DeArmond

Harry DeArmond (January 28, 1906 – October 12, 1999) invented the first commercially available attachable guitar pickup in the mid-1930s. He established a working relationship with Horace 'Bud' Rowe's company, Rowe Industries, to manufacture and develop these items. The company was located at that time at 3120 Monroe Street in Toledo, Ohio. A DeArmond pickup was famously used on a 1939 English Clifford Essex Paragon De Luxe guitar for the original James Bond Theme. Vic Flick was the guitarist making the recording at CTS studios in Bayswater, London.

They began with four models—two for flattop guitars (the RH, and the RHC), with an integral volume control—and two for archtop guitars (the FH, and FHC with a volume control). Initially called guitar mikes, these passive electromagnetic pickups shared the same wide shallow coil shape with individual alnico 2 pole-pieces.

The RH type flush-fitted into the guitar's sound hole, retained with adjustable springs to minimize damage to the instrument and facilitate removal. To avoid interfering with playability, It projected only a few millimeters above the soundboard and had an edgewise, almost flush potentiometer knob.

The FH type comprised a coil assembly, first in a plain chrome-plated brass cover, a single slot—then finally a two slotted cover fixed to a 1/8" rod parallel to and slightly below the sixth (low "E") string. DeArmond called the rod a pressure rod. Players soon nicknamed the assembly (with pickup) the "monkey on a stick" because of a resemblance to a popular child's toy of the time. The rod ("stick") passes through a small hole on the left side of the pickup (the "monkey"), which lightly grips the rod. This rod clamps to the guitar strings behind the bridge. A half moon shape loop goes around the bridge continuing just short of the fingerboard. The pickup slides along the length of the rod, from bridge to neck, providing an infinite variation in tonality.

The FHC-B has a 12' cable but no volume control, and was commonly sold with a volume pedal. The FHC-C has a volume control (potentiometer) in a small box on the cable, 10 inches from the pickup. Many felt that clamping the rod to the strings helped sustain and tone, as the entire unit vibrates in concert with the strings—and provided a good ground connection to reduce hum. A better ground is achieved by clamping the rod to the strings and using the player's body as a ground while playing. This grounding method is still used today on most electric guitars.

...
Wikipedia