From Preface: "In carrying out such a policy with reference to the subject under consideration, the Bureau of Mines invited the State geologists, mine inspectors, and a number of coal operators and oil and gas well drillers from the States interested to meet representatives of the Bureau of Mines in Pittsburgh, Pa., for a discussion of the subject during February 7 and February 8, 1913. This adjourned meeting of the conference will be held at an early date and its report will be printed in a later edition of this bulletin, with such additional suggestions as may be received by the Bureau of Mines. The bureau will be glad, therefore, to receive at the earliest practicable date any additional suggestions or any additional information throwing light on the matters discussed in this bulletin."