spread very rapidly in heavy timbering, and that footprints had been discovered in a drainage tunnel below the shaft collar. Against this was the difficulty of anyone climbing 3,000 feet up the manway without discovery; moreover, other places in the shaft nearer the surface could have been fired more easily and probably with greater damage to the mine.

The following points stand out in this fire as a guide to preventing future loss of life in such circumstances:

1. Men in the mine should be warned immediately.

2. An attempt should be made to hoist them.

3. All underground doors that can be reached should be opened to short-circuit the air; or all of them, including those along every level, should be closed to confine the fire within the shaft and smother it. 4. The fan should be readily reversible.

5. Doors should be so hung and arranged as to permit air to be reversed without short-circuiting.

6. Stoppage of the fan is of debatable value; unquestionably the natural draft of the fire in such a case would reverse the normal downcast tendency of the Argonaut shaft.

7. Timbered shafts should be fireproofed or fire-protected or at least the timbered stations fireproofed. Particularly, the space around electrical devices and switches should be protected against fire.

8. Every mine should have an organization for preventing and controlling fires, as well as fire-fighting equipment and a good water supply immediately available.

MAGMA MINE FIRE, SUPERIOR, ARIZ.

A fire in the No. 2 shaft of the Magma mine of the Magma Copper Co. about 3 a. m. November 24, 1927, caused the death of 7 men. There were 49 in the mine at the time of the fire. The mine is developed by 5 shafts, of which the No. 2 was 2,700 feet in depth and Nos. 3 and 5 shafts 2,550 feet. Shafts 2, 3, and 5 are connected on the 2,550-foot and other levels. The No. 2 shaft had 3 compartments, 2 for hoisting and 1 used as a manway; it also contains electric power and light lines.

Ventilation of the Magma mine at the time of the fire was directed by three surface and three underground fans, as well as various small blowers. An exhaust fan with a capacity of about 95,000 cubic feet per minute exhausted from No. 4 shaft but had been shut down a few minutes before the fire. Another exhaust fan at No. 1 shaft ventilated the upper levels of the mine. Shafts 2, 3, and 5 were intakes.

About 3:30 a. m. the fire in No. 2 shaft was discovered by the shift boss, who was investigating the continued steady ringing of the electric bells in both hoisting compartments of the shaft. He found smoke at the 1,200-foot level and by signaling with the pull bell was returned to the 500 level, where he carried the cage tender, who had been overcome by gas, through the ventilation doors and reported the fire. Shortly afterward a cage with one man on it was lowered; he died, presumably from burns or suffocation, and the cable was burned off. The men in the mine smelled smoke and proceeded for the most part to No. 3 shaft, where they were quickly hoisted. Some men came to the 2,200 station and saw the fire roaring up the shaft,

but no smoke was coming out into the station. They were unable to attach a hose to the fire connection because it was at the shaft and in the fire.

The fire in the No. 2 shaft was controlled and eventually extinguished by streams of water turned down the shaft from two levels. The No. 2 shaft had been gunited and concreted in part; but from the 1,600 level to the bottom it was timbered without fire protection, except at the stations, which were gunited to the 2,000 level. Guniting had been discontinued because of its stated tendency to promote and conceal timber decay. Gunited station timbering was fired during the shaft conflagration and continued to burn for days within the concrete shell after the main fire had been extinguished.

The fire evidently originated at or near the shaft at the 2,250 station, which was dry and timbered; the shaft timber was also dry. Oily waste at the car-repair station near the shaft ignited by a carbide lamp or possibly a cigarette butt was the origin of the fire; a transformer, a motor-driven fan, and light and power wiring, all at the 2,250 station, are also suspected.

Some 19 conclusions are drawn by the Bureau of Mines from this fire; among the more important are the following:

1. All main working shafts and stations should be concreted or otherwise rendered fireproof or fire-resistant; this applies particularly to downcast shafts or shafts in which men are handled.

2. All electrical equipment should be placed in a fireproof location and, if feasible, not in or near shafts or shaft stations.

3. Stations and all workings should be kept clean of all flammable material, and refuse should not be allowed to accumulate in a mine.

4. Placing of water lines on shaft stations, as was done at Magma, undoubtedly saved much additional damage to the Magma mine. Connections for hose attachments, however, should be at least 50 feet from the shaft in order that they may be reached in case of fire in the shaft.

5. Underground electrical wiring and equipment should be placed even more carefully than surface installations and should be inspected at least monthly by a competent electrician. Any defects should be remedied without delay.

6. If smoking is allowed underground it should be limited to prescribed areas in the mine where a minimum fire hazard exists; preferably smoking should not be permitted in dry timbered areas.

7. During the Magma fire the gunite definitely acted as a fire retardant. It appears that, even when the fire burned the gunitetimbered region, the progress of the burning was retarded to such an extent that there was a minimum of caving as compared with the large amount in ungunited timbered regions. If the No. 2 shaft had been entirely gunited or concreted and the station at the 2,200-foot level gunited the fire might not have had an opportunity to start.

8. It is dangerous to send men down on a cage when there is fire in a timbered shaft, even though the shaft is downcast. Fire quickly climbs up a downcast timbered shaft and converts such shaft into an upcast; this may occur even when the shaft is damp or fairly wet.

9. The excellent ventilating system in the Magma mine was responsible for the escape of most of the 43 underground workers who came

out alive; the foresight of the company in having 3 downcast shafts with hoisting equipment in them deserves high commendation.

As showing that the improbable sometimes happens, 3 days after the fire in the No. 2 shaft started and when it was practically under control, No. 1 shaft caught fire, although there was no possibility of fire being transmitted from the No. 2 shaft to the No. 1 shaft. This second fire apparently started from embers dropping down the shaft from a surface fire built near the shaft by a watchman on a cool night. This shaft contained no wiring or electrical equipment. There

FIGURE 3.-Portal and burned buildings, Capital Glenn mine, California.

was a water tank on the hillside just above the collar of the shaft, and it was possible to turn the water into the shaft both from this tank and from the fifth level. The fire was controlled in a few hours. During the time it burned, however, there was considerable danger that the fire might reach the magazine which contained 65,000 No. 8 detonators, located in the 200 station near the No. 1 shaft. To avoid this, an oxygen breathing apparatus crew removed the detonators to the outside.

GLENN MINE FIRE, PLACER COUNTY, CALIF.

A fire originated in some unknown manner in the wooden surface structures near the portal of the Glenn mine of the Capital Glenn Mining Co. on July 14, 1930, about 10:15 a. m. (fig. 3).

This mine is an underground placer property operated through adits driven into the hillside to recover the auriferous gravel from an old stream bed. The uppermost adit, the part of the mine then working, had been driven 1,121 feet from the portal and connected at about 758 feet from the portal with the middle or Moss adit, by means of an incline dipping about 150. The Moss adit was part of some old workings of a similar nature but was not kept repaired.

The ventilation was natural; fresh air entered the top adit at a velocity of nearly 200 feet per minute, followed down the incline, and left through the Moss adit and its connections.

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The surface compressor house and shop building was about 25 feet from the portal of the upper adit, to which it was connected by a snowshed. The snowshed extended to the edge of the dump, connecting with the powder house about 75 feet from the end of this shed. When the fire started no one was near the portal of the adit on the surface, and five men were working at the faces; these men tried to escape by going down the incline and out the Moss adit but were overcome and died in the attempt.

The fire burned all of the structures on the surface near the portal and about 70 feet of timbered adit inside of the portal, jumped an untimbered gap of 63 feet, and ignited other timber sets; on account of the wetness of these sets, the fire died out when the timber at the portal was consumed.

No fire-fighting equipment was available at or near the mine, and equipment of the United States Forest Service was brought in to extinguish what was left of the fire.

Like many small properties, little or no consideration had been given to the possibilities of fire and its results, consequently no protection had been provided or plans made for combating fire or preventing smoke from entering the mine.

CAUSES OF METAL-MINE FIRES

Most metal-mine fires may be grouped as to cause under the following headings:

Electric wiring and equipment.

Open lights, matches, and smoking.
Spontaneous combustion.

Explosives and fuse.

Incendiarism.

Ignition of explosive gases.

Heating appliances.

Greasing and welding.

Miscellaneous.

ELECTRIC WIRING AND EQUIPMENT

The latest available data indicate that between 30 and 40 percent of present-day metal-mine fires owe their origin to electricity. This percentage is likely to increase with the widening use of electric locomotives, pumps, hoists, blower fans, slushers, drills, and like equipment. Some samples of electrically caused fires are the following:

1. A timber in a shaft gave way, breaking electric wires; timbers were ignited by an electrical short circuit.

2. Fire was caused by contact of a heated electric-light globe with some "dope" used for a belt.

3. A fire was caused by a spark from a short circuit in the hinge on a knife-type trolley switch.

4. The contact of a trolley wire with the cap of a sagging set of timber in a wet drift caused a smoldering fire, with dense smoke.

5. Fire was started by the contact of electric wires with 12 by 12 inch timber, probably due to defective insulation.

6. A small transformer and a starting compensator ran hot, setting fire to a wooden frame.

7. A short circuit in the electric-power cable set fire to a timber in a wet shaft.

8. A fire was caused by an overheated resistance on an electric tugger.

9. A trolley wire fell and heated, causing the insulation on the feeder wire to burn, starting a fire in the shaft. The ground was insufficient to operate the circuit breaker at the shaft.

10. Current was left on the controller of a hoist, the hoist motor became overheated, and the timber foundation began to burn.

11. The wiring at an electrically operated blower fan started a fire when squeezing ground caused short-circuiting of the wires.

12. An oil switch controlling the power lines of a mine failed and started a fire at the shaft collar, which spread into the mine.

13. An overloaded trolley feed cable heated and caused a fire because the circuit breaker had been fastened in.

14. Electric welding and bonding of rails set fire to ties in a mine. Evidently the utmost care should be taken in the selection, installation, use, inspection, and repair of underground electrical equipment. and wiring.

OPEN LIGHTS, MATCHES, AND SMOKING

Candles, and later, carbide lamps, have been responsible for many fires. It is estimated that between 20 and 30 percent of all recent fires in metal mines have been due to smoking, carbide lamps, and open fires or flames used for various purposes. Some such fires are briefly described as to cause as follows:

1. A shaft fire was started by a carelessly thrown cigarette.

2. A miner going off shift threw a lighted piece of paper down a chute to see how much ore was in the chute and a fire resulted.

3. A fire was started close to the fan motor on one side of a shaft station by contact between a miner's carbide cap lamp and canvas tubing taking air from the fan.

4. A match started a fire in a station close to a timbered shaft. 5. A pumpman burning newspapers on a concrete floor in a pump room set fire to adjacent timber.

6. The bark on a timber cap piece was fired, probably by coming in contact with a miner's carbide lamp.

7. A candle used for illumination was left burning by a miner and caused a fire.

8. A fire was found in a raise at a point where spent carbide was thrown.

9. A mechanic's helper, while welding a water line, searched for a leak in an acetylene line with an open carbide light. The timber caught fire.

10. The open-flame lamp of a man who was recovering some tools that he had hidden where there was some dry lagging came in contact with the timber and caused a costly fire.

11. A lighted carbide lamp which a powderman placed on a shelf under a large fuse box started a fire by igniting the paper between the boards.

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12. Mine officials inspecting some long-abandoned pillars of ore with a view to planning their removal sat down and smoked at a certain place, and about 24 hours later a fire was giving off so much smoke that the mine had to be closed until the fire could be extinguished.