infinitely easier. The best plan of all, however, is to use an automatic regulator, which not only reduces the pressure so as to permit of the required adjustments being made at the jet-taps, but also maintains a practically steady supply as the cylinder empties, thereby obviating continual readjustments. Regulators are now so inexpensive that they have come into almost universal use, and are generally reckoned an indispensable part of a limelight lantern equipment. The form of regulator in most common use is that usually known as 'Beard's,' having been originally designed and patented by Messrs. R. Beard & Sons, though as the patent has now expired it is open to any firm to make the same article if they desire.
The construction of Beard's Regulator is shown in Fig. 11. The gas enters from below into a rubber bag, C, from which it can emerge through the nozzle.
Any accumulation of gas raises the bellows against the pressure of a spiral spring pressing it down, and this brings into action an arrangement of so-called 'Lazy Levers,' which in turn presses down a small conical valve and closes the supply from the cylinder, this valve re-opening immediately the pressure diminishes.
The outward form of this regulator is shown in Fig. 12,
which incidentally also illustrates the usual form of connection to the cylinder, referred to later on.
In Beard's Regulator the pressure at which the gas can be delivered is determined by the strength of the spiral spring, and can only be altered by changing this spring.
In practice Beard's Regulators are supplied set to a low pressure for ordinary mixed or 'blow-through' jets and for a higher pressure (14-16 inches) for 'injector' jets. At this latter pressure the rubber tubing used must be fairly thick and strong and well tied on, and even so the taps of the jet should not be turned entirely off unless the gas at the cylinder is likewise turned off immediately afterwards. The British Oxygen Company make a regulator which can be set to any desired pressure, but it is not quite so delicate in its action as Beard's, and Messrs. Clarkson also make a pattern regulator which is widely used and well spoken of. The attachment of any of these fittings to the cylinder is a somewhat peculiar one, as will be seen on reference to Fig. 10 or Fig. 12. The regulator or nozzle ends at its lower extremity in a screw and cone, the latter being intended to make a gas-tight connection with the internal cone on the cylinder, and over this screws a loose wing piece with another outer screw, this latter fitting the thread in the cylinder.
In making the connection care must be taken that the wing piece is not screwed too far down the inner screw, or the cone will not reach down and make a tight fit on its