needle can glide to the extremity of its course its point touches the projectile. The surgeon has then only to draw it out with his forceps. So precise is this method and so accurate are the instruments that fragments of grains of lead have been withdrawn from the brain. The localizations it achieves are rigorously exact-to the half millimeter. Altogether it renders so practicable intracranial operations formerly considered impossible that one of our most celebrated surgeons acknowledged it a guiding light which renders easy and safe the extraction of hidden projectiles.

By the same geometric method, somewhat simplified and with modified apparatus, the exact location of foreign bodies lodged in any part of the body may be discovered. Also, as will easily be seen, since this method gives a precise indication of a single point, it will do similar service for a series of points. A projectile encounters a bone and flies into fragments, a subject has been struck by several bullets, a bone is shattered into splinters; in any of these cases the various parts are located with as much precision as is the single ball.

The number of exact localizations that the radiograph can make is almost unlimited. In practical radiography this ability to take a number of observations is very valuable, especially in the case of malformation, for it permits an exact determination of the contour of the bony matter and of faults of conformation.

Thus metroradiography permits of exact measurements of all parts of the organism which give clear images under the X rays. It bears the same relation to simple radiography that quantitative chemical analysis does to qualitative; that is to say, in most cases in medicine, as well as in surgery, a knowledge of the nature of the case is as nothing compared with a knowledge of the importance of the

case.

Early in the article we noticed that in spite of the disfavor into which radiography had fallen through misdirected activity, yet a few serious physicists continued their work and obtained now and then remarkable results, which have done much to redeem the good name of radiography. A great part of the progress must be attributed to two men, whose names should always be recognized—the physicist Villars, and Chabaud, the perfecter of the Crookes tubes. Among the radiographers themselves should be cited A. Londe, who, during the early years, did worthy work in his photographic studies at Salpêtrière. His efforts were directed toward the better selection and installation of radiographic material and then toward perfecting it and employing it with more method. To him we are indebted for the first practical treatise, which although superseded and discredited in part, was of much interest in its day. Unfortunately, however, after a few years of radiography, Monsieur Londe gave up his operations at the Salpêtrière.

From the very discovery of the X rays, Monsieur Contremoulins, at that time preparator to the Faculty of Medicine, has by the employment of reasonable and scientific methods attained the best results, which have been described in his numerous communications to the academies. He was the first to obtain clear images of the cranium, the thorax, and the pelvis. While studying with the late Dr. V. Lemoine on the possible applications of radiography to zoology and paleontology, he made marvelous images of bony structures and radiographs of fossils, which have never been surpassed. Applying the X rays to anatomical study, he obtained by injections of metal into the vessels clear radiographs of the arteries and their ramifications in the finger tips. Images of the muscles of the hand he got in a similar

manner.

I do not wish to neglect in this article any of those who are working with radiography, and who, through their publications or their communications to the learned societies, are accredited with having created something good or interesting. If I fail to mention them, I will appear partial, which I am not; if, on the other hand, I do cite them by name, I must necessarily characterize with a word or so the value, defects, or insignificance of their work.

Doctor Béclère has written and spoken much on the X rays, especially on radioscopy, which must not be confounded with radiography. In this connection let us look for a moment at the principles of radioscopy. Under the action of X rays from a Crookes tube a screen treated with platinocyanide of barium is completely illuminated. Now, if a hand is interposed between the Crookes tube and this screen, the image of the hand will appear on the screen, not, however, as a mere silhouette, but with the flesh, muscles, nerves, and veins, and bones shadowed more or less deeply according to their resistance to the rays. Thus may be seen on the screen the bones of the thorax, and some of its organs, like the heart, whose movements may be discerned without difficulty.

Such a method of investigation and analysis is naturally seductive. Whether it is really as valuable as radiography is a many-sided question and one which I hardly care to discuss here; so I content myself for the present with a single statement. The radioscope in a limited number of cases, such as the study of the movements of the thoracic. organs, is of incomparable value and in a few other cases is complementary to the radiograph.

Doctor Guilleminot is the author of a really original and thorough work on chronoradiography. The value of his method and its processes is another question I am unwilling to attempt to settle; facts are already beginning to indicate a lack of success, but time alone will determine its legitimate place.

Marie and Ribaut have given much study to a method of investigation and X ray analysis based upon stereoscopy. These experiments are by no means lacking in interest, their radioscope-stereoscope being particularly meritorious, though experience has demonstrated, especially in the case of extracting projectiles, that human vision, however perfect it may be, is a poor substitute for a mechanical guide to the location of the foreign body.

Doctor Bouchacourt is the author of a method of investigation with the X rays which he calls endodiascopic (ɛvɗov, from within; Sia, through; 6кояƐι, to examine). He employs specially constructed Crookes tubes, which are introduced into the body through the natural apertures. The tube projects a silhouette on a screen (endodiascopy-radioscopy) or on a plate (endodiascopy-radiography) of the parts of the organism coming between it and the screen or the plate.

Marie and Cluzot, James Makenzie, Davidson and Hedley, Mergies, Leduc, Massiot, Maunory, and others are also engaged in endeavors to work out problems in various directions of research.

The science of the application of the properties of the X rays to the analysis of the human body is an admirable and valuable development, but one around which, unfortunately, harmful misapplications have clustered since its beginning.

In conclusion, the utilization of the X rays in medicine and surgery since its inception with Roentgen's discovery has developed into a science essentially exact, precise, and certain-a science with which you especially must sympathize because in its highest form radiography has borrowed so much from photography. Moreover, it is a science to interest us all, because it is constantly being called upon to play a more or less important rôle in the relief of those ills the flesh is heir to.

But learn how to discriminate between the good and the bad methods of applying the X rays; discover how to select the rational and valuable processes of analysis; begin this by noting that simple radiography and metroradiography are capable of meeting every exigency.

The skeleton is perhaps the part of the human organism that may best be studied with radiography and metroradiography. The radiograph pictures the bones of the infant as soon as they begin to form, before birth even. Although these observations during gestation may not be of any general interest, it is of great value to the parents to know that their child has a well-formed skeleton. While the bones of the infant are still soft a close watch on their development may permit the prevention or reduction of malformations which might be difficult to correct later. Parents anxious about their children's