`A physical experiment which makes a bang is always worth more than a quiet one. Therefore a man cannot strongly enough ask of Heaven: if it wants to let him discover something, may it be something that makes a bang. It will resound into eternity.`
Georg Christoph Lichtenberg 1742-1799
Georg C. Lichtenberg was born in Darmstadt, Germany and if you have not heard of him then get to know him, for his aphorisms, letters and his electrical figures. Like many of his kind he had melancholy, `His body is so constituted that even a bad draughtsman working in the dark would be able to draw it better. I saw the grave on my cheeks,April 16th 1777.`
`A girl, 150 books, a few friends and a view about four miles in diameter, were his world`.
He was very perceptive and was years in front of depth pyschology. Anyway on to Lichtenberg`s figures:-
These involve very high voltages - working in the dark - high risk. For these reasons I will not give technical details of apparatus used to obtain the photographs. The idea here is to give you a look at the figures with minimum detail but interspersed with Lichtenberg`s aphorisms so that ,hopefully, you will wish to learn more of the man and his writings.
There is no reason you should not try a version of GCL`s own experiment but use polythene sheets separated and then sprinkled with Lycopodium. I have never done this but it is worth a try. Perhaps talcum powder would work.
The other thing is to keep an eye open in future and you will begin to find Lichtenberg`s figures in all manner of places - eg the inside dusty case of your computer - on film wound on in sub-zero conditions. I was well and truly duped by this when I set up a camera to make a time exposure of star trails over about two hours. When the film came back from processing there were star trails alright but across the centre was an enormous electrical discharge to one side of the out of focus long wire antenna to the lightning flash counter. I convinced myself that a static discharge had shot out of one side of the long wire immediately above the camera and been photographed `The myths of the physicists -GCL` . The slide was examined at Farnborough and thus I learned of static discharge on films wound on in the camera in sub zero conditions - I have since seen Lichtenberg`s figures flickering across films taken from planes during WW2.
Lightening Flowers are Lichtenberg Figures etched out in the capillaries just beneath the skin when someone is hit by lightning. When the stupified crowd gathered around the even more stupified victim they peered at the strange patterns - "Ahh there be the church". "Aye an there be the hedge up long meadow". "Eer ain`t that you sittin outside the pub?" Of such are tales born.
`He loved pepper and zig zag lines.`GCL.
I photographed the figures which follow as discharges across a water surface. Each is about 8 inches (16cm) in diameter - voltage 8,000 current 100 mA. A figure is described as negative or positive according to the polarity of the centre electrode.
`At the ball, when the company went out to supper, it had settled around a couple of girls like filings around a magnet.`GCL.
A positive figure. More branches appear in positive discharges.
`People who have taken no intellectual food for ten years except a few tiny crumbs from the journals are found even among professors; they are not rare at all.`GCL.
A negative figure.
`God, who winds our sundials`.GCL.
A particularly beautiful positive figure.
`Everyone is a genius at least once a year. The real geniuses simply have their bright ideas closer together.`GCL.
A very brief explanation
The discharge originates in intense ionisation of air molecules between the point electrode and the surface. Ultra-violet radiation produces ionisation of any adjacent molecule. This now is a conducting path and is self replicating outwards - more UV ionises another and so on and the figure develops as branches of current/ions which emit electromagnetic radiation (crackles on radios and light for the photograph). This continues until the stored electricity is depleted.
This was investigated by F.H. Merrill and A. von Hippel - `The Atomphysical Interpretation of Lichtenberg Figures and Their Application to the Study of Gas Discharge Phenomena` Journal of Applied Physics vol.10. No.12. December 1939. I cite this paper because C.E.R. Bruce gave me his copy from which he deduced the Glow to Arc Transition theory of Lightning.
To examine Lichtenberg Figures it is best to take Black and White negatives, on which the figures appear black and detail is very clear. (The same procedure is used to examine star fields).
`The fly that doesn`t want to be swatted is most secure when it lights on the fly-swatter`.GCL
`He had names for his two slippers`.
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