Comprising a strong U-shaped magnet and a pair of brass rails with 4mm socket terminals. A brass axle with plastic discs is free to roll along the rails and completes the electrical contact between them. When the axle is placed on the rails between the poles of the magnet and a power supply unit is connected, the axle is repelled and rolls along the rails away from the center of magnetic field. Dimensions 175x60x58mm high.
Gravesande's, ring mounted in rod with handle, ball with chain. Cold ball passes through the ring but does not pass when heated the ring & the ball with separate handles.
To illustrate expansion of metal on heating and contraction on cooling, with steel bar of length 100 x 10 mm and plated brass gauge with a cut-out to just accommodate the bar and two holes through which the bar passes when cold.
For demonstrating the conversion of electric energy into mechanical energy. Star-shaped copper disc 9 cm. Diameter rotatable vertically on pair of adjustable centers and dipping into mercury trough between the vertical limbs of a small horseshoe magnet on a wood base 15x 10 cm. Disc adjustable vertically on metal pillar which is connected to one of two terminals mounted on base. The other terminal is connected to the mercury trough. The apparatus will operates on 4 volts at which voltage it takes 1.8 amps., without battery.
Pipette type, comprising glass float calibrated having coloured zones for charged, partly charged and uncharged conditions. Compressible bulb and rubber tube with fittings to glass body.
