in the regulations under the Federal Explosives Act 16 and recommendations incident thereto. These have been included to serve as a guide in the prevention of accidents that may result in personal injuries, loss of life, or damage to property.

Surface magazines should be provided for the storage of explosives at bituminous-coal mines. Recommendations pertaining to storage follow:

1. High explosives (permissible explosives or dynamites) in amounts exceeding 125 pounds should be stored in permanent magazines.

16 Bureau of Mines, Federal Explosives Act of December 26, 1941 (55 Stat. 863), as amended. Regulations issued under Federal Explosives Act. Recommendations for Stor

ing, Handling, and Transporting Explosives: Rev. as of June 1, 1944, 55 pp.

2. High explosives in amounts of 125 pounds or less may be stored in permanent magazines; if not so stored, such explosives should be stored in box-type magazines.

3. Black blasting powder in amounts exceeding 125 pounds should be stored in permanent magazines.

4. Black blasting powder in amounts of 125 pounds or less may be stored in permanent magazines; if not so stored, it should be stored in box-type magazines.

FIGURE 24.-Standard sand-filled or weak concrete-filled magazine.

Surface storage magazines should be constructed of incombustible material or covered with fire-resistant material and be reasonably bulletproof. Permanent magazines are preferably building types, and the walls should meet the following specifications or be con

2"x12" baseboard

LONGITUDINAL SECTION

Opening to be no larger than 72 sq. in.

FIGURE 25.-Magazine of simple construction for storing small quantities of explosives; capacity, 4,000 to 4,500

pounds.

3. Lined construction such as steel plate not lighter than No. 14 gage, lined

with weak concrete, cement mortar, brick, or with softwood not less than 3 inches in thickness.

The foregoing wall specifications should govern the construction of any artificial enclosing wall for tunnel- or dugout-type magazines on or exposed to the surface of the ground.

Foundations of building-type magazines should be substantially constructed, and any space between the floor and the ground should

2"

Tie beam.

?" tongue-and-groove

or wallboard

Sand-filled or weak concrete

structed of other materials that will make them at least equally theftand bullet-resistant:

1. Solid construction, not less than 6 inches in thickness, of materials such as concrete, masonry, medium-soft brick, or wood; or

2. Filled construction, such as concrete blocks with the cells filled with screened sand, weak concrete, cement mortar, or other effective bullet-resistant filler; or exterior and interior wooden walls not less than 6 inches apart with the space between filled with screened sand, weak concrete, cement mortar, or other effective bullet-resistant filler, and the exterior walls covered with sheet iron not lighter than No. 26 gage, or other fire-resistant material; or

Sand-filled or weak concrete-filled magazine with sand-tray ceiling

2"x6"

FIGURE 26.-Method of installing sand trays and ceilings in various types of magazines.

be enclosed in such a manner as to prevent the entrance of persons, animals, sparks, and firebrands.

Figures 23 and 24 show a standard brick magazine and a standard sand-filled magazine, respectively. Both types are recommended by the Institute of Makers of Explosives.

Figure 25 shows a magazine of simple construction suitable for storing small quantities of explosives. A magazine of this size would hold 4,000 to 4,500 pounds of explosives.

Roofs of storage magazines should be fire-resistant and substantially constructed to resist theft, as for example, by 34-inch sheathing covered with sheet iron or slate. Roofs not constructed of fire

FIGURE 27.-Method of constructing a sand-tray ceiling.

proof material should be covered with sheet iron not lighter than No. 26 gage or other fire-resistant material. The roofs of magazines so located that it would be possible to fire bullets directly through the roof into the explosives should be made bullet-resistant by material of construction, or by a ceiling that forms a tray containing not less than a 4-inch thickness of sand or other equally effective bullet-resistant filler erected in the interior of the magazine, or by other methods. Figures 26 and 27 illustrate methods of installing sand trays and ceilings in various types of magazines and constructing a sand-tray ceiling, respectively.