Speed
I
ROY CHAPMAN ANDREWS tells of a race with a startled gazelle which he surprised on the flat table-land of the Gobi Desert. When the speedometer of his car was registering fifty miles an hour, the gazelle was easily going sixty, and in a few minutes had become a rapidly diminishing speck far ahead.
A rabbit has been clocked at thirty-five miles an hour. English foxhounds can travel forty, but the fox usually leads them for many miles. Reindeer have been reported to run fifty miles an hour when pursued.
Winged animals travel faster. Recently an American pigeon flew 300 miles at seventy-one miles an hour. In Europe there is a vulture known as the lammergeier. An officer of the British Royal Air Force saw one of these vultures flying, and started in pursuit. The bird led until the airplane’s speedometer reached 110 miles an hour, when the lammergeier gave up the race in a graceful nose dive.
A swallow was taken from her nest under the eaves of a house in Antwerp, carried to Compiègne, 148 miles away, and there released. She was back on her nest in an hour and eight minutes, having flown at the rate of more than 134 miles an hour. It is a profound mystery how this frail bird, which could hide in your coat pocket, can get such speed out of mere muscle power.
Human muscles make a poor showing by comparison. The fastest mile a man has run on foot was raced by Nurmi in 1925, at a rate which figures a little more than fourteen and a half miles an hour; but perched on a camel he has traveled that distance at sixteen miles an hour, and astride a horse at nearly forty miles an hour. Swimming, a man has been able to go a mile at approximately two and a half miles an hour. A whale can propel its huge bulk four times as fast, and a silver salmon parts the water at seventeen miles an hour in sudden spurts. To get the greatest possible speed from human muscles man has had to take to the ice; skating, he has traveled a little better than twenty-three miles an hour.
But. these motions are a mere crawl compared with the speeds attained during the last year by means of mechanical devices with metal muscles and electrical nerves and with man as the brain controlling the speed machine. Major Segrave caroming over a Florida beach at 231 miles an hour, and Captain Orlebar in his super-marine airplane meteoring off the Isle of Wight, at 357 miles an hour, are both a demonstration and a prophecy.
They are a demonstration of what man can do toward annihilating distance, when he rides in a vehicle that is nearly all motor.
They are a prophecy of super-speeds that in a few years may be commonplaces of travel, when there will be room in the machine and carrying capacity not only for the engine and the engineer, but also for passengers, mail, freight, parlor compartments, dining saloons — all the luxuries of the Limited. Such is the forecast of the experts.
II
Mechanical speed came slowly. The steam engine had been pumping water from mine pits for nearly a hundred years before anyone tried the experiment of putting an engine on wheels and making it propel itself. Railways were almost two hundred years old before anyone substituted for the draft horses that pulled the early cars a steam machine moving under its own power. The first railway locomotive chugged along a tramway in Wales in 1804 at about five miles an hour, but twenty-five years passed before any railway management adopted the idea as a means of motive power.
People were afraid of speed. ‘What can be more palpably absurd than the prospect held out of locomotives traveling twice as fast as stagecoaches!' exclaimed the staid English Quarterly Review in 1825. ‘We should as soon expect the people of Woolwich to suffer themselves to be fired off upon one of Congreve’s ricochet rockets, as trust themselves to the mercy of such a machine going at such a rate.’
Speed was a live public question then because the proposed Liverpool and Manchester Railway had petitioned Parliament for a franchise. It was known that the chief engineer of the projected railroad, George Stephenson, had experimented with steam locomotives and favored them over stagecoaches. But scarcely a technical man in the United Kingdom agreed with him. Tredgold, in his Practical Treatise on Railroads and Carriages, published in 1825, pronounced the prevailing judgment of the engineering profession: ‘That any system of carrying passengers would answer, to go at a velocity exceeding ten miles an hour, or thereabouts, is extremely improbable.’ And Lardner, lecturing in London on the steam engine at about the same time, said: ‘Carriages could not go at anything like the contemplated speed. If driven to it, the wheels would merely spin on their axles, and the carriages would stand stock-still.’
With such science proclaimed by the learned authorities it is no wonder that the legislative authorities hesitated to license a railway to be guided by Mr. Stephenson’s ‘insanity.’ Before the engineer testified in the Parliamentary hearing regarding locomotives, the railway’s attorney cautioned him against claiming unbelievable speeds, such as twenty miles an hour. If he did, warned the lawyer, he would ‘inevitably damn the whole thing’ and be himself regarded as ‘a maniac fit for bedlam.’ Thus primed, Stephenson reined in his knowledge of what steam might do, and limited his prediction to twelve miles an hour. Even so, members of the committee murmured doubts as to his sanity, and voted denial of the application for a charter.
Speed was a live public question in America, too. The usual stagecoach speed was six or seven miles an hour. When the stage from Boston to Providence rattled over its forty miles in four hours and fifty minutes, the feat was regarded as little short of miraculous. ‘If any one wants to go faster, he may send to Kentucky and charter a streak of lightning,’ wrote one traveler, describing a journey over this famous route in 1822.
Kentucky horses were the nearest to a streak of lightning that the lay mind could imagine then. Apparently the controlling professional mind had no greater vision, for when construction of the Baltimore and Ohio Railroad began in 1828 the roadbed was laid out for horse-drawn cars. John Stevens of Hoboken and Oliver Evans of New York had been preaching the gospel of steam transportation for more than a decade, but the business men who were putting their dollars into the railroad gave scarcely a thought to these vagaries, and proceeded to lay the track for horse power.
Old Peter Cooper thought that was too bad. A steam railroad would be ever so much more progressive. He hastily improvised a locomotive by mounting a small boiler and engine on wheels, and brought it to Baltimore to try the curves of the eighteen-mile track. The ‘Tom Thumb’ did n’t work very well at first, but after some months of tinkering and remodeling Cooper managed to operate it with fair success at a speed of about six miles an hour.
Then a horse drawing an equivalent load raced Cooper’s midget engine; the machine failed in that crisis, and horseflesh trotted in to easy victory. A horse-propelled locomotive in which the animal operated a treadmill was also tried, but it collided with a cow and upset, spilling some distinguished passengers. Experiments were made with a sail-driven car, but the wind was erratic and operation on a regular schedule impossible. After these trials the management felt confirmed in its original choice; so horse-drawn cars were installed, and continued on the Baltimore and Ohio until 1831.
Meanwhile, in England, history was making. The Liverpool and Manchester Company had somehow got its charter. Before installing stationary engines to operate a tram, as was generally favored, Stephenson begged the company to give a trial to steam-onwheels, and the management graciously — and surprisingly — acceded. It announced a competition to be held on the railway at Rainhill, and invited inventors to enter their iron steeds. If a locomotive proved that it could run thirty-five miles at an average rate of ten miles an hour, and also met other conditions of safe and efficient operation, it would be considered for use on the railway. A prize of five hundred pounds was offered for the best performance.
And so was staged, a century ago, in October 1829, the great locomotive speed contest. The event excited unusual public interest and curiosity. Ten thousand people gathered to witness the trials. Five locomotives were entered, one the invention — or construction — of Stephenson.
I have often wondered why Stephenson called his locomotive the Rocket. Perhaps he still smarted under the Quarterly Review’s twitting comparison of his project to Congreve’s skyrockets. Certainly in his complete victory that day he rocketed into fame and became almost at one bound the acknowdedged engineering genius and authority of Britain.
The Rocket’s speed, pulling a train of loaded cars, averaged fifteen miles an hour. Then Stephenson detached the cars and gave an extra demonstration of what his machine could do unencumbered. He ran it up to twenty, twentyfive, thirty, and finally thirty-five miles an hour. The grandstand was aghast; then wild with applause. The engine did not disintegrate into atoms, the wheels did not spin helplessly on the axles, the engineer did not burst a blood vessel or fall into a coma. At the end of the run he stepped down from his smoking engine very much alive, exhilarated by the experience. Here was a new kind of horse indeed — one that was not only faster, but tireless.
III
The railroad made its highest speed record in 1901, when a train of the Plant System in Florida traveled five miles in two and a half minutes. Such velocity was possible, of course, only on a straight level track, and could not be maintained around curves and up grades. The record for a run of more than 500 miles was made by a train of the Lake Shore and Michigan Southern in 1905. It ran the 525 miles from Buffalo to Chicago in seven hours and fifty minutes, an average speed of sixty-seven miles an hour.
There is a tendency among American railroads to-day to increase the average rate of speed, but they show no serious ambition to make the high records of the past the normal running speed of modern trains. Twenty years ago two rival roads maintained a schedule of eighteen hours between New York and Chicago, but now the fastest, regular trains operated by these same lines take twenty hours for the trip. The average speed of the Twentieth Century Limited is forty-eight miles an hour. The Broadway Limited, connecting the two cities over the shorter Pennsylvania route, needs to travel only fortyfive and four-tenths miles an hour to reach its destination in twenty hours.
In 1929 both the New York Central and the Pennsylvania companies added new fast trains between Chicago and New York, but it is noticeable that all content themselves with the twenty-hour schedule. Safety, comfort, and economy rule the modern rails, rather than speed.
The automobile was arriving just as the railroad was making its most spectacular records. A musty old copy of t he Horseless Age recalls that in 1901 — the year in which that Florida train ran five miles at 120 miles an hour — Henry Ford won his first automobile race. His speed was just under forty-five miles an hour.
In Europe somewhat better automobile records were being made; but the locomotive experts saw nothing to fear in the gasoline buggy. Then, in 1903, Henry Ford rode into the front-page headlines for the first time by driving his racing car at better than ninety miles an hour, thus bringing the world record for automobile speed to America. In the same year a New York Central train made a short run at close to 110 miles an hour. Automobile speed was going up, locomotive speed coming down.
Year by year the automobile record climbed. By 1910 it was 141 miles an hour; by 1920, 150 miles; by 1926, 170. In 1927 Major H. O’n. de H. Segrave electrified the headline artists by reaching and passing the 200-miles-an-hour rate. Like most speed honors, his distinction was short-lived; in 1928 Ray Keech drove a car at better than 207 miles an hour.
This was a surprise. Many authorities had predicted that Segrave’s record would stand for years. He himself had announced, following his 1927 triumph, that he would never race again. But the speed bacillus is a tantalizing and even a domineering bug. Major Segrave came back to Florida in 1929 with a new 1000-horsepower car. In it he swept across the sands of Daytona Beach at 231 miles an hour — almost four miles a minute. And, at least until the next races, this will stand as the record for speed on the earth’s surface.
IV
But meanwhile man has left the surface of the earth and in the ocean of air has learned a new magic in mechanical power and a new meaning in speed.
The first airplane flight — by Orville Wright, on December 17, 1903 — was 120 feet in twelve seconds, something over six miles an hour. Almost any eighteenth-century stagecoach could do better.
But give the birdman time — time to learn the use of wings. Two years later Orville Wright flew eleven miles at better than thirty-six miles an hour. And in 1908 he met the rigorous requirements of the United States Army by flying forty miles an hour.
Then James Gordon Bennett offered an international challenge cup for speed, and the first airplane race was held at Rheims, France, in August of 1909. Glenn H. Curtiss, flying a biplane of his own design, won at a rate which averaged close to forty-seven miles an hour.
Every year the record for speed leaped ahead. Grahame-White took the cup away from Curtiss to England, C. T. Weyman brought it back to America, and then Vedrines carried it off to France by a spurt of 105 miles an hour. This was in 1912, and the next year France showed that its spurt was a permanent gain, for it won a second time. After the war’s interruption, racing resumed in 1920; France won for the third time, and thus possessed the famous cup outright. The winning speed in 1920 was close to 170 miles an hour.
Meanwhile, another speed contest had been instituted by Jacques Schneider, a wealthy patron of sport in France. It is a tragic irony that M. Schneider died in poverty in 1928, as competitors for his trophy were spending millions of dollars in preparation for the contest. But back in 1912 he was heir of the great and prosperous Gun Works at Creusot, and his desire to encourage the development of seagoing aircraft prompted him to offer a trophy for the best speed made by a seaplane.
The aviator who won the first Schneider race, M. Prevost of France, also won the James Gordon Bennett race of that year. His speed in the landplane was better than 120 miles an hour, and in the seaplane only a little over forty-five miles an hour. This was in 1913, and these two records fairly represent the comparative speed efficiencies of land and sea planes at that time.
But now — what a difference! The swiftest flyers are seaplanes. Under the spur of the Schneider trophy competition a seaplane was the first vehicle to reach 300 miles an hour. Indeed, so far as the records show, it is the only vehicle in which a man has traveled at that velocity. To the Italian, Major Mario de Bernardi, belongs the honor of being the first to pass this mark. The winning speed in the Schneider races of 1929 was 332 miles an hour, achieved by H. R. D. Waghorn of the British Royal Air Force. Five days later one of his team mates, Captain A. H. Orlebar, made a new record by driving a seaplane at better than 357 miles an hour.
At present, the latter figure stands as the peak measure of human restlessness, man’s highest attainment of motion — almost six miles a minute in the air, to compare with a maximum of almost four miles a minute on the automobile track and two miles a minute on the railroad.
V
What is the future of speed? Have we reached the limit, or are there still higher velocities attainable mechanically and controllable by man?
Sir Alan Cobham, whose experience gives weight to his words, recently predicted that within the lifetime of the present generation 300 miles an hour will be normal cruising speed in commercial and passenger transport.
Professor A. M. Low, the distinguished British engineer, says: ‘We must accustom ourselves to the idea that in the future 500 miles an hour will be an every day — or night — affair.’
Louis Blériot, flight pioneer of France, forecasts that within ten years air racing at faster than 700 miles an hour will be an accomplished fact. Other authorities do not shrink from 1000 miles an hour. Two years ago General J. H. MacBrien, president of the Canadian Aviation League and a former officer of the Royal Air Force, predicted that aircraft will reach this speed. And F. H. R. Folland, the engineer who designed the swift GlosterNapier super-marine plane which competed in the Schneider trophy contest in 1929, said at that time, ‘I see no reason why the trophy should not be won twenty years hence at a speed of 1000 miles an hour.’
One difficulty is the lack of a motor able to push a plane through the air — and against the air — at that rate. Three great enemies are air resistance, friction, and centrifugal force. Every airplane designer is continually at war with these opponents. The Dædalus who comes nearest to conquering them — or escaping from them — will be the first to fly 1000 miles an hour.
Centrifugal force can destroy. A physicist has computed that when Segrave’s automobile traveled 200 miles an hour its wheels were making thirty revolutions a second and each tire was writhing under a centrifugal force equal to the pull of four tons. With every increase in the rate of rotation this pull increases, until finally a critical speed is reached: the molecules of matter can stand the strain no longer; they fly apart and the tire explodes. The same kind of force applies to a rotating propeller and the motor which drives it.
Every owner of an automobile knows what friction costs in lubricating oil, but only an engineer knows its toll on power. Major Segrave’s car had motors of 1000 horsepower. Ten per cent of their energy went to overcome friction. As speed increases, the problem of lubricating the engine is additionally complicated by the danger of chemical changes in the lubricating oil. This necessitates the addition of a cooling system to guard the engine against overheating and consequent break-up of the lubricant. But a cooling system always means lessened power — 20 per cent of the gasoline burned in even the better types of motors goes to make up for the loss of power through cooling, a loss directly chargeable to friction.
Speed’s arch-enemy is air resistance. After 100 of his horsepower had overcome friction, Major Segrave had 900 mechanical horses left, which would seem to be ample, but — 500 spent themselves in overcoming air resistance!
Air resistance is a glutton for power. Suppose you find that a ten-horsepower engine will drive you thirty miles an hour, and you wish to travel sixty. Is it enough to double your horsepower? No; experimenters have found that the power required to overcome air resistance varies as the cube of the speed. Therefore, to double the speed of an airplane, you must increase its motive power eight times. If a ten-horsepower engine develops thirty miles an hour, an eighty-horsepower engine is necessary to develop sixty miles an hour — assuming that all other things are unchanged.
But designers of airplanes do not leave all other things unchanged. Alexandre Gustave Eiffel, who built the tower in Paris that bears his name, made experiments to determine the stresses and strains produced by winds. He dropped objects of different shapes and measured their behavior in the air. He found that a cylinder with hemispherical ends encountered only one fifth the air resistance that was met by a cylinder with flat ends. Aeronautical engineers have conducted similar investigations in wind tunnels, and out of these researches has come the modern science of streamlining.
By streamlining is meant shaping the body and each exposed part so as to facilitate the flow of the air around it with the minimum of disturbance. Even before the aeronautical studies in this field, naval engineers both abroad and in America had experimented with models of ships in towing tanks, and had discovered the influence of a ship’s shape upon its speed. The principles apply alike to motion through water and to motion through air.
To-day not only airplanes, but racing automobiles, motor boats, and the super-swift ocean liner, the Bremen, are streamlined The principle is even applied to the shape of buildings, and in Dayton, Ohio, a large hangar for dirigibles was designed with rounded corners and curving surfaces in accord with the laws of streamlining.
There is a limit to the gain that can be made in this direction, however. The air is essentially, and will continue to be, a resistant medium. We are driven back to the question of motors.
Henry Ford remarked in a published interview that there is no such thing in existence as an airplane engine, explaining that the engines used in aircraft to-day are ‘really automobile engines in all their fundamental principles. ' Mr. Ford indicated that he is experimenting with the Diesel engine. The Packard Motor Company has already demonstrated an aircraft motor of this economical oil-burning type. President Charles L. Lawrence, of the Wright Aeronautical Corporation, has indicated that his hope for the future motor is a machine operating on the turbine principle — a rotary engine in which every movement will produce transmittable power.
New types of motors will inevitably come. But — remembering the greed of air resistance for power — will it be possible to make motors able to push through the enormous opposition that the air will offer to a craft moving 1000 miles an hour? An obvious way to defeat air resistance is to rise above it. At ten miles up, the air is one tenth its density at sea level. At twenty miles, the density is only one one-hundredth of that to which we are accustomed at the surface of the earth. Above that level the air thins to the vanishing point. The same power that produces the ordinary cruising speeds of 100 and 125 miles an hour at our usual flying levels would easily produce many times that speed in the thin upper air.
But our present aircraft are dependent on air density. The propeller must have air to bite into; the wings must have air to push through; the motor relies on air to supply oxygen for its ignition. A gasoline engine suffocates when it gets above a certain height. The high-altitude flyers carry an auxiliary device, a super-charger which pumps air under pressure into the motor, and so by a process of concentration strengthens the diluted rations of the upper sky. But a supercharger adds weight. It is a fact that only a few airplanes have been driven higher than seven miles above sea level, so dependent is the gasoline-driven craft on air density. To travel 1000 miles or more through the higher levels would seem to call for a radically different system of motive power.
VI
A motive power which is independent of the air is the rocket— for Dr. Robert H. Goddard, director of the Physics Laboratory at Clark University, hias shown that the efficiency of a rocket increases as the air in which it operates thins.
In his now historic experiments, which are preserved in a publication of the Smithsonian Institution, Dr. Goddard obtained from a steel rocket operated in the air an ejection of gases at the rate of 8000 feet a second. Experiments in a vacuum with smaller rockets showed greater speeds there than in the air; the rates, applied to the large rocket, gave for it a velocity of 9700 feet a second in the vacuum. These results were obtained with smokeless powder. Later experiments with a liquid explosive show that gas velocities of at least 12,000 feet — more than two miles — a second are possible.
Thus we have in this spectacular heat engine — which most of us think of only as a device for celebrating the Fourth of July — a speed machine that is independent of the air and that has no rotating parts to generate friction, create lubrication problems, and develop centrifugal force.
Dr. Goddard is almost alone in America among scientific investigators in this field; though in Europe, and particularly in Germany, the idea has been taken up in recent years with spectacular results. A society devoted to the study of rocket travel exists in Germany and publishes a monthly journal of rocket lore. A similar organization has been formed in Russia. In 1928 both Fritz von Opel and Curt Volkner successfully piloted rocketdriven automobiles over the Avus Speedway in Berlin. Max Valier installed a battery of powder rockets in a thirty-foot sled, and in trials on frozen Lake Starnberg in February of 1929 this rocket-propelled vehicle is reported by Valier to have attained a speed of 235 miles an hour. Again, in September of 1929, Fritz von Opel piloted a rocket airplane for a distance of one and a quarter miles at a speed of sixty miles an hour — the first recorded flight of man by rocket power. In each instance the rocket burned gunpowder.
What does the engineering profession think of the rocket as a source of power? An editorial under the title, ‘The Rocket Airplane,’appeared in the Journal of the American Society of Mechanical Engineers (July 1928), of which the following are brief excerpts: —
Like all engineering achievements, rocket propulsion starts in a crude way, to be refined and developed as time goes on and information accumulates. The chamber may ultimately have to be cooled, and we may yet witness a controversy between the advocates of air and water cooling for trans-oceanic rockets. Powder may be replaced by explosions of gasoline-air mixtures, and the chamber given more complicated shapes and therefore made more efficient. . . .
The spinning top, once a child’s toy, has been developed into the gyroscope. It would be nothing surprising if the rocket, once an amusement device, should be harnessed to do work in super-swift transportation.
A recent visit to Dr. Goddard’s laboratory at Worcester, Massachusetts, disclosed that the very problems mentioned in the editorial are already live ones with the rocket designers.
Thus, the shape of the rocket has proved to be an important element. Early in his experiments Dr. Goddard found that a cylindrical explosion chamber is not so efficient as one which widens toward the exit in the form of a cone. The flaring vent allows for greater expansion of the discharging gases, hence greater speed of ejection. Since a rocket works on the reaction principle, — the reaction of the metal chamber against the expanding gases, — its rate of movement forward is directly proportionate to the speed of ejected gases backward. Therefore the rocket designer does everything possible to speed up the gases.
Not only the shape of the rocket, but also the fuel, has been changed as a result of Dr. Goddard’s experiments. He began with black gunpowder which had a heat content of 545 calories.
Next he tried smokeless powder, which burns with a generation of more than double the heat—namely, 1238 calorics. Since 1920 the scientist has been working entirely with liquid explosives, and during the last three years with a liquid which has a much higher heat content than even smokeless powder. The temperature of this exploding liquid is 3000 degrees Fahrenheit. Advantages of using liquid propellant are twofold: (1) because of its higher output of heat it gives greater velocity of ejection than any form of gunpowder, and (2) it opens up the possibility of feeding the explosive from a reservoir into the firing chamber of the rocket. The latter arrangement would greatly facilitate the control of explosions during flight — one of the fundamental problems.
It should be added that Dr. Goddard’s experiments were begun with the purpose of sending an exploratory rocket into the upper air. Scientists of the Weather Bureau, radio laboratories, astronomical observatories, and other research institutions are eager to get some direct evidence of the air levels above twenty miles. Dr. Goddard conceived the idea of using a rocket as a means of sending up a thermometer, a barometer, an air trap, and other measuring and sampling devices, and began to work on the problem at Princeton in 1912. Transferring to Clark University, he continued his studies there. Since 1916 the investigations have been prosecuted under the auspices of the Smithsonian Institution and with its financial support. Several short but successful rocket flights have been made with liquid propellants, and in July of 1929 a rocket carrying recording instruments and equipped with a parachute was sent up. The instruments — a barometer and photographic camera — were brought down on the rocket uninjured. Present work is centred on building a large rocket capable of ascending to a height of several miles.
Dr. Goddard believes that the most important outcome of his research, from the engineering point of view, is its demonstration of the high efficiency of the rocket as an engine. The waste of power in most of our present powerproducing machines is notorious. At the foot, of this page is a table of efficiencies of various types of engines that will give an idea of the comparative waste.
The high efficiency possible for the rocket results from two conditions. First, most of the heat energy of the explosive can be converted directly into motion energy of the swiftly escaping gases, this being particularly true in thin air. Secondly, in a rocket consisting largely of propellant, the rocket itself can receive a large share of the energy of the propellant, easily 50 per cent in the case of a rocket which has
| Percentage of Efficiency | Source of Information | |
| Steam engine, locomotive | 5 | Chatfield, Airplane Dynamics |
| Steam engine, ocean liner | 15 | Chatfield, Airplane Dynamics |
| Corliss engine | Under 20 | Prof. C. A. Read, Worcester Polytechnic Institute |
| Steam turbine | 22.8 | Account of modern installation in Power, 1929 |
| Airplane gasoline engine | 25 | Chatfield, Airplane Dynamics |
| Diesel engine | 30-34 | Fulton Iron Works, manufacturers of the Diesel |
| Rocket | 50 | Prof. R. H. Goddard, Clark University |
three quarters of its weight in explosive material.
What of speed? The rate of ejection of gases is a direct index to the possible speeds. Dr. Goddard has computed the elements of a rocket capable of a steady acceleration which at a height of 740 miles above the earth would be moving 6.4 miles a second — enough speed, at that height, to escape into space. Such a rocket would need to have 90 per cent of its weight in fuel. Indeed, as planned by the physicist, it would be a composite of several rockets arranged in series, the empty shells of the outer rockets to drop off as their fuel is consumed.
VII
Can the human body endure greater speeds? That is an old question. It was raised in Stephenson’s time; it crops up perennially. The best answer, perhaps, is to recall that as passengers on this whirling planet we are already moving at speeds far beyond anything that is even imagined by the most speculative dreamer of future transport. As Dr. A. S. Eddington puts it, in his Gifford Lectures: ‘Motion does not tire anybody. With the Earth as our vehicle we are traveling at 20 miles a second around the Sun; the Sun carries us at 12 miles a second through the galactic system; the galactic system bears us at 250 miles a second amid the spiral nebulæ; the spiral nebulæ ... If motion could tire, we ought to be dead tired.’
Flesh and blood could not endure the below-zero temperatures of the upper atmosphere, nor could it breathe in the thin air. Any high-traveling craft would necessarily carry its passengers and crew in sealed cabins, heated and ventilated artificially.
But are greater speeds desirable? The rapid success of the air mail is striking evidence that speed of communication is desired by the public. The recent linking up of rail and air lines in passenger transport which brings the Pacific Coast within two days’ travel of New York is additional evidence. There is demand for swift transportation of serums, medicines, and relief forces and supplies In time of disaster, and for the quick carriage of perishable commodities, emergency freight, and emergency passengers at all times.
An aircraft flying 1000 miles an hour would be able to carry a letter or a passenger from New York to Chicago within one hour, and to San Francisco in less than four hours. It would be able to make a circuit of the earth within twenty-four hours. At such speed the machine would keep pace with the rotation of the globe, and, in Kipling’s phrase, ‘hold the Sun level in his full stride.’
Finally, there is that ultimate possibility, that daring dream. J. B. S. Haldane predicts it in his prophetic essay on Man’s Destiny: —
Man will certainly attempt to leave the Earth. The first voyagers into interstellar space will die, as did Lilienthatl and Pilcher, Mallory and Irvine. There is no reason why their successors should not succeed in colonizing some, at least, of the other planets of our system, and ultimately the planets, if such exist, revolving around other stars than our Sun. There is no theoretical limit to man’s material progress but the subjection to complete conscious control of every quantum of radiation in the universe.
What speed is necessary to escape from the gravitational control of the earth? Seven miles a second at the surface of the globe, lesser speeds as you rise above the surface. And rockets can be made to produce that speed, say the men who in the laboratory are experimenting with the mysterious power of expanding gases.