Hydraulic Phonograph Pickups

Gallery opened 24 July 2018

Updated: 3 Aug 2018

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Chichester Bell, first cousin of Alexander Graham Bell, the telephone pioneer, did a good deal of work on hydraulic microphones. An offshoot of this work was a patent for a bizarre of way of reading information from recorded discs and cylinders, taken out by both Chichester Bell and Alexander Graham Bell, with a Mr Tainter making up a trio. This was US patent 341,212 on May 1886.

The basic notion was to use a jet of gas or liquid to trace hill-and-dale grooves; the patent text suggests either can be used, though their behaviour would surely have been quite different. It seems to me very unlikely that a gas jet could give any useful results; I am far from sure that the liquid version would give any either. The idea was to direct a narrow jet at the groove and detect small pressure variations as the hill-and-dale profile moved past it.

Left: The Bell/Bell/Tainter pneumatic phonograph pick-up: 1886

This version in Figure 1 of the patent is pneumatic, using air at a pressure of 1 to 1.5 psi; apparently higher pressure gave louder reproduction. The nozzle is about 1/30 inch in diameter; it has a cap 159 around it, and this cap is placed closer to the record than the nozzle, approx 1/50 of an inch above the record surface. Air emerges from the cone-shaped nozzle and its flow is modulated by the hills and dales in the record groove. Here is shown a vertically mounted recorded disc F, which is moved up or down by the enigmatic mechanism labelled C, so that the nozzle stays in alignment with the record grooves.

156 is an ear-piece so the pressure variations can be heard. 157 is a rubber diaphragm to prevent the air escaping. The text of the patent states that this may instead be connected to the tube 160. Frankly the description of operation is all a bit vague.

As to the practicality of this arrangement, my hopes are not high. The nozzle needs to be very carefully aligned with the record groove, without any mechanical stylus to track it. Clearly varigroove isn't going to work. As to the linearity of the groove & jet process, I can think of no reason why it would not be highly non-linear.

From US patent 341,212 of May 1886

Left: The Bell/Bell/Tainter pneumatic and hydraulic phonograph pick-ups: 1886

Here are two pneumatic and three hydraulic phonograph pick-ups from US patent 341,212; these appear to be intended to work with phonograph cylinders rather than discs. The passages in quotes are taken directly from the text of the patent.

"In Fig. 6 the sensitive air jet plays against a flame from a pin-hole burner, and produces sounds in the surrounding atmosphere."

"In Fig. 7 a liquid (water) is used. It enters the tube 173 under a head of, say, four feet, and the sensitive jet plays upon a small rubber membrane, 177, stretched over the end of the sound-conveying tube 178."

"In Fig. 8 the sensitive jet of liquid plays against a lighted gas-jet from a pin-hole burner a little to one side of the axis of the flame." Presumably the gas flame then radiates the sound.

"In Fig. 9 the liquid (which must be a conductor of electricity and is preferably water acidified with one part by volume of sulphuric acid of 66° Baumé, free from lead, to three hundred of water) plays against the end of a platinum wire, 179, embedded in a block of hard rubber, and spreading out in a thin film makes contact with a platinum ring, 180, surrounding the end of the block. The wire and the ring form the terminals of a galvanic circuit in which a telephone is to be placed in order to receive the sound." This is the same arrangement used in some hydraulic microphones.

"In Fig. 10 the tube 181 has its end in close proximity to the record. The air in the tube being thrown into vibrations by the recording presses similar vibrations upon a sensitive air-jet issuing from the tube 182 and playing upon the receiving-tube 174."

Somehow I'm having trouble believing that any of these methods are at all practicable.

From US patent 341,212

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