Also called an aethographic transmitter (although properly that is only one half of the machine, the other being an aethographic receiver). This is a wireless communication apparatus that does not suffer from electromagnetic disruption like the telegraph (which was abandoned as a failure). Two machines with matching valves (properly termed crystalline valve frequensors) can transmit messages through the aether to each other. The message transmitted is called an aetherogram.
There are a little under 100 aethographers in the United Kingdom at the time of Changeless.
Each machine is very large, with two rooms: one containing the aethographic transmitter for sending messages and the other containing the aethographic receiver for retrieving messages. 
A prototype of the valve used in these devices was stolen by Monique de Pelouse in Etiquette & Espionage. Several groups sought to acquire the prototype, including Mademoiselle Geraldine's Finishing School for Young Ladies of Quality, a group of flywaymen, and the Picklemen.
A metal plate with the message to be sent is placed in a frame and exposed to chemicals that cause phosphoric burn of the message's letters into the plate. The device spins two counter-rotating hydrodyne engines which generate opposite magnetic impulses, sending needles racing across the metal plate. These needles throw a spark wherever there is a gap from a burned-in letter. This spark creates a distinct radio wave which bounces off aether and is received by a second machine with a matching transmitting valve. 
A skilled operator must tune out all ambient noise. The receiving room contains two large glass plates with magnetic particles suspended between them. Letters from the transmitted message appear two at a time on the receiving sketcher component and are recorded by the operator before the next set comes in, erasing the first. The operator must then decide where spaces go in order to decipher the message. 
The Aethographor developed and patented in the United States in 1867 by Samuel F. B. Morse after the failure of his previous invention, the Morse Telegraph (which was not compatible with ambient aetheromagnetic gasses).
- "Espionage in the Aether: Security Challenges Inherent in Aetherographic Transmissions," a guest presentation by Micah Lee.