Page 16 of Every Little Boy’s Book details the folding of a piece of paper such that "when thrown from the hand, rarely hits the object aimed at, as it generally makes a graceful curve in passing through the air." To modern eyes, the instructions, description and illustration are exactly those of a paper airplane. But Phil Edwards for Vox.com points out that these instructions were printed in 1864, 39 years before the Wright Brothers first flew their airplane.
Humans dreamed of flight long before they put humans in the air. Back in the early 1500s, Leonardo da Vinci had designed a man-powered flying machine. Mathematician Archytas of Tarentum reportedly created a mechanical wooden dove that flew for 200 meters in 250 B.C.E. So paper airplanes flying from the hands of children during the Civil War Era aren’t that surprising — although the book calls them 'paper darts,' not airplanes. But despite the name, the design is very familiar and so was the play, apparently. Edwards writes:
People even used paper darts the same way kids use paper airplanes today: to be annoying. An 1881 description of the New York Stock Exchange noted an unusual punishment: "to throw a paper dart or ball at a member during the session of the Board is to incur a fine of ten dollars." Naturally, people threw paper darts at teachers, too: an 1889 story recalls the many times "a paper dart has glided noiselessly down the room, amidst the suppressed applause and smothered hilarity of the students."
When the term "paper aeroplane" first appeared in the 1890s, the toys it referred to looked more like birds than the aircraft that eventually lifted off the ground. They even included ways to flap the wings. It wasn’t until the 1950s and 60s, when airplanes finally looked like the paper toys of the last century did "plane" fully replace "dart" in the toy’s name.
The lag of that change indicates just how fixated people were to the idea that flying machines would imitate birds. Then again, humans have experimented with a lot of very odd-looking aircraft. Of course, now engineers and designers have truly dialed in the performance of real airplanes as well as the paper variety.