cement of the voltaic-pile invention
were years of intense experimental activity with this device. Many new
chemical elements were discovered, beginnings were made on the
electrochemical series of the elements, the electric arc and
incandescent platinum wires suggested the possibilities of electric
lighting, and various electrochemical observations gave promise of other
practical applications such as metal-refining, electroplating, and
quantity production of certain gases. Investigators were keenly aware
that all of the available means for measuring and comparing the
_electrical_ aspects of their experiments (however vaguely these
"electrical aspects" may have been conceived), were slow, awkward,
imprecise, and unreliable.

The atmosphere was such that prominent scientists everywhere were ready
to pounce immediately on any reported discovery of a new electrical
"effect," to explore its potentialities for instrumental purposes. Into
this receptive environment came H. C. Oersted's announcement of the
magnetic effects of a voltaic circuit, on July 21, 1820.[9]

[Illustration: Figure 2.--"GALVANOMETER" WAS THE NAME given by Bischof
to this goldleaf electrostatic instrument in 1802, 18 years before
Ampere coupled the word with the use of Oersted's electromagnetic
experiment as an indicating device.]

Oersted's Discovery

Many writers have expressed surprise that with all the use made of
voltaic cells after 1800, including the enormous cells that produced
the electric arc and vaporized wires, no one for 20 years happened to
see a deflection of any of the inevitable nearby compass needles, which
were a basic component of the scientific apparatus kept by any
experimenter at this time. Yet so it happened. The surprise is still
greater when one realizes that many of the contemporary natural
philosophers were firmly persuaded, even in the absence of positive
evidence, that there _must_ be a connection between electricity and
magnetism. Oersted himself held this latter opinion, and had been
seeking electromagnetic relationships more or less deliberately for
several years before he made his decisive observations.

His familiarity with the subject was such that he fully appreciated the
immense importance of his discovery. This accounts for his employing a
rather uncommon method of publication. Instead of submitting a letter to
a scientific society or a report to the editor of a journal, he had
privately printed a four-p