O is for Oratorium
Oratoria are tall, slender stone towers constructed according to the secret specifications of the Guild of Aethereologists, allowing nearly instantaneous communication over very large distances. As the costs of building an oratorium are exorbitant, only the largest cities can afford one, and for a city to boast one brings with it undeniable prestige. In addition, a handful of wealthy nobles and merchant families have commissioned the guild to erect a private oratorium on their estates in the last three centuries, though this private ownership is very rare indeed. Depending on the size of the oratorium, one to eight apprentice Aethereologists are expected to be present to maintain the complex devices in the top of the tower, called the machinaria, as well as perform the necessary mathematical calculations to establish the two-way communication. This of course brings with it even more expenses. City-owned oratoria are usually reserved for the affairs of the town council and public servants, though in many cases well-to-do citizens can schedule an appointment for the use of the structure, rates depending on the requested time slot and duration. Certain rich ladies are known to talk with friends and relatives in distant cities in this fashion on a daily basis.
The exact workings of the oratorium are a jealously guarded secret of the Guild, though it is speculated that the process is of a mechanical nature, rather than magickal. Through a series of precisely calibrated convex metal disks, the vibrations of sound are carried through the Aether at a much higher acceleration than in ordinary circumstances; an array of attuned concave disks on the receiving end capture the message and disperse it throughout the turret room. The resulting dialogue is not unlike having a conversation with an invisible interlocutor in a hall of echoes. The nature of the process, however, limits the communication to previously determined points. Each machinaria can only send and receive to one other attuned location; if one desires to talk to another location, both ends must align themselves accordingly. This request is usually send through conventional means, such as couriers or carrier birds, though in emergencies a message can be sent through the network of oratoria, each location relaying the request for direct communication to the ultimate recipient. To combat this problem, large oratoria can house up to four different machinaria, each one directed at a different location.
Understandably, the attendants of the Guild are obligated by their employers to take an oath of secrecy, as valuable information that could make or break fortunes and cities passes within earshot of one of them every day. Though the confidentiality provided by the Guild is legendary, the Aethereologists have indirectly benefited from their foreknowledge on many occassions, and become powerful and wealthy in their position as information brokers.