the somewhat irksome
necessity of remaining absolutely still.

Another method of seeing the denser tissues of the body is by direct
observation. A means of seeing through the thinner parts of the body,
such as the fingers or the toes, has been devised simultaneously by
Salvioni of Italy, and Professor Magie of Princeton. Their instruments
are practically identical, consisting of a hollow cylinder a few inches
long, one end of which is applied to the eye, the other end, instead of
having a lens, being covered by a piece of paper smeared with a
phosphorescent salt, the double cyanide of platinum and barium. When the
hand is held before a Crookes tube, and is looked at through the
cylinder, we can see the bones of the hand or foot almost as clearly as
is shown in Figure 2. It has not yet, I believe, been applied to thicker
parts of the body. Figures 3 and 4 show a baby's foot and knee as seen
through this tube. The partial development of the bones accounts for the
peculiar appearance. There is no bony knee-pan, or patella, at birth,
and the bones of the toes consist only of cartilage, which is
translucent, and therefore not seen. The name given by Professor
Salvioni to this sort of "spy-glass"--if one may apply this term to an
instrument which has no glass--is that of "cryptoscope" (seeing that
which is hidden). The name suggested by Professor Magie is "skiascope"
(seeing a shadow.)

This leads me to say a word in reference to the nomenclature. The very
unfortunate name "shadowgraph" has been suggested and largely used in
the newspapers, and even in medical journals. It has only the merit of
clearness as to its meaning to English-speaking persons. It is, however,
an abominable linguistic crime, being an unnatural compound of English
and Greek. "Radiograph" and its derivatives are equally objectionable as
compounds of Latin and Greek. The Greek word for shadow is "skia," and
the proper rendering, therefore, of shadowgraph is "skiagraph,"
corresponding to photograph.

The first question that meets us in the use of the method in medicine is
what normal constituents of the body are permeable or impermeable to the
X rays. It may be stated, in a general way, that all of the fleshy parts
of the body are partially permeable to the rays in a relatively short
time; and if the exposure is long enough, they become entirely
permeable, so that no shadow is cast. Even the bones, on
_prolonged_ exposure, do not present a sufficient obs