Chalk River Electrometer
This instrument, a variant of the Lindemann electrometer, was built at Chalk River Canada, probably in the 1940s. It has been opened up so that its internal structure can be seen. In the photograph above, a screw-on cap (held by a beaded chain) at the bottom of the unit protects the electrical connection for an ion chamber.
The quadrants are of a different construction than the flat plates of the Lindemann electrometer. If viewed from the side, each quadrant looks somewhat like the letter "F."
The sensing element is a short (ca. 2 cm) rigid fiber that is attached at the middle to a taut suspension fiber. The latter is attached at each end to a vertical post.
In the photograph to the right, the moveable quartz fiber, but not the suspension fiber to which it is attached, is barely visible.