1851 Great Exhibition: Official Catalogue: Class V.: W. K. Whytehead

101. WHYTEHEAD, W. K. — Exhibitor.

• 1. McNaught's steam-engine indicators, for measuring and recording pressures; used principally for ascertaining the power and working order of steam-engines, for which purpose, a communication is made between the cylinder of the engine and the cylinder of the indicator. The varying pressure of the steam acting on the piston of the indicator, raises or depresses the pencil in opposition to the internal spiral spring, and registers itself on the paper.

[To ascertain by this apparatus the pressure at various points of the stroke of the engine, the paper is moved by a string attached to some working part of the engine, so that its motion may coincide with that of the engine piston. By the shape of the diagram thus traced, the exact power given out by the engine (as distinguished from "nominal power"), the most advantageous adjustment of the valves, the friction of the engine, the power required by any portion of the machinery, the neglect or attention of the engine-driver, and the friction of the machinery when using different oils, can be ascertained. The instrument is fitted with two springs and a double scale, one for high-pressure steam divided to a small scale, and one for low pressure, to a scale of twice the size. The importance of an indicator may be estimated from the enormous amount of fuel consumed in this country for steam-power, a large quantity of which would be saved were the value of the indicator better understood by the proprietors of steam-engines.]

• 2. Drawing of section of large indicator, showing the construction.

• 3. Indicator diagrams to an enlarged scale.

• 4. McNaught's oil-testing machines. In spinning, weaving, etc., a large number of small spindles are kept in rapid motion, and if lubricated with an inferior oil, their friction, and, consequently, the non-productive load on the engine, is materially increased. A small quantity of the oil to be tested is poured into the cup, a plate is then placed on the top of the oil, and the cup set in rapid motion. The plate is dragged round also, by the tenacity of the oil, and raises the weight on the steelyard• by adjusting which, until an equilibrium is established, the friction of the oil can be read off on the scale. Invented by W. McNaught, C.E., of Glasgow.

• 5. Design for the application of McNaught's patent expansive principle to a 30-horse engine. By this plan, high-pressure steam can be applied with safety to engines which have been designed originally for low-pressure steam only. A small cylinder is applied at the crank end of the beam, at about half-stroke, and the steam from it passes into the existing cylinder, where it expands, and whence it finally escapes into the condenser, in the usual way. By this means, a saving of from 30 to 40 per cent. of fuel is effected, and the power of the engine may be increased, if desired, to the same extent.

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