A Manned Moon Shot — In 1865
“I MAKE USE OF PHYSICS. I GO TO THE MOON IN A CANNON ball, discharged from a cannon. He [H. G. Wells] goes to Mars in an airship, which he constructs of a metal which does away with the law of gravitation. That’s all very well, but show me this metal. Let him produce it.”
Thus, in his scathing review (in T.P.‘s Weekly ) of Wells’s The First Men in the Moon (1901), Jules Verne points up the gulf between Wells’s romantic fantasy and his own meticulously detailed From the Earth to the Moon (1865) and its sequel, Around the Moon (1870). In his two extraterrestrial science fiction adventures, Verne launches his astronauts from a gigantic cannon, has the trajectory of their space capsule altered by a passing asteroid—which results in their orbiting the moon—and then has them use rockets intended for braking to return the projectile to Earth.
Jules Verne did not invent science fiction; the genre began with ancient wonder stories featuring such superheroes as Odysseus, the Argonauts, and Sinbad the Sailor. More recent antecedents include Francis Bacon’s New Atlantis (1627) and Jonathan Swift’s Gulliver’s Travels (1726). But Verne was the first popular author to strive for believable scientific accuracy in his science fiction. His novels include such familiar titles as Journey to the Center of the Earth (1864), From the Earth to the Moon, Twenty Thousand Leagues Under the Sea (1870), Around the Moon, Around the World in Eighty Days (1873), and The Mysterious Island (1875), as well as many more obscure ones.
For an author of Verne’s limited education, his books contain an amazing profusion of technical detail. He documents and quantifies every piece of hardware. As the encyclopedist Henri Peyre points out, “Verne’s novels carry the reader all over the earth, under it, and above it. They build up breathless tales around balloons, submarines, and the already anticipated rockets and interplanetary travel.… Verne is never condescending or falsely childish in tone. He wrote for adults and for serious readers, as did Mark Twain and Alexandre Dumas.”
Jules Verne was born in Nantes, France, in 1828. At the age of nineteen he was sent to Paris to study law by his father, Pierre, an austere, conservative lawyer who expected his son to follow in his footsteps. Instead, young Jules plunged into the bohemian intellectual community of Paris almost at once. He lived on the Left Bank, helped found a bachelors’ club, and devoured literature by French, English and American authors of the day, including Sir Walter Scott, James Fenimore Cooper, and especially Edgar Allan Poe. He met Victor Hugo and Alexandre Dumas père , who became his friend and mentor.
Soon Verne was writing stories of his own (in his native French) with titles like The Fate of Jean Morenas, Yesterday and Tomorrow , and A Recent Tragedy . His first play, Broken Straws , was produced at Paris’s Théâtre Historique in 1850. Ultimately, to his father’s dismay, Jules wrote him, “I can make a good literary man but a bad lawyer, for I can see things on the humorous side.” After working in the theater and then as a stockbroker, in 1863 he published Five Weeks in a Balloon , based on a contemporary real-life adventure by French balloonists. It was his first science-fiction work, and upon its success he decided to devote himself to writing full-time.
Some of Verne’s satire is more than a little macabre, as becomes apparent at once in From the Earth to the Moon , published the year the Civil War ended. The story opens in a gentlemen’s club in Baltimore, Maryland, shortly after the war. There the author describes one member “carbonizing his wooden legs in the fireplace of the smoking room” and finds grim entertainment in the “caoutchouc jaws, silver craniums, platinum noses,” and other bizarre prostheses of the mutilated veterans who make up the membership of the Gun Club. Shrugging off their war wounds, these Union field-artillery veterans suffer instead from paralyzing boredom as they long for a venture worthy of their ballistic skills.
The project they choose is the design and construction of a cannon big and powerful enough to target the moon. When the project is in its final stages, it becomes even more ambitious: The Gun Club’s president, Impey Barbicane, receives a telegram from a French adventurer named Michel Ardan, who urges: SUBSTITUTE FOR YOUR SPHERICAL SHELL A CYLINDRO-CONICAL PROJECTILE. I SHALL GO INSIDE. SHALL ARRIVE BY STEAMER ‘ATLANTA.’ (Ardan’s last name is an anagram for Nadar, a famous French photographer and enthusiastic aeronaut who was the first to take pictures from a balloon. His real name was GaspardFélix Tournachon.) The telegram dramatically changes the Gun Club’s objectives as well as the design of the projectile, whose passengers will eventually include three men and two dogs.
Although Verne never visited the United States, he strides into Americana in the book’s opening lines: “During the Civil War, a new and influential club was established in the city of Baltimore in the State of Maryland. It is well known with what energy the taste for military matters became developed amongst that nation of ship-owners, shipkeepers and mechanics. Simple tradesmen jumped their counters to become extemporized captains, colonels, and generals, without having passed the School of Instruction at West Point. Nevertheless, they quickly rivaled their compeers of the old continent, and, like them, carried off victories by dint of lavish expenditure in ammunition, money, and men.” Verne goes on to praise “the Yankees, the first mechanicians in the world, engineers—just as the Italians are musicians and the Germans metaphysicians—by right of birth.”
AFTER SUCH A LYRICAL DESCRIPTION of the American character, Verne can be forgiven for his “prairies of Arkansas” and other occasional lapses. They are compensated by his wisdom, for example, in choosing one of Colorado’s highest mountains, Longs Peak, on which to erect a giant 48,000-power telescope to observe the missile. It is also interesting that the site where he chooses to construct his interplanetary cannon is near “Tampa Town,” almost directly across the Florida peninsula from today’s Cape Canaveral.
Verne admits in print that From the Earth to the Moon was inspired by Poe’s The Unparalleled Adventures of One Hans Pfaal , and in Chapter Two he has the entire assemblage of the Gun Club roar, “Cheers for Edgar Allan Poe!” Hans Pfaal is a lighthearted hoax of a story in which the protagonist travels to the moon “in a balloon filled with a gas extracted from nitrogen, thirty-seven times lighter than hydrogen.”
In adapting the plot, Verne resolved to clean up the physics, in which Poe had little interest. His research was obviously exhaustive. He shares much of it with the reader, recounting how Galileo calculated the height of lunar mountains from their shadows; how the Italian astronomer’s estimate of their mean altitude (27,000 feet) was reduced by Hevelius of Danzig to 15,600 feet; how Herschel further reduced the figure to 11,400 feet; and how it was then corrected upward by others, whose data he meticulously quotes. His final “summit of all towers” altitude of 22,806 feet is only slightly shy of today’s estimate of 26,000 feet for the Leibnitz and Doerfel mountain ranges. He quantifies the light of the full moon as being 1/300,000 as bright as the sun; the modern figure is about 1/465,000.
The author cites the moon’s diameter as 2,150 miles, which compares quite satisfactorily with the 2,160 miles agreed upon today. His apogee and perigee (the moon’s maximum and minimum distance from the Earth during its orbit) of 247,552 and 218,657 miles, respectively (center to center), differ slightly from today’s accepted figures of 251,980 and 225,750. He knew that one revolution of the moon about the Earth takes 27 1/3 days, which is shorter than the roughly 29 days between new moons. This is because a new moon depends on the alignment of sun, moon, and earth. As the earth moves around the sun, the moon must travel slightly more than one revolution to return to alignment.
To launch their space vehicle, Gun Club members resolve to cast in place a vertical gun tube rooted deep in the ground. Verne devotes an entire chapter to its design. To achieve the requisite velocity of escape from the Earth, the veterans decide to quadruple Civil War design parameters, which specified that the length of a gun should be 20 to 25 times the diameter of the shot. Thus they settle on a length of nine hundred feet, since the giant cannon would have a ninefoot bore, unrifled to avoid frictional drag. The designers specify a wall thickness of six feet—a reasonable safety factor to reduce the danger of bursting, since the principles of stress analysis were known to few engineers at the time.
Rejecting the use of a standard bronze alloy for cannon (one hundred parts of copper, twelve of tin, and six of brass), the club’s president argues for cast iron because of its cheapness (two cents a pound, he quotes—one-tenth the cost of bronze), ease of molding, and recent field performance: “At the siege of Atlanta, some iron guns fired one thousand rounds at intervals of twenty minutes without injury.” (By this he means that the guns didn’t explode—a not uncommon military accident at the time.) Here Verne misses a contemporary development: the Krupp munitions works at Essen had by this time produced cast steel gun tubes and exhibited them at London’s Crystal Palace Exhibition in 1851. The innovation would help Prussia defeat Austria in 1866 and France in 1870-71. Verne calculates the weight of his cast-iron gun at 68,400 tons, a figure that stands up well under analysis when the weight of the breech is taken into account.
Production of the mammoth artillery piece rates two chapters. The job begins with dramatic flair as President Barbicane addresses his assembled foremen: “You are well aware, my friends, of the object with which I have assembled you here in this wild part of Florida. Our business is to construct a cannon measuring nine feet in its interior diameter, six feet thick, with a stone revetment of nineteen and a half feet in thickness. We have, therefore, a well of sixty feet in diameter to dig down to a depth of nine hundred feet. The great work must be completed within eight months, so that you have 2,543,400 cubic feet of earth to excavate in 255 days; that is to say, in round numbers, 10,000 cubic feet per day.”
After digging through six inches of black earth with their picks and shovels, the workers encounter two feet of fine sand, four feet of “some compact white clay, resembling the chalk of Great Britain,” and, finally, “the solid hard bed of the soil; a kind of rock formed of petrified shells, very dry, very solid, and which the picks would with difficulty penetrate”—a very creditable description for an author who never set foot in the United States. Less plausibly, Verne places this action at a site 1,800 feet above sea level, to avoid problems with ground water. In fact, the highest point in Florida is 345 feet above sea level, and that’s in the panhandle; the terrain in the peninsular part of the state is very low and flat.
The vast well is lined with masonry, “always reserving some vent holes to permit escape of gas during the operation of casting.” The men fabricate a 900-foot cylindrical casting core to form the inside diameter of the gun tube (”composed of a mixture of clay and sand, with the addition of a little hay and straw … firmly fixed at certain intervals by cross-clamps fastened into the stone lining”). Then twelve hundred iron furnaces of fireproof brick, each six feet wide and containing 114,000 pounds of iron, are erected three feet apart around a circle about 1,200 yards in diameter—each with its own trench leading to the central pit mold. Upon being signaled by a cannon shot, all the furnace ports are simultaneously opened, releasing twelve hundred radial rivers of glowing molten iron plunging into the abyss—”a whole Niagara of molten metal!” Artificial clouds “spiral 1,000 yards into the air.” After a month and a half of cooling, the gun tube is “bored with great precision … by the aid of powerful machines,” details of which are left to the imagination of the reader.
IN DESIGNING HIS PROJECTILE, VERNE ONCE AGAIN REVEALS HIS knowledge of state-of-the-art technology: The space capsule is made of aluminum. In 1845 the German chemist Friedrich W’f6hler had discovered that aluminum was a very light metal when he produced the first lumps large enough to be weighed. In 1855 Henri Etienne SainteClaire Deville exhibited a shiny bar of the metal; as a result, Napoleon III commissioned the establishment of the world’s first aluminum plant in a suburb of Paris in 1859. Although he probably never saw a sample, Verne snapped up the new material for his man-carrying missile, having the perspicacious Barbicane declare, “This valuable metal possesses the whiteness of silver, the indestructibility of gold, the tenacity of iron, the fusibility of copper, and the lightness of glass.”
Most of these claims are borne out. Cast aluminum has a density of 168 pounds per cubic foot—the middle of the range for glass, which runs from 150 to 175. Its melting point, 660°C (1,220°F) is significantly lower than that of copper, 1,082°C (1,980°F); both, however, are much lower than iron, at 1,535°C (2,795°F). The ultimate tensile strength of cast aluminum is 13,000 pounds per square inch (psi), while that of cast iron is 20,000 psi. (By comparison, wrought iron’s tensile strength is 50,000 and steel’s is 60,000; hard-drawn aluminum wire can run as high as 30,000 to 40,000.) But iron is three times as heavy as aluminum, so by volume Verne’s pronouncement about the light metal’s “tenacity” is certainly valid.
Aluminum is, as he says, a silverywhite metal, and until the Hall-Héroult electrolytic process was developed in 1886, it was quite expensive. Indeed, when the Washington Monument was completed in 1884, the novel but still precious metal was selected for its lightning-conducting cap, instead of platinum. Deville was able to reduce its price to seventeen dollars a pound by 1859. Verne quotes its price in 1865 to be nine dollars a pound, a level it would not in fact reach for another two decades.
In its pure state aluminum is far from indestructible; in fact, it is among the most reactive of metals and dissolves readily in weak acids. Verne was right nonetheless, because in air aluminum instantly develops a transparent oxide coating, which resists further oxidation and preserves its silvery luster. Certainly aluminum was a reasonable choice for Verne’s space capsule.
Verne adapted some legitimate chemistry to permit his three human and two canine astronauts to breathe. He is aware that “air consists principally of twenty-one parts of oxygen and seventy-nine of nitrogen.” In breathing, he explains, “the expelled air loses nearly five percent of the former and contains nearly an equal amount of carbonic acid [i.e., carbon dioxide], produced by the combustion of the elements of the blood.” To absorb this carbon dioxide, Verne provides trays of “caustic potash” (potassium hydroxide, KOH). To replace the oxygen, he heats “chlorure of potassium” (potassium chlorate, KClO 3 ) to 400°C (750°F), where it breaks down into potassium chloride (KCl) and oxygen gas. The passenger compartment is heated and lit by a gas mantle, which, he notes, will also consume some oxygen. Gaslight was a reasonable choice for the time; although crude electric incandescent lamps existed as early as 1859, Edison didn’t perfect his first practical carbonfilament lamp until 1879.
AS REVEALED IN AROUND THE MOON , THE SPACE CAPSULE is fitted with retrorockets. Again, Verne’s chemistry is above reproach: “Although these rockets were to burn in space … oxygen would not fail them, for they could supply themselves with it.” Their means of ignition were less than high-tech, however. In preparation for landing, fuses for the rockets were to be lit from the spaceship’s interior with matches struck by the astronauts.
To propel his projectile, Verne rejects the venerable black powder recipe that had been used in cannon since the fourteenth century. Instead he chooses “pyroxylin,” also known as guncotton or nitrocellulose, whose use as a propellant had been proposed in 1846 by the Swiss chemist C. F. Sch’f6nbein. Barbicane explains the advantages of pyroxylin: “It ignites at 160 degrees [centigrade, or 320°F] in place of 240 [464°F, for black powder], and its combustion is so rapid that one may set light to it on top of ordinary powder, without the latter having time to ignite … it imparts to projectiles a velocity four times superior to that of gunpowder… . So, then, in place of 1,600,000 lbs. of powder, we shall have 400,000 lbs. of fulminating cotton; and since we can, without danger, compress 500 lbs. of cotton into 27 cubic feet, the whole quantity will not occupy a height of more than 180 feet within the bore of the Columbiad. In this way the shot will have more than 700 feet of bore to traverse under a force of 6,000,000,000 litres of gas before taking its flight towards the moon.” In a rare lapse, explained perhaps by the devilishly complicated nature of cannon design, Verne makes no attempt to correlate the weight of the projectile with the amount of propellant required; instead, the members of the club simply guess. A very rough calculation suggests that their figure is at least reasonable.
According to modern explosives engineers, a charge of black powder will burn at a constant velocity of approximately five hundred meters per second, but a nitrocellulose explosion accelerates as it progresses. As a propellant, therefore, it could indeed increase the muzzle velocity of a projectile—perhaps by a factor of two and a half compared with black powder. As formulated today, nitrocellulose is not used in pure form, as Verne proposed, but is blended with nitroglycerine in the manufacture of gelatinized explosives.
While Verne was quite at home with chemistry, he was somewhat out of his element in the area of analytical mechanics, the interaction of force, mass, and acceleration. In Twenty Thousand Leagues Under the Sea , when the submarine Nautilus goes through some spectacular aerial maneuvers (”after having leaped into the air like a flying fish, she fell back, throwing up waves to a tremendous height”), Captain Nemo’s expensive collection of bric-a-brac remains undisturbed on its pedestal, and the crew survives with neither crash helmets nor seat belts.
In Around the Moon , as Verne’s projectile coasts toward its lunar destination, he explains that “as it distanced the earth, the terrestrial attraction diminished; but the lunar attraction rose in proportion.” Then, when the craft reaches a point “situated at 47GOths of the whole journey,” his astronauts and their canine companions suddenly, and for the first time, begin to float about the cabin. In fact, they would have been in free fall ever since leaving the muzzle of the cannon.
With good reason, then, the author sought the help of a distant cousin, a mathematician named Henri Garcett, to calculate the dynamics of the lift-off, which are thoroughly detailed in a very long letter from the director of the Cambridge (Massachusetts) Observatory. In the letter one J. M. Belfast specifies the latitude of the cannon’s location, the angle at which it is to be aimed (”pointed directly toward the zenith of the place”), the precise moment at which it is to be fired, and its time of flight (97 hours, 13 minutes, and 20 seconds).
For comparison, in NASA’s first moon-landing mission, Apollo II, the time from leaving earth orbit until entering moon orbit was 72 hours, 51 minutes. But because our astronauts spent 2 hours, 38 minutes in earth orbit before boosting out and circled the moon for just over 24 hours before launching the landing vehicle, the total time from lift-off to landing was 100 hours, 46 minutes.
The requisite velocity to escape the earth’s gravitation is repeatedly quoted in the book as 12,000 yards per second, quite close to today’s accepted value of 6.95 miles, or 12,200 yards, per second—in a vacuum. When air resistance is taken into account, however, the figure is 7.5 miles per second. Barbicane blithely attempts to sidestep this problem when he declares, “Air resistance is unimportant. The earth’s atmosphere is only 40 miles thick. At a speed of 36,000 feet per second, the shell will go through it in five seconds, and that time is so short that we can regard air resistance as insignificant.” A century and a quarter later and many moon missions wiser, aerospace engineers know that during those five seconds Verne’s astronauts would have wished that Barbicane had been less categorical. Besides slowing down the projectile, taking off at such speed would generate so much friction that the nose of the projectile would have required a heat shield to keep it from burning up.
To study the shock of the launch, Gun Club members set up a test using a thirty-two-inch mortar “from the arsenal of Pensacola.” It is an experiment worthy of such American empiricists as Charles Lindbergh or the Wright brothers: “A hollow projectile had been prepared for this curious experiment. A thick padding fastened upon a kind of elastic network made of the best steel, lined the inside of the walls… . Within this shell were shut up a large cat, and a squirrel belonging to J. T. Maston, and of which he was particularly fond.…
“The mortar was charged with 160 lbs. of powder, and the shell placed in the chamber. On being fired, the projectile rose with great velocity, described a majestic parabola, attained a height of about a thousand feet, and with a graceful curve descended in the midst of the vessels that lay at anchor.” A small boat with divers aboard retrieves the projectile, which is opened within five minutes. What emerges is Verne’s black humor: “Hardly had the shell been opened when the cat leaped out, slightly bruised, but full of life, and exhibiting no sign whatever of having made an aerial expedition. No trace, however, of the squirrel could be discovered. The truth at last became apparent;—the cat had eaten its fellowtraveler!”
A much more sophisticated energy-absorption system is designed for the full-scale man-carrying missile. The projectile vehicle is fitted with an internal capsule resting on a wooden disk on top of a three-foot bed of water: “This body of water was divided by horizontal partitions, which the shock of the departure would have to break in succession. Then each sheet of the water, from the lowest to the highest, running off into escape tubes toward the top of the projectile, constituted a kind of spring; and the wooden disc, supplied with extremely powerful plugs, could not strike the lowest plate except after breaking successively the different partitions.… The upper walls were lined with a thick padding of leather, fastened upon springs of the best steel, behind which the escape tubes were completely concealed; thus all imaginable precautions had been taken for averting the first shock; and if they did get crushed they must, as Michel Ardan said, be made of very bad materials.”
AT LAST, AFTER TWENTY-FIVE CHAPTERS AND MORE THAN A year of careful, painstaking preparation, the two Americans (President Barbicane and his rivalturned-friend, one Captain Nicholl) and Monsieur Ardan, their French companion (who has been awarded honorary American citizenship by the President of the United States), enter the projectile and settle themselves into what they hope will be the most comfortable positions to withstand the shock of lift-off. By the end of the countdown, Verne has readers on the edge of their seats: “Instantly Murchison pressed with his finger the key of the electric battery, restored the current of the fluid, and discharged the spark into the breech of the cannon.
“An appalling, unearthly report followed instantly, such as can be compared to nothing whatever known, not even to the roar of thunder, or the blast of volcanic explosions! No words can convey the slightest idea of the terrific sound! An immense spout of fire shot up from the bowels of the earth as from a crater. The earth heaved up, and with great difficulty some spectators obtained a momentary glimpse of the projectile victoriously cleaving the air in the midst of the fiery vapors!”
Alas! Although Verne’s astronauts somehow manage to show up later in Around the Moon , a calculation of the physics of their launch—accelerating a projectile to the author’s understated 12,000 yards per second escape velocity in 720 feet —reveals that Ardan, Barbicane, and Nicholl were subjected to an average of 28,000 g’s during lift-off. Not even Verne’s imaginative shock absorber, sturdy as it was, could have stood up to that. Each man would have been crushed under more than 2,000 tons of his own weight, and the trio, intermingled with the remains of their canine companions, would have formed a thin layer of uniform thickness on the floor of the spacecraft.
With his dark sense of humor, Jules Verne would probably have found that funny, albeit embarrassing.