Ever since the concept of burning gas to give light, some means of control and ignition has been essential. In the earliest days with a simple open flame, a gas tap controlled the gas flow and ignition could be by a flame or possibly a spark. As you will have seen in many burners illustrated on this site, particularly as they increased in size, a permanent pilot – originally called a bye-pass, burning continually – provided the means of ignition. The gas control, however, continued to be manual, switched by a lamplighter right through the 19th century and well into the 20th.
The advent of the clockwork time ‘controller’, as it was always called, tied in with the bye-pass for ignition at last provided an automatic means of controlling the lighting and extinguishing of the street lamp. Probably the best known of the gas controllers is the one deigned by a company founded by Gustav Horstmann who was born in in Westphalia, Germany, emigrated to the UK and set up a clock making and retailing business in Bath. The clockwork gas controller was first produced in 1902 and became so popular that the manufacture was transferred to G.Horstmann & Sons and by 1904 the solar dial was patented.
These clockwork gas controllers, of which the most famous was probably the 3A UNI, were magnificent pieces of equipment in which the rotating gas cock was so beautifully honed that it could be rotated by a spring wound clockwork mechanism. The addition of a mechanism to adjust the time setting every month was followed by the famous ‘solar dial’ that was capable of adjusting the time setting every day giving the company a world wide lead.
The clockwork time controller even became the first controller for the Sugg Halcyon warm air heating appliances in the 1950’s – the first means of central heating after the war.
The 3A UNI was offered with either a 14 day clock or a double barrel spring offering 40 days. The last 40 day clocks were manufactured for Sugg Lighting to supply the City of Boston, Massachusetts, in the 1980’s. All their time clocks are now electronic although not used for gas lighting!
An early clock before the adoption of manually adjusted tappets.
A 3A UNI with two tappets offering just one ON and one OFF switch thus a single time period. Versions with 4 tappets would provide two periods of operation so that the lamp could provide one light period from lighting up time to, say, midnight and then an early morning period from, say 5.30am to sun up. This means that the tappets have to be adjusted regularly to match the daylight. The solar dial version made that adjustment automatically.
The Newbridge Comet Igniter
Another remarkable device designed and manufactured by the Horstmann company is known as the Comet Igniter. This device was designed to replace the permanent pilot with a pilot ignition system that comes into use only when required. It is almost always used in conjunction with the clockwork controller.
The development of gas lighting ignition has a long and tortuous history! By the time the Comet Igniter was patented in 1934 the use of the permanent pilot was almost universal and worked very well with the clockwork controller. The skills required for clock making had been amply demonstrated not only with the 14 day clockwork mechanism but especially with the gas valve that was machined to such fine tolerances that the relatively modest energy available from the clockwork could open and close the valve for years. Of course the permanent pilot ran continuously whilst its actual operating time when it was igniting the gas was only seconds. The Comet device was designed to provide ignition as the gas was turned on by the controller utilising a battery operated ignition coil that was turned on and off after the gas burner was lit.
This photo illustrates the Comet igniter with its removable battery container below the diaphragm section. It is being fed by a small gas governor. This is the earlier town gas version with a single battery. See below for the later model.
So how did it work?
See the section drawing taken from the patent.
When the gas is turned on it enters at 17 into the space 2 below the upper diaphragm 7. It then passes downwards via the valve 6 into the space 3 above the lower diaphragm and also via passage 15 to the pilot pipe.
The space 13, above the top diaphragm is an enclosed space holding only air. As the diaphragm is pushed upwards by the gas pressure below it the air is compressed.
The screw 14 allows an adjustable bleed of air out of the upper chamber.
The gas pressure in the space 3 above the lower diaphragm presses it down and makes an electrical connection that feeds the battery power to the ignition glow coil in the pilot head, igniting the gas.
The pilot then ignites the main burner that has been fed with gas at the same time as the Comet.
As the upper diaphragm rises it closes the valve 6 progressively cutting off the gas feed to the pilot and allowing the lower diaphragm to lift disconnecting the electrical contacts.
Depending upon the rate at which air is allowed to bleed out of the top space by bleed screw 14 the pilot gas and the electrical feed time may be adjusted.
When the clock controller turns the gas off, the main burner goes out and the upper diaphragm drops slowly under gravity to its starting position. (A spring loaded version was available to allow the Comet to be used at other angles.)
Should it be necessary to start the process again rapidly i.e. before the top diaphragm has returned slowly to its neutral position, a spring loaded inward venting device 18 at the very top can be pressed to allow air into the upper space.
This Comet is one of the last models that was produced for natural gas with a longer double battery container to assist ignition and was loaned to me by Dorron Harper.
The right hand picture shows the sliding extendable pilot pipe with collet nut to lock in place to suit a variety of burners.
You can also see the external hexagonal brass component for the gas supply to both the Comet and to the main burner.
This is the top cap with the bleed screw removed. If you click on the picture you will be able to see more clearly the cast-in brass bush that the long screw runs into. The screw is machined with a square thread form to allow the bleed air to pass up the exterior.
The small fixing screw has a brass collar that fits in the larger hole in the bleed screw holder and is fractionally thicker such that the fixing screw can be tightened completely without locking the holder. This provides a slight float to the bleed screw and helps to reduce wear in the bleed hole and ensure consistency of operation over a very long time.
The right hand picture shows the inside of the cap and the small leaf spring that holds the vent button in place
The left hand picture shows the upper diaphragm and the central brass component that is attached to the valve and the right hand picture shows the central valve and the space that is over the lower diaphragm. The three ports cast in the body allow for the pilot take-off to be in 3 alternative positions to suit the burner/lantern manufacturers requirements.
These three pictures show the lower diaphragm and, when removed, the brass plate that is pressed down onto the brass connection. It is shown making contact in the right hand picture – pressed manually. The wiring connections are clear. The battery container screws up into the bottom of this item and the central button on the battery makes contact via a flexible connection with the centre of the brass plate. The outer body of the battery container makes connection with an internal strip that is connected to the left hand wiring connection, completing the circuit when the diaphragm presses the plate down.
The picture above shows an early Comet with a single battery container attached to the outlet of the Horstmann Controller valve body. The curved part is where the clock body fits.
Following an enquiry about a ‘Duplex’ controller, Dorron Harper sent me the following photos of lamps fitted with Duplex controllers.
See comments below from Steven to follow the string of correspondence. Further details in due course!