Page:Popular Science Monthly Volume 52.djvu/587

Rh workmen's baths said to have been established in Germany prior to 1896. In the case of school baths in Germany, the average cost of a warm shower bath is said to be one quarter of a cent, and it is safe to say that, leaving the interest on the plant out of account, the cost in the workmen's baths is about the same, or even less. The cost of the latter baths varies all the way from three hundred and fifty dollars to five thousand dollars—a very good twelve-cabin shower bath, with one hundred and seventy towels and bath caps, having been built at Dalken in the Düsseldorf district for three hundred and forty dollars. Of the great importance of cleanliness in promoting hygienic conditions, it is hardly necessary to speak, and we hope that a similar movement may spring up among the mill owners and large manufacturers in this country. The public schools are also worthy the close attention of our public-school officials.

Explosiveness of Dynamite.—From an article in Industries and Iron, we take the following: In the early days of dynamite the mischievous and often fatal doctrine was thoughtlessly promulgated that under the influence of fire that explosive would only burn, and that nothing would cause it to explode except the application of a proper detonator. Notwithstanding the efforts which have been made to cause the public to unlearn this foolish doctrine, it still lingers. The doctrine preached by those who know anything about the matter is that explosives are only comparatively safe at the best, and then only so long as they are treated as absolutely dangerous. There is no reliance whatever to be placed on the theory that dynamite and many of its congeners can be burned without exploding. This has been illustrated over and over again with fatal results, and the ignorance, crass stupidity, and recklessness occasionally shown by those accustomed to the daily use of high explosives are really incredible. Were the author of a highly flavored story to introduce into his plot the instantaneous death of a newly married couple by an explosion of dynamite in the stove of their sitting room, the explosion being brought about by the bridegroom's brother baking the dynamite in the oven, the author would probably be accused of going beyond the bounds of probability after the sensational, and yet this combination of circumstances did actually occur in a mining district in England. The ingenuity exercised in devising means for thawing dynamite in the most unsafe way possible is certainly very remarkable. This thawing-out process is the most fruitful cause of accidents with dynamite. The dynamite becomes inert at about 40° F., and, while this is a very valuable property for transportation purposes, it plainly also has its disadvantages. To thaw these cartridges tin warming pans constructed on the principle of the glue pot should be provided. This keeps the explosive away from any possible contact with the fire, and prevents the possibility of an excessively high temperature.

Radiography in Medical Practice.—Dr. Francis H. Williams, in an address before the Association of American Physicians, gives an interesting account of his year's work with the X rays, and shows that they must now be accepted as one of the valuable instruments in the general physician's equipment. The varying resistance which the different tissues of the body offer to the passage of the X rays depends upon difference in bulk and chemical composition. The soft tissues of the body contain a large percentage of water, so that they offer about the same resistance as an equal thickness of the latter. The rays, however, pass through air much more readily than they do through water. It is this fact which gives the X ray its special value in physical examinations of the chest. The radiograph of the normal chest shows two clearly marked out lungs, divided by a dark line representing the sternum, and crossed by dark horizontal bands, the ribs. The lower internal portion of the left lung is partially obliterated by the heart, as is also a small segment of the lower portion of the right lung. This picture is normally very sharp and unmistakable, so that any abnormal state of affairs in the lungs and any variation in the size or position of the heart are readily made out by the use of the fluoroscope. In his summary Dr. Williams claims that the X rays, and more especially the fluoroscope, have already proved to be an important addition to the ordinary methods of physical examination, and that