Introduction: "This bulletin abstracts and reviews essential details of reports on 59 fires in different coal mines in the United States, describes the circumstances of origin and the methods of controlling or extinguishing the fires, and points out the lessons taught."

Report published by the U.S. Bureau of Mines which is a compilation of accidents in quarries located in the United States with data regarding the number and kinds of accidents as well as information about the mining operations (e.g., number of men employed, kinds of quarries, amount of work performed, etc.).

From Introduction: "This paper gives the results of sampling the gases from blasting drift rounds at five mines-the United Verde Extension, Calumet & Arizona, Old Dominion, Mountain Copper, and the United Verde-and of tunnel rounds at the Big Creek water tunnel and Moffat railroad tunnel. The paper also describes the rounds blasted and the methods of sampling and analyzing the gases. In all, 99 rounds were fired and 376 samples were taken."

Report presenting the Bureau of Mines' investigation into acid processes of extracting alumina. The paper discusses the sulphuric acid processes and other work with hydrochloric and nitric acids so that the comparative advantages can be appreciated.

Report issued by the U.S. Bureau of Mines covering accidents that happened in metal mines located in the United States including statistics for injuries, fatalities, kinds and causes of accidents, and operational data, such as number of mine workers and shifts worked.

Report compiled by the U.S. Bureau of Mines including statistics on fatalities in coal mines located in the United States as well as data regarding the various operations (e.g., number of miners employed and average production). The information is organized into tables for comparison and the text draws some overall conclusions in the summary.

From Introduction and Summary: "This bulletin describes the third series of coal-dust explosion tests by the Bureau of Mines in its experimental mine and covers a period from 1919 to the end of 1924, inclusive. A few related tests made in 1925 are also included."

From Introduction: "The purpose of this bulletin is not to describe individual quarries but to describe general methods of operation and give typical illustrations. The methods employed are discussed critically in an effort to elucidate the best working principles and to assist manufactures of lime in correcting errors and establishing their industry on the most economical and efficient basis."

From Review of Sponge-Iron Processes: "This review of the development if the sponge-iron process to its present state gives only the important types of furnaces or processes tried."

From Introduction: "In large measure the work was an outgrowth of that done by the bureau in the investigation of burning problems for Four Heavy Clay Products Associations."

From Introduction: "This bulletin presents some of the methods and devices used in the oil fields of the United States for reducing the number of accidents at derricks.

From Introduction: "The drilling and blasting practices described in this bulletin are chiefly those in use at the time of these visits. Information, obtained by correspondence, on recent changes at certain mines is also included. The bulletin is confined to descriptions and comparisons of drilling and blasting methods at the six open-cut mines."

From Scope of Bulletin: "This paper is confined largely to a discussion of methods of mining potash salts in France and Germany, in view of the possible application of similar methods when mining of the deposits in the southwestern part if the United States is undertaken, but it also includes a brief history of the German and French potash industry, a discussion of the geology of the deposits, a short description of the refining of crude salts for export, and an estimate of the cost of production."

Report discussing petroleum refinery statistics for 1926.

From Introduction: "The purpose of this report is twofold-to give a permanent printed record of all past data and to present them on the recently adopted basis of barrels instead of gallons."

From Scope of Bulletin: "This bulletin gives the results of a study of present conditions in Alaska placer mining, including the methods employed and the costs, and will be helpful to placer miners, engineers, and all others interested in the industry."

From Introduction: "This report describes the methods used and the results obtained in a series of experiments on the resistance that metal-mine airways offer to the flow of air."

From Introduction: "The Birmingham district holds large deposits of red hematite, coal, and flux extends from Springville on the northeast to below on the southwest. The work was begun in July, 1923, and ores from a number of points within the Birmingham district have since been studied. A method of magnetic concentration has been investigated which, it is believed, will successfully remove a large part of the gangue and incur only a small loss of iron.

From Preface: "The importance of fluorspar in the industrial development of this country, particularly in the open-hearth steel industry, has only begun to be realized fully, The World War showed that fluospar was an essential mineral and was not as abundant as has been supposed. Mr. Ladoo visited nearly all the important fluorspar mines and mills in the United States and obtained as much information as possible regarding foreign deposits, production and methods."

"Tests have been made by the National Advisory Committee for Aeronautics on the air flow in an open jet wind tunnel with various sizes, shapes, and spacings of cones, and the flow studied by means of velocity and direction surveys in conjunction with flow pictures. It was found that for all combinations of cones tested the flow is essentially the same, consisting of an inner core of decreasing diameter having uniform velocity and direction, and a boundary layer of more or less turbulent air increasing in thickness with length of jet. The energy ratio of the tunnel was obtained for the different combinations of cones, and the spilling around the exit cone causing undesirable air currents in the experiment chamber was noted" (p. 1).

"A series of tests has been conducted by the National Advisory Committee for Aeronautics, in the variable density wind tunnel on several airfoils of different sizes and sections to determine the effect of tunnel wall interference and to determine a correction which can be applied to reduce the error caused thereby. The use of several empirical corrections was attempted with little success. The Prandtl theoretical correction gives the best results and its use is recommended for correcting closed wind tunnel results to conditions of free air" (p. 1).

Strips of german silver, steel, copper, duralumin, nickel and brass were tested in tension in an apparatus in which the change in deflection with time was measured by means of an interferometer. This change in deflection with time caused by the application and removal of a load is defined as "drift" and "recovery," respectively. It was measured in the time interval from approximately 5 seconds to 5 hours after loading. The data are given in a series of graphs in which the drift and recovery are plotted against time. The proportional drift and recovery in five hours are given for a number of the tests, and in addition are shown graphically for nickel and steel.

"The saving of time that results from flying across country on compass headings is beginning to be widely recognized. At the same time the general use of steel tube fuselages has made a knowledge of compass correction much more necessary than was the case when wooden fuselages were the rule. This paper has been prepared primarily for the benefit of the pilot who has never studied navigation and who does not desire to go into the subject more deeply than to be able to fly compass courses with confidence" (p. 1).

The ultimate test of a load factor formula is experience. The chief advantages of a semi rational formula over arbitrary factors are that it fairs in between points of experience and it differentiates according to variables within a type. Structural failure of an airplane apparently safe according to the formula would call for a specific change in the formula. The best class of airplanes with which to check a load factor formula seems to be those which have experienced structural failure. Table I comprises a list of the airplanes which have experienced failure in flight traceable to the wing structure. The load factor by formula is observed to be greater than the designed strength in each case, without a single exception. Table II comprises the load factor by formula with the designed strength of a number of well-known service types. The formula indicates that by far the majority of these have ample structural strength. One case considered here in deriving a suitable formula is that of a heavy load carrier of large size and practically no reserve power.