Mercury and Maia, fueled and overhauled, are waiting in the Tay at Dundee, for favorable weather to start the flight to the Cape, a distance of 6,370 miles. The composite machine moored in the Tay River, at Dundee, on September 23, 1938. (Photo by AP Photo)

Ukrainian serviceman fires with a heavy machine gun during a combat with Russia-backed separatists on the front line near Gorlivka, Donetsk Region on September 28, 2019. (Photo by Anatolii Stepanov/AFP Photo)

Children are engulfed by foam during the Bubble Show event in Beijing, China, Sunday, June 26, 2016. Thousands of residents enjoy colored foam churned out by machines along a running track at the event designed for children and parents' interaction. (Photo by Ng Han Guan/AP Photo)

The Enemy, 1944. With the outbreak of world war two, photojournalism was enlisted in defence of Mother Russia. In this photo by Anatoli Egorov, who was wounded in action, corporal Stepan Vasiljevich Ovcharenko shoots at enemy troops with a machine gun. (Photo by Anatoli Egorov/Lumiere Brothers Center for Photography)

A machine engraves information on an ingot of 99.99 percent pure gold at the Krastsvetmet non-ferrous metals plant, one of the world's largest producers in the precious metals industry, in the Siberian city of Krasnoyarsk, Russia October 24, 2016. (Photo by Ilya Naymushin/Reuters)

Two robotic legged squad support system (LS3) machines by the Defense Advanced Research Project Agency follow a technician during a demonstration at Joint Base Myer-Henderson Hall, Virginia, on September 10, 2012. (U.S. Marine Corps photo by Sgt. Mallory S. VanderSchans via The Atlantic)

British band Florence and the Machine performs at the Bilbao BBK Live festival in Bilbao, Spain, early 13 July 2018. Bilbao BBK Live festival runs from 12 July to 14 July 2018. (Photo by Miguel Tona/EPA/EFE)

A boy holds a machine gun at a military hardware exhibition during a swear-in ceremony for new recruits of the Russian military-patriotic club “Yunarmia” (Young army) in the Black Sea port of Sevastopol, Crimea, October 27, 2018. (Photo by Pavel Rebrov/Reuters)