Science Behind Civil War Balloons

NYS Standards: MST 1, 4, 5, 6; SS 1 ELA Common Core SL 1, 2, 3, 4

Goal—The goal of this lesson is to learn about balloon use during the Civil War along with the scientific concepts involved in lighter-than-air flight.

Objectives • Students will identify the function of balloons in combat. • Students will demonstrate understanding of buoyancy. • Students will identify the gas generation process as a chemical reaction. • Students will identify the gas generation reaction as an exothermic reaction. • Students will explain the gas generation process in terms of chemical formula and end result. • Students will define “combustion” and identify the byproducts of the combustion reaction. • Students will demonstrate knowledge relating to Thaddeus Lowe, the foremost of the Civil War balloonists.

Materials • Video of hydrogen creation (link on GCV&M website) • Clear drinking glass • Marble • Ping Pong Ball • Deflated party balloon • Civil War Balloon images (download from GCV&M website)

I. Brief history of ballooning: A. The first hot air and hydrogen balloons were built and flown in France in 1783. Ballooning was a popular entertainment in Europe and in America starting in 1793 with Jean Pierre Blanchard. B. The French army used balloons starting in the 1790s. France and other European countries used them for war throughout the early 19th century. C. Ask: what do you think were balloons used? What purpose could they serve in battle? Make a list of answers (either mentally/verbally or on a whiteboard) D. Discuss the uses of balloons: map-making, drawing enemy positions and fortifications, watching troop movements, counting troop numbers (using tents/fires), directing artillery fire; compare to the use of surveillance planes and drones in modern warfare. E. Balloons were considered for use during the 1830s Seminole Wars and the 1846 Mexican War in the United States, but nothing came of it. John Wise was the most

Science in the Civil War Focused Field Study Online, Spring 2020, www.gcv.org

well-known American aeronaut, but other “young upstarts” like John LaMountain, James Allen, and Thaddeus Lowe started making and flying balloons in the 1850s. II. Thaddeus Lowe: A. From NH and interested in science from a young age. Went to a one-room schoolhouse a few months out of the year but had no more than the equivalent of a 6th Grade education. B. He read about science and conducted experiments on his own. One involved placing the family cat in a cage beneath a huge kite and attached a lantern beneath it when he was 16 years old. He fastened kite to a hitching post and left it flying there all night. The kite supposedly rose 1,000 ft. into the air. The next day local newspapers reported seeing strange lights floating about in the evening. The cat fled once he brought the kite down and released it. He decided then and there not to put another animal in harms way again. His thoughts of using a kite to life himself off the ground were stopped, and he started reading everything he could find on aeronautics. C. Lowe became an assistant to a traveling science lecturer (Professor Reginald Dinkelhoff), and by age 18 began touring and doing scientific lectures all over the country. D. He made enough money to start making and flying balloons. E. When the Civil War started, he demonstrated his balloons in Washington, D.C. He was the first person to use a telegraph machine from a balloon. This impressed President Lincoln who introduced him to the commander of the army. Lowe eventually was put in charge of the balloon corps. III. How did the balloons fly? A. Army balloons used during the Civil War were NOT hot air balloons. Ask: what were they filled with that made them float? B. Explain that the balloons were filled with either coal gas from city gas lines (normally used for lighting) or with hydrogen gas. These gasses were used because they were lighter than air and made the balloon buoyant. C. Discuss buoyancy: buoyancy is an upward force exerted by a liquid or gas that opposes the weight of an immersed object. If an object is more dense than the liquid or gas around it, it will sink. If an object is less dense than the liquid or gas around it, it will rise. D. Demonstrate buoyancy: i. Fill a clear drinking glass with water. ii. Drop a glass or metal marble and observe it sink. Explain that since the glass/metal is more dense than the water, the object sinks. In other words, the weight of the object and the downward force caused by gravity is stronger than the buoyancy or upward force of the water. iii. Push a ping-pong ball down into the water and observe it rise. Explain that since the air inside the ball is less dense than the water, the object floats. In other words, the upward buoyant force exerted by the water is stronger than the downward force caused by the object’s weight. iv. Explain that this same concept works for a party balloon full of helium or a Civil War balloon full of hydrogen. Since the gas was less dense than the air

Science in the Civil War Focused Field Study Online, Spring 2020, www.gcv.org

around it, the upward buoyant force was stronger than the downward force caused by gravity. Thus, the balloons would rise rather than sink. v. Blow up a party balloon. Ask: will this balloon sink or rise? Why? It will, of course, sink. This is because the air inside is the same density as the air outside and the downward force caused by the weight of the balloon is stronger than the upward buoyant force exerted by the surrounding air. Release the balloon and show the result. E. Thaddeus Lowe designed a machine to manufacture the hydrogen gas needed to make his balloons buoyant. i. Show the original Civil War photograph of the gas generators being used to inflate the balloon. ii. Explain that the generators were basically big tanks. Several ingredients would be combined in the tanks. They would then react and give off a new material: hydrogen gas. Ask: what kind of a reaction is this? A chemical reaction. iii. The materials to be combined were 3,300 lbs. of iron, water, and 10 large carboys of sulfuric acid. The resulting reaction would produce ferrous sulfate byproduct, about 32,000 cubic feet of hydrogen gas, and a great deal of heat. iv. Write the formula for the reaction on the board: Fe + H2SO4 → H2 + FeSO4 and explain each of the components (Iron+sulfuric acid makes hydrogen+ferrous sulfate). v. Ask: A chemical reaction that gives off heat is called what? An exothermic reaction. Explain the parts of that term: exo-meaning to give off, and thermic-meaning heat, as in a thermometer. F. Demonstration of the gas generation process. i. Show video of hydrogen gas production ii. Talk through process, prompting students to see if they understood what took place during video. a. Explain that the first flask represents the large generator boxes used during the Civil War, just on a much smaller scale (and not on wheels!). First, hydrochloric acid was added. Tell the students that sulfuric acid would have been used during the Civil War, because it was more readily available. Ask: who do you think dumped this hazardous stuff into the tank? Soldiers. b. Explain that the second flask represents the cooler/purifier boxes. These boxes will clean any left over acid out of the gas and cool the gas down. If hot gas goes into the balloon, it will soon cool and contract and the balloon will not float. c. Aluminum foil balls (about 15) added to the acid. Explain that iron would have been used during the Civil War and would have been provided by the navy yard, with what was left over after making steam boilers and ironclad warships. d. As the reaction began, point out that there was a lot of heat. Ask: what kind of reaction is this? Exothermic.

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f. Observe as the gas fills the balloon. Reinforce that the water in the 2nd flask is cooling the gas. This means that it will not cool and contract inside the balloon. g. After a few moments, the water from the 2nd flask was sucked into the first. This is because the pressure of the gas in the 1st flask was much less than that of the outside air. The air pushes the water into the 1st flask! h. Ask: why did the balloon float? Why? The density of the gas inside is less than the air outside. Therefore, the upward force exerted by the surrounding air will be stronger than the downward force caused by the balloon’s weight making it buoyant! i. Hydrogen gas is highly combustible. Ask: what does combustible mean? Combustion is a highly exothermic chemical reaction where a combustible material, like hydrogen, reacts rapidly with oxygen to create extreme heat. Another word for this would be an explosion! The formula for hydrogen combustion: 2 H2 + O2 → 2 H2O + heat. Explain the components (hydrogen+oxygen makes water+heat/fire). Explain that when the gas is exposed to the flame, it will rapidly combine with oxygen and combust. This will make a ball of fire and a big boom! There is some moisture left behind on the exploded pieces of the balloon. This is the water created by rapidly combining the hydrogen and oxygen to make H2O.

IV. Dangers of Civil War ballooning. A. Show the picture of Lowe ascending in the Intrepid. Point out the size of the basket. Explain that most flights were tethered (tied-down) by ropes held by teams of soldiers, but would still usually go between 500 and 1,500 feet in the air, sometimes as high as 2,000 or even 3,000 feet. B. Ask: What were some dangers of flying balloons during the war? Falling out, soldiers on the ground loosing their grip, being fired upon, hydrogen gas combusting, etc. C. Explain that, miraculously, no balloons ever exploded during the Civil War. This is amazing for two reasons: 1) the people doing the mixing were soldiers, not necessarily well trained or scientifically educated, and 2) the balloons were under nearly constant fire by Confederate forces. Luckily, the ammunition used at the time was all “cold shot.” This means that it was not on fire when it hit the balloon and therefore did not ignite and cause the combustion of the gas. The large silk balloons could be punctured numerous times before they would start to slowly descend (and could be patched). D. Have students imagine going up in a balloon during a battle. The men doing this were civilians, not trained army officers or soldiers. They would go up an average of 1,000 feet in a basket that came up to their knees, being shot at the whole time, with only men holding ropes keeping them from floating away!

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V. Balloons in the Civil War (highlight the years and battles they were involved in) A. telegraph wires from balloon to the ground would allow instant communication from the air; sometimes lines would be extended to the army headquarters and even all the way back to Washington, DC. B. Summer 1861-early Spring 1862: balloons used around Washington, D.C. to watch Confederate camps. Artillery fire was directed from a balloon for the first time in September, using flag signals. C. Spring 1862-Summer 1862: Peninsula Campaign. Balloons were used extensively during the Siege of Yorktown, the Battle of Fair Oaks/Seven Pines, the Battle of Mechanicsville, and the Battle of Gaines Mill (army and balloons fall back; 2 generators captured). The G.W.P. Custis balloon boat was used to transport the balloons, generators, and crews. D. Winter 1862: The Battle of Fredericksburg. Balloons were used the day of the battle to observe the carnage. As usual, the balloon took heavy fire. Lowe reported a shell coming within 20 feet of the basket. E. Spring 1863: The Battle of Chancellorsville. Balloon observations integral in Union forces initially taking Confederate works behind Fredericksburg. F. Summer 1863: Captain Comstock supervises Lowe and the balloon corps. He fires several civilian assistants and cuts Lowe’s pay. Commanding generals also loose interest in balloons. Lowe resigns and the balloon corps is disbanded shortly thereafter. VII. Conclusion A. Though the program did not survive the war, balloons were used effectively. Thaddeus Lowe’s innovations revolutionized aerial reconnaissance. In particular, his use of the telegraph and portable gas generators were all useful and practical advances. Lowe and his assistants demonstrated great courage and competence in their duties during their service.

Further Study • Learn about the history of the telegraph and its use by balloonists during the Civil War by downloading lesson materials from GCV&M website • Students can do additional internet research on Professor Lowe and the use of balloons in the Civil War, www.civilwar.org “Civil War Ballooning During the Seven Days Campaign” • Recommended reading for young people: Lincoln’s Flying Spies (Gail Jarrow),

Science in the Civil War Focused Field Study Online, Spring 2020, www.gcv.org