than one test lasting two hours shall be made in any one day. The tests shall be completed within 60 days from date of beginning unless conditions arise which are beyond the control of the mine-safety engineer in charge.

All tests of apparatus shall be conducted in a specially equipped gallery filled with irrespirable atmosphere at the Pittsburgh Experiment Station of the bureau. Before beginning each test the apparatus shall be examined and tested to make sure that there is no leakage under working conditions.

The apparatus under test shall be worn during each and all of the 2-hour periods of the 15 tests by the bureau safety engineer in charge of testing or by one or more of his assistants. Immediately before participating in any of these tests the prospective wearer shall satisfactorily pass a physical examination by a qualified physician. If it is impossible to carry any of these tests to completion solely on account of the poor physical condition of the wearer, where such condition has been brought about through no fault of the apparatus under test, such test shall be disregarded and the apparatus under test shall not be penalized or disqualified. At the conclusion of each test a note shall be made of the general physical condition of the apparatus and the amount of oxygen, if any, remaining in the container.

SCOPE OF APPROVAL

The listing by the Bureau of Mines of any self-contained mine rescue breathing apparatus as permissible shall be construed as applying only to apparatus of that specific type, class, form, and rating made by the same manufacturer which have the same construction in all details directly or indirectly affecting the safety features of the apparatus.

Manufacturers before claiming the bureau's approval for any modifications of a permissible self-contained mine rescue breathing apparatus shall submit to the bureau drawings or parts showing the extent and nature of such modifications, so that the bureau may decide whether a test of the remodeled apparatus will be necessary for approval.

By winning a place on the Bureau of Mines permissible list each apparatus listed has been adjudged safe for use in irrespirable and poisonous atmospheres. In meeting all the requirements of the bureau permissible apparatus have passed the following rigid tests:

1. They protect the wearer against any and all irrespirable and poisonous mine gases for a period of at least 2 hours when working and for approximately 15 hours if the wearer remains quiescent.

2. They are strong enough to withstand a reasonable amount of rough handling without serious injury to vital parts.

3. The design of such permissible apparatus is based on sound principles. The apparatus are carefully constructed and theoretically and practically as safe as it is possible to build equipment of this kind.

STATUS OF BREATHING APPARATUS

The use of mine rescue apparatus is no longer an experiment and has been introduced in every coal and metal mining field in the United States. Thousands of miners have been trained by the Bureau of Mines, State departments of mines, and mining companies or groups of companies. In some States, notably Utah and Washington, mining codes require rescue apparatus to be part of the equipment at mines of certain size and character. State mine rescue stations have been established by Illinois, Ohio, Kentucky, Kansas, and West Virginia. Mine insurance rates under compensation insurance laws for certain classes of mines are considerably lowered in a number of States by the installation of mine rescue apparatus and mine rescue stations. The use and knowledge of mine rescue apparatus has become widespread and several thousand have been sold in the United States. The bureau alone owns about 300 sets. Many large progressive mining companies maintain regular trained corps of five or more men each, equipped with the necessary apparatus. Some companies have established joint rescue stations, and four States maintain such stations.

The bureau has no authority to require the installation of mine rescue stations, the purchase of mine rescue apparatus, or the training of miners; such authority rests with States alone. The bureau, however, gives training, advice, and assistance at the request of operators, miners, and State departments of mines and maintains. the closest possible contact and cooperation with them. For details. of construction, testing, and assembly of self-contained oxygen breathing apparatus see the Bureau of Mines Handbook.16

RESUSCITATION "

Men engaged in fighting or sealing mine fires or in recovery work following mine explosions should have a knowledge of first aid to the injured. It is vitally important that every man be able at least to perform artificial respiration and properly use an oxygen inhaler on a person overcome by poisonous mine gases, oxygen deficiency, or electric shock. Men engaged in recovery work are often overcome by poisonous gases, and occassionally men are found overcome in

10 Parker, D. J.; McCaa, G. S.; and Denny, E. H., Self-Contained Mine-Rescue Oxygen Breathing Apparatus-A Handbook for Miners: Bureau of Mines, 1923, 139 pp. Revised in 1928, 229 pp. 17 Manual of First-Aid Instruction: Bureau of Mines, revised 1921, 221 pp.

a mine after an explosion or fire. In both cases prompt and efficient treatment is necessary to save life. The victim should be removed immediately to fresh air and artificial respiration started.

The bureau recommends the manual and oxygen inhaler methods of treating persons who are unconscious from poisonous gases, drowning, asphyxiation, or electric shock.

MANUAL METHODS

The Schaefer or prone-pressure method of artificial respiration should be used where possible; however, the Sylvester method may be used advantageously in certain cases.

FIGURE 18.-First position for giving artificial respiration by the prone-pressure method

18

Lay the patient on his belly, one arm extended directly over the head, the other arm bent at the elbow, and the face turned outward and resting on the hand or forearm, so that the nose and mouth are free for breathing. (See fig. 18.)

Kneel, straddling the patient's thighs with your knees placed at such a distance from the hip bones as to allow the palms of your hands to be placed on the small of the back with fingers resting on the ribs, the little finger just touching the lowest rib, with the thumb

18 This method has been approved by the following: American Telephone & Telegraph Co., American Red Cross, American Gas Association, Bethlehem Steel Co., National Electric Light Association, National Safety Council, Bureau of Medicine and Surgery, Navy Department, office of the Surgeon General, War Department, U. S. Bureau of Mines, U. S. Bureau of Standards, U. S. Public Health Service.

and fingers in a natural position and the tips of the fingers just out of sight. (See fig. 20.)

With arms held straight, swing forward slowly so that the weight of your body is gradually brought to bear upon the patient. The

prone-pressure method

shoulder should be directly over the heel of the hand at the end of the forward swing. (See fig. 19.) Do not bend your elbows. This operation should take about two seconds.

Now swing backward immediately so as to completely remove the pressure. (See fig. 20.) 19 After two seconds swing forward again. Repeat slowly the double movement of compression and release 12 to 15 times a minute, making a complete respiration in four or five seconds.

Continue artificial respiration without interruption until natural breathing is restored (if necessary, four hours or longer) or until a physician declares the patient is dead.

As soon as artificial respiration has been started and while it is being continued an assistant should loosen any tight clothing about the patient's neck, chest, or waist. Keep the patient warm. Do not give any liquids whatever by mouth until the patient is fully

conscious.

To avoid strain on the heart when the patient revives, he should be kept lying down and not allowed to stand or sit up. If the doctor has not arrived by the time the patient has revived, he should be given some stimulant, such as one teaspoonful of aromatic spirits of ammonia in a small glass of water or a hot drink of coffee, tea, etc.

Resuscitation should be carried on as near as possible to where the patient received his injuries. He should not be moved until he is breathing normally of his own volition and then only in a lying position. Should it be necessary, due to extreme weather conditions, etc., to move the patient before he is breathing normally, resuscitation should be carried on while he is being moved.

A brief return of natural respiration is not a certain indication that resuscitation should be stopped. Not infrequently the patient after a temporary recovery of respiration stops breathing again. The patient must be watched, and if natural breathing stops artificial respiration should be resumed at once.

In applying resuscitation it may be necessary to change the opera tor. This change must be made without losing the rhythm of respiration. With this method no confusion results when the operator is changed and a regular rhythm is maintained.

HOW TO GIVE ARTIFICIAL RESPIRATION BY THE SYLVESTER METHOD

To use the Sylvester method, place the patient on his back. Remove from his mouth all foreign bodies, such as false teeth, tobacco, gum, etc. The tongue must be held out, as otherwise it will fall back and block the windpipe. Grasp it in a dry cloth or with pincers. Have someone hold it out, or, better, hold it out by a bandage or rubber band over the tongue and under the jaw. Place a rolled-up coat, a pad, or something similar under the patient's shoulders. This will straighten his windpipe. Kneel just above the

19 In actual work the hands may or may not be entirely removed from the patient. In contests for uniformity the operator will entirely remove the hands and assume the position shown in Figure 18 between each complete respiration.