1 large adjustable spark gap with 1/2 mm separation scale from 0 to 100 mm. Balls plated brass; silver coloured. For detecting spark transmissions following Hertz's method.
large concave mirror set in dark wooden frame. In style of demonstration equipment from first half of 18th century and may well date from then. Original would have been held in a mirror stand.
18 small glass beads, all but one numbered. In circular wooden box. Instructions for use on paper stuck inside lid. Likley to be the box of spirit bubbles' purhcased in 1833 by Prof William Knight.
