DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

BULLETIN 369

THE PREVENTION OF MINE EXPLOSIONS

REPORT AND RECOMMENDATIONS

VICTOR WATTEYNE

Inspector-General of Mines, Belgium

CARL MEISSNEE

Councillor for Mines, Germany 

AND

ARTHUR DESBOROUGH

H. M. Inspector of Explosives, England

WITH LETTER OF TRANSMIT!AL BY

JAMES RUDOLPH GARFIELD

Secretary of the. Interior

WASHINGTON

GOVERNMENT PRINTING OFFICE

1908

LETTER OF TRANSMITTAL.

DEPARTMENT OF THE INTERIOR,

Washington, October 20,1908.

SIR: I send you herewith the report of Messrs. Watteyne, Meissner, 

and Desborough, the three foreign mining experts who, at my 

request, and in accordance with the appropriation made by Congress 

for the investigation of mine explosions, have made a very thorough 

examination and study of the mine conditions in our country. They 

have visited the principal coal-mining districts of the country, making 

personal examination of the representative mines. Their report is of 

great interest and will be of the highest importance in aiding Congress 

and the different state governments in providing legislation which will 

insure more efficient and careful operation of coal mines, by the 

adoption of mining methods and safety appliances which will materially aid in preventing the terrible losses of life that have occurred 

through mine explosions in recent years.

Each of these gentlemen has had the widest experience in his own 

country, and it is fortunate that we have been able to obtain their 

services in making this examination and report.

The report is preliminary to the more extensive investigations now 

being conducted by the technologic branch of the Geological Survey, 

and shows the vital importance of studying in a thoroughly scientific 

and at the same time practical way the conditions under which the 

more than half a million coal miners are daily risking their lives. 

Very respectfully,

JAMES RUDOLPH GARFIELD,

Secretary.

THE PRESIDENT.

3

THE PREVENTION OF MINE EXPLOSIONS.

REPORT.

To THE HONORABLE

THE SECRETARY OF THE INTERIOR.

SIR: In response to your request that we cooperate with the United 

States Geological Survey in the inauguration of its investigations looking to the prevention of mine explosions, and that we submit for the 

consideration of those connected with the coal-mining industry in the 

United States such recommendations as experience in our own countries and observation among American coal mines indicates may be 

useful in providing for greater safety, we beg to submit the recommendations given below.

Since coming to the United States, we have given careful attention 

to and approve the investigations in relation to this subject begun 

by the Geological Survey. We have visited typical mines in the 

more important coal fields of the United States, and have discussed 

the mining problems with many coal operators, miners, and state 

inspectors.

To be effective, investigations for the benefit of mining must be continuous. The opening up of new mines, the deepening of old mines, 

the meeting with new conditions,.the changing of explosives, and the 

inauguration of new processes and methods will call for continuous 

investigations, to be followed by continuous educational work.

Our investigations and recommendations relate primarily to questions of safety in mining; but in this connection we have been greatly 

impressed with another closely associated phase of the industry, viz, 

the large and permanent loss of coal in mining operations in many 

portions of the United States. This is a serious, permanent, and 

national loss. It seems to be a natural outcome of the ease with which 

coal has been mined in the United States and the enormously rapid 

growth of the industry.

The active competition among the operators and the constant resulting effort to produce cheaper coal has often naturally led to the mining of only that part of the coal which could be brought to the surface 

most easily and cheaply, leaving underground, in such condition as to

5
6 PEEVENTION OF MINE EXPLOSIONS.

be permanent!}- lost, a considerable percentage of the total possible 

product. Certainly much of this loss can be prevented through the 

introduction of more efficient mining methods, such as the long-wall 

system, more or less modified, the flushing method. (See " H," 7, p. 10.) 

In the preparation of these recommendations we have recognized 

fully the great differences between the mining conditions in Europe 

and those in America, where the industry has developed so rapidly 

that thorough organization has not yet been possible; where a large 

percentage of the men entering the mine are unfamiliar either with 

mining methods or the English language; and where the price of coal 

at the mine is less than half that in Europe. Nevertheless, we believe 

that these recommendations will be found useful in the further development of the American coal-mining industry for safety and efficiency The cordial reception everywhere accorded us leads us to 

believe that these recommendations will be received ~by the operators 

and miners in the same spirit of good will as that in which they have 

been prepared. But the success of this movement for greater safety 

and efficiency will depend upon the hearty and patient cooperation of 

the operators and the miners, working together for the accomplishment of this purpose.
RECOMMENDATIONS.

A. SELECTING THE EXPLOSIVES TO BE USED.

. (1) We recommend that the Government of the United States examine the explosives now and hereafter used in mining1 , with a view to 

eliminating the more dangerous explosives and to improving and 

standardizing such explosives as may be considered most suitable f01' 

such use, these to be designated by the Government "permissible 

explosives."

The term "permissible explosives" is suggested for the reason that 

no explosives are entirely safe, and all of them develop flame when 

ignited; and we advise therefore against the use in the United States 

of the terms "safety explosives" or "flameless explosives," as these 

terms may be misunderstood and this misunderstanding may endanger 

life.

(2) We recommend that the operators and miners of coal use only 

such explosives as are included in a list of "permissible explosives," 

when the same has been published by the Government, in all mines 

where there is risk of igniting either dust or gas, selecting that one 

which their own experience indicates can be used to the best advantage under local conditions.

(3) We also recommend that investigations be conducted to determine the amount of charge of such "permissible explosives " which 

may be used to the best advantage under different conditions with a 

view to reducing danger to the minimum.

B. CARRYING THE EXPLOSIVES INTO THE MINES.

(1) All explosives should be made into cartridges and placed in closed 

receptacles before being carried into the mine, and the quantity carried into the mine during one day by any miner should be limited as 

nearly as practicable to the quantit}^ needed by him for use during 

that day. Handling loose explosives and making them into cartridges 

b.y an open light in the mine should be prevented.

(2) Detonators or caps should be handled with great care, and should 

be carried only by a limited number of responsible persons.

7
0 PREVENTION OF MINE EXPLOSIONS. 

C. USE OF EXPLOSIVES IN THE MINE.

(1) Shooting in or off the solid should not be practiced.

(2) The depth of the shot h6le* should be less by at least 6 inches 

than the depth of the cutting or mining. The use of very deep shot 

holes should be avoided as unnecessarily dangerous.

(3) The overcharging of shots (the use of a larger charge than is 

required to do the work satisfactorily) should also be avoided as 

unnecessary and dangerous. The proper standardization of explosives 

used in coal mining will greatly facilitate the carrying out of this 

.recommendation. (See also "A," 1, p. 7.)

(4) Shots should never be tamped with fine coal or material containing coal. Clay^or other suitable material should be supplied and used 

for this purpose.

(5) The firing of two or more shots in one working place, except 

simultaneously by electricity, should not be allowed until a sufficient 

interval has elapsed between the firings to permit an examination of 

the working place in order to see whether any cause of danger has 

arisen.

(6) Before a shot is fired the fine coal should be removed from the 

working place, as far as practicable, and the coal dust on the floor, 

sides, and roof, for a distance of at least 20 yards from the place where 

the shot is to be fired, should be thoroughly wet, unless it has been 

demonstrated that the dust in the mine is not inflammable. (See also 

"E,"l,p. 9.)

(7) If gas is known to occur in the mine, no shot should be tired 

until, in addition to the watering, an examination made immediately 

preceding the time for firing, b}7 a competent person, using a lamp 

which will easily detect 2 per cent of gas, has shown the absence of 

that amount of gas from all spaces within 20 yards of the point where 

the shot is to be fired.

(8) Believing that such will be one of the greatest advances which 

can be made in safeguarding the lives of the miners, we recommend 

the adoption of a system of electric shot firing, in all mines where 

practicable, by which all shots in the mine, or in each ventilation district of the mine, may "be fired simultaneously^ at a time when all 

miners and other employees are out of the mine.

D. KEEPING THE MINE ROADWAYS CLEAN.

(1) The roadways of the mines should be kept as free as possible 

from loose coal which ma}r be ground into dust and of rubbish in 

which such dust may accumulate, in order to facilitate the removal 

and wetting of the dust.
BECOMMENDATIONS. » 

E. WETTING THE COAL DUST.

(1) In all coal mines where explosives are used it is desirable, and 

in all mines containing gas it is highly important, that the dust on the 

walls, timbers, and floors of the working places and roadways should 

be kept continual^ wet prior to and during the work in the mine. 

If, however, conditions of roof or lack of water render this general 

watering impracticable, at least the dust within 20 yards of each shot 

should be wet before each firing, and other precautions against explosions should be practiced with unusual care.

It is our opinion that a system of watering which occasionally 

sprinkles the floor only and leaves dry the dust on the walls and 

timbers of the roadways is useless and is also dangerous'in that it 

may generate an unwarranted feeling of security against an explosion.

F. SPECIAL PRECAUTIONS FOR MINES CONTAINING GAS.

(1) In any mine where as much as 2 per cent of gas can be detected 

by suitable method only locked safety lamps of an approved type 

should be used so long as such condition exists or is likely to recur.

All safety lamps should be maintained in good condition, cleaned, 

filled, kept in a special room at the surface, and carefully examined 

both when delivered to the miner and when returned by him at the 

close of each day's work. A defective safety lamp is especially dangerous because of the false feeling of security it engenders.

In the filling of lamps with benzine or other low-flash oils, which 

should always be done at the surface, special precautions against fire 

or explosions should be taken.

G. USE OF ELECTRICITY.

(1) Electricity in mining operations offers so many advantages, and 

has been so generally adopted, that no reasonable objection can be 

made to its use under proper restrictions. The electrical equipment, 

however, should be installed, maintained, and operated with great care, 

and so safeguarded as to minimize danger from fire or shock. The 

fact that the effectiveness of some insulating materials is soon destroyed 

in most mines should not be lost sight of.

We recommend the following precautions: For distribution underground the voltage should not exceed 650 direct current or 500 alternating current, these voltages being intended for transmission to 

machinery operating at 500 volts direct current and'440 volts alternating current, respectively. Even lower voltages are preferable. The 

trolley wires should be installed in such manner as to render shocks 

least likely; that is, placed either high enough to be bej^ondeasy reach 

or to one side of the track and properly protected.
10 PKEVENTION OF MINE EXPLOSIONS.

Where current at a potential of more than 650 volts is employed 

for transmission underground, it should be transmitted by means of a 

completely insulated cable; and where a lead or armored covering is 

used, such covering should be grounded.

In all mines having electric installation special precautions should 

be taken against the setting on fire of coal or timber. Inclosed fuses 

or cut-outs are recommended, and each branch heading should be so 

arranged that the current may be cut off when necessary.

No live electric wire should be permitted in that part of any mine 

n which gas is found to the amount of 2 per cent.

In all mines producing gas in dangerous quantities, as indicated by 

a safety lamp which will detect 2 per cent of gas, the working places 

should be examined for gas by a qualified man, using such a lamp, 

immediately before any electric machine is taken or operated there.

H. PRECAUTIONS AGAINST MISCELLANEOUS ACCIDENTS.

(1) In all new construction, shaft lining and superstructures about 

the entrance of the shaft (or slopes or drifts) should be built as far as 

practicable of noncombustible materials.

About the entrances to mines, every possible precaution should be 

taken to prevent fires or the injury of the equipment for ventilation 

and haulage. Ventilating fans should be placed to one side of the mine 

opening, and hinged doors or light timbering should render easy the 

escape of the explosive force in direct line of the shaft or slope.

Proper precautions should be taken for immediately preventing the 

entrance into the mine of heat and gases and for facilitating the escape 

of the men in case of surface or shaft fires.

(2) The surface equipment for handling the coal should be so arranged as to prevent coal dust entering into the mine shaft.

(3) In all new mines, and in all old mines as far as practicable, suitable man roads should be provided for the men separate from the main 

haulage roads.

{4) In connection with the sj^stem of ventilation it is recommended 

that in the more frequented roads connecting the intake with the 

return air courses, two doors be provided, these doors to be placed at 

such a distance apart that while one is open the other is closed.

(5) In view of the large number of accidents from falls of coal or 

roof, under the existing practice with single props, more attention 

should be given to the introduction in mines where the roof is bad of 

better systems of ° timbering, such as have been long in use with 

econoni}^ and safety in man}^ well managed mines.

(6) In undercutting coal by hand, the premature fall of the coal 

should be prevented by sprags or other suitable supports.

(7) We believe that the difficulties and dangers encountered in the 

working of coal seams which are thick and steeply pitching, or of
RECOMMENDATIONS. 11

which the coal is highly inflammable in character or subject to firing 

from spontaneous combustion, and in mines where the subsidence of 

the surface must be avoided, may be successfully and economically 

overcome in many cases through the adoption of the flushing system 

of mining that is, the filling with sand or other similar materials of 

the space from which the coal is removed. This system originated in 

the United States and is now successfully practiced in portions of 

Germany, Austria, Belgium, and France.

I. MINE SUPERVISION AND INSPECTION.

(1) We can not too strongly emphasize the fact that thorough 

discipline about the mine is absolutely essential to safety, and that 

thorough discipline can be brought about only through the hearty 

cooperation of the operators, the miners, and the State.

(2) We are of the opinion that the responsibility for safety in the 

mine should primarily rest with some person, such as the manager or 

superintendent, clothed with full authority; and that such person can 

greatly facilitate the attainment of safety through the employment of 

a sufficient number of foremen, and also of one or more inspectors 

whose special duty it shall be to see that the regulations are strictly 

enforced.

(3) The State can not exercise too much care concerning the experience, technical training, and selection of its inspectors. Their positions should be made independent of all considerations other than that 

of efficiency; and their continuance in the service should be coexistent 

with good behavior and proper discharge of official duty.

J. TRAINING FOE MINE FOREMEN, INSPECTORS, ETC.

We are of the opinion that the cause of both safety and efficiency 

in coal mining in the United States would be greatly aided through 

the establishment and maintenance in the different coal regions of 

special schools for the training of fire bosses, mine foremen, superintendents, and inspectors. The instruction in such schools should be 

practical rather than theoretical.

The work of these schools would supplement most effectively that of 

the colleges already established in many parts of the country for the 

more thorough training of mining engineers. 

Respectfully submitted.

VICTOR WATTEYNE. 

CARL MEISSNER. 

ARTHUR DESBOROUGH.

O