Beverly could feel the thump of big Stirling engine No. 6 roll through her body, and thought with excitement, The Heart of the City is actually beating in my chest!
Thirty-two thumping engines, each twenty meters tall and sixty long were ranged more or less symmetrically around the circumference of the envelope. They capitalized on the temperature difference between the air and ice outside the envelope and the steam jets originating from geothermal energy coming from deep in the ground below, where the molten rock was still hot and close to the surface.
Engineers worked hard – had in fact built entire complex systems – to keep the Stirlings desynchronized as they generated the life-giving electricity the city required. Once, when she was seven, the systems failed and the huge engines, rolling through their endless but minutely varied cycles, eventually all fired at once in a single city rattling convulsion that caused massive city-wide damage. Windows shattered all across the city, water mains broke, and a four story building had collapsed.
Most distressingly, the envelope had suffered the first of only two unplanned breaches in its 130 year history. A lot of heads rolled too, and in the intervening 12 years there hadn’t been any more failures until No. 17 had been all but destroyed when the envelope was compromised during the attack last year. It wasn’t expected to be operational again for another six months.
And there was old No. 6, affectionately known by various names, such as Old Faithful, Lady Liberty, and by most; The Heart of the City. No. 6 was the last of the original eight energy pumps created in the early days of the envelope and the city, and she pumped louder than her sleeker, more modern sisters. Stronger, somehow, like it mattered more.
Standing here atop No. 6 next to the this windows of the access airlock, Beverly could see outside to the brightly lit staging platform standing out in sharp relief against the heavy grey of the sky. But the exhilaration of being here waiting for Sam and his survey team to return from their sortie outside the envelope paled in comparison to the childish thrill of being this close to the big engine and feeling the deep, heavy throb of the mythical machine rumbling through her ribcage.
The Heart of the City is actually beating in my chest!