Franklin's Discovery of the Electron

In celebrating the anniversary of the discovery of the electron, it is a mistake to concentrate attention solely on J. J. Thomson's paper of 1897. I do not in any way underestimate the importance of that paper in bringing about general acceptance of the electron theory of matter, through the evidence presented in it for the existence of a charged particle of mass about 1/1000 the mass of the hydrogen atom. However, to this particle Thomson gave the name ''corpuscle," rather than electron, doubtless because the word "electron" had already been assigned by G. Johnstone Stoney to the hypothetical atom of electricity, that is, of electric charge, whether that charge is positive or negative. The existence of this atom of charge, or of the atomic constitution of electricity, was asserted with great clarity by Benjamin Franklin because of experiments begun in 1747, so that 1947 is both the 200th anniversary of Benjamin Franklin's discovery of the existence of an a tom of electric charge and the 50th anniversary of J. J. Thomson's proof of the existence of a charged particle whose mass, as he then phrased it, was about 1/1000 that of the hydrogen atom

Dependence of electron emission from metals upon field strengths and temperatures

This paper contains a full presentation of the reasons for believing, contrary to results recently obtained elsewhere, that field currents are only independent of temperature up to about 1100°K, and that at that temperature the energy of thermal agitation begins to assist the fields appreciably in causing the escape of electrons from metals. The precise form of function describing this dependence is not accurately determinable experimentally, but the form originally suggested by us fits the facts of observation thus far known satisfactorily, not better, however, than does the theoretical form suggested by Houston

On the question of the constancy of the cosmic radiation and the relation of these rays to meteorology

Mean cosmic-ray intensities have been measured with much precision both at Pasadena, California (latitude 34) and at Churchill, Manitoba (latitude 59), the latter a distance of 730 miles from the North magnetic pole. (1) The observed equality in these intensities indicates that these rays enter the earth's atmosphere as photons rather than as streams of electrons. (2) Evidence is presented that the incoming rays are of a uniform intensity in all directions and in all latitudes, the small and apparently erratic fluctuations found by many observers at different stations arising simply from eruptions, waves, or ripples which change the thickness of the atmospheric blanket interposed between the source and the observer. (3) The cosmic-ray electroscope thus acquires significance as a meteorological instrument. (4) The influence of these rays in the maintenance of the earth's charge is considered

Further experiments on the uniformity of distribution of the cosmic radiation

More careful and prolonged observations on the small, daily variation before reported in the measured intensities of the cosmic rays, the new observations being made under such conditions as to eliminate the possibility of a slight temperature effect suggested by Bowen and Millikan's recent explanation of ionization-pressure relations in high-pressure electroscopes, yield the definite result that within the limits of the author's present observational uncertainty which is of the order of a third of a percent, the sun has no direct influence on cosmic-ray intensities. New evidence is presented that if observed and apparently systematic variations of the order of a third of a percent are in fact real they are best interpreted as the result of small changes in the blanketing effect of the earth's atmosphere due to air currents

Cosmic-ray ionization and electroscope-constants as a function of pressure

1. The residual ionization in an electroscope at infinite depth in water, that is, its zero reading, is found to be an inverse function of the pressure. Thus, in a particular electroscope the zero at 1 atmosphere was 5.13 ions cc/sec., while at 30.1 it had fallen to 1.2 ions cc/sec. 2. Also, when in this electroscope the pressure was changed from 1 atmosphere to 30.1 atmospheres the observed ionization current rose but 13.80 fold, which multiplying factor was found the same for gamma rays and for cosmic rays. 3. Both of these pressure effects are shown to be due to lack-of-saturation in high pressure electroscopes, as first explained in Nature of October 3, 1931, by Bowen and the author. 4. From the multiplying factor found in (2) in the measured ionization at Pasadena in this 30 atmosphere high-pressure electroscope, the number of cosmic-ray ions at 1 atmosphere (24°C 74 cm pressure) in this electroscope at Pasadena is found to be fairly accurately 2.63 ions cc/sec. 5. The sea level value of the ionization in this electroscope is 2.48 ions cc/sec

New techniques in the cosmic-ray field and some of the results obtained with them

Each new field of scientific study goes through a period of development which may be likened to the development of a man child. Up to the age of six or seven a boy interests everybody intensely. In babyhood he is new and sweet and altogether charming because of the awakening qualities which bloom forth as he becomes a real person, and from then on up to seven or eight he is intensely interesting because he is revealing day by day what kind of a person he is likely to be. Then from say eight to thirteen he goes through a period in which he is in general best described as a whining brat who knows no law, is always against the government, and has no real friend except his mother. From about thirteen on he begins to find himself as a member of the human family, and by the time he is twenty-one is ready to don the toga and be admitted regularly into the ordered society of adults

The Present Status of the Evidence for the Atom-Annihilation Hypothesis

The purpose of this paper is to present a brief review of such evidence as we have obtained in the geomagnetic studies which we have been conducting from this laboratory during the past twenty-five years for the atom-annihilation hypothesis as to the origins of cosmic rays in intergalactic space