Excerpt from Roentgen Induction Coils for Quick Work It is thus apparent that when a radiograph is taken, at least two kinds of radiation tend to affect the photographic plate, one which is weak tending to fog the plate, and the other which is comparatively strong and which produces the desired image. Should the exposure be long there will be sufficient time to permit of an appreciable fog by the secondary radiation from the tissues. The experience of every radiographer furnishes data for a confirmation of this fact. For it is well known that if it requires two minutes to produce a good radio graph of a particular case the good radiograph taken in the two minutes is not twice as good as the radiograph of the same case taken in but one minute. In fact, the radiograph taken by means of the shorter exposure will often show detail which is entirely lacking in the one made with the long exposure. Then again, the differentia tion between the tissues in a skiagraph of the pelvic region seems to be less than it should be even when allowance is made for the extreme density of all the parts. If the exposure be short enough, however, to prevent this second ary radiation which emanates from the tissues themselves from fogging the plate, the action on the plate will be by the x-ray shadows alone and the negative will be sharper than with the long exposure. It is readily seen that in an ordinary radiograph of the denser parts of the body the fogging action is at a maximum because of the long expos ure necessary to secure penetration and because of the large number of the sources of secondary radiation. This conclusion is borne out by practice, and the efforts of the best workers are now directed to the making of their negatives in the shortest time possible. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.