Section 92.—WEIGHING, MEASURING, INDICATING PRESSURES, etc.
[1724]. Weighing by a beam with equal arms. Weights A = package B.
[1725]. Weighing by a beam with unequal arms. Weight A constant; leverage of ditto variable by shifting it along the graduated arm of lever.
[1726]. Graduated measuring vessel.
[1727]. Similar principle applied by compound levers with unequal arms. The table is supported on four points on the arms of levers loosely jointed together in the centre; one lever is extended and coupled by a rod to a graduated lever with sliding weight. Knife edges are used for bearings for all weighing machines by leverage. See [No. 958]. This construction is the basis of most of the ordinary weighing machines in use.
[1728]. Duckham’s patent hydraulic weighing machine. The article to be weighed is suspended from the hook, and exerts a pressure on the ram. The corresponding pressure on the liquid (usually oil or glycerine) is indicated on the pressure gauge, which is graduated to show the weight.
[1729]. Spring balance.
[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.
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[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.
[1737]. Measuring wheel.
[1738]. Double slide measurer.
[1739]. Automatic tipping scale. When full, to equal the weight, it falls and tips by striking a fixed stop; the scale then turns over and returns to its position, and is refilled.
[1740]. An ordinary piston and cylinder are often employed to measure liquids, and fitted with a reversing valve on the same principle as [Nos. 1026], [1027], and [1741]. See also [note] to [Sec. 93].
Most of the rotary devices (see [Section 75]) have been employed as meters for liquids and gases. See [No. 1692].
Dry gas meters usually employ an expanding bellows, or light piston, with a self-reversing valve, similar to [Nos. 1299] and [1026]. See also [Section 44].