The series spectra of the stripped boron atom (BIII)

In a preceding article [1], we have brought forward evidence that in "hot spark" spectra the strongest lines generally correspond to atoms from which the valence electrons have all been stripped off, so that the resulting spectrum is hydrogen-like, i.e., is due to one single electron moving between the series of levels characteristic of a simple nucleus-electron system. For such a nucleus-electron system the Bohr theory in its elementary form [2] which dealt only with circular orbits, i.e., with variations in azimuthal quantum numbers, the radial being always zero, yielded at once the result that the energies corresponding to a given quantum state, e.g., quantum number 1, increased in the ratio 1, 4, 9, 16, etc., as the nuclear charged increased in the ratio 1, 2, 3, 4, etc. This meant physically that the frequencies corresponding to jumps from infinity to an orbit of given quantum number, technically called term-values, when divided by the square of the nuclear charge should come out a constant; otherwise stated that the constant term in the Rydberg formula should become N, 4N, 9N, 16N

Experimental evidence for the essential identity of the selective and normal photo-electric effects

In the fall of 1913, while studying the photo-electric properties of freshly cut surfaces of the alkali metals in extreme vacua, we observed that immediately after first cutting, the fresh surface of sodium showed very large photo-sensitiveness when tested with monochromatic light of wave length 5461 A., even when the vacuum was of the order 10(-6) mm. as measured by a McLeod gauge. But after several weeks of experimenting and many cuttings a condition was reached in which a freshly cut surface was completely insensitive when illuminated with this wave length. The lost sensitiveness reappeared, however, in the course of not more than two minutes after cutting, and grew rapidly to a very large value in fifteen or twenty minutes. When the gas pressure was of the order of 0.01 mm. the same phenomenon occurred but the rise to a maximum value was less rapid. From these results we began to surmise that photo-electric currents must be due to the influence of some active gas, which diffused from the walls to the metal and whose action upon the surface was retarded by the presence of an inert gas

A proper understanding of Millikan

Ruth Millikan’s teleological theory of mental content is complex and often misunderstood. This paper motivates and clarifies some of the complexities of the theory, and shows that paying careful attention to its details yields answers to a number of common objections to teleological theories, in particular, the problem of novel mental states, the problem of functionally false beliefs, and problems about indeterminacy or multiplicity of function

The Electron Theory of Matter

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Brownian Movements in Gases at Low Pressures

The essential improvements which the "oil drop method" introduced into the study of Brownian movements consisted in 1. Enabling the observer to hold a given particle under observation as long as desired, even in a rarified gas, by counteracting the downward pull of gravity by the upward pull of an electrical field. 2. Eliminating completely all uncertainty as to the resistance offered by the medium to the motion of the drop through it

Atomic Energy Its Release, Utilization, and Control

The PROCEEDINGS OF THE I.R.E. is publishing, in accordance with the policy of the Institute, a series of papers dealing with instrumentation and controls in the field of the production and utilization of fissionable materials. The members of the Institute present at the IRE West Coast Convention at Los Angeles in 1948 were fortunate in hearing a paper dealing with the broad aspects of atomic energy, delivered by a world-renowned physicist. The speaker was a Nobel prize winner, a pioneer in the field of studies of atomic structure and of cosmic rays, and a leader in physical research. The utilization to best advantage of fissionable materials available on earth is manifestly of major human importance. The following paper deals primarily with this subject, and is commended to the attention of the readers of the PROCEEDINGS OF THE I.R.E. -The Editor

High frequency rays of cosmic origin II. Mountain peak and airplane observations

The elimination in penetrating ray experiments of temperature and pressure effects is accomplished through new features in the design of Wulf electroscopes, but especially through immediate reduction in situ of all deflections to volts. Variation of penetrating radiation with altitude and with time of day. — When suitable precautions are taken for eliminating the activity of adjacent rocks, both airplane and mountain peak observations agree in showing a definite variation of the penetrating radiation with altitude alone. Within the limits of experimental error all observations are consistent in showing no dependence of the penetrating radiation upon the time of day or upon the position of heavenly bodies. Absorption coefficients of penetrating rays. — Absorption experiments made on Pikes Peak with lead sheets 4.8 cm thick furnish evidence for the existence on mountain peaks of copious new rays of local origin of no greater hardness than that of gamma rays. If these new rays are assumed to be homogeneous their absorption coefficient is about 3.1 per meter of water. These experiments, however, furnish no definite evidence for the existence of very penetrating rays of cosmic origin. Necessary characteristics of cosmic rays if they exist — Such rays cannot produce as much as 2 ions per cc per sec. at sea level if they have an absorption coefficient not less than 0.25 per meter of water. If cosmic rays exist at all they must be less intense than this, or else they must be more penetrating than anyone has as yet suggested

New precision in cosmic ray measurements; Yielding extension of spectrum and indications of bands

Method of measurement of capacities of the order of one cm. — A method is described which leads to greatly increased precision in the measurement of capacities of the order of one electrostatic unit. More penetrating cosmic rays than we have previously found are indicated by a new absorption curve obtained in Gem Lake (9080 ft.) and Lake Arrowhead (5125 ft.) with much greater precision than hitherto possible. Cosmic-ray spectrum. — The new curve affords definite evidence for the existence of bands in the spectrum of cosmic rays. The measurements indicate that the cosmic rays consist chiefly of two bands about three octaves apart of mean absorption coefficients 0.35 and 0.04 to 0.05 per meter of water. The total energy of cosmic rays at the top of the atmosphere is found to be very nearly one-tenth that due to starlight and heat as computed from Seares' data

High frequency rays of cosmic origin I. Sounding balloon observations at extreme altitudes

Discharge rate of an electroscope at altitudes from 5 to 15.5 km.—Four specially designed instruments, each comprising a recording electroscope, thermometer and barometer and each weighing but 190 gr were sent up with sounding balloons from Kelly Field, Texas. Three were recovered and of these two had satisfactory records of their flight during which they reached altitudes of 11.2 and 15.5 km, respectively. A comparison of the recorded electroscope reading at the 5 km level during ascent with the reading at the same level during descent shows that the average discharge rate of the electroscopes while above the 5 km level was about three times their discharge rates at the surface of the earth, and corresponded to an average rate of production of ions of 46.2 ions per cc per sec. This is only 25 percent of the value to be expected from the observations of Hess and of Kolhörster and constitutes definite proof that there exists no penetrating radiation of cosmic origin having an absorption coefficient as large as 0.57 per meter of water