ic,
that if the wire of the circuit was first passed above the needle, in
the magnetic meridian, then folded and returned in a parallel path below
the needle, the deflecting effect on the needle would be repeated, and a
more sensitive indicator would result, assuming that any additional wire
introduced has not affected the "circuit" excessively.

Since 1821, historical accounts of the origins of electromagnetism seem
to have limited their credit assignments for the conception and
observation of this electromagnetic "doubling" effect (or "multiplying"
effect, if the folding is repeated) to three persons. Almost without
exception, however, these accounts have given no specific information as
to precisely what each of these three accomplished, what physical form
their respective creations took, what experiments they performed, and
what functional understanding they apparently had of the situation. The
usual statement is simply that a compass needle was placed in a coil of
wire.[13] The main purpose of the present review is to recount some of
these details.

The following are the three candidates whose names are variously
associated with the "invention" of the first constructed electromagnetic
instrument, or "multiplier," or primitive galvanometer.

JOHANN SALOMO CHRISTOPH SCHWEIGGER (1779-1857) in 1820 had already been
editor for several years of the _Journal fuer Chemie und Physik_, and was
professor of chemistry at the University of Halle.

JOHANN CHRISTIAN POGGENDORF (1796-1877) in 1820 had only recently
entered the University of Berlin as a student following several years as
an apothecary's apprentice and a brief period as an apothecary. Four
years later, he succeeded Gilbert as editor of the influential _Annalen
der Physik_, a position he held for more than 50 years.

JAMES CUMMING (1771-1861) in 1820 was professor of chemistry at
Cambridge University.

Chronology and Priority

The earliest established date in the "multiplier" record is September
16, 1820, when Schweigger read his first paper to the Natural Philosophy
Society of Halle. There seems to be no reason to doubt that this report
justifies the frequently used label "Schweigger's multiplier."

In an exuberant support of Schweigger's position, Speter[14] with no
mention of Cumming and no hint of "invention" details, shows that
Poggendorf in 1821 admitted Schweigger's priority, but suffered some
lapse of memory 40 years later when writing sectio