Balloons could get you up in the air, but they weren't
steerable. Various inventors tried to build powered airships which could fly
anywhere the pilot wished to go, but during the first half of the 19th Century
they were stymied by the massive weight and enormous fuel consumption of
available engines. Turns out railroad technology isn't easy to repurpose for
aviation.

The first airship which could be called steerable was the one
constructed by French inventor Henri Giffard in 1852. Giffard's day job was
inventing high-efficiency steam engines, so he was able to create a
3-horsepower power plant small enough to be carried aboard a 144-foot airship.

It almost worked. Giffard's airship could turn and go in circles
— but in even a modest breeze it still drifted downwind even with the stoker
shoveling coal into the boiler as fast as he could.

Still, for fictional purposes it's not out of the question
to imagine that Giffard was able to squeeze a bit more efficiency out of his
engine, or use some of that newfangled petroleum as fuel. So 1852 is about the
earliest date for a "realistic" powered airship in fiction. You can
have passenger-carrying airships in the 1870s, opening the door to daring
airship robberies in the Old West, ex-Confederate airship pirates operating out
of secret bases in Brazil, and aerial expeditions to lost lands at the poles.

For a slightly more fantastical steampunk airship, consider
the Aereon, built by Dr. Solomon Andrews of Perth Amboy, New Jersey, in 1863. It was supposedly a
steerable, controllable airship with no engine at all!

Here's how it worked (in theory). Imagine holding a foam
kickboard under the water in a swimming pool. It wants to float upward but
you're holding it down. If you tilt it slightly and let go, the board shoots
off in the direction of the tilt as it rises to the surface. Evidently Solomon
Andrews spent some time as a boy fooling around with pine boards down at the
swimming hole, because that's exactly how the Aereon was supposed to work.

The airship consisted of multiple balloons held within a
light framework, making a broad and flat shape. The intrepid aeronaut rode in a
basket underneath, and controlled the gas valves and ballast. Tilt the nose of
the ship up in the direction you want to go, drop some sandbags, and shoot
away! Once you reach maximum height, tip the nose down, valve some gas, and
glide back down again.

Andrews built it, and flew it in front of a large crowd.
Witnesses said the Aereon defied the winds and returned to its takeoff point.
The trouble is, it shouldn't have worked. Air isn't as dense as water, so there
isn't as much resistance, especially at the slow speeds of an ascending gas
balloon.

My guess is that Andrews got lucky with the winds on his maiden
flight, knew he'd gotten lucky, and that's why he dismantled the Aereon after
its test flight and never took it up again. Otherwise he could have made his
fortune and reputation as the Father of Aviation forty years before the Wright
Brothers and Count Zeppelin.

An alternate history steampunk story can handwave away the
petty objections of aeronautical engineers and their so-called "laws of
physics" and fill the skies with clean, fuelless Aereons gliding and
darting about. The secret of the Aereon can be the MacGuffin that Sinister
Forces are desperate to learn or suppress. The relative independence of an
Aereon means it's ideal for sky raiders over the Wild West or the high seas.

 Next time: where's my flying carriage?