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1. To “feed the arc" as the carbons are continually burning away (like a match) ; if the gap
between the carbons becomes too great, the arc will be lost. The resultant "black out"
stimulates a savage response from the audience.
2. To correct alignment of the carbons for most efficient operation (there are two controls
for this purpose);
3. To provide vertical adjustment to centre the arc crater in the optical axis;
4. To provide horizontal adjustment for centering the arc in the optical axis;
5. TO tilt the arc to get the best crater angle for even coverage across the screen.
As well as these adjustments the whole arc assembly could be moved back and forth to focus the
maximum amount of light on to the picture aperture.
The Travelling Picture Show Men faced another problem too. Up to the 1940s some country
towns had no electric power at all.
Others with power had a variety of voltages, some AC some DC, and often with a limited or
fluctuating current supply. So, to be on the safe side, the showmen carried their own DC
generators. Huge heavy things that they drove from a pulley on the back axle of their old Ford
Van.

After unloading the projection plant and lugging it up the back steps into the "Bio Box", they
would jack up the back axle of the Ford, put a flat belt on the pulley (attached to the axle) then
after positioning the generator, slip the belt over its pulley. At showtime they would start the Ford
engine and it would chug away happily all night generating power for the arc. Some Picture Show
Men used a stationary engine like the single cylinder De Dion (illustrated below) to power the
generator in both permanent and travelling Picture Shows.
In the 1930s arc design was greatly improved with the use of horizontal arcs and large elliptical
mirrors, bigger and better power supplies and copper coated hi-intensity carbons. But that's
another story.

Today the early limelight burners are very rare beasts and the old vertical electric arc assemblies
are an endangered species too. They deserve to become collectors’ items, so, now that you know
their story - go to it.
Finally, I take my hat off,
not only to those
wonderful old time
Showmen but to the many
highlyskilled professional
Cinema Projectionists of
the golden years who made
sure that the show did go
on, with a pride and
standard of presentation
that made "going to the
pictures" something special
for generations of
Australians. Today, sadly,
the computers have taken

10 REEL DEALS September 2020