DRAEGER NO. 2, 1910 TYPE.

The 1910-type Draeger apparatus (fig. 2) works on the same principle as the 1907 type, but is differently built. The 1910 type has the following parts: A knapsack with one oxygen bottle which contains, at a pressure of 150 atmospheres (2,205 pounds per square inch), oxygen enough for two hours' service; a reducing valve which regulates the supply of oxygen from the oxygen bottle; an injector nozzle which makes the air circulate; a pressure gage, readable by the

FIGURE 2.-Circulating system of Draeger 1910-type apparatus, with mouth-breathing
device. A, pressure gage; B, regenerator; C, oxygen injector.

wearer, which indicates the length of time the oxygen in the cylinder will last; a chest union to which are attached the circulating tubes and one breathing bag; a helmet or a device for mouth breathing; a regenerator can (or cartridge), which contains potash grains arranged on shelves to absorb the carbon dioxide exhaled in the wearer's breath; and a tube for cooling the purified air.

A relief valve on the chest union permits air to escape from the breathing bag when the bag gets too full. There are no valves in the

circulating system. The helmet is of leather and has a mica window fastened in a metal frame. The facial tube is made to press against the forehead, the cheeks, and the under side of the chin; it should not cover the temples. As in the 1907 type, the facial tube is inflated by pressing a rubber bulb. The sponge and its supporting rod are held in place by a spring inside of the helmet.

These two types of Draeger apparatus have been subjected to many working tests, both at the mining experiment station at Pittsburg and in coal mines.

A more recent model of the 1910 type has two breathing bags, mica valves in the circulating system, and separate tube connections with the helmet for the inflow and outflow of air. A mouth-breathing attachment may be substituted for the helmet.

WESTFALIA.

The Westfalia breathing apparatus (helmet and mouth-breathing types) has, like the Draeger, a knapsack that is suspended from the shoulders and rests on the back. This knapsack has a frame supporting two oxygen cylinders, a regenerator, a pressure gage, a reducing valve, and an injector. Resting on the breast of the wearer are two breathing bags; one is connected to the oxygen supply tube and the helmet, and the other to the exhalation tube and the regenerator. The helmet, like that of the 1907-type Draeger apparatus, covers the front half and top of the head and is held in place by a strap. A flexible rubber lining fits about the face and keeps out the external air. Ordinarily the lining makes a tight enough fit, but for greater safety a rubber tube around the edge of the lining may be inflated by an attached rubber bulb. The Westfalia apparatus is so arranged that the mouth-breathing device may easily be substituted for the helmet.

The reducing valve is adjusted to keep a pressure of 8 to 10 centimeters (3.15 to 3.94 inches) of water column on the oxygen circulation and to deliver 2 liters (122 cubic inches, or about 2 quarts) of oxygen per minute. The injector nozzle moves 50 liters (1.77 cubic feet) of air per minute.

The circulating system of the Westfalia helmet-type apparatus is shown in figure 3.

FLEUSS OR PROTO.

The Fleuss (or Proto) breathing apparatus (fig. 4) consists of a pair of steel cylinders or bottles, containing oxygen at a pressure of 120 atmospheres (1,764 pounds per square inch); a reducing valve equipped with a by-pass valve; a breathing and regenerating bag that contains, when ready for use, 4 pounds of caustic soda in sticks, a saliva trap, a cooler, and a relief valve; and mouthpiece, nose clip, 1415°-Cir. 4-11- -2

FIGURE 3.-Circulating system of the Westfalia helmet apparatus.

and passed through a pair of leather loops upon the body side of the breathing bag holds the bag in position when the wearer stoops or crawls. The breathing bag and cylinders may be hung from a pair of

goggles, and skullcap. A face mask that covers the nose and mouth may be used instead of the mouthpiece.

The whole apparatus is supported upon a broad belt which is fastened around the body. A leather strap attached to the belt

REGENERATOR

TUBE FOR EXHALED AIR

OXYGEN

shoulder braces that can be adjusted by straps and buckles at the back to suit the height of the wearer.

Putting on the apparatus.-All that the wearer has to do is to put the equipment over his shoulders, fasten the belt, and take the plug

FIGURE 4.—Circulating system of the Fleuss, or Proto, apparatus.

out of the mouthpiece. The moment the mouthpiece is put into the mouth or the mask is adjusted, the main valve is opened not more than one turn, when the necessary supply of oxygen flows into the bag. At the start it is advisable to open the by-pass in order to partly inflate the breathing bag, but after the bag is inflated this

valve should be screwed tight and should not be touched except in an emergency; that is, when the bag becomes deflated.

Should the reducing valve by any chance get out of order, the wearer should open the by-pass from time to time to give himself the necessary quantity of oxygen, but he should do this only when the breathing bag becomes deflated. The best guide as to the quantity of oxygen to admit by opening the by-pass is the fullness of the breathing bag. The working of the apparatus is most satisfactory when the bag is kept moderately full.

Care of the apparatus.-After the apparatus has been in use the caustic soda should be removed from the bag at once; but if it is not removed and becomes caked it must be dissolved out with warm water before a fresh supply is put in. The caustic soda may be removed from the bag, washed, dried, and used again, or it may be removed, melted, and recast into sticks for future use. Caustic soda damages canvas and leather and will burn the skin if allowed to remain upon it.

If the apparatus is not to be used again for some time, the indiarubber breathing and regenerating bag should be washed out with warm water and dried inside with a cloth or towel before recharging; but if it is to be used at once, washing and drying are unnecessary. Before it is emptied or recharged the rubber bag must be removed from the canvas bag which incloses it.

The rubber mouthpiece (or mask, as the case may be) should be washed with soap and water after use. This not only cleans the indiarubber, but helps to preserve it.

The small relief valve is to be opened (by pressing it with the finger) only when the bag becomes too full.

See that the inlet and outlet valves and the connections are screwed tight.

Heat helmet. For the protection of the wearer in fighting a mine fire a heat helmet is supplied when desired. This helmet is made of rawhide and has a mica window in front, but it has nothing to do with breathing.

GOGGLES AND NOSE CLIP.

Goggles.-Goggles are used with the mouth-breathing patterns of apparatus only when a man has to work in smoke or in gases that affect the eyes. The wearer should adjust the goggles beforehand so that they have an air-tight fit; wetting the rubber cushion with water helps to insure such a fit.

Before the goggles are put on, the glasses should be wetted inside to prevent fogging."

Nose clip. In the use of the mouth-breathing patterns of apparatus a clip is worn on the nose to close the nostrils. This clip has adhesive plasters which make it fit the nose firmly. To keep the