Lodge Model B igniter
In the course of his experiments into electrostatics Sir Oliver Lodge found out how to make sparks in adverse conditions (wet and oily, poor insulation etc.) by a fundamental understanding of difference between sparking under what he characterised as "steady strain", the 'normal' situation where 'plus' and 'minus' charges build up on opposing conductors until the insulation between them (e.g. air) breaks down and a spark passes between them in "a prepared path" and the alternative "impulsive rush". In the former situation everything has to be dry and well insulated but for "impulsive rush" the conditions are different and produce sudden rushes along uninsulated conductors.
In his own words "These sudden rushes along uninsulated conductors had been specially emphasised in my experiments with the Leyden jars. There is nothing absolutely new in these experiments. Everyone knew, if they thought, that a circuit had to be completed whenever the knobs of two Leyden jars sparked into one another, or, in other words, that an insulated Leyden jar could neither be charged or discharged. When a charge leaves the inner coating, an equal and opposite charge must leave the outer coating. But the consequences of this knowledge had not been emphatically called attention to. The peculiarity of the discharge from the outer coating is that, before it occurs, the coating is at zero potential, and consequently no prearranged path for the discharge can be prepared: it has, so to speak, to take any path that is open to it, in a hurry..............One might have two plates fairly uninsulated and each connected to the outer coat of one of a pair of Leyden jars standing on a table, or otherwise roughly earthed,. The two knobs being now charged by a Voss machine, oppositely, whenever they spark into one another the opposite charge leaves the outer coatings of the jars, and give an unprepared flash whenever they can. If they are prevented from doing this, neither can the knobs be discharged, except in a partial, hesitating and leaking manner."
The spark from the previously nil potential outer non insulated coatings was the basis for the invention of the Lodge igniter which lead directly to the sparking plug which totally revolutionised the development of the internal combustion engine at the beginning of the twentieth century and was applied for this purpose by Lodge's sons, Brodie 23 and Alec 22 who set up the company Lodge Bros & Co in 1903 (with minimal capital) to market the invention.
Their first product in 1903 was the Lodge Model B igniter using a Leydon jar, (No Model A was ever manufactured - presumably it didn't work properly). This is a critically important "World First" which is offered for sale here. There is modest damage to the case but otherwise it seems likwe a good example. I have no real idea of just how rare examoples are today but "certainly not common".
There is an interesting historical follow-up to this first product. "Towards the end of the war the development of the jet engine demanded fresh thought`about ignition, for in the absence of cylinders a single jet-igniter took the place of the vast array of sparking plugs needed in a conventionally driven aircraft (as many as 244 in an airliner with four piston engines). Once more Lodge worked out a satisfactory answer in an untried field that today (1956) its jet-igniters are the only type used in the jet-engines made by Rolls-Royce and De Havilland. And by chance it was found that the circuit employed by Sir Oliver Lodge in his original "B" spark igniter system was ideal for the new engines."
The plate on top reads: "Lodge Igniter Type B For One Cylinder Engines Only Lodge Bros & Co Birmingham". Size 4,5" (115 mm) x 3.5" (90 mm) x 7" ( 178 mm)
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