CHAPTER II.

INJURIES FROM ATMOSPHERIC CHANGES.

THE

unquestionable benefit which free

exposure to the air in all weathers confers is subject to certain drawbacks. It is not necessary to consider sunstroke, in the case of day-laborers, nor accidents by falling from roofs, or from railroad collisions, as forming an element in "industrial hygiene;" but there are certain causes which affect the health permanently, as bronchitis and pneumonia; and to this may be added a liability to paralysis of the facial nerve, which is especially the possession of drivers of carts, etc.

Bronchitis and rheumatism are common enough also among those whose trade exposes them to great heat, as blacksmiths, stokers on steamships, forgemen, puddlers, glass-blowers, dyers, and washerwomen. It is, in fact, neither heat nor cold that causes the trouble, but excessively rapid transitions from heat to cold.

The trade of baker is apt to be very unhealthy, owing to the confined, close, dark, overheated quar

ters in which it is carried on; also the night-work, and occasional excess of work.

There is a peculiar and interesting class of disease which attacks those who work in diving-bells or caissons. It is caused by the excess of atmospheric pressure which exists under water, which may equal several times that to which men are exposed on land. The symptoms do not, however, attack the laborer on going down, but rather on leaving work. The case, in fact, is parallel to that of the aëronaut when he rises in his balloon, or the climber of mountain peaks. The symptoms, dependent upon the removal of pressure, are as follows: Extreme pain; sometimes nausea and vomiting; sometimes paralysis; sometimes headache and dizziness. They are frequently associated with a sudden rush of blood to the brain and spinal cord. The precautions to be observed are quite interesting. It is recommended that only wiry men be selected for the work; that their time of labor be shortened in proportion to the pressure; that they take all possible care of themselves, never going to work on an empty stomach, eating meat and drinking coffee, and, when coming out of the caisson, taking time to do it gradually, passing into an intermediate atmosphere first, and resting an hour afterwards.

Miners. The health of a miner is exposed to special causes of injury. In addition to the danger of being blown up, or knocked down by falling

stones, he is constantly at work in the presence of great masses of minerals which generate noxious gases, not to mention the effluvia which arise from his own person, the flame of his candle, and the burning of powder. To this is added, in many cases, an excessive heat, often a steaming, sultry heat, or else a continual cloud of dust proceeding from the coal or rock under the blows of his pick. And if we further consider the confined position in which he often works, the excessive exertion, the exposure to draught, and the total deprivation of sunlight, we shall be ready to admit that his life is an unnatural one, and full of singular risk.

But man can adapt himself to almost anything. With proper precautions, it is said that the life of a miner is almost as safe, and his health quite as good, as those of other classes in general; better, in fact, than those of his own family. If this be so, it is certainly a great triumph of the hygienic art.

The precautions to be taken relate first and foremost to ventilation.

"Fire-damp" is a name given to light carburetted hydrogen, which is given off abundantly in the carboniferous strata and in enormous quantities from the gas-wells of North America. In our own coal-mines it is much more abundant than it is at present in America. When mixed with seven or eight times its own volume of common air, it is highly explosive. After

an explosion, the passages are filled with the irrespirable mixture of nitrogen, carbonic acid, and the vapor of water, resulting from its combustion.

"Choke-damp," or "black-damp," is a name for carbonic acid, a common product of most combustions, and of respiration. It abounds in badly-ventilated mines. Nitrogen is not a poison, by itself. Carbonic oxide, however, is one of the most dangerous of poisons, and so is sulphuretted hydrogen when present in any considerable quantity. Both the latter are called "white-damp."

The heated flue, as a means of exhausting air from mines, has obvious dangers in coal-mines; and its special disadvantage lies in the variations which different atmospheric conditions produce in its working.

The steam-fan, driven by a small engine, may be used either for drawing air from the mouth of a mine or for forcing it in through tubes to the places where it is most needed. It is, altogether, the best means of ventilating mines.

Another reason for supplying abundance of fresh air to mines is furnished by the great heat which is found under ground. In the Cornish mines, the temperature is said to increase regularly about one degree Fahrenheit in every fifty feet in the upper parts, and one in every eighty-five feet in the lower parts; and this is, with local exceptions, nearly the rate at which the temperature rises in other mines. Some of the

exceptions, however, are very remarkable. The deep levels of the mines on the Comstock Lode in Nevada have temperatures varying from 105° to 130° Fah. ; and this excessive heat is mitigated by blowing upon the men fresh air at 90° or 95°, which seems to be most conducive to comfort. The men, under these circumstances, work with great vigor, but have to be frequently relieved.

This great heat is said to be very productive of heart-disease. There is no doubt that this effect is intensified by excessive barometric pressure and by dampness of the air, preventing evaporation from the body. It is affirmed that the system in use at the Comstock is so thorough as to do away with most of the danger from all of these sources.

To spare the men a needless and wasteful expenditure of bodily force, it has been found best to use cages worked by engines to raise and lower those who are going to or from work.

The excessive quantity of coal-dust which chokes the air of badly-ventilated mines has been previously alluded to as affecting the lungs. But there are other causes of pulmonary trouble, quite obvious in their nature, such as sudden changes from heat to cold, and deliberately sitting down in draughts to cool off after working in the high temperatures mentioned. On the whole, the principal diseases are miners' asthma, consumption, and rheumatism, and, among those