according to some general plan." It is but a short step from
that proposition to the Proutian hypothesis.


NEW WEAPONS--SPECTROSCOPE AND CAMERA

But the atomic weights are not alone in suggesting the compound
nature of the alleged elements. Evidence of a totally different
kind has contributed to the same end, from a source that could
hardly have been imagined when the Proutian hypothesis, was
formulated, through the tradition of a novel weapon to the
armamentarium of the chemist--the spectroscope. The perfection
of this instrument, in the hands of two German scientists, Gustav
Robert Kirchhoff and Robert Wilhelm Bunsen, came about through
the investigation, towards the middle of the century, of the
meaning of the dark lines which had been observed in the solar
spectrum by Fraunhofer as early as 1815, and by Wollaston a
decade earlier. It was suspected by Stokes and by Fox Talbot in
England, but first brought to demonstration by Kirchhoff and
Bunsen, that these lines, which were known to occupy definite
positions in the spectrum, are really indicative of particular
elementary substances. By means of the spectroscope, which is
essentially a magnifying lens attached to a prism of glass, it is
possible to locate the lines with great accuracy, and it was soon
shown that here was a new means of chemical analysis of the most
exquisite delicacy. It was found, for example, that the
spectroscope could detect the presence of a quantity of sodium so
infinitesimal as the one two-hundred-thousandth of a grain. But
what was even more important, the spectroscope put no limit upon
the distance of location of the substance it tested, provided