At top left is the reference to water-cooled gramophone pickups, though they are described as 'transmitters'. The writer seems a bit confused because the water was for cooling, while the steam jacket on a steam engine cylinder is there to keep it hot, and so improve its efficiency. The need for cooling suggests that the gramophone pickups worked on the same principle as a carbon microphone; it would have to generate a hefty signal to drive 100 subscriber lines, and so a big current had to flow through it. The signal from the 'transmitters' was almost certainly passed through step-up transformers to match the impedance of the lines.
The image is not of stunning quality. but shows five turntables with tone-arms that have a big box over the needle end and a bigger box over the pivot end. This is consistent with a carbon-mic type pickup. On the nearest turntable it is just possible to see what look like two rubber hoses running into the tone-arm, presumably carrying the colling water; this must have imposed seriou side-loads on the needle.
There is a Wikipedia page on the system, which it calls the Tel-Musici system; no technical information is given. Where that name came from is currently unknown; it does not appear in the Popular Electricity article, and Googling has so far yielded nothing. The Wikipedia page says that 'Magnaphone' was actually the name given to the special loudspeakers used by subscribers.
Source: Popular Electricity, Dec 1912
