The DuLuc Dry Pile
High-voltage source
©1996 William J. Beaty

The Duluc Dry-Pile (also called the Zamboni Pile) was an "electrostatic battery" permanent power supply used in the early 1800s and constructed from silver foil, zinc foil, and paper. Foil disks of 2cm dia. were stacked up several thousand thick and then either compressed in a glass tube with endcaps and a screw assembly, or stacked between three glass rods with wooden endplates. Of course this is simply a Voltaic Pile, a multi-cell electrochemical battery, albiet one with output potential in the range of kilovolts. Each cell used nearly-dry paper as electrolyte, with zinc foil for one electrode and silver foil as the other.

I have a friend who runs a diecutting printshop who might be able to turn out the disks in large quantities. I suspect that zinc foil is hard to find, but probably is not required. Perhaps aluminized paper and copper foil, or even silver leaf paper can be obtained, then simply punched out and stacked up. Or perhaps carbon paper can act as both electrolyte and electrode, using aluminum foil as the second electrode on each disk.

A 5ft dry pile should raise the hair of anyone who touches the end. Or a shorter one could act as a "magic wand": hold one end, touch someone's body with the other to charge them up, then touch their nose with your finger. SNAP!

A book on the history of Perpetual Motion Machines showed photos of "genuine" perpetual motion devices based on the Dry Pile. DuLuc's version was composed of two series-connected Dry Piles operating a pendulum electrostatic motor of the "Franklin's Bell" type. The drypile stacks were of the 3-glass-rod variety, and had been insulated by dipping in liquid sulfur (no plastics in 1806!) The device in the book is owned by Dr. A.J. Croft of Oxford's Clarendon Lab. At the time of publication of the book, this device had been tinkling away for over a century, and the owner of the device mentioned that the clapper-bead was starting to take on a distinct hourglass shape, and may need to be replaced in the next few centuries! A second device by Zamboni was a perpetually rotating "Franklin's wheel" electrostatic motor powered by two dry piles. Zamboni experimented with drypile-powered clocks in the early 1800s.

Dry piles found commercial use as the power supplies of electrostatic voltmeters (quadrant electrometers), and in infrared converter "night vision" scopes used in World War II.

Highly recommended: ELECTROSTATICS by A. D. Moore (lots of projects), also others


PERPETUAL MOTION, The History of an Obsession, by Arthur Ord-Hume, St. Martin's Press, NY 1977, ISBN 0-312-60131-X

STATIC ELECTRICITY with 30 experiments, by J.H. Pepper, Lindsay Publications, Bradley IL, pp246-248

Some references from Ord-Hume's PERPETUAL MOTION:


   ANNALEN DER PHYSIK, vol. 23 1 1806


   M. J. Jamin, COURS DE PHYSIQUE, Gauthier-Villars, Paris, 
   1869, 2nd Ed., Vol 3, p39

   Brugnatelli, GIORNALE DI FISICA... DEL RIGNO ITALICO, vol. 5, 
   Dec. 1812 pp 424-46

DULUC PILE BY G.J. Singer, detailed instructions




  TH. Pratt and A. Elliott, ELECTRONIC ENGINEERING, Sept 1948 and 
  Oct 1948  (w/info about WWII IR viewers powered by dry-piles)


If the Franklin's Bell constitutes a capacitance of maybe 5 picofarad (5E-12 Farad,) and if it is connected to a 1KV constant voltage battery, how small must the battery's internal resistance be in order to recharge the capacitance of the bell device several times per second? The minimum resistance in ohms may suprise you, it is very high and should easily be achieved even by a stack of non-moist paper disks. A Dry Pile won't run if its paper is totally dessicated, but usual environmental humidity is enough to keep it working.

A 1.5v AA cell can provide about .5 ampere for 1 hour before being exhausted. If the Dry Pile has about the same energy density as a double-A cell and is about 30 times larger in volume, how long will it be able to operate the Franklin's Bell at a recharge rate of several times per second? The answer in years is impressive. These devices were called "Electric Perpetum Mobile." While not truly perpetual, they could outlast their creators by quite a few centuries!

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