voltaic electricity which we at present possess. For without being
at all affected by variations in time or intensity, or alterations
in the current itself, of any kind, or from any cause, or even of
intermissions of actions, it takes note with accuracy of the
quantity of electricity which has passed through it, and reveals
that quantity by inspection; I have therefore named it a
VOLTAELECTROMETER.[6]

In passing, Faraday commented that the efforts by Gay-Lussac and Thenard
to use chemical decomposition as a "measure of the electricity of the
voltaic pile" in 1811 had been premature because the "principles and
precautions" involved were not then known. He also noted that the
details of _metal deposition_ in electrolysis were still not
sufficiently understood to permit its use in an instrument.[7]

The heating of the wires in electric circuits must have been observed so
early and so often with both electrostatic and voltaic apparatus, that
no one has bothered to claim or trace priorities for this "effect." The
production of incandescence, however, and the even more dramatic
combustion or "explosion" of metal-foil strips and fine wires has a good
deal of recorded history. Among the first to burn leaf metal with a
voltaic pile was J. B. Tromsdorff of Erfurt who noted in 1801 the
distinctly different colors of the flames produced by the various common
metals. In the succeeding few years, Humphry Davy at the Royal
Institution frequently, in his public lectures, showed wires glowing
from electric current.

Early electrical instrumentation based on the heating effect took an
unusual form. Shortly after 1800, W. H. Wollaston, an English M.D.,
learned a method for producing malleable platinum. He kept the process
secret, and for several years enjoyed an extremely profitable monopoly
in the sale of platinum crucibles, wire, and other objects. About 1810,
he invented a technique for producing platinum wire as fine as a few
millionths of an inch in diameter, that has since been known as
"Wollaston wire." For several years preceding 1820, no other instrument
could compare the "strengths" of two voltaic cells better than the test
of the respective maximum lengths of this wire that they could heat to
fusion. One can sympathize with Cumming's comment in 1821 about "the
difficulty in soldering wires that are barely visible."[8]

Electrical Instrumentation, 1800-1820

The 20 years following the announ