Oh and a big thank you to Zen Wickentower for his consulting regarding many things Steampunk. He really gave me some fine input!
Here we go:
A is for Aether
|Aetherous entities at Pteron|
Also called luminiferous aether, æther, or simply ether for its friends. The concept of aether in Steampunk is based on the 18/19th-century theory that aether is the medium which was responsible for the propagation of light, electromagnetic waves and gravity. It was first postulated by Aristoteles in the 4th century B.C. as the element which fills the region of the universe above the terrestrial sphere. For alchemists it is the 5th of the classical element and the material all heavenly bodies and - to a much lesser portion - all terrestrial do consist of.
Creative Steampunk scientists have found many applications for this exotic material and its at times bizarre qualities. You can find it in ray-guns and aether-rifles (using aether catridges instead of conventional and much more boring bullets), specially designed aether-armor, propulsion systems, in detectors for supernatural beings, in powerplants. aether-ships (which are sailing on aether winds between the stars), in monitors, time-machines, dimensional portals and potentially in everything glowing, flashing, buzzing and sparking.
Despite the many ways aether is used its far from being tamed or completely understood. It is the material supernatural beings often consist of and its always good for big and small disasters. Often with pretty spectacular effects (rare footage of an aether experiment can be found here, well... sort of).
B is for Brass
|Oooh! Shiny brass!|
Brass is one of THE definite materials for Steampunk constructions! Being an alloy of copper and zinc it has a nicely golden colour which makes it ideal for shiny fine mechanics like gears (lots of them!), pipes, vents and alike. Its used widely (and wildly) for all kinds of gadgets, accessories, goggles, furnitures, tools, (music)instruments, weapons, artificial limbs, etc, etc.
Therefore brass has a much nicer job than it's rugged brothers steel and iron, which are much better suited for heavy constructions, frameworks, boilers, ship hulls etc. Its always a good idea to decorate or brace your creations with brass ornaments - there can't be a "too much" (see "Overengineering")!
C is for Clocks
|A Steampunk Clock!|
Clocks are one of the most important items for a Steampunk! No matter if they are room-decoration, fashionable accessory, components of time-machines, time-bombs or evil machineries to take over the world. Steampunks love their clocks! The more the better! Clocks are cool because they have nice clockfaces with fancy letters and lovely ornamental clock-hands and a clockwork with (I hope you guessed) tons of gears!
Steampunks usually love to tinker with clockworks and if a construction doesn't has lots of gears and springs which happily move and turn and ticktock along, its likely that it won't work at all!
Mechanic clocks combine both traditional elegance and technology in perhaps the best possible way and are therefore one of the definite icons of the Steampunk culture. If you don't get the clock-thing, you surely won't get whole steampunk-thing too.