[Illustration:  FIGURE 2.—­SKIAGRAPH OF A FOOT, SHOWING AN EXTRA BONE IN THE GREAT TOE, WHICH WAS REMOVED BY PROFESSOR MOSETIG.

(From the “British Medical Journal.")]

When we attempt to skiagraph the thicker portions of the body, for example, the shoulder, the thigh, or the trunk, even the parts consisting only of flesh obstruct the rays to such an extent, by reason of their thickness, that the shadows of the still more dense tissues, like the thigh bone, the arm bone, or the bones of the trunk, cannot be distinguished from the shadows of the thicker soft parts.  Tesla ("Electrical Review,” March 11, 1896) has to some extent overcome these difficulties by his improved apparatus, and has skiagraphed, though rather obscurely, the shoulder and trunk, and Rowland has been able to do the same.  Doubtless when we are able to devise apparatus of greater penetration, and to control the effect of the rays, we shall be able to skiagraph clearly even through the entire thickness of the body.

It might be supposed that clothing or surgical dressings would prove an obstacle to this new photography, but all our preconceived notions derived from the ordinary photograph must be thrown aside.  The bones of the forearm or the hand can be as readily skiagraphed through a voluminous surgical dressing or through the ordinary clothing, as when the parts are entirely divested of any covering.  Even bed-ridden patients can be skiagraphed through the bed-clothes, and, therefore, without danger from exposure.

[Illustration:  FIGURE 3.—­SKETCH OF A BABY’S FOOT AS SEEN THROUGH THE SKIASCOPE.

(From the “American Journal of the Medical Sciences,” March, 1896.)]

[Illustration:  FIGURE 4.—­SKETCH OF A BABY’S KNEE AS SEEN THROUGH THE SKIASCOPE.

(From the “American Journal of the Medical Sciences,” March, 1896.)]

One of the principal difficulties of the method at present is the time ordinarily required to obtain a good picture.  Usually this time may be stated at in the neighborhood of an hour, though many good skiagraphs have been taken in a half hour or twenty minutes.  It is stated that Messrs. McLeennan, Wright, and Keele of Toronto have reduced the necessary time to one second, and that Mr. Edison has taken even instantaneous pictures; but I am not aware of the publication of any pictures showing how perfect these results are.  Undoubtedly, as a result of the labors of so many scores of physicists and physicians as are now working at the problem, before long we shall be able to skiagraph at least the thinner parts of the body in a very brief interval.  The brevity of the exposure will also better the pictures in another way.  At present, if the attempt is made to skiagraph the shoulder or parts of the trunk, we have to deal with organs which cannot be kept motionless, since the movements incident to breathing produce a constant to and fro movement of the shoulder, the lungs, the heart, the stomach, the liver, and other organs which, hereafter, may be made accessible to this process.  There is no serious discomfort excepting the somewhat irksome necessity of remaining absolutely still.