Air Tunnel
A means of sending trains through the air.

Through the Air Tunnel (1929)

Aircab
A flying autonomous taxi cab.

The Barrier (1934)

Atomic Percolator
Make coffee with radiation.

The Golden Girl of Munan (1928)

Beam Car
A vehicle like an elevator car, but which travels on a radio and magnetic beam, from the surface of a planet up to a satellite.

Lost City of Mars (1934)

Flame Pistol
A hand-held weapon that incinerates opponents.

Invisible Ships (1931)

Flame Projector
Handheld device shoots flame.

Water-Bound World (1932)

Gateway
A device that opens a portal to another dimension.

Wanderer of Infinity (1933)

General Strike of the Robots
All over the world, robots cease their labors.

Rex (1934)

Harvest Power From Stray Energy
A means of collecting enough energy from stray electronic impulses to power a device.

The Golden Girl of Munan (1928)

Levitators
Allows free flight in the interior volume of a vast sphere in space.

Lost City of Mars (1934)

Neutralizing Wall
A barrier that stops electrical and mechanical vibrations, rendering the protected area effectively invisible.

The Golden Girl of Munan (1928)

Optophone (Opto)
A video call system.

Too Many Boards! (1931)

Polyceltron Iconoscope Televisor
A portable camera and microphone setup that could broadcast on-the-spot news.

Newscast (1939)

Ray-Pistol
An early version of the raygun.

The War of the Planets (1929)

Robot Skin Covering
Realistic covering for the bodies of robots.

Rex (1934)

Robot-Control Wave Band
Special command circuit for robots.

Rex (1934)

Robot-Surgeon
A perfect robot for perfected human beings.

Rex (1934)

Rocket Float
A sea-going floating platform for rocket launches.

Too Many Boards! (1931)

Self-Aware Robot
A robot that thinks and reasons for itself.

Rex (1934)

Silica Sphere (Dyson sphere)
An enclosed environment, excavated on Mars, and then placed into the heavens (it's Phobos)

Lost City of Mars (1934)