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By A. B. Hooker, Ilsley. L. C.

"Several writers have called attention, in the technical press, to the possible failure of flame safety lamps in coal-dust laden atmospheres. Such writers question the safety or a flame lamp that has been proved only in atmospheres containing methane, believing that the resistance of the lamp to explosion would be lessened it coal dust constituted a part of the explosive mixture.If this be true, it follows that any series of tests devised to prove the safety of flame lamps for use in gaseous and dusty coal mines should not only embrace tests in mixtures containing various proportions of methane, but also in some of the tests the effect of adding coal dust to the explosive gaseous mixtures should be investigated.Some attention has been given this question by investigators, but the more common practice has been to make all tests in gas and air mixtures only, using methane when it was readily available. Apparently the English Accident Committee (1879-1886) who conducted tests upon 250 different lamps did not use coal dust in their tests. The first British requirements for the testing of safety lamps, issued as a result of the Coal Mine Act of 1911, made no mention of tests with coal duet.The Austrian Fire-damp Committee (1890) conducted a series of tests in which coal dust was used in some of the tests. In certain tests, the addition of coal dust apparently lowered the resistance of the lamp 1 meter per second. The Belgium investigators, Messrs. Watteyne and Stassart, conducted a series of tests in 1904 in which coal dust was used in a few tests without any marked difference in safety."

Dec 1, 1920

By W. H. Herschel, E. W. Dean

"IntroductoryThe common practice of the petroleum industry is to measure viscosity by the use of instruments of the efflux or capillary tube type. The Saybolt universal viscosimeter has been tentatively adopted as a standard by the American Society for Testing Materials and is used extensively in the United States.Several instruments of foreign origin are also more or less familiar, such as the Redwood, the Engier, and the Baroey.Effina-type viscosimeters are well adapted to the ordinary needs of petroleum testing laberatories as they are simple and rugged in construction and away to manipulate, even in the hands of operators lacking scientific training. They have, however, certain limitations and for certain spacial types of work there are notable advantages incident to the use of the so-called torsion types of type of viacosimeter. The most satisfactory type of torsion viscosimeter now available in the market some to be that of MacMchael, which has been discussed in detail in a recent paper (Herschel, W. H., The MacMichael Torsional Viscosimeter. Jour. of Int. and Eng. Chem., vol. 12, 1920, pp. 282-286). The present paper indicates conditions under which this viscosimeter may be used to advantage in the petroleum laboratory, and outlines simple methods of operation and calibration."

Jan 1, 1921

By D. Harrington, B. W. Dyer

"One of the products of the activities of the United States Chemical Warfare Service is a simple device and method for nearly instantaneous determination of small quantities of carbon monoxide in air. Since the war, this device has been diverted to commercial uses, and is now being marketed in connection with rapid determination of the comparatively small but dangerous quantities of CO, which may be found in garages, in sewers, about blast furnaces, etc. Also, it probably has a definite field of use in both coal and metal mines in connection with fires and explosions, as well as in confined places after firing of explosives) the latter applica-tion being of especial importance in metal mining.The device as marketed is readily portable, being small and light enough to carry in a coat pocket of medium size. In operation, a sample of the air mixture is drawn into a small rubber bulb, then forced through a small glass tube filled with certain chemicals upon which CO has the effect of changing the original color from gray or white to shades of green, the deepness of the green determining the percentage of CO in the air. A color scale is attached for purpose of comparison and determination of CO percentage. Only a few minutes are consumed in obtaining the result, all work being done on the ground.The exact effect of minute quantities (up to 1/10 of 1 percent) of CO on the human system is somewhat uncertain, and much research has been and is being done to obtain definite data on this point. It is, however, definitely known that in air containing more than 1/10 of 1 percent CO men doing hard work are quickly and seriously affected. As the gas is tasteless, colorless and odorless, methods of determining the presence of both small and large quantities have been of much importance. Technical Paper 11 of the U. S. Bureau of Mines gives much data as to effect of CO on mice and canaries. It was found that mice show very little distress until the CO content is about 0.20 percent, but quickly succumb when that percentage is exceeded; canaries are somewhat more susceptible; they quickly show distress in as little as 0.15 percent 00, and soon collapse when that percentage is exceeded."

Jan 1, 1921

By Dorsey A. Lyon

"The ceramic industry of the United States has a total yearly manufactured product of nearly half a billion dollars, despite large foreign importation.After careful investigation of the industry by the Bureau of Mines, it is the belief of those in charge that the usefulness of the industry can be greatly enlarged and the importations greatly lessened through the development of processes that will lead to a greater and better development of the ceramic resources of the United States. This will result in a greater industry with more men employed than ever before, and perhaps a world's supremacy in ceramic trade matters.Investigations in behalf of the ceramic industry are being made at the Bureau of Mines experiment ceramic station at Columbus, Ohio, under the supervision of R. T. Stall, superintendent, who reports a number of instances of practical, beneficial cooperation between the industry and the station during the last fiscal year.Graphite to Crucibles:Prior to 1914, practically all graphite crucibles manufactured in the United States were made from Ceylon graphite bonded with German Klingenberg clay. It was the general belief among graphite crucible manufacturers and users that good crucibles could not be made from American bond clays and graphites.Graphite crucibles were essential for melting certain alloys and special steels urgently needed for the manufacture of war materials. The demand for such metals was so great that it created an unprecedented demand for graphite crucibles.After the European war began no Klingenberg clay could be shipped out of Germany. However, it was fortunate for the cyucibly makers that they had large stocks of Klingenberg clay on hand. When the stock of Klingenberg clay became exhausted, it was necessary for the credible makers to turn their attention to American clays. There were no data or other information available to guide the crucible makers in the selection of good bond clays for their crucibles. It was necessary for them to select their clays more or less by ""guess"", which resulted in the period of service or life of graphite crucibles being shortened 15 to as much as 60 per cent."

Feb 1, 1921

By S. H. Katz

Artisans and laborers in mineral industries where the air is dusty with particles of reel: are subject to a peculiar pulmonary disease known as miners' phthisis or stone cutters' consumption. In granite cutters the disease is specifically designated as granite pneumoconiosis. Very fine particles of the harder rocks are especially injurious when inhaled into the lungs. It is estimated particles about one micron (1/23000 part of an inch in diameter) are most injurious, because larger particles are more readily removed by the cilia and,wet surfaces of the respiratory passages before reaching the lungs, while smaller particles either do not readily lodge or are more easily eliminated. Silica, of which quartz and flint are composed, and which forms a large part of granite, is one of the hardest of the common rock-forming materials. It is also very insoluble when silica lodges in the lungs elimination is difficult. Rock constituents of granite other than silica are probably injurious but in a lesser degree, and this is also probably true of limestone and the softer rocks. Ultimately a worker who daily inhales much granite dust has considerable deposited in his lungs. If he continues at his trade the lung tissue becomes harder and less elastic, he finds himself short winded, and in extreme cases death may come either directly or indirectly as a result of lung failure.

Feb 1, 1921

By E. W. Dean

In the early winter of 1919 the Pittsburgh petroleum laboratory of the Bureau of Mines undertook the work of testing fuel oil samples representing purchases of the United State Shipping Board for ships sailing from the port of New York. fuel oil was, at this time, being bought on a contract which involved specifications issued by the United States Navy under dace of October 2, 1920 (See Bulletin 1, Oil Division, U. S. Fuel Administration.)The object of the Bureau of Mines in undertaking this inspection work was twofold. (1) The Bureau was in position to give, and the Shipping Board needed, reliable laboratory service for checking the quality of the fuel oil purchased, the value of which ran into millions of dollars for,year's supply. (2) It was believed, and later demonstrated, that the existing specifications did not insure the obtaining of a reliably satisfactory quality of oil.The objection to the specifications concerned the employment of a clause limiting the gravity of the oil. The inadequacy of gravity specifications for several types of petroleum products has long been recognized, and there was every reason to reason to believe that they were no more desirable for fuel oil than for gasoline, kerosene, or lubricating oil. A first and obvious objection was the fact that it is somewhat difficult to make accurate gravity tests on ""heavy"" residuum fuel oils. (The Bureau found it necessary to employ or such tests a rather tedious procedure involving the use of a picnometer and an accurate balance, as the simpler methods, employing hydrometer or displacement balance, proved unreliable in a large proportion of cases.) A second and more important objection was that gravity tests, even when accurately made, do not provide a reliable index of the actual quality of the oil.

Feb 1, 1921

By J. J. Bourquin

"The Keely mine at Dagger, Indiana, is one of the few mines that is being operated successfully on a cooperative basis. This shaft mine is developing 133 acres of coal in the Indiana No. 6 bed, which here averages 5-1/2 feet thick and. lies about 110 feet below the surface. Thirty seven (37) miners and twenty (20) company men or day man are employed, and the daily output is around 300 tons. Practically the entire production is sold by contract for railroad use. No mining machines are used and all coal is produced by pick work.The mine was originally owned and operated by the Stockton Coal. Co. of Dugger, but about eight years ago it was leased to Mr. Roy Price. He sub-leased the property to ten miners, who formed an association known as the Dugger Mutual Coal and Mining Co., to work the mine cooperatively.At first many difficulties were encountered; the cooperative idea is an old one, but the practice was new to those interested. Some of the men were energetic, ambitious workers; others were inclined to let their associates produce the coal but wanted to share in the profits. In time, after a hard struggle and many changes in the personnel of the company, business-like methods were adopted and the mine was put on a paying basis."

Feb 1, 1983

By E. D. Gardner

An explosion occurred in a high-pressure compressed-air line in October, 1930, at an Arizona copper mine. The explosion was unusual, and nothing had teor. noted by the plant operators to indicate the possibility of such an occurrence. It is necessar The air is The mining company uses compressed-air locomotives to haul about 4,500 tons of ore per day from the stopos to the pockets at two hoisting shafts. The ore cars hold five tons each, and are pulled in trains of 30 cars. to charge the locomotive with compressed air at both ends of the trip. conveyed from the compressors at the surface to the distributing points unier roun in special high-pressure four inch steel pipe that was tested to withstand 2500 pounds per square inch before being installed. The air is delivered to the loco- motives at a pressure of 1000 pounds per square inch. There are no receivers in the system. The air for running the locomotives is compressed by one three-stage and two four-stage compressors which have capacities of 600 and 300 cubic feet per minute, respectively. These machines are operated by electric power, and are in an end of the main compressor building in which air is compressed to supply the air drills in the mine. Whenever the demand decreases, as at the noon hour, one or more of the Compressors are shut down. On this particular occasion, at the end of the noon hour, one of the operators was approaching the high-pressure compressors to start the two smaller machines that were not running, when the explosion took place under the floor a few fost ahead of him. The man was mocked down and received some superficial cuts and bruises, but was not seriously injured. The floor was torn , the side of the building blown out, and holes imo cited in the roof some twenty feet above. The explosion was immediately followed by a fire which was quickly put out by the plant operators with hand fire extinguishers. At the time of the explosion the 600 cubic foot compressor was running alone, and the pressure in the system at the machine registered 1040 pounds por square inch. On examination it was found that two 6-fout sections of pipe, about tan feet apart, were completely ruptured into twisted fragments; the rest of the pipe line, apparently, was not injured. The destroyed sections were in that part of the pipe near the large compressor and above the connection from the two smaller machines. It is not definitely mom what caused the explosion. Explosions in other compressed-air systems have taken place, and, although of rare occurrence, have caused loss of life. Such explosions are not confined to high-pressure installations and several have occurred at plants compressing air te one hundred pounds per square inch, or less. plosions of this nature are not to be confused with the rupturing of compressor cylinders from excessive air pressure caused by the discharge valve being closed.

Feb 1, 1921

By D. B. Dow

The transportation of any commodity which is actually or potentially a source of fire or explosion, has been made safe, insofar as humanly possible, by rigid requirements as to inspection mechanical safety devices, and by printed labels. For the most part these precautions have been sufficient. This is evident when it is considered that in the thousands of instances in which commodities with a great fire risk have been transported, few disasters have occurred. This paper deals with the recent gasoline explosion which occurred at Memphis, Tennessee. At 7:50 a.m. January 24, 1921, vapors from a tan: car of gasoline became ignited and resulted in a blast that killed eleven people and badly injured nineteen others. Probably forty or fifty men, women, and children received slight injuries from falling debris or from burns. The explosion wrecked an oil plant, leveled a block of frame buildings, and broke window panes within a radius of five blocks.

Feb 1, 1921

By N. A. C. Smith

[The beau of Mines made its first survey of motor gasolines sold throughout the United States in 1915, a second in 1917, and a third in April. 1919. These surveys shored that motor gasoline had become notably less volatile during each two-year interval. In order to ascertain whether this change was continuing, it was planned to institute semi-annual surveys, the first of which teas made in January, 1920. Contrary to expectations based on the previous surveys, the average volatility of the gasoline tested at this time was practically identical with that of the average volatility of the gasoline from the same districts in 1919. The next survey, made in July, 1920, showed a very marked decrease in volatility but as it has long been recognized that the volatility of motor gasoline manufactured for sale during the summer months is loss tan that of gasoline made and sold during the winter, part at least of the change was attributed to this factor. The average boiling point of the samples collected in the present survey is 263 degrees Fahrenheit, as compared with 264 a year ago. This shows that the average gasoline marketed at the present time is fully as volatile as that marketed a year ago. There has been, however, a noticeable change in the character of the product: the initial boiling point and 20 per cant point are lower than a year ago, whereas the 90 per cent and end-points are higher, which indicates a greater proportion of gasolines made by blending casing-head, or natural gas-gasoline, and naphtha.]

Jan 1, 1921

By C. A. Alien

The increasing activity in oil shale has had a tendency to direct the attention of the industry to any substance from which gasoline or other oils can be secured . Cannel coal for many years has been known, as a source of oil and formerly it was the only substance from which kerosene was obtained . The name of coal oil was given to kerosene because it was derived from cannel coal before any flowing wells were brought in in the United States . In an isolated region in Southern Utah there is an unusually thick and clean bed of cannel coal which laboratory experiments indicate can be made to yield about seventy gallons of oil to the ton . This coal was first described in Bulletin 341 of the United States Geological Survey under the title of Colob coal field . This field lies at the western and southern base of the Colcb plateau and extends from the town of Cedar City southward to Kanarra and then southeastward to the town of Mount Carmel . Cedar City is 35 miles south of east from Lund on the Los Angeles and Salt Lake Railroad which is the nearest railroad point . Mount Carmel is about 90 miles south of Marysvale , on the Denver and Rio Grande Railroad , which is the nearest railroad point from the eastern end of the field . The Colob coal occurs in Lower Cretaceous rocks and a number of wagon mines have been opened on the seam in the vicinity of Cedar City , Kanarra , and Mt. Carmel , but between these places the field has been very little prospected . The cannel coal , so far as known at present , is limited to a small area on the head waters of the north fork of the Virgin River in Township 39 and 40 South , Range 9 East . In this region it occurs as a bed 5-1 /2 feet thick over which lies a layer of bituminous coal 2 feet and 5 inches thick .

Feb 1, 1921

By Dorsey A. Lyon

At the main experiment station of the U. S. Bureau of Mines , situated in Pittsburgh, Pa . , three phases of its work in behalf of the safety of the coal miner are the establishment of permissible explosives for use in gaseous and dusty mines , the development of electrical equipment that can be used with safety in mines of this character , and improvement in the safety of mechanical devices used in and about the mines . Also That these efforts are beginning to have a cumulative effect in lives. saved is evident from the fatality statistics of the industry . Although nearly 80,000 more men are employed in coal mining than ten years ago and much more coal is mined , the fatalities each year are considerably less than ten years ago . the amount of coal mined in a year for each life lost has risen between 60,000 and 70,000 tons . In 1909 , the year before the Bureau was created , the production of coal for each life lost was 174,416 tons . In 1920 , the production for each life lost was 285,000 tons .

Mar 1, 1921

By L. C. IlsLey, R. A. Kearns

As the use of electricity becomes more and more general in mining opera- tions, interest in regulations governing its application becomes greater. During the past year the electrical section of the Bureau of Mines has made a study of State regulations now in force relating to the use of electricity in coal mines. Technical Paper 271, entitled "State Mining Laws on the Use of Electricity in and about Coal Mines", has been published as a result of this study. The present paper represents a compilation of all laws relating to accident prevention with respect to electrical circuits. This group of regulations is perhaps the most important of any that relate to safety in coal mines. Its importance is shown by reference to accident statistics in Bulletin 115, (Fay, A.H., Coal-Mine Fatalities in United States, 1870-1914, Bureau of Mines, 1916), which show that about 77 per cent of the fatalities due to electricity in and about coal mines were caused by direct or indirect contact with trolley or other power circuits. In actual number this means that of 710 men killed by electricity, 546 were killed by contact with electric wires. Undoubtedly, a large percentage of these accidents might have been prevented had the wires been properly guarded. The compilation follows:

Mar 1, 1921

By PHILIP A. ZANG

The rapidly increasing use of motor vehicles in the United States has introduced an entirely new problem in the proper ventilation oftunnels , subways , and other confined spaces through which such machines must pass . This problem was brought to the attention of the Bureau of Mines by the New York and New Jersey State Bridge and Tunnel Commissions with reference to the ventilation of the proposed vehicular tunnel under the Hudson River . This tunnel , consisting of twin tubes 29 feet in diameter and 8500 feet long between entrance and exit , presented an unprecedented problem in ventilation both on account of its length and on account of the traffic density , which is expected to reach a maximum of 1900 vehicles per hour . An exhaustive study by the tunnel engineers of all available data on the amount and composition of automobile exhaust gas disclosed very little information on the percentage of carbon monoxide in motor exhaust gas from the average run of automobiles and trucks under actual operating conditions on the road. It was well known that carburetor adjustment and other operating factors changed the percentage of the poisonous constituent , carbon monoxide , from practically 0 to 12 or 13 per cent ; but no safe estimate could be made of the most probable figure without further investigation .

Mar 1, 1921

By Charles E. Munroe

"It has been recently learned that certain foreign manufacturers are offering far importation into this country detonators at greatly reduced prices, some of these detonators being of such low grade (No.4), that their use would greatly increase the dangers in blasting.Detonators and electric detonators are used in initiating the explosion of the various high explosives that are now so extensively employed in a great variety of mining operations. Originally a large number of different grades (or ""strengths"") of detonators and electric detonators were marketed, the grade number indicating the weight of the charge of fulminating material contained in the copper case of the detonator. As late as 1914, a report of the Bureau of Mines (Bulletin 80, A primer an explosives for metal miners) shows that grades Nos. 3, 4, 5, 6, 7, and 8, containing from 0.54 to 2.00 grams each, were being offered for use. However, the writer bad observed as early as 1896, when the more insensitive types of explosives like nitro-substitution explosives began to be introduced for use in mining and other blasting operations, that use of a high-grade detonator was essential to insure certainty of discharge."

Mar 1, 1921

By F. B. Tough

An inusual job in controlling a gas well was executed on No. 1 well, Inland Oil and Refining Co., situated on the Alkali Butte structure, Freemont County, Wyoming. The work was done by the company in cooperation with the . S. Bureau of Minos, and resulted in a fuel saving of $5,000 in one season and of a repair job estimated at $15,000, or a total of $21,000. The woll had an open flow of 6,000,000 cubic feet of gas per day with a rock pressure of 560 pounds per square inch. A string of 6-1/4 inch casing with a toothed shoe was set on the cap rock above the gas sand at 2181 feet. Then the well was shut in, the gas worked out around both the 6-1/4 inch and 6-1/4 inch strings, breaking through the ground surface at several points under the derrick. Casing troubles encountered while drilling made it unsafe to attempt Coving the 6-1/4 inch string. Moreover, it was important from the standpoint of good management to make the gas from this well immediately available for fuel in other operations and, in addition, to save the gas from wasting. An ordinary mudding and cementing job would have necessitated sitting down this well for probably two months out of a very short operating season. For these rousons it was determined to mud the well, if possible, between the 6 and 8 inch strings by pumping mud fluid through the connection from the gas clamps. The gas clamps used wore of ordinary construction with a side outlet, making them equivalent to a Braden-hoad. When the mud fluid was pumped through the gas clamp into the space between the two strings, it began to appear inside the 6-1/4 inch string. It apparently entered the well either around the toothed shoe or through a "line sawed" leak in the string and was blown out of the well as fast as it was pumped in. In order to stop the leaks, about a half a gunny sack of finely chopped bull ropa was fed with the mud between the casings as before. The hemp gathered around the valves of the mud pump to some extent, and it also stuck in the casing-head fittings a few times. An obstruction in the casing- head would be removed by permitting the woll to "blow back" for a few seconds, and one in the pump valves, by removing the valves when necessary. In two days' time sufficient hemp and mud had been pumped into these strings to kill external and internal pressure. The wall was shut in and allowed to stand over night. The next day, by opening and closing the master gate at intervals,

Mar 1, 1921

By C. W. Davis

Two general schemes have been used for the determination of gold and silver in material containing considerable quantities of copper ; one is known as the " all fire " method , and the other as the , " combination " , or " wet and dry" method . The all fire crucible method , using an excess charge of litharge , has been found satisfactory when the copper content of an ore is under 6 per cent , ( Loevy , J. , Zur Edelmetallbestimmung in hochprozentigen Kupfererzen : Chem. Ztg . Jarhrg . 35 , 1911 , p . 278 ) , or where the precious metal value is so great that a small sample can be used . In the latter case , silica is added until the copper ratio is sufficiently low . If there is more than 6 per cent of copper in an ore , the lead button obtained from a crucible fusion will require repeated scorification before . it can be cupelled successfully . Rescorification is not only tedious , but also causes a slag loss of precious metals . In combination methods , the copper is dissolved , and the gold and silver in the residue . is determined by fire assay Although some combination methods have given satisfactory results for gold and silver , they are not applicable when an estimation of the platinum metals is required . Since substances containing platinum are frequently high in copper , a study of methods which might be used for the estimation of small quantities of gold , silver , and the platinum metals in such material was considered worth while . The estimation of platinum in ores by fire assay methods has been described in Technical Paper 270 of the bureau; ( Davis , C.W. , The detection and estimation of platinum in ores : U. S. Bureau of Mines Tech . Paper 270 , 1921. ) the present paper , which is supplementary to that report , deals chiefly with the application of combination methods , taking them up to the point where the fire assay is to be applied .

Mar 1, 1921

By L. C. Karrick

The Bureau of Nines has received many inquiries on the subject of assaying oil-shales, both from individuals who desire to wake their own assay while in the field, and also from Commercial assayers and investigators. The present paper describes the assay retort used by the Bureau of Mines. in the research work on oil-shales now in progress at the Intermountain Experiment Station of the Bureau at Salt Lake City, Utah, and at the Colorado cooperative oil-shale laboratory, Boulder, Colorado. This retort, which was developed through experimentation in the bureau's laboratories, has been found to be convenient in use and. capable of yielding reproducible results. M. J. Gavin, Oil-Shale Technologist, gave valuable assistance in preparing the subject matter for publication and made many helpful suggestions during the experiments made by the writer in the course of the development of the assay retort. L. A. Anderson, research "fellow" University of Utah, assisted in the preliminary development of the assay retort.

Jan 1, 1921

By Oliver Bowles

It is noteworthy that 80 to 95 per cent of the gross production of all slate quarries in the United States is discarded as waste . In view of the loss involved in handling so much waste , and the consequent added cost of the finished product , the Bureau of Mines has undertaken a study of the slate industry for the purpose of devising the best means of reducing the proportion of waste , and of utilizing the unavoidable waste . The utilization of waste has received special attention , and the cooperation of many prospective purchasers of waste slate has been enlisted in testing its adaptability for various uses .

Mar 1, 1921

By H. Foster Bain

Ten years ago there was no general , country-wide service for the systematic training of miners in matters relating to safety . A beginning only had been made at a few scattered points . Under the old conditions each man was left largely to look out for himself in meeting the hazards of his day's work, and the foreman , shift bosses , and superintendents chiefly relied upon improvision when major accidents occurred . So long as the mines were small and the workers highly intelligent and well trained in routine mining methods , and when too , the pressure for output had not yet speeded up industry to the extent it has since those days , there was something to be said for this lais- sez faire attitude . When , however , the rapid expansion of industry lead to the introduction of new and little trained labor and to units of production of greatly increased size , the natural dangers of mining were greatly intensified . An accident in a small mine affects only a few; the same accident in a large mine , unless proper precautions have been taken , may cost the lives of many . The public does not generally recognize that the greatly increased outputs of the mines , of coal mines in particular , have been in recent years , obtained from substantially the same number of miners as ten years ago but with a personnel not nearly so well trained in mining . It is inevitable under : such conditions that more care must be devoted to avoiding accidents and much more elaborate preparations made for meeting them . In the years immediately preceding the establishment of the Bureau of Mines this speeding up of industry , change in the character of mine labor , and increasing hazard had all begun to be felt . Immediately prior to the organization of the Bureau of Mines , public attention had been drawn to a series of disastrous coal-mine explosions , to the increasing frequency of these disasters , and to the terrible loss of human life . resulting therefrom. One of the first problems , therefore ; confronting the Bureau was clearly that of finding methods of reducing the number of such disasters and lessening the severity of those that continued to occur . Toward this object were immediately directed the energies not only of the Bureau of Mines but also those of State mine inspectors , mine operators and various other agencies , all of whom were urged to cooperate in this great humanitarian work. The results of this work naturally cannot be measured by figures only . Work for increasing the health , safety , comfort , and happiness of human beings may not be gaged with mathematical precision . But certain features of this work as revealed by the record from year to year are of much interest . ”

Apr 1, 1921