distinction between living and non-living things. The scientific impetus of the preceding century
continued unabated however, and the results of new experiments and new ideas were quick to appear.
In the early decades of the eighteenth century a young Englishman, Stephen Gray, began a
series of experiments in which he demonstrated that the static charges of electricity could be conducted
by various materials for distances as great as 765 feet, discovering in the process that some materials
were "conductors" while others were not. Gray is best remembered for his experiment in which he
"electrified" a human subject with a static charge. Gray published his observations in the 1731
Philosophical Transactions in a paper entitled "Experiments concerning electricity." This was only five
years before his death at age forty-one.
Working during the same period, also in England, was another Stephen -Stephen Hales, a young
rural clergyman who had already made important contributions to the knowledge of blood circulation.
Hales made the startling suggestion that perhaps nerves functioned by conducting "electrical powers"
as did the conductors of his countryman Gray. Since the time of Descartes the vital role of the nervous
system as the principal regulator of all biological activity had been recognized. As a result, the
postulated "vital spirit" had come to be located in the nerves, and the importance of Hale's suggestion
lay in the fact that he was proposing that this mysterious, all-important entity was electricity! Support
for this concept was forthcoming, but from a different aspect of the problem entirely. It had occurred to
both Swammerdam in Holland and Glisson at Cambridge that the humoral concept of nerve-muscle
activity required that the muscle increase in volume as the active "humor" flowed into it from the
stimulated nerve. In separate experiments they both showed that the muscles did not increase in volume
when they contracted. Therefore the "humor" must be "etherial" in nature and Hales' electricity seemed
to be a good candidate.
Interest in electricity and its relationship to biology increased and experiments involving
electricity and living things became commonplace. The Abbe Nollet expanded Gray's observations on
the electrification of the human body using von Guericke's machines to produce larger static charges.
He also attempted to remedy paralysis in patients by administering such charges, but without success.
Another rural English clergyman, Abraham Bennet, invented the gold-leaf electroscope, far superior to
Gilbert's for detecting and measuring electric charges. Van Musschenbroeck in Holland invented the
Leyden jar for the storage of electrical charges (priority probably should have gone to von Kleist, a
German), and by the mid-1700's electricity was being generated, stored and transmitted through wires
for distances exceeding two miles! Watson, Cavendish and others even attempted to measure its speed
of transmission through wires and decided that it was "instantaneous." Many physicians, unfortunately
including a number of outright charlatans, were by now empirically using this new modality to treat a
number of afflictions and reporting success. One, Johann Schaeffer, went so far in his enthusiasm as to
publish a book called Electrical Medicine in Regensburg in 1752 .
While speculation concerning the role of electricity in living things was increasing, particularly
regarding the nervous system, physical knowledge of its properties did little to support this idea. The
most prominent physiologists of the era, Haller at Gottingen and Monro at Edinburgh, rejected it as
impossible, basing their opinions on the then available knowledge of metallic conduction and the need
for insulation. Despite obvious difficulties, the "humors" and "vital spirits" were still invoked as the
best explanation of how living things differed from non-living. This, of course, did not daunt the
majority of practicing physicians who continued to use this new modality with enthusiasm for an
increasing number of clinical conditions.
It was as though the stage was set for a major event; for 200 years a spirit of free inquiry and
communication had produced a revolution in the way man looked at the world and himself. Yet the
ELECTROMAGNETISM & LIFE - 10