[1730]. Appliance for indicating depth of water in a cistern by an air bell and pipe connected to a U water gauge. The pressure on the air in the bell varies with the depth or head of water above it, and is indicated on the gauge. A modification of this is employed for sounding at sea.

Weights of substances may be ascertained by their displacement in water or mercury, or by supporting the weighing scale on a free piston resting on an ascertained area of water or mercury, the pressure produced being indicated by a gauge.

[1731]. Micrometer gauge.

[1732]. Radial arm weighing machine.

[1733]. Small weighing device, depending upon the angle the card assumes in respect of the vertical pointer, which is on a free pivot.

[1734]. Automatic measuring or weighing device. The material fills one compartment until it overbalances, when it falls and empties itself; the material then fills the other compartment, and so on.

[Larger plate.]

[1735]. Wet gas meter. The gas enters at the centre, and as the compartments fill they rise out of the water, the gas being discharged at the outer ports into the casing.

[1736]. Measuring wheel.