Governor or Regulating Guage.
The governor or regulating guage, the construction of which has already been detailed, [page 171], we shall here consider as an instrument by means of which the gas flames of lamps and burners are kept of one steady and uniform magnitude.
The velocity of the gas in the mains and pipes of supply, is in the first instance as various as there are differences in the altitude and extent of the mains and pipes of supply. A main, at one place will furnish with a certain pressure of gas, a flame one inch high, while at a different altitude it will furnish a flame double that height.
If again the direction of the pipe has many turns or angles, and contractions, the velocity of the gas will be different on that account, than if it were direct and uniform. And if the pipe is of any great length, and of an uniform bore, but unequally furnished with veins or branch pipes at certain parts, the burners will be very unequally supplied with gas, those which are near its head will be supplied with a fuller stream of gas, than those which are situated towards its termination.
And independent of these differences thus arising from diversity of local positions, there will always be one grand variety in the velocity of the gas, occasioned by the variety of periods during which lights are required by different individuals supplied from the same main or system of pipes, as for example: when a certain number of burners are to be supplied, and it happens that one half of these burners are shut sooner than the rest, then in consequence of this, the velocity of the gas in the mains will be materially altered.
The inequality thus occasioned, may be seen particularly exemplified in the case of houses situated in the vicinity of any large establishment, such as either of the great theatres of the metropolis, and supplied with gas from the same mains. While the theatres are open, the lights in the adjacent houses are low and feeble, often too much so for the necessary purposes of the consumer, but the moment the theatres are shut, the great quantity of gas which they previously carried off, being transferred to such of the private houses as continue to be lighted, the gas flames at the latter are raised to an extravagant height, and burn with an intensity which makes the gas light partake more of the character of a nuisance than of a benefit.
It may be necessary for the better appreciation of the extent of this nuisance to observe, that it does not arise merely from the excess of light produced, but from the imperfect combustion of the gas, and hence a disagreeable odour is produced. When the flame is suffered to rise beyond the standard height, the combustion of the gas becomes imperfect, part of the gas passes through the flame unburnt, and occasions the source of the offensive odour alluded to, which the gas lights never produce when the combustion of the gas is complete. The remedy for all these inconveniences thus resulting from the various degrees of velocity of the gas in the mains, is to be found in the instrument now under description.
The effect of this machine, as already mentioned, is, that it causes the gas to issue from the aperture of the burners or lamps with one uniform velocity, whatever may be the variations which take place in the pressure which urges the gas to pass through the pipes of supply. And such is the efficiency of the operation of the machine, that it regulates the flow of the gas through any burner, tube, or opening, with a greater degree of exactness, than the centrifugal apparatus, regulates the action of the steam engine.
The construction of the regulator to effect this purpose is precisely similar to the apparatus already described, [page 171]. When applied for regulating the magnitude of the gas flames, it is of course usually made much smaller, of iron plates, japanned within and without. Fig. 4, [plate III.], exhibits a perspective view of the machine; a, is the inlet pipe, b, the outlet pipe; P, is the regulating cone, passing through the regulating aperture x, T. The floating vessel u, x, y, z, receives the gas introduced into the machine; A, B, C, D, is the outer air tight case of the regulator.