Amazing old battery - who invented it?

Per the story below who originally invented this thing?

the Dry Pile By Barry Fox

In 1840 an Oxford science student was shopping in London and found a perpetual motion machine. As if by magic a couple of bells, on top of some yellow pillars, were ringing merrily. The salesman assured him that they would go on for ever.

The student bought the machine and was mocked by his colleagues. But he had the last laugh. The machine is still going strong and likely to carry on chiming for several hundred years more.

The bells are likely to wear out before the mysterious source of power dries up. Visitors now come from all round the world to see the Dry Pile, now inside a bell jar in the Clarendon Laboratories.

Each pillar is a stack of 2,000 zinc foil and paper disc pairs, impregnated with manganese dioxide. The yellow colour comes from a coating of molten sulphur which keeps the internal moisture content stable. There is just enough water trapped inside to serve as an electrolyte, but not enough to cause internal short circuits.

Each pillar generates around 2,000 volts, but at a current of only 1 nanoampere. During the war, the Admiralty needed a very high voltage, very low current source for the image converter tube of a top secret infrared telescope. An Oxford physicist working there remembered the Dry Pile. The Navy built a large number of replica Dry Piles which successfully delivered the 3,000 volts needed for the lead sulphide cathode of the tube

From “Perpetual Motion” by Arthur W.J.G. Ord-Hume:

“The first to construct a dry pile was an experimental scientist called Behrens who used zinc and copper plates separated by discs of flint…” (1803)

But it was J.A. de Luc, a Fellow of the Royal Society who first built the “perpetual chime” (his term) you describe. He first published an account of his work in 1810, but seems to have worked on dry piles as early as 1800.

2000 Volts times 1 nanoamp = 2 microwatts. If it started at 1840, thats about 160 years. 160365.262436002e-6 = about 10000 joules of energy delivered since 1840. That’s a pretty small amount of energy- two D-size batteries contain more energy (about 12000 joules). It sounds to me like the dry pile perpetual motion machine is just powered by a very well-built battery.

Two D batteries would still be powering the thing also, if they were built to last 160 years.


I don’t think there is a commercially available battery whose internal leakage is anything like as low as this so it is a pretty amazing bit of kit - unless someone knows better.

I read a little further into the PM book I cited in my first post and thought you might be interested in the following. (Incidentally, the link in the OP is no longer working, so forgive me if my post is redundant with the info that was given there.)

"One other man should be chronicled. This is George John Singer who published detailed instructions on how to make dry piles. Singer’s version of the de Luc pile used as a “perpetual chime” comprised two glass insulators supporting two German silver bells each having a dry pile mounted on it. The tops of the piles were connected by a wire stirrup from which a striker hung on a fine thread.

There is at least one dry pile chime on the Singer principle still in existence - and still softly ringing its way across the years. This is preserved in the exhibition case of the Clarendon Laboratory of Oxford University under the care of Dr. A.J. Croft who has traced its origins and made an assessment of its life. It was purchased from a london firm of instrument makers, Watkin & Hall and a piece of paper bears the manuscript legend “Set up in 1840.” The handwriting has been identified as that of Dr. Robert Walker, the then Reader in Experimental Philosophy."

It goes on to say: “… The operation is only broken for occasional short periods when the humidity is high. It has proved impossible to determine exactly the voltage being produced but it is estimated to be in the order of one volt plus or minus 0.5, and the current at between one and ten nono-amperes.”

Given the glacial, but noticable, wasting away of the mechanical striker (there is a tiny pile of metal dust on the base of the device) the author estimates that this “perpetual chime” may have a lifespan of about 500 years. Not bad if you ask me.