PERSONNEL.

The physical tests of explosives were in charge of S. P. Howell, explosives engineer, aided by J. E. Crawshaw, explosives testing engineer, J. E. Tiffany, assistant explosives engineer, W. J. Montgomery, junior explosives engineer, and Charles Schuler, shot-firer, throughout the year, and A. B. Coates, assistant mechanical engineer, J. L. Sherrick, explosives engineer, and E. Stein, junior explosives engineer, during various parts of the year.

EXPERIMENTAL MINE.

EXPLOSIBILITY OF COAL DUST.

The study of the factors governing coal-dust explosions, and the development of methods for preventing or stopping explosions was continued at the experimental mine, near Bruceton, Pa., though restricted by war work during the early part of the fiscal year. Explosion tests were made with two subbituminous coals from Colorado. Tests of barriers were made in connection with these explosions.

After the resignation of W. L. Egy, physicist, in October, 1918, the work was conducted by H. C. Howarth, coal-mine superintendent, and H. P. Greenwald, assistant physicist, under the direction of J. W. Paul, chief of coal-mine investigations, and G. S. Rice, chief mining engineer. The laboratory work was conducted by Alan Leighton, assistant (physical) chemist under the direction of Messrs. Paul and Rice.

USE OF GEOPHONES.

During the period of the war, experiments with the geophone were made in cooperation with Capt. E. B. Stephenson, United States Engineers, to determine the distances that various sounds could be detected through the earth and the factors influencing the transmission of energy from a blow to the earth.

An investigation of the value of the geophone for mine rescue and mine-survey work is nearly completed. The instrument has been considerably improved over the form employed by the War Department and has been successfully used in locating mine fires, mining in drifts, and raises and leaks in water pipes. The investigation has shown that the instrument will be of great value for locating entombed miners.

GALLERY TESTS OF COAL DUST AND INDUSTRIAL DUSTS.

The horizontal dust-explosion gallery at Bruceton has been used to test the inflammability of a number of samples of coal dust. Re

ports on the inflammability of steel-mill dusts, coke dust, pitch dust, and other dusts have been made. In the course of some cooperative work on the explosibility of grain dusts with Dr. H. H. Brown of the Bureau of Chemistry a new vertical dust explosion gallery was constructed, which will be of value in testing the inflammability of dust clouds by different flames.

Supplementary to a paper by G. B. Taylor and H. C. Porter on the Momentary Heating of Inflammable Dusts, H. L. Lentz, assistant chemist, has been gathering data on the volatile matter in a dust during an explosion and has done some experimental work.

FUELS AND MECHANICAL EQUIPMENT DIVISION.

During the year, the building and moving program of the laboratories at Pittsburgh being practically complete, the headquarters of the chief mechanical engineer, O. P. Hood, was transferred to Washington.

WORK OF CHIEF MECHANICAL ENGINEER.

The following work was directly conducted from the Washington office by the chief mechanical engineer.

COOPERATION WITH UNITED STATES FUEL ADMINISTRATION.

The bureau continued to function in an advisory capacity to the fuel conservation section of the Unites States Fuel Administration. A study of possible coal standards was made in connection with the matter of bunker coal.

The several functions of the Fuel Administration having to do with fuel conservation were examined, with a view to possible continuance of those proving successful and desirable.

SPECIFICATIONS FOR FUEL INSPECTION.

A system of Federal fuel inspection was devised fitting the present needs of producers and consumers. A bill authorizing such work was prepared.

UTILIZATION OF LIGNITE.

An investigation of lignite under a bill appropriating $100,000 for the purpose (Public, No. 259) was begun and a plan of procedure was outlined as well as a study of plant detail. A field investigation in Texas and the Dakotas revealed cooperating facilities aggregating several times the amount of the Government appropriation. S. M. Darling, fuel engineer, assisted in this work.

COOPERATION WITH AMERICAN SOCIETY OF HEATING AND VENTILATING ENGINEERS.

Cooperation was arranged with the American Society of Heating and Ventilating Engineers to conduct joint research work at the Pittsburgh laboratories of the Bureau of Mines on matters pertaining to the efficient use of fuels.

COOPERATIVE TESTS OF COKE OVENS.

Jointly with the Bureau of Standards and at the direction of the President, a test of Illinois coal was made in a Roberts by-product coke oven at Dover, Ohio. A similar test was also made in a Koppers oven at St. Paul, Minn. F. K. Deitz and W. A. Selwig assisted in this work.

GOVERNMENT FUEL INSPECTION.

The work of inspecting fuel purchased for the Government was under the direction of George S. Pope, engineer, for three months, and H. M. Cooper, assistant chemist, nine months. They were assisted by Ned H. Snyder, assistant engineer; H. A. Goodman and R. J. Swingle, inspectors. Coal for the Panama Canal and the Panama Railroad Co., and mines in Kentucky and Tennessee were inspected and sampled. Assistance was rendered the United States Fuel Administration and State fuel administrations. The offices of this section, and the fuel-inspection laboratory are situated at Washington.

The fuel-inspection laboratory was under the supervision of H. M. Cooper, assistant chemist, aided by E. L. Wallace, assistant chemist, Geo. Bornscheuer, W. A. Gonzalez, H. R. Dunbar, F. C. Hull (resigned), and R. N. Crow, junior chemists; G. F. Pfeffer (resigned) and H. P. Rue, chemical laboratorians. The work of the laboratory consisted of analyzing coal belonging to or for the use of the United States Government, and coal samples for the United States Fuel Administration and State fuel administrations, and for State institutions under cooperative agreements. During the year equipment for determining the fusing temperature of ash was added to the laboratory, and improvements were made in the multiple-unit calorimeter installation.

WORK CONDUCTED FROM THE PITTSBURGH STATION.

The following work was conducted from the Pittsburgh office, under the general supervision of the chief mechanical engineer and the immediate direction of Henry Kreisinger, engineer.

COOPERATIVE WORK WITH UNITED STATES SHIPPING BOARD.

In February, 1918, under an agreement with the Emergency Fleet Corporation the bureau undertook to make all temperature measurements and furnace-gas analyses at tests of marine boilers of different design for the Emergency Fleet. The first boiler tested was at the Erie City Iron Works, Erie, Pa., 22 tests being made with George's Creek coal. The temperature measurements indicated that the performance of the boiler could be improved by making changes in the furnace and baffles. As a result of such changes the over-all boiler efficiency was raised from about 60 to 72 per cent, this high efficiency of 72 per cent being obtained when the boiler evaporated 5 to 6 pounds of water per square foot of heating surface, a rate considerably higher than the practice in the average stationary plant. Thus the fuel section helped in developing a highly efficient boiler and also obtained much data of practical value.

The next boiler tested at the Murray Iron Works, Burlington, Iowa, was of the water-tube type, fitted with a superheater. In all, 32 tests were made with oil and 12 with coal. The oil tests were made with Dahl and Coen burners.

The third boiler was tested at the plant of the Erie City Iron Works, 22 tests being with a hand-fired furnace and 10 tests with an E-type underfeed stoker. Another series of tests is now in progress with fuel oil and several designs of oil burners.

A Scotch marine boiler is to be tested at the plant of the Sun Shipbuilding Co. at Chester, Pa., using coal and oil, and several designs of oil burners. When these tests are completed the comparative performances of water tube and Scotch marine boilers will be available for study. No reliable data for such comparison has ever been obtained before.

These investigations were in charge of W. R. Argyle, assistant physicist, who had the aid of A. R. Mumford, assistant engineer; W. H. Miller, junior chemist; J. R. Darnell, laboratory assistant; and J. P. Stein, fireman.

POWDERED COAL.

A general survey of the use of powdered coal is planned, the purpose of this survey being the preparation of a bulletin giving the facts without bias. Many of the published articles on powdered coal were prepared by people interested in manufacturing powdered coal equipment, and some of the information in such articles is misleading.

Arrangements have been made with the Erie City Iron Works for cooperative research to determine how boiler furnaces should be designed to eliminate the troubles at present met in burning pow

dered coal. Particular attention will be given to the formation of slag in the furnace and the disposal of ash. These investigations will be in charge of A. R. Mumford, assistant engineer, assisted by D. J. Jenkins, fuel engineer, and R. J. Hinch, laboratory aid.

USE OF FUEL FOR DISTILLING OIL.

In cooperation with the Sinclair Refining Co. of Chicago, a thorough test is being made of several oil stills fired by different types of stoker in order to determine what design of furnace will utilize the fuel most efficiently. It is planned to make a complete heat balance of the performance of each oil still and each design of furnace. This work is in charge of W. R. Argyle, assistant physicist, assisted by Marcus Sturve, assistant chemist, and J. R. Darnell, laboratory assistant.

COKE FOR HOUSE-HEATING PURPOSES.

Tests have been started to determine the best method of burning domestic-size coke in the heating apparatus now used in dwellings. Tests will be made in steam boilers of several makes, in hot-air furnaces, heating stoves, and open grates-comparative tests being run with coke, anthracite coal, and high-volatile bituminous coal. Another series of tests will be made to determine the principles governing the design of apparatus for burning coke. These investigations will be made in cooperation with several coke-producing companies and designers of by-product plants. Part of the work will be done at the Minneapolis station.

Alfred Iddles, fuel engineer, will be in charge of the work at Minneapolis, assisted by two men paid by the Koppers Company. The work at the Pittsburgh station will be in charge of C. E. Augustine, assistant engineer, aided by H. W. Jarrett, assistant engineer, Charles Schramm, mechanic, and J. P. Stein, fireman.

HEAT-TRANSMISSION INVESTIGATION.

The object of this investigation is to determine the effect of the various factors governing the transfer of heat from the hot furnace gases into the water of a steam boiler. The plant for the work, consisting of a tubular boiler 20 feet long and a gas furnace, is being rebuilt, with some modifications, in the new fuels-testing laboratory at the Pittsburgh station. The temperature of the gases before entering the boiler, along the path of heat flow, and after leaving the boiler, and the volume of the gases passing into the boiler tubes will be measured precisely.

In connection with the heat-transmission investigation the relative heat conductivity of "sil-o-cel" and fire brick in a furnace wall, will