_Organization, and Character of the Work._--The mine rescue
investigations, carried on at the Federal testing station, at Pittsburg,
Pa., include five lines of attack:
1.--Investigations in the mines to determine the conditions leading up
to mine disasters, the presence and the relative explosibility of mine
gas and coal dust, and mine fires and means of preventing and combating
them.
2.--Tests to determine the relative safety, or otherwise, of the various
explosives used in coal mining, when ignited in the presence of
explosible mixtures of natural gas and air, or coal dust, or of both.
3.--Tests to determine the conditions under which electric equipment is
safe in coal-mining operations.
4.--Tests to determine the safety of various types of mine lights in the
presence of inflammable gas, and their accuracy in detecting small
percentages of mine gas.
5.--Tests of the various artificial breathing apparatus, and the
training of miners and of skilled mining engineers in rescue methods.
The first four of these lines of investigation have to do with
preventive measures, and are those on which ultimately the greatest
dependence must be placed. The fifth is one in which the result seems at
first to be the most apparent. It has to do, not with prevention, but
with the cure of conditions which should not arise, or, at least, should
be greatly ameliorated.
During the last 19 years, 28,514 men have been killed in the coal-mining
industries.[2] In 1907 alone, 3,125 men lost their lives in coal mines,
and, in addition, nearly 800 were killed in the metal mines and quarries
of the country. Including the injured, 8,441 men suffered casualties in
the mines in that year. In every mining camp containing 1,000 men, 4.86
were taken by violent death in that year. In the mining of coal in Great
Britain, 1.31 men were killed in every 1,000 employed in the same year;
in France, 1.1; in Belgium, 0.94, or less than 1 man in every 1,000
employed. It is thus seen that from three to four times as many men are
being killed in the United States as in any European coal-producing
country. This safer condition in Europe has resulted from the use of
safer explosives, or the better use of the explosives available; from
the reduction in the use of open lights; from the establishment of mine
rescue stations and the training with artificial breathing apparatus;
and from the adoption of regulations for safeguarding the lives of the
workmen.
The mining engineering field force of the Geological Survey, at the head
of which is Mr. George S. Rice, an experienced mining and consulting
engineer, has already made great progress in the study of underground
mining conditions and methods. Nearly all the more dangerous coal mines
in the United States have been examined; samples of gas, coal, and dust
have been taken and analyzed at the chemical laboratories at Pittsburg;
extended tests have been made as to the explosibility of various
mixtures of gas and air; as to the explosibility of dust from various
typical coals; as to the chemical composition and physical
characteristics of this dust; the degree of fineness necessary to the
most explosive conditions; and the methods of dampening the dust by
water, by humidifying, by steam, or of deadening its explosibility by
the addition of calcium chloride, stone dust, etc. A bulletin outlining
the results thus far obtained in the study of the coal-dust problem is
now in course of publication.[3]
After reviewing the history of observations and experiments with coal
dust carried on in Europe, and later, the experiments at the French,
German, Belgian, and English explosives-testing stations, this bulletin
takes up the coal-dust question in the United States. Further chapters
concern the tests as to the explosibility of coal dust, made by the
Geological Survey, at Pittsburg; investigations, both at the Pittsburg
laboratory and in mines, as to the humidity of mine air. There is also a
chapter on the chemical investigations into the ignition of coal dust by
Dr. J. C. W. Frazer, of the Geological Survey. The application of some
of these data to actual mine conditions in Europe, in the last year, is
treated by Mr. Axel Larsen; the use of exhaust steam in a mine of the
Consolidation Coal Company, in West Virginia, is discussed by Mr. Frank
Haas, Consulting Engineer; and the use of sprays in Oklahoma coal mines
is the subject of a chapter by Mr. Carl Scholz, Vice-President of the
Rock Island Coal Mining Company.
An earlier bulletin setting forth the literature and certain mine
investigations of explosive gases and dust,[4] has already been issued.
After treating of methods of collecting and analyzing the gases found in
mines, of investigations as to the rate of liberation of gas from coal,
and of studies on coal dust, this bulletin discusses such factors as the
restraining influence of shale dust and dampness on coal-dust
explosions. It then takes up practical considerations as to the danger
of explosions, including the relative inflammability of old and fresh
coal dust. The problems involved are undergoing further investigation
and elaboration, in the light of information already gathered.
_Permissible Explosives._--The most important progress in these tests
and investigations has been made in those relating to the various
explosives used in getting coal from mines. Immediately upon the
enactment of the first legislation, in the spring of 1908, arrangements
were perfected whereby the lower portion of the old Arsenal grounds
belonging to the War Department and adjacent to the Pennsylvania
Railroad, on the Alleghany River, at 40th and Butler Streets, Pittsburg,
Pa., were transferred to the Interior Department for use in these
investigations. Meantime, in anticipation of the appropriation, Mr.
Clarence Hall, an engineer experienced in the manufacture and use of
explosives, was sent to Europe to study the methods of testing
explosives practiced at the Government stations in Great Britain,
Germany, Belgium, and France. Mr. Joseph A. Holmes also visited Europe
for the purpose of studying methods of ameliorating conditions in the
mines. Three foreign mining experts, the chiefs of investigating bureaus
in Belgium, Germany, and England, spent three months studying conditions
in the United States at the invitation of the Secretary of the Interior,
to whom they submitted a valuable report.[5]
Under the supervision of the writer, Chief Engineer of these
investigations, detailed plans and specifications had been prepared in
advance for the necessary apparatus and the transformation of the
buildings at Pittsburg to the purposes of this work. It was possible,
therefore, to undertake immediately the changes in existing buildings,
the erection of new buildings, the installation of railway tracks,
laboratories, and the plumbing, heating, and lighting plant, etc. This
work was carried on with unusual expedition, under the direction of the
Assistant Chief Engineer, Mr. James C. Roberts, and was completed within
a few months, by which time most of the apparatus was delivered and
installed.
One building (No. 17) is devoted to the smaller physical tests of
explosives. It was rendered fire resistant by heavily covering the
floors, ceiling, and walls with cement on metal lath, and otherwise
protecting the openings. In it are installed apparatus for determining
calorific value of explosives, pressure produced on ignition,
susceptibility to ignition when dropped, rate of detonation, length and
duration of flame, and kindred factors. Elsewhere on the grounds is a
gallery of boiler-steel plate, 100 ft. long and more than 6 ft. in
diameter, solidly attached to a mass of concrete at one end, in which is
embedded a cannon from which to discharge the explosive under test, and
open at the other end, and otherwise so constructed as to simulate a
small section of a mine gallery (Fig. 2, Plate VI). The heavy mortar
pendulum, for the pendulum test for determining the force produced by an
explosive, is near by, as is also an armored pit in which large
quantities of explosive may be detonated, with a view to studying the
effects of magazine explosions, and for testing as to the rate at which
ignition of an explosive travels from one end to the other of a
cartridge, and the sensitiveness of one cartridge to explosion by
discharge of another near by.
[Illustration: PLATE VI.
Fig. 1.--Explosion from Coal Dust in Gas and Dust Gallery No. 1.
Fig. 2.--Mine Gallery No. 1.