by Barry Parker
THE DYNAMO (GENERATOR)
The Civil War was the first war in which electricity began to play a large role in many different ways. And its impact extended far beyond the telegraph. Initially, most electrical currents were produced by batteries, but batteries are limited in the amount of electrical power they can generate. And for factories and mills, considerable power was needed. The Civil War was, in fact, one of the first truly industrialized wars. Mass-produced weapons, ironclad steamships, large factories producing various goods for the war, railroads, and so on all played important roles. Electricity was central to many of them, and at this point, many of its properties and applications were still not well understood. Furthermore, a cheap source of electricity was still not known.
Nevertheless, the first step had already been taken. Faraday demonstrated electromagnetic induction in 1831 when he showed that a brief current would flow when he moved a magnet in a solenoid. The problem was that the current was too brief, and even if the magnet was moved back and forth, only a fluctuating current could be produced. Faraday decided to look into the possibility of producing a more useful current. To do this he set up a thin copper disk that could be turned on a shaft. The outer rim of this disk would pass between the poles of a strong magnet, and as the disk turned it cut through magnetic lines of force. As a result, a potential difference, or voltage difference, was set up on the disk. The voltage was highest near the rim of the disk, since that was where the disk moved the fastest. Faraday then set up two sliding contacts on the disk, with wires attached to them, one near the edge and one closer to the center. If a galvanometer was placed in the circuit, a current flowed through it, and as long as the disk moved, the current flowed continuously.10
But Faraday's disk created only a small voltage difference because it contained only a single current path through the magnet. Soon it was found that much higher voltages could be generated by winding multiple turns of wire into a coil. In 1832 a French instrument maker, Hippolyte Pixii, improved on Faraday's device. He used a permanent magnet that could be rotated by a crank. Placing the magnet so that its poles passed a piece of iron wrapped in insulated wire, Pixii found that the spinning magnet produce a pulse of current in the wire each time a north or south pole passed the coil. But the two poles induced currents in opposite directions. To overcome this, so that both currents were in the same direction, Pixii placed a split metal device, called a commutator, on this shaft (with springs attached to it) that pressed against it.
The result was generally continuous, but not the direct current that we know today. Within a few years, however, a smooth direct current was produced. This was the first dynamo, or simple generator—in short, a device that generated an electrical current as a result of mechanical motion. It meant, however, that you had to have something to push the device around to create circular motion. The steam engine could be used for this, or water in the form of a waterfall, or just flowing water. Electricity, and therefore electrical currents, could therefore be produced if an appropriate outside source of mechanical power was available. The dynamo was the first device that allowed a large amount of electrical power to be generated, such as that needed for a factory.
THE GATLING GUN
Strangely, one of the best “super weapons” of the Civil War saw little action. The Gatling gun was designed by Dr. Richard Gatling in 1861 and patented in November 1862, but the army appeared to have little interest in it at first. Also strange is the fact that Gatling abhorred war and hoped that his weapon would overcome the need for large numbers of soldiers on the battlefield. Even more so, he hoped it would show how gruesome and terrible war could be, which might convince nations to think twice before they went to war.11
The Gatling gun used multiple rotating barrels to fire two hundred bullets per minute. The barrels, six in all, were mounted around a central shaft, and the entire assembly could be rotated with a hand crank. Each barrel fired a single shot as it rotated to a certain point. The shells consisted of steel cylinders containing black powder and a percussion cap. Compared to other attempts to increase firepower, the shells used in the Gatling gun were gravity fed into the breach from a hopper on the top of the gun. After each bullet was fired the empty cartridge was ejected and a new round was loaded. One of the major problems in earlier attempts at such a gun was overheating of the barrels. In this case the barrel was allowed to cool as it rotated; in addition, in the earliest models, fibrous matting that had been soaked with water was stuffed between the barrels.
Gatling demonstrated his new weapon to the Union army in December 1862, several months before the Battle of Gettysburg, but the army was slow to accept it, perhaps for the best, since it would soon have become a major killing weapon.
THE WAR AT SEA
While war raged on land, war was also taking place on the high seas and in the bays along the Gulf of Mexico, and even up the larger rivers such as the Mississippi. Soon after the war began, Lincoln ordered a blockade of the seaports in the South, and it was, indeed, a smart move. The South had limited resources and had hoped to get support, or at least supplies, from Europe, and with the blockade on, they didn't get much of either. The blockade was particularly effective because the navy, as limited as it was at the time, remained loyal to the Union. At the time, in fact, it had only wooden ships, which would soon become so vulnerable to gunfire that they were of little use, unless guarded by an “ironclad.”
As guns got bigger and bigger, it soon became obvious that wooden ships were sitting ducks. Something would have to be done. Iron or steel plating was placed over the wood at first, but it soon became apparent that it would be better to make the entire hull out of metal. Such ships became known as ironclads.
Early on most ships were propelled by a giant paddlewheel, which in turn was powered by a steam engine. But paddle wheelers were large, cumbersome, inefficient, and vulnerable. One well-directed artillery shell and the ship would be out of commission. Engineers were therefore looking for something better for propulsion, and the obvious thing was some sort of “screw” device. Centuries earlier Archimedes had used a screw-like propeller for lifting water for irrigation, and the Egyptians had used a similar devise for years to irrigate their lands. Furthermore, Leonardo da Vinci had used the same principle in his design for a simple helicopter. It was obvious it could move water and exert a force against water. One of the first to propose that such a device could be used to propel a boat was James Watt, but strangely there's little evidence that he suggested using it with his steam engine.
The first “screw” propellers were, indeed, in the form of a long screw. But in 1835 Francis Smith made an important discovery. He was experimenting with long-screw propellers when a large section of the screw broke off. To his surprise, the remaining piece of the propeller seemed to work even better than the long screw. This was the beginning of the shorter, modern propeller that we know today. The man who perfected the design was the engineer John Ericsson of Sweden. By 1836 he had added larger blades and made it much more efficient. He worked in England for a while but came to the United States a few years before the Civil War, and his talent soon came to the attention of the naval officer Captain Robert Stockton. Stockton was ambitious and was determined to modernize the navy with armored steamships and much larger guns. With the help of Ericsson, he designed and built one of the most formidable warships of the day, naming it the Princeton, after his hometown. Its guns were in turrets, the two largest of which had twelve-inch barrels that fired 212-pound cannonballs. In addition it had twelve forty-two-pound guns, and it was powered by Ericsson's new propeller.12
In 1844 it was paraded out before President Tyler and a large audience in Washington, DC. Stockton, eager to show off its guns, ordered a demonstration. As the third shot was fired, the large gun exploded, spraying the attending crowd with fragments of iron. The secretary of state, the secretary of the navy, and several other officials were killed. It was a tremendous blow to both Stockton and Ericsson, who had helped in t
he design.
When the Civil War broke out, however, Eriksson was employed by the Union to design a new and even better warship. When completed, it was called the USS Monitor. It was heavily armored in iron and was 179 feet long and powered with a steam engine that drove a nine-foot propeller. It looked rather strange in that its deck was only eighteen inches above the water, but this made it an extremely poor target for enemy ships.
In the meantime the Confederate navy had also built an ironclad, which they named the CSS Virginia; it was the pride of the South. In March 1822, the two ships met at Hampton Roads, Virginia. The Virginia attacked the Union blockade squadron at Hampton Roads and destroyed two small frigates. Early in the battle the large frigate Minnesota had run aground while attempting to engage the Virginia. But it got dark before the Virginia could finish off the Minnesota, so early the next morning it returned, but in the meantime the Union navy had brought the Monitor in, and it was waiting for the Virginia. The two ironclads blasted at one another with their guns but did little damage, then the Virginia tried to ram the Monitor, but this also did little damage. The two ships continued to battle for hours, but in the end it was a draw. However, the Monitor had stopped the Virginia from destroying the Minnesota and several other ships.
Pleased with the performance of the Monitor, the Union soon built an entire fleet of ships modeled on it. They also built a fleet of smaller ironclads referred to as the “City” class, which were used in the west—the bays of the Gulf of Mexico and the larger rivers such as the Mississippi.
The Confederate navy also built several smaller ships, but it was soon obvious that they could not keep up with the Union navy, and they could do little on top of the water to stop the blockade.
PHYSICS OF THE PROPELLER
Propellers of the time had two or more blades that were attached to a rotating shaft. As the propeller turned, it transmitted power to the boat by converting rotational motion into forward thrust. Basically, a pressure difference was produced on opposite sides of the blade, with the pressure on the rear surface greater than that on the front, and this differential forced the ship forward. In effect, the blades imparted momentum to the water, which created a force on the ship.
Propellers can turn clockwise or counterclockwise, according to the design of the blades. The force on the blade depends on its area (A), the fluid density (), the velocity (v), and the angle of the blade to the fluid flow (α).
One way to look at the propeller is to compare it to a screw. You know that to screw it into a wall, you apply torque to the head of the screw. The helical thread of the screw converts this torque into a “pushing” force that drives the screw into the wall.
Basically, a propeller is a machine that moves the ship through the water as it is turned. Machines, as we saw earlier, are devices that multiply or transform forces. So a propeller is a machine that moves the ship forward by pushing water backward, where the force on the backward-moving water is equal to the force on the forward-moving ship, according to Newton's third law. Also, since the force is a result of a change in motion, a propeller gives a ship forward momentum by giving the water backward momentum.
“DAMN THE TORPEDOES”
When the Confederate navy finally realized it was no match for the Union navy it decided to fight the embargo in other ways. And two of the most effective things they used were torpedoes and submarines. Indeed, the Confederates sank twenty-two Union ships and damaged twelve others using torpedoes, while losing only six ships to the Union navy in return. These “torpedoes,” however, are not what we usually think of as torpedoes, even though they were referred to by that name at the time. They were what we might call “mines” today.
Two types of torpedoes were used extensively: the spar torpedo, in which an explosive device was mounted at the end of a long spar (up to thirty feet long). It was usually mounted at the bow of an attacking vessel. When driven against an enemy ship it exploded. The only problem is that it frequently did considerable damage to the vessel carrying it. Torpedoes were also towed on long ropes or lines behind a vessel, usually at an angle of about forty-five degrees. Using an appropriate maneuver they could also be projected at an enemy ship. And, of course, many “torpedoes” were merely set in the water. They could be detonated electrically by an operator on the shore or by some type of percussion cap.
One of the most famous battles in which torpedoes played in important role was the Battle of Mobile Bay, Alabama. It occurred in August 1864. On the Confederate side, guarding the bay was Admiral Franklin Buchanan, a veteran of numerous battles at sea. His flagship, the Tennessee, was an ironclad modeled after the Virginia. Outside the bay was Union admiral David Farragut, who had four ironclads modeled after the Monitor, along with several wooden ships. And he faced more than just the Tennessee and a few smaller ironclads. Two forts were guarding the entrance to the bay: Fort Morgan, with several large guns, and Fort Gaines. But the biggest fear for Farragut was the “torpedoes” that were floating throughout the bay. The only way through them was a narrow path directly under the guns of Fort Morgan.13
Farragut planned to attack using a formation of two columns of ships. One, which would pass close to Fort Morgan, consisted of four well-protected ironclads similar to the Monitor. The second column consisted of four wooden warships, lashed together for safety. If one was hit, it was less likely to sink. Farragut was in the second of these, in the Hartford; ahead of him was the Brooklyn. On August 5, Farragut's armada approached the bay, and as they closed in, the guns at Fort Morgan began firing at them. The Union ships began firing back, but Farragut was not looking for an extended battle with them; he planned on rushing by them into the bay.
As the two columns approached the bay entrance, the captain of the lead ironclad, the Tecumseh, spotted Buchanan's Tennessee. It was a major danger to the column of wooden warships. But as he moved to intercept it, he forced the wooden ships into the minefield. When the captain of the Brooklyn saw the mines ahead he ordered his ship to stop. But directly behind him was Farragut in the Hartford. Annoyed, Farragut sent a message (flag message) to the captain of the Brooklyn to continue on. Confusion reigned, as both ships were under heavy fire. All at once an explosion rocked both ships. The lead ironclad, the Tecumseh, had hit a mine, and within seconds it was at the bottom of the bay.
Confusion continued, as the Brooklyn stopped again. It appeared as if the entire column of ships was going to collide into one another. Farragut issued an order that the line to his ship be cut, and he pulled out and began steaming past the Brooklyn. The captain of the Brooklyn yelled at him, “There are torpedoes directly ahead,” to which Farragut replied, “Damn the torpedoes…full speed ahead!” (a phrase that has become legendary). As the Hartford steamed ahead it struck several mines, but luck was with them. None of the mines exploded.
Meanwhile, Buchanan, who was aboard the Tennessee, watched in astonishment as all the Union vessels passed safely into the bay. He ordered the Tennessee to steam directly at the Hartford, which was now leading the Union ships. He planned to ram it, but the Tennessee was large and slow, and the Hartford easily eluded it as gunners from the two ships fired at one another. The Tennessee then made runs at several other ships, hoping to ram them, but it did little damage, so Buchanan broke off and returned to Fort Morgan.
But the fight was far from over. After inspecting his ship for damage, Buchanan ordered it out to sea again. And again the two ships—the Hartford (at ten knots) and the Tennessee (at four knots)—steamed directly toward one another. It looked like they were going to collide when, at the last moment, the Tennessee veered slightly. As they passed one another at point blank range, sailors on both ships fired with muskets and pistols.
Once the Tennessee was past the Hartford, however, it was surrounded by Union warships, all firing at it at the same time. And with the range being exceedingly close, they did a tremendous amount of damage. Furthermore, the gun port for one of Tennessee's guns jammed, and some of its other guns misfired.
Then one of the incoming shells took out the Tennessee's steering, and it could no longer maneuver. Finally, Buchanan himself was struck by flying debris. There was nothing left for him to do but surrender, and he did.
SUBMARINES
The first submarines also saw action during the Civil War. Actually, the first submarine had been built many years before the war, in 1776 in England. It was a one-man, hand-cranked machine. And the American inventor Robert Fulton had constructed a submarine for the French navy.
As we saw earlier, the Confederates soon realized that they were badly outgunned on the surface, so much of their effort went into the region under the surface—in particular, they used submarines. In 1862 they built the first of several submarines, all of which were called “David.” (The name no doubt came from the biblical story of David challenging the giant Goliath.) It was steam driven, and, as such, it needed a smoke stack, and since both the smokestack and the breathing tube had to penetrate above the surface, it was quite limited. Its major weapon was a spar torpedo, which was mounted on the bow.14
Within a short time Horace Hurley and two partners launched the Pioneer, and in 1862 they launched Pioneer II. By now they were experimenting with electric engines, but the only electrical engines that were being manufactured were in the North. They attempted to smuggle some in but failed. The following year, the much larger Hurley was built (named for the maker). It was forty feet long and was about four feet in diameter, and it had an eight-man crew that turned a hand-cranked propeller. The hand crank was no doubt used in an effort to keep the machine as silent and undetectable as possible. The Hurley had a spar torpedo, and there is evidence that it was used several times in battles, and no doubt several crews died in their attempts to do so. Nevertheless, it is the only submarine that managed to sink an ironclad during the war. In 1864 it sank the Union sloop Housatonic. Unfortunately, it did not survive the attack and was never seen again. In 1995, however, its remnants were found off the coast of South Carolina, and it was raised in 2000. There is some evidence that it was only twenty feet away from the Housatonic when it exploded, and the concussion likely disabled it.