that during the discharge of _one_ kind of rays of force from the
cathode pole in a Crookes tube _another kind_ of rays are set free,
which differ totally in their nature and effects from anything
hitherto known. It is this fact which has indissolubly connected the
name of Konrad Roentgen with that great bound in scientific knowledge
which seems likely to modify nearly all the other scientific knowledge
of mankind.

Everywhere, in the first months of 1896, the experimenters went to
work to verify and apply the discovery of the German philosopher. It
was at once discerned that the new force, since it would freely
traverse opaque bodies and produce afterward chemical changes on
sensitized surfaces similar to those ordinarily produced _by_ light,
might be used for delineating (we can hardly say _photo_ graphing) the
interior outlines and structure of opaque bodies!

On this line of experimentation the work at once began, and with
remarkable success. Roentgen himself was the first man in the world to
obtain, as _if_ by photography, the invisible outline of objects
through opaque materials. He soon obtained a delineation of the bones
of a living hand through the flesh, which was only dimly traced in the
resulting picture. In like manner coins were delineated through the
leather of pocketbooks. Other objects were pictured through
intervening plates of metal or boards of wood. The possibility of
discovering the visible character of invisible things, and even _of
seeing directly through_ opaque materials into parts where neither
light nor electricity can penetrate, was fully shown.

The work of picture taking in the interior of bodies and through
opaque materials was quickly taken up by philosophers in England,
France and the United States. Almost everywhere the physical
laboratories witnessed daily this form of experimentation. Swinton, of
London; Robb, of Trinity College, Dublin; Morton, of New York; Wright,
of Yale University, and in particular Thomas A. Edison, of Menlo Park,
attacked the new problem with scientific zeal, and with startling
results. It remained for Edison to discover that the new force acted
in some respects in the manner of _sound_ rather than in the manner of
_light_. Thus, for example, he showed that the invisible rays not only
_pass through_ substances that are opaque to light and non-conductors
of electricity, but that the invisible rays _run around the edges and
sides_ of plates, then proceeding