Thesis (Ph. D.)--Princeton University 1916. / "From the Philosophical magazine, vol. xxxiii, March 1917."

Thesis (Ph. D.)--Princeton University, 1912. / Cover title. "Reprinted from the Philosophical Magazine for March, 1913." On folder, 25 cm. Sheard, C., grad. student, 1911-12.

Thesis (Ph. D.)--Princeton University, 1912. / Cover title. "Reprinted from the Philosophical Magazine for March, 1913." On folder, 25 cm. Sheard, C., grad. student, 1911-12.

Thesis (Ph. D.)--Princeton University 1916. / "From the Philosophical magazine, vol. xxxiii, March 1917."

Thesis (Ph. D.)--University of Chicago, 1919. / "Private edition distributed by the University of Chicago Libraries, Chicago, Illinois." "Reprinted from the Physical review, vol. XVI, no. 4, October, 1920." Includes bibliographical references. Also available on the Internet.

In recent years a number of publications have shown a renewed interest in the possible effects of atmospheric electricity on biological systems. The work here presented is an attempt to measure the changes in the behaviour, or the power output, of certain insects during stationary flight in a unipolar atmosphere. Since several published references indicate the existence of a "weather sense" in insects, which has been attributed to sensitivity to atmospheric space charge fluctuations, various species of flies were chosen for this study. Various studies have been carried out on insect flight endurance with flight mills. For this work a new type of closed insect flight, apparatus has been developed, in which environmental conditions can be altered, and the pull and wing beat frequency of the fly under test recorded simultaneously. Insects were attached to a mechano-electrical transducer either directly or indirectly. The transducer output was resolved into an AC component, whose frequency corresponds to the wing beat frequency, and a DC component whose magnitude corresponds to the force exerted by the insect in flight. Both components were traced on graphical recorders. In a modified apparatus two transducers were used for measuring the pull and wing beat frequency independently. Even under identical physical conditions insects were found to behave in an erratic manner, so that possible small effects due to variations of the ion concentration were difficult to establish. The spiracles of some flies were dilated by increasing the ambient CO₂ concentration up to 15% causing various changes in the flight patterns without rendering them more regular. From a statistical analysis of the energies produced, some evidence can be obtained that individuals of Muscina stabulans and Lucilia sericata under a negative ionization excess display greater activity than those under normal conditions or under positive ion excess. More tests will be necessary to substantiate the results. The use of the apparatus as an entomological olfactometer or for the test of other insect responses is suggested; several insect repellents were tested on the same apparatus. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

By utilizing the dependency of the efficiency of a Geiger counter upon the primary ionization of a counted particle, the mimimum primary specific ionization of electrons in several gases has been determined. The values obtained are: (1) Gas (2) ion pairs/centimeter/atmosphere Helium 5.47 ± 0.09 Neon 11.6 ± 0.4 Argon 29.8 ± 1.5 Ethylene 40.1 ± 1.0 Ethyl alcohol vapour 6l.5 ± 1.5 The dependence of specific ionization upon the energy of the primary electron has been investigated between the energies of O.158 and 0.351 MeV. The primary specific ionization of positrons and electrons of the same energy has been found to be the same to within 1%. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Electron impact ionization is an important phenomenon touching many areas of science, and much research has been done over the years on various aspects of this process. Efforts to establish the precise variation of ionization cross section with energy were initiated in the early 1950's; however, severe disagreements between experimental data concerning fine structure observed in the electron impact ionization efficiency curves were reported from laboratory to laboratory. The work in this thesis has been largely devoted to establishing the credibility of the method of electron impact ionization by monoenergetic electron beam in the study of such fine structure. The design and construction of an apparatus to study the ionization of atoms and molecules by an electron beam of narrow energy width are described, and preliminary data on krypton and argon near the ionization threshold energies discussed. A sound basis has been laid for further development in this field. / Science, Faculty of / Chemistry, Department of / Graduate

Thesis--Catholic University of America. / Bibliography: p. 33.

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