he was about to unleash on the scholarly community beyond the borders of the Dutch
Republic. His directorship of the Holland Society’s natural history cabinet had already
provided him with the means to become acquainted with foreign scholars - Alessandro Volta
for instance had visited the cabinet in 1782, and many years of fruitful correspondence
between the Italian and van Marum ensued. But the electrostatic generator of course provided
an even better way to attract the attention of other researchers, already because of its sheer
force. This political angle also helps explain why van Marum was so quick to publish a
treatise describing the machine itself and detailing the experiments he had already conducted
in the few months of its existence!!- although a genuine desire to share these results and
contribute to the body of scientific knowledge as a whole are, as ever, equally indisputable
with van Marum. There is no reason to doubt his statement in the publication’s preface that
“My principal object in making so great an effort to obtain a greater electrical force and to
experiment with it, has been no other than to satisfy my desire to contribute something to the
advancement of Natural Science, a science which, as it gives us more than any other human
knowledge, some insight into the great wisdom of the Creator, I hold in the highest respect.”
Yet it is perhaps equally revealing that an immense budget was reserved for the illustrations
accompanying van Marum’s descriptions of the electrostatic generator. Amazingly, the costs
for the prints that were included in the first treatise ultimately even exceeded those of the
machine itself!14 As the adage goes, “a picture says more than a thousand words”, and the
more impressive an image, the more likely it will leave an indelible impression on the
reader’s memory. If the aim of the illustrations accompanying the treatise was indeed not only
to help the reader understand the experiments and their results, but also to impress the reader,
this was part of a longer term strategy on van Marum’s part: in the instructions van Marum
had drawn up for himself as director of Teylers Museum in 1784 he had already mentioned
such illustrations.
Another point van Marum included in the 1785 treatise probably as much out of a sense of
genuine altruism as for the purpose of piquing fellow experimenters’ curiosity in an effort to
engage with them, was an offer to perform any experiment suggested to him by others. He
even promised not to be selective about the experiments he performed, writing:
“”[...] I invite every Physicist (and this is the main reason which prompted me to an early
publication of the description of this machine and of the experiments with it, demonstrating its
great power) to kindly let me know his ideas or views on further experiments, which, with the
aid of so great a force as is provided by this machine, may give any hope of leading to some
fresh discovery. Any experiments so suggested I will gladly carry out, provided the required
equipment is available, and report on the result in the first sequel to this volume, specially
mentioning the name of whomsoever has given me the idea for such an experiment.” 15
13 Marum, “Description o f a Very Large Electrical Machine Installed in Teyler’s Museum at Haarlem and o f the
Experiments Performed with It,” 7.
14 Wiesenfeldt, “Politische Ikonographie von Wissenschaft: Die Abbildung von Teylers ‘ungemein großer’
Elektrisiermaschine, 1785/87,” 222.
15 Marum, “Description o f a Very Large Electrical Machine Installed in Teyler’s Museum at Haarlem and o f the
Experiments Performed with It,” 7.
Although the actual publication of the description of the experiments suggested by others was
delayed for many years, only coming out in 1795, van Marum apparently was contacted by
many fellow experimenters in the immediate aftermath of the first treatise, and did keep his
promise. As he reported to his fellow members of the Second Society in October 1785, “after
the publication of the experiments that had been carried out with the large electrostatic
generator belonging to this Foundation” he had been “stimulated from all sides by many
prominent men to carry on with these experiments, and to continue them in all possible ways,
while they promised to cooperate, and to communicate their own findings”.
Van Marum saw to it that his treatise was widely circulated, i.e. sent to academies around the
world, from Petersburg to London. What’s more, he did not only wait for other scholars to
approach him, but actively sought out other researchers whom he thought might be interested
in his results.
That he managed to speak to Benjamin Franklin was already mentioned before. This
happened during a trip of van Marum’s to Paris, for which he set out in June 1785. He had
already been elected a foreign correspondent of the Academie Royale des Sciences two years
previously, but now set out to acquaint himself with this illustrious institution, taking with
him letters of recommendation from Petrus Camper, and copies of the treatise on the
electrostatic generator.17 Franklin was about to leave France to return to America, but agreed
to see the young Dutchman just two days before his departure. In all likelihood the mam
reason the famous American granted van Marum some of his scarce time was that the latter
claimed to have found proof of Franklin’s one-fluid theory of electricity. At the time there
was much debate about the nature of electric charges, the general assumption being that there
was such a thing as an electric fluid. But whereas many scholars were convinced there were
two such fluids, corresponding with the two kinds of mutually exclusive and repelling charges
that could be measured, Franklin posited that there was but one such fluid, and that a lack of
this substance led to what he labeled as “minus” electrification, whereas an excess of this
substance led to “plus” electrification.18 What van Marum, together with Cuthbertson, had
succeeded in doing was to create 24-inch long, “snake-like sparks of the thickness of a
fountain-pen”. As has been explained elsewhere, “[tjhese sparks had numerous side branches,
by carefully noting their form and direction, they [van Marum and Cuthbertson] found that the
latter was the same for all ramifications.” 19 Van Marum, maybe a little hastily, concluded that
this proved Franklin’s theory. The great man himself as well as others such as Volta, fully
accepted this. Van Marum reported Franklin as saying “C’est done par la que ma theorie d’un
16 “na d’uitgaave van de gedaane proeven met de groote electriseer-machine van deeze Fondatie”; “door veele
voomaame mannen, van alle kanten [was] aangespoord, met deeze proef-neemingen te continueeren, en die, op
alle mooglijke wijzen, voort te zetten, onder belofte van denzelver mede-werking, en mededeehng van hunne
bevindingen”; “Notulen Tweede Genootschap”, 27.10.1785, Haarlem, AT$| vol. 1382. _
17 Trevor H. Levere, “Martinus van Marum and the Introduction o f Lavoisier’s Chemistry in the Netherlands,
vol. I Martinus vanMaram: Life & Work (Haarlem: Tjeenk Willink & Zoon, 1969), 183-184.
18 John L. Heilbron, Electricity in the 17th and 18th Centuries: a Study o f Early M odem Physics (Berkeley; Los
Angeles; London: University o f California Press, 1979), 328-330. ^
19 Levere, “Martinus van Marum and the Introduction o f Lavoisier’s Chemistry in the Netherlands, 177. bee
also: Heilbron, Electricity in the 17th and 18th Centuries: a Study o f Early Modem Physics, 441-442.