CHAPTER THREE

Bertholon and the Electro-Vegetometer

Pierre Bertholon de Saint-Lazare was a priest of the Lazarist order and a professor of experimental physics at Montpellier. He was a friend and correspondent of Benjamin Franklin, and an energetic promoter of Franklin’s lightning rod in France. He wrote on the electricity of meteors, the electricity of the human body in health and disease, and, in 1783, on the electricity of plants.

De l’électricité des végétaux is the founding document of electroculture. It is where the scattered pot experiments of the 1740s become a program for agriculture.

The argument from the weather

Bertholon’s reasoning went like this. Franklin had shown in 1752 that lightning is electricity and that the atmosphere is electrified. Farmers had always said that crops grow best in thundery weather and that rain from a thunderstorm does more good than water from a well. The laboratory had shown that electricity quickens plants. Therefore, Bertholon concluded, atmospheric electricity is a natural fertilizer, one of the ordinary means by which the Creator feeds the fields, and an ingenious man might gather more of it and bring it down to his garden.

It was a beautiful argument. Parts of it were even right. Thunderstorms do fertilize the earth: lightning forces nitrogen and oxygen in the air to combine, and the rain washes the resulting nitrates into the soil. But that is chemistry, not a direct electrical feeding of the plant, and no mast in a garden can imitate it. Bertholon could not have known this; nitrogen had been identified only eleven years earlier.

The machine

His device, the électro-végétomètre, was a tall mast set in the garden. At its top was an insulated metal arm carrying sharp points, to draw electricity from the air as a lightning rod does. A conductor led down to a second set of points held over the plants, where the collected electricity was supposed to shower down onto the beds. The arm could be swung to carry the influence over different parts of the garden.

Bertholon also proposed watering with electrified water, the gardener standing on an insulated cart connected to a machine, and suggested electricity as a remedy for insect pests and plant diseases. He reported that his electrified plots flourished.

The first passive device

Notice what had changed. Nollet’s electricity came from a machine and could be measured, crudely, by the length of its spark. Bertholon’s came from the sky, with no way to say how much of it there was or whether any of it reached the plant. His electro-vegetometer is the direct ancestor of every antenna, spiral and coil sold to gardeners since. And it shares their central weakness: it offers a mechanism that sounds reasonable and results reported by the inventor, with nothing in between that an outsider can measure.

Bertholon’s book was widely read and translated. For a few years electrified gardening was fashionable. Then a better experimenter looked into it, and the fashion ended.