In Caverns Below by Stanton A. Coblentz — Read

The Ventilating Company, as I soon discovered, was the most powerful corporation in Wu. It was literally the breath of the country, for it controlled the fresh air-supply, and, with the aid of ninety-six subsidiaries, was said to be highly influential in finance, politics, and war. Owned by a group of First Class citizens, who supported themselves in luxury on a fraction of their dividends, the Company was declared to number Dictator Thuno Flâtum himself among its stockholders; hence its interests were carefully considered in the councils of State, and a recommendation of its Directorate was tantamount to the enactment of a law. It was common gossip that more than one war had been commenced on the decision of the Ventilating officials, and that the current conflict with Zu had been stimulated by them, owing to the fact that the workers had been threatening a strike, and that it was believed that they needed something to distract their attention.

Whatever one might think of the management, one could easily understand the influence of the Ventilating Company. Truly, it brought a marvelous service to the people! The more I observed the vast system of air-tubes and wheels, the more I admired the ingenuity of its creators. I was informed how ventilating pipes, opening in narrow ducts in the Overworld, received a constant supply of the fresh air that always blew in that uninhabitable domain; and I was told how this air, forced downward by mighty pumps operated by the power of Mulflar, was delivered in pipes and conduits to every gallery, chamber and private residence in Wu. This it was that kept the air always fresh and sweet, and that had averted those noisome odors usually found in underground passageways. Yet stop the ventilating wheels for a few short hours only, and the whole country would be faced with danger of suffocation. Little did I realize what a deadly advantage I was later to find in this fact!