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.
_Directions to Workmen for fixing the Governor and Gas Metre._[49]
[49] Copied from Messrs. Clegg’s and Crossley’s printed directions to workmen, for fixing governors and gas metres.
The governor must be fixed perpendicularly, so as to admit its floating vessel _u_, _x_, _y_, _z_. Fig. 4, plate III., or fig. 9, plate III., to be taken out of the outer case of the machine if occasion should require it.