A DISCUSSION of electric batteries anteceding Alessandro Volta’s first experiments of the year 1800 or even Luigi Galvani’s first publication of 1791, not by a few years but by many centuries, would have seemed wholly absurd only ten years ago. But there is now reason to believe that electric batteries were actually known and in use long before the time of Volta and Galvani. It is true that those that built and used these batteries at about the time of Christ—or even earlier—had, in all probability, no conception either of chemical reactions or of electric currents as we understand these terms. To them it was only empirical knowledge, that they could expect certain results when doing certain things. It might be added that the knowledge of such results were confined to narrow boundaries, the center of which was the famous old city of Bagdad.
Dr. Wilhelm Koenig of the Iraq Museum in Bagdad reported recently that a peculiar instrument was unearthed by an expedition of his museum in the summer of 1936. The find was made at Khujut Rabu’a, not far to the southeast of Bagdad. It consisted of a vase made of clay, about 14 centimeters high and with its largest diameter 8 centimeters. The circular opening at the top of the vase had a diameter of 33 millimeters. Inside of this vase a cylinder made of sheet copper of high purity was found—the cylinder being 10 centimeters high and having a diameter of about 26 millimeters, almost exactly 1 inch.
A replica and diagram of one of the ancient electric batteries (cells) discovered near Baghdad
The lower end of the copper cylinder was covered with a piece of sheet copper, the same thickness and quality as the cylinder itself. The inner surface of this round copper sheet—the one that formed the inner bottom of the hollow cylinder—was covered with a layer of asphalt, 3 millimeters in thickness. A thick, heavy plug of the same material was forced into the upper end of the cylinder. The center of the plug was formed by a solid piece of iron—now 75 millimeters long and originally a centimeter or so in diameter. The upper part of the iron rod shows that it was at first round and while the lower end has partly corroded away so that the rod is pointed now at the lower end, it might be safely assumed that in the beginning it was of uniform thickness.
An assembly of this kind cannot very well have any other purpose than that of generating a weak electric current. If one remembers that it was found among undisturbed relics of the Parthian Kingdom—which existed from 250 B.C. to 224 A.D.—one naturally feels very reluctant to accept such an explanation, but there is really no alternative. The value of this discovery increases when one knows that four similar clay vases were found near Tel’Omar or Seleukia—three of them containing copper cylinders similar to the one found at Khujut Rabu’a. The Seleukia finds were apparently, less well preserved—there are no iron rods in evidence any more. But close to those four vases pieces of thinner iron and copper rods were found which might be assumed to have been used as conductive wires.
Similar “batteries” were also found in the vicinity of Bagdad in the ruins of a somewhat younger period. An expedition headed by Professor Dr. E. Kuehnel, who is now director of the Staatliches Museum in Berlin, discovered very similar vases with copper and iron parts, at Ktesiphon—not far from Bagdad. These finds date from the time when the dynasty of the Sassanides ruled Persia and the neighboring countries—224 A.D.—651 A.D.
While the probable date of the invention is entirely open to conjecture, it seems likely that it was made in or near Bagdad, since all known finds were made in the vicinity of this city. It must be assumed, of course, that the subjects of the Sassanides had some use for them, and Dr. Koenig, the discoverer of the best preserved of all these vases, suggests that this use might still be in evidence in Bagdad itself. He found that the silversmiths of Bagdad use a primitive method of electroplating their wares. The origin of their method cannot be ascertained and seems to date back a number of years. Since galvanic batteries of the type found would generate a sufficiently powerful current for electrogilding small articles fashioned of silver, it might very well be that the origin of the method has to be sought in antiquity.
For much more on the ancient Bagdad electric batteries and on ancient electric lighting, see The Electric Mirror on the Pharos Lighthouse and Other Ancient Lighting."