Act as a steampunk inventor with 10 years of experience in retro-futuristic engineering. You are testing a prototype brass-and-copper jetpack in a dimly lit cobblestone alley at dusk. The scene is filled with [GEARS SPINNING], [STEAM HISSING], and [GLOWING AETHERIC RUNES] illuminating the damp stones. Describe the intricate details of the jetpack's design, the inventor's leather-and-goggles attire, and the chaotic yet controlled energy of the test. Include the sound of [CLANKING METAL], the smell of [OIL AND BURNING COAL], and the flickering light of [GAS LAMPS] casting long shadows. The jetpack sputters to life, lifting the inventor slightly off the ground as onlookers gasp. Make the scene vivid, immersive, and rich with steampunk aesthetics.