments will be necessary before the Schlick gyroscope will come into general use. The apparatus has been tested, however, on a German coast steamer. It may not be very long before craft of the size of Channel steamers and boats that go to Cuba and the Bermudas are equipped with the device. Naturally enough, this prospect excites the liveliest popular interest. Visions of pleasant ocean voyages come before the mind's eye of many a voyager who hitherto has dreaded the sea.
But whatever the future of the gyroscope as appliedto pleasure-craft, there can be little doubt about its utility as applied to vessels of war. It seems a safe enough prediction that all battle-ships will be supplied with this mechanism in the not distant future. Amid the maze of engines of destruction on war-vessels, one more will not appal the builder; while the advantage of being able to fling a storm of projectiles from a stable deck must be inestimable.
IFit were possible to regard all medieval literature without more than a grain of doubt, we must believe that aerial flight by human beings was accomplished long before science had risen even to the dignity of acquiring its name. Thus, it is recorded by a medieval historian that during the reign of Charlemagne some mysterious persons having acquired some knowledge of aerostatics from the astrologers, who were credited with numerous supernatural powers, constructed a flying-machine, and compelling a few peasants to enter it, sent them off on an aerial voyage. Unfortunately for the unwilling voyagers, so the story runs, they landed in the city of Lyons, where they were immediately seized and condemned to death as sorcerers. But the wise bishop of the city, doubting the story of their aerial journey, pardoned them and allowed them to escape.
That such a fabulous tale could gain credence is explained by the prevailing belief in the powers of the astrologers and sorcerers at that time. People who could seriously believe that an alchemist could create gold and prolong life and youth indefinitely, would find nothing startling in the announcement that he could also perform the relatively simple feat of flying—a thing thatbirds and bats accomplish with such obvious facility. And nothing is more certain than that attempts at aerial flight have been made at various times since the beginning of history.
As with almost everything else in the matter of modern scientific advancement, the mysterious writings of the monk, Roger Bacon, are supposed to contain passages to show that the worthy friar had an inkling of the secret of air navigation. But he himself admits that he had only a theoretical knowledge of the subject, and had never seen a flying-machine of any kind in actual flight.
Much more definite and tangible are the designs of possible flying-machines still extant in the sketch-book of Leonardo da Vinci, made in the fifteenth century. From Leonardo's sketches it appears that the artist had conceived the idea of constructing jointed wings to be worked with strings and pulleys, the motive power to be that of a man's arms and legs. It appears also that later he had very definite ideas as to the possibilities of an aerial screw, and he is believed to have constructed one of these screws made on the same general plan as that of the ordinary type of windmill in use at that time. But nothing of practical importance came of any of Leonardo's experiments.
It is probable that his abandonment of the project of flying by means of wings worked by muscular force was due to the discovery that the strength of the muscles of even the strongest man was relatively slight as compared with the corresponding muscle of birds. Leonardo was peculiarly capable of discerning this discrepancy in strength, since he himself was one of the strongest menof his time. It is said that he could bend and straighten horseshoes with his hands. But in his experiments with the aerial screw he probably discovered very soon that even such muscular force as he was capable of exerting was entirely inadequate; and there being no other mode of producing power at that time, the idea of aerial navigation by this means was also abandoned.
About this time some imaginative persons, realizing the possibilities of muscular development when begun in childhood and persistently practiced, attempted the development of a race of men whose abnormally strong pectoral muscles would enable them to use artificial wings for flying. For this purpose a certain number of young boys were selected and constantly drilled in exercises of flapping the arms, to which broad sails were attached. These attempts were persisted in for several years, and it is said that some of these boys became so expert that by skipping along the surface of the ground and vigorously flapping their wing-attachments, they could travel at incredible speed, although never able actually to rise from the ground.
In 1678, a Frenchman named Besnier invented a flying-machine that is credited with being more successful than any hitherto attempted. His machine consisted of two bars of wood which were so hinged to a man's shoulders that they could be worked up and down by movements of the hands and feet. At the ends of these two bars were muslin wings made like shutters, so arranged that they were opened by a downward stroke and closed automatically by a reverse motion. The general appearance presented by these wings was thatof four book-covers fastened by their backs to the ends of the bars, opening and closing alternately as the bars were worked up and down.
The inventor began his experiments in a modest way. His first attempt at flight was by jumping from a chair; next he tried a table; and finally, emboldened by his success, he made flights from window-sills and even house-tops. On one occasion he is said to have sailed from his attic window over the roof of a neighboring cottage, alighting, without injury, some distance beyond. It was even rumored at one time that he would try to fly across the Seine, but if such a feat was ever contemplated, it was never attempted.
Half a century later, however, the Marquis de Bacqueville actually made such an attempt with a machine somewhat similar to that of Besnier. The marquis had practiced in private with his machine with such encouraging results that he felt confident the feat was not an impossible one—in fact, that he was sure of accomplishing it. He therefore announced publicly that at a certain time the attempt would be made, and on the appointed day an immense crowd of people gathered on the banks of the river to witness the spectacle. Starting from a building some little distance away from the stream, the marquis made good progress at first, but just as he reached the river-bank his machine collapsed and he was tumbled out, alighting on a barge moored at the edge of the stream. Fortunately, the only injury he sustained was a broken leg; but this single attempt seems to have satisfied his aeronautic ambitions.
Until this time all attempts made at aerial flight hadbeen those in imitation of birds; but during the early part of the eighteenth century the idea of the balloon was developed. This was the result of the numerous important discoveries made about that time as to the qualities of the atmosphere, and also several other "airs," as gases were called, such as their expansion and contraction under different conditions of temperature.
In 1766 the English philosopher, Henry Cavendish, discovered that hydrogen gas has only about one-seventh the weight of an equal bulk of air, this scientific discovery pointing naturally to balloon construction, since obviously if such a light gas were confined in a suitable receptacle, the device would rise to a certain height through the heavier atmosphere, as a cork rises through water. At the same time the experiments of the chemist, Dr. Joseph Black, and those of his younger contemporary, Doctor Priestly, were directed along the same lines, all of them pointing to the possibility of constructing an aerostat with buoyancy and lifting-power, and Priestly'sExperiments Relating to the Different Kinds of Airis said to have been directly responsible for stimulating the efforts of Stephen and Joseph Montgolfier, the French paper manufacturers, who finally invented and sent up the first balloon.
Even before Montgolfier's invention, Tiberius Cavallo, an Italian living in England, had demonstrated the possibility of making toy-balloons. But the balloons of Cavallo were small affairs made of bladders or paper bags filled with hydrogen gas. One of these materials being too heavy and the other too porous for successfulballoon construction, the performances of these toy-balloons were not conclusively demonstrative.
Throughout the entire spring of 1783, all Auvergne, in France, was kept in breathless expectancy by constant rumors that the two Montgolfiers had really solved the problem of aerial flight, and would soon be seen soaring over the country in a strange birdlike machine. Rumor pictured this machine in various forms and sizes, but in point of fact there was really very little secrecy on the part of the inventors themselves, who frankly explained the principle of the balloon they were constructing. It was hardly to be expected, however, that most persons would believe the plain truth that so simple a device as a bag filled with hot air would do what had long been considered impossible.
Spring advanced and lapsed into summer, however, and as no flying-machine made its appearance, public clamor became so loud that the Montgolfiers felt they could postpone their demonstration no longer, although the balloon they were working on was not completed to their entire satisfaction. Nevertheless, they fixed on the definite date of June 5, (1783) as the day and Annonay as the place for making the trial, and their faith in their invention was shown by the fact that special invitations were sent to the leading persons in the vicinity, and a general invitation extended to the world at large.
But in place of some complicated and birdlike machine, as rumor had pictured the flying-machine, themultitude that gathered about the starting-point found only an immense cloth bag about thirty-five feet in diameter, without machinery or wings, and capable of containing some twenty-two thousand cubic feet of air, which the Montgolfier brothers and their assistants were inflating with heated air. As the bag filled, one of the brothers announced with all seriousness, that as soon as it was completely filled it would "rise to the clouds," carrying with it a frame weighing some three hundred pounds.
This announcement was not received with the same seriousness with which it was given. The idea of expecting anyone to believe that an ordinary cloth bag would fly excited the risibilities even of the more serious members of the crowd. Nevertheless, as the great globe filled it became evident to the spectators that it was tugging at the restraining ropes in efforts to rise, in a most extraordinary manner; and when, at a signal from the inventors, the ropes were cast off and the monster shot skyward, the crowd's smiles were turned to expressions of gaping astonishment. Straight into the air the monster mounted, and then, wafted by a gentle breeze, it continued to soar and rise until in ten minutes it had reached an altitude of six thousand feet, sailing easily in a horizontal direction for a short distance, then gradually descending and alighting some eight thousand feet from the starting-point.
The news of this triumph travelled quickly to Paris, and the Parisians clamored to see the wonderful performance repeated in the capital. The king and court were as interested as the savants and the populace, andan order was sent at once by his Majesty, bidding the brothers bring their balloon to the city.
In the meantime, however, a savant named Charles had started the construction of a balloon that was to be filled with hydrogen gas instead of heated air. This was a much more expensive undertaking, as a thousand pounds of iron filings and five hundred pounds of sulphuric acid were necessary to manufacture a sufficient quantity of gas to fill the varnished silk bag. But by the 23rd of August everything was in readiness for the filling process, and the following day this first gas-balloon rose from the Champs de Mars to a distance of three thousand feet and disappeared into the clouds. Three-quarters of an hour later it descended in a field near the little village of Gonesse, to the great consternation of the inhabitants of the neighborhood, who supposed it to be some monster bird, animal, or flying dragon. Arming themselves with scythes and pitchforks, therefore, but keeping at a safe distance, the boldest of the peasants sallied out and surrounded the field in which the creature had alighted. As it made no offensive movement, however, one bold huntsman armed with his trusty fowling-piece, crept cautiously within range and fired, tearing a hole in the monster's side and causing it to writhe and collapse, giving off what appeared to be a foul-smelling, poisonous gas in its death-struggles. When finally it lay flat and still the villagers became emboldened, and rushing upon it cut and tore it to shreds, ending the performance by tying the fragments to a horse's tail and sending the animal scurrying across the fields.
In anticipation of some such demonstration as this, the French Government had sent out a proclamation on the day of the ascent. "Anyone who should see in the sky a globe, resembling the moon in an eclipse," the proclamation ran, "should be aware that far from being an alarming phenomenon, it is only a machine, made of taffeta, or light canvas covered with paper, that cannot possibly cause any harm, and will some day prove serviceable to the wants of society." But apparently none of the villagers of Gonesse had seen this proclamation.
The success of these balloon ascensions sent a wave of enthusiastic interest in aeronautics all over France. The novelty and possibilities of ballooning appealed to the French temperament, just as the possibilities of submarine navigation and automobiling did a century later. As a result, France became at once the centre of ballooning, the whole nation being eagerly absorbed in the subject of navigating the air. In the theatre of action, the Montgolfiers continued to occupy the centre of the stage, and at all times showed themselves worthy of the leading rôle. Pursuant to the order of the king, M. Montgolfier had come to the capital, and on September 19th, before Louis XVI and his queen and the court at Versailles, sent up another hot-air balloon, or "Montgolfier," as this kind of balloon had come to be called.
A novel and important feature of this exhibition, however, was the substitution of living animals for sand-bags or other ballast, as used heretofore. In a wicker cage a cock, a duck, and a sheep were fastened, and thesewere carried some fifteen hundred feet into the air, descending uninjured, two miles from the starting-point, a few minutes later. The cage was broken open in the descent, but its occupants escaped injury, and the sheep was found quietly grazing when the rescue party arrived.
The successful voyage of these caged animals stimulated the balloonists to attempt the crucial test of sending up a balloon carrying a human passenger. But from this perilous undertaking the boldest spirits recoiled, even the Montgolfiers refusing to venture. In those days, however, there was always a means of securing human beings, willing or otherwise, for any undertaking. Where gold would not tempt, it needed but a word of the monarch to commute the death-sentence of some criminal, placing him at the disposal of the scientists for a better or worse fate than the gallows, as the case might be. And so when Louis XVI heard of the plight of the balloon-makers, he came to their assistance with the offer of two condemned prisoners to be sent on the first aerial voyage. This offer had an unexpected effect. The pride of a certain high-minded aeronaut named Rozier, who had hitherto refused to risk his life, was touched at the thought of criminals performing an act that all honest men refused. "What! are vile criminals to have the glory of being the first to ascend into the air?" he exclaimed. "No, no, that must not be." And forthwith he offered his own services for the hazardous undertaking.
The royal decree was accordingly repealed, to the chagrin of the criminals, no doubt, and preparations made for the momentous attempt. Montgolfier wasengaged to construct a large balloon, and on the 15th of October, 1783, the trial was made in a garden in the Faubourg St. Antoine. Let no one suppose, however, that this first man-carrying balloon was cut loose from the earth and sent skyward to shift for itself, as might be gathered from the reluctance of persons to make the ascent. On the contrary, the balloon was held by strong cables, and allowed to rise only to a height of eighty feet—to the level of some of the lower windows of a modern sky-scraper—the aeronaut keeping it afloat for about five minutes by burning wool and straw in a grate made for the purpose.
Those who have witnessed the reckless manner in which the modern balloonist mounts thousands of feet into the air, seated on a trapeze or clinging to flying rings attached to an old balloon, patched and frequently rotten, may be inclined to sneer at the brave Rozier. But it should be remembered that in 1783 people had not learned nineteenth-century contempt for altitude. Furthermore, no one could tell what might be the effect upon the human system of ascending to a great height when away from a building or other terrestrial object. Fainting, hemorrhages, heart-failure, and death had been predicted, and could not be practically refuted. In short, it was an absolutely new and untried field; and it required far greater courage on the part of Rozier to mount eighty feet in a captive balloon than for a modern aeronaut to sail thousands of feet skyward. In proof of this is Rozier's subsequent record of ascents in free balloons, and dangerous voyages, in the last of which he lost his life.
To France, therefore, belongs the honor of inventing the balloon and being first to test it with a human passenger. On this last point, however, France only eclipsed America by a few days. For while the craze for balloon-making was at its height in France during the summer of 1783, a somewhat similar craze on a small scale had started in some of the American cities. Two members of the Philosophical Academy of Philadelphia, Rittenhouse and Hopkins, constructed a peculiar balloon having forty-seven small bags inflated with hydrogen attached to a car. On November 28th, six weeks after Rozier's ascent, this balloon was sent up, with James Wilcox, a carpenter of Philadelphia, as passenger. Everything was going well with the voyager until he suddenly discovered that the wind was wafting him toward the Schuylkill River, which so alarmed him that in attempting to descend quickly he punctured the bags so freely that he came to the ground with considerable force, escaping, however, with a dislocated wrist.
Meanwhile, in Europe, a new danger to balloonists had arisen. Fanaticism was rife, particularly in the vicinity of Paris, and many members of the cloth were tireless in denouncing this "tampering with God's laws by invading the inviolability of the firmament." Fortunately, the king took a broader view, and his soldiers were supplied freely for protecting balloonists and their property; but even with this protection both were roughly handled at times.
By this time England had become aroused; balloon-making became popular across the Channel, and some new records for time and distance were soon made.One balloon sent up in London landed in Sussex, forty-eight miles away, making the voyage in two hours and a half. A few days later a small balloon sent up in Kent was blown across the Channel and landed in Flanders. But neither of these balloons carried passengers.
As yet there had been few serious attempts at constructing dirigible balloons, but now Jean-Pierre Blanchard opened a new era of experiments by combining an ordinary balloon for obtaining the lifting power with wings and rudder. In this balloon there was also placed an umbrella-shaped sail interposed horizontally between the car and the body of the balloon, which was to act as a sort of parachute in case of accident. On the first voyage in this balloon Blanchard was to have had for companion a Benedictine monk; but as the machine began to rise from the ground the monk was seized with fear, turned deadly pale, crossed himself, and seemed about to collapse. Fortunately at this moment a leak was discovered in the balloon and it was accordingly lowered for repairs. When these were completed the aeronaut decided to dispense with the company of the monk, who was only too willing to gratify his wish. But just as the car was again ready to start, a stripling student from the Military Academy forced his way through the crowd, jumped into the car, and announced his intention of making the ascent. Being ordered from the car by Blanchard, he declared that he had the king's license, and when asked to produce it he drew his sword, declaring that this was the license he referred to. By this time the crowd had lost patience; some one seized the young man unceremoniously by the collar,hauled him from the car, and turned him over to the police.
A few years later particular attention was called to this incident by a rumor, which finally grew into a fixed belief in France, that the young military student in question was none other than the youthful Napoleon Bonaparte, then a student at the Academy. Throughout the entire reign of the emperor this was the general belief, and if it was denied at all by Napoleon, the denial was not made with due emphasis. At St. Helena, however, the captive emperor finally stated definitely that he was not the hero of this escapade, who is now known to have been a student by the name of Chambon.
Nothing of importance came of Blanchard's first attempt at guiding a balloon with rudder and wings, except perhaps to emphasize the fact that wings of an oarlike type were useless for propulsion; but nevertheless Blanchard soon prepared a somewhat similar balloon in which he proposed to steer himself across the English Channel. Before this time, as will be remembered, several balloons had crossed the Channel, but none of them had carried passengers. On this voyage Blanchard proposed to make the attempt, taking with him as companion an American physician named Jeffries. On January 7, 1785, these two embarked from the cliffs of Dover, a strong wind at the time setting toward the French coast. Before their journey was half completed they discovered that an insufficient amount of ballast had been shipped, and that the balloon was gradually descending at a rate which would land them in the Channel several miles from shore. To avert thiscalamity they were obliged to throw out everything in the car—books, provisions, anchors, ropes, the "wings" that were intended for guiding, and also most of their garments. They were, indeed, about to cut loose the car itself, and climb into the shrouds, when suddenly the balloon, caught by a fresh current of air, began to rise, and was wafted to a safe landing place. This was the most daring exploit as yet performed by the aeronauts.
Although at least fifty different persons had made more or less extended aerial voyages during the two years that had intervened since the invention of the first balloon, no one of them had been seriously injured. Indeed, this apparently most dangerous undertaking had been relegated to the grade of commonplace in popular opinion, owing to these fortunate results. But the world was soon to learn that its first estimates of the dangers of ballooning had not been exaggerated.
Since the invention of the Montgolfier balloon two distinct schools of balloonists had arisen, one of which favored the hot-air, and the other the hydrogen balloon. By the advocates of the hot-air balloon it was claimed that the relatively small expense, and the fact that the balloonist could descend at any time and renew his supply of fuel, made this the most desirable type, at least for long-distance voyages. By the advocates of the hydrogen balloon it was shown that the hot-air balloon must be constructed much larger to obtain the same amount of lifting power, could be maintained in the air for a comparatively short time at most, and was in constant danger from the fire that must be kept burning in the grate. In reply to this last charge the hot-airadvocates pointed out that a tiny spark of electricity, which would not affect the hot-air balloon, might explode the hydrogen balloon, thus introducing an element of danger quite as great as that of the fire in the hot-air balloons.
As an outcome of these disputes, Pilatre de Rozier, the first man ever to make an ascent, proposed to attempt to cross the Channel in a new-type balloon, a combination of hot-air and hydrogen machine, which was supposed to represent the good qualities of both types. Several months were consumed in constructing it, and when finally completed he and a companion attempted to cross the Channel, as had been done by Blanchard and Jeffries a short time previously. All went well at first and the balloon was several miles on its journey when suddenly the wind changed, the balloon was blown back over the heads of the anxious watchers below, and when a short distance inland, suddenly burst into flames. At first it descended with an oscillating movement, and then, freed from the restraining silk and canvas, it shot downward, striking the earth with terrible force, the two occupants being killed. Thus the man to make the first ascent in a balloon was also the first to lose his life. Rozier himself seems to have expected some such ending to his voyages, and just before making his last ascent he remarked to a friend that, whatever the outcome, "one had lived long enough when one had added something to humanity."
The fate of Rozier and his companion being known, and the awful dangers of balloon ascensions thus forcibly brought home, there was a popular outcry against suchattempts and efforts were made to pass laws forbidding them. But no such demand or suggestion came from the balloonists themselves. They could point to the fact that, while as yet the balloon had been of no importance commercially, it had at least been turned to some account in the field of science, which was simply a stepping-stone to commercial advancement. It had been the means of settling forever the question of temperature and rarefaction at different altitudes, besides numerous less important although no less interesting subjects.
While it was true that many of the experiments of the aeronauts had added largely to human knowledge, some of them were both dangerous and foolhardy. An exhibition of this kind of folly was given by the Frenchman, Testu-Bressy, who, wishing to test his theory that large animals would bleed from the nose at a much lower elevation than man, despite the thicker consistency of their blood, made an ascent mounted on the back of a horse. On this occasion the aeronaut did not, even take the simple precaution of tying the horse's feet to the car; and what seems most remarkable, the animal made the journey without moving or showing any sign of fear.