Late 1700s Frictional Static Electric Machine
This extraordinary piece of history was sent to me by Andy Barr.  Andy has a fantastic barber shop that he converted into a part
time museum decorated with electrical, scientific, industrial, and medical apparatus.

This machine was from the late 1700s and was found in a barn 30 miles outside of Philadelphia.  Not only was it existing in the 
earliest days of The United States Of America, it was sitting in an area where the  likes of Benjamin Franklin and Joseph Priestley
lived, two of the greatest minds, philosophers, and electrical pioneers of the 18th century.


To operate this machine, the glass globe or cylinder was hand cranked clockwise with your right hand. 
 As the cylinder turned away from you, a leather cushion covered in an obscure metal alloy generated static electricity against the glass, 
which was collected by the row of points in the back that stored electricity in the long brass cylinder behind the machine.



Normally the points of the collector would be very close to the cylinder, but given the age of this priceless machine I simply have the
collector next to it.  I don't want to risk scratching the glass, and being such a fragile machine it will not be one I demonstrate often.

Here is a detail of the "rubber", not rubber really but something "that rubs".  It is a mahogany block with one end terminating in 
a horse-hair stuffed leather cushion.  The surface of the cushion against the glass is covered with a layer of amalgam...



The crank on this is amazing on its own.

An iron crank that terminates in a tapered square...

It rides in a broached square hole in one of the wooden end caps...Note the slot is used
to take up any mechanical differences in the tolerance of things as it rotates.

The other end is a centre that is cast with a lead bearing material so that it rides smooth.









Here is the machine as it first arrived...

Making the brass collector from doorknobs and brass pipe.  To seat the knobs properly, the ends of the pipe
must be chamfered heavily...any sharp edges after assembly would leak whatever electrical charges were collected as fast
as they were generated...

Now it needs a good polish...

Sanding the finish...

Near completion...

We put an English brown patina on the collector to age it...

This is electrical amalgam, something that existed from the 1700s until about the 1830s... I don't think its been made since.
It consists of (by weight) 50% tin and 50% zinc, combined with an equal weight of mercury.

By stirring, a new alloy or "amalgam" forms which starts off like chewing gum and gradually hardens to a solid but very ductile metal.
This metal is ground in a mortar and pestle and applied to the leather cushions using lard to help it stick...
The friction pads here above are for a later form of static machine, and are shown just for reference.

Here is my dear friend Ashley Smith making the friction pad.  Mahogany, horse hair, calf leather, and tacks...
She also made the electrical amalgam and helped with the patina of the collector.  Ashley is a master
craftsman of many fields, and is a top Harley mechanic.  I'd say she is the next big thing in the motorcycle world,
but that wouldn't even scratch the surface of her potential...she's a  female Jesse James and a true Rosie the Riveter for
the next generations...and is a real honor to work with.  

Here is a book from 1759, quite a bit older than our own country...

Note the priceless 1757 Philosophical Transactions article on "The effects of electricity in Paralytick cases" by Benjamin Franklin.
Years later, this sort of machine was used to treat those cases, and also study the basic properties of the new field of "electricity".


Endless thanks to Andy Barr for his generosity, and to Ashley Smith for her valuable help.
One could live a lifetime and never experience such a rare piece of electrical history...
and being from Philadelphia in a time when the country's most brilliant minds in this
field were alive and prospering, well, there is no telling this machine's real history
and significance...suffice to say it's "priceless" in the true sense
of being absolutely magical in every sense!







(C) Jeff Behary , 2013