With an unsymmetrical wing and a rotating Magnus cylinder, the lift is produced by the superposition of parallel and circulatory flows. An explanation of the circulatory flow is furnished by the boundary-layer theory of Prandtl and the consequent vortex formation. According to this explanation, it must evidently be possible to increase the circulation either by increasing the size of the stronger (lower) vortex or by decreasing the size of the weaker (upper) vortex.

Many treatises in regard to construction of airship sheds are lacking in data on air currents, for which reason this phase of the problem will be here thoroughly discussed in connection with the accompanying photographs of currents.

From Forward: "The first edition of the record setting forth the history of the boundaries of the United States and the several States and Territories was prepared by Henry Gannett, assisted by Franklin G. Butterfield, and was published as Bulletin 13 of the United States Geological Survey in 1885. The present bulletin is a revision and enlargement of Bulletin 226 and includes additional matter incidentally connected with boundaries."

Brief summary of the habitat, habits, food and economic status, measurements, subfamilies, and subgenera of genera Sorex and Microsorex.

Report presenting information on the production of lead since 1800.

Report issued by the Bureau of Mines covering petroleum laws of the U.S. and surrounding oil producing countries. As stated in the preface, "this bulletin includes the petroleum laws of (1) United States; (2) the several oil-producing States; (3) Canada; (4) Mexico; (5) the Republics of Central and South America" (p. iv).

Report of the annual conference on weights and measures, hosted by the U.S. National Bureau of Standards in Washington D.C. It includes conference proceedings, a list of attendees, information about committees and officers, and other reports or commentaries discussed at the meetings.

From Introduction: "This bulletin is the third of the series of yearly petroleum bibliographies being published by the Bureau of Mines."

Report of the annual conference on weights and measures, hosted by the U.S. National Bureau of Standards in Washington D.C. It includes conference proceedings, a list of attendees, information about committees and officers, and other reports or commentaries discussed at the meetings.

From Introduction: "Responding to the imperative need for increasing to the utmost the petroleum supply of the United States, the Geological Survey, since we entered the war, has largely concentrated its investigations of oil fields in the most promising undeveloped territory, such as Wyoming and the midcontinent-Texas region, and especially in the Osage Reservation in Oklahoma. This report is therefore issued to supply an evident need for geologic information regarding the Osage lands. In the separate papers the most practical and immediately available conclusions reached by geologists as to the structure and oil prospects in the townships already examined are published for the immediate use of the oil man."

From Introduction: "This glossary is published by the Bureau of Mines as a contribution to the mining literature in the belief that it will fill a long-felt need. It contains about 20,000 terms; these include both technical and purely local terms related to metal mining, coal mining, quarrying, petroleum, and natural gas, and metallurgical works; names of useful, important, and common minerals and rocks; and geological terms. It presents in one comprehensive volume the available standard, technical terms relating to the mining and mineral industry, as well as provincialisms that have been or are now in use in English-speaking countries."