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The continuous spectrum of hydrogen
CURRENT
TOPICS.
An Experiment Planned to Test the Ether Theory of Light. A. H. BUCHERER. (Z&t. f. Phys., 41, No. I.)-Much interest is being manifested at the present time in the Michelson-Morley experiment. To the negative results obtained1 from it arose the supposition that the dimension of moving matter is shortened in the direction of motion and, further, they had much to do with the establishment of the Theory of Relativity. On the other hand, Dayton C. Miller within the last years has obtained positive results that are interpreMore recently both in America tated as militating against the theory. and in Europe other investigations have challenged the accuracy of Miller’s results so that at the present time the whole matter is under consideration and much hangs on the issue of the scientific process under way. ‘1here are points in the interpretation of any results furnished by the experiment that are not clear. For example, there is uncertainty as to just what takes place when light is reflected from a mirror in rapid motion. Thus Professor Bucherer is led to seek a crucial experiment free of theoretical complications. He suggests the use of a tube whose length is 10,000 times its diameter, because the velocity of light is about 10,000 the velocity of the earth in its orbit about the sun. Let the tube be placed in the direction of the earth’s motion It will reach the and let a beam of parallel light enter at one end. other end. On the other hand, turn the tube so that its length is at right angles to the direction of the earth’s motion and again send in at the end a beam travelling parallel to the tube. As the light advances along the tube the latter is carried sidewise by the earth so that finally the light will strike the side of the tube instead of emerging at the end). This result is predicted on the basis that light from a moving source spreads out in the ether just as it would from a source at rest. Actual experiments according to the method mentioned are in preparation. Instead of the eye a thermo-element or eventually a photographic plate will be used to register the arrival of light at the “ However this experiment may turn out, whether end of the tube. for or against the theory of ether previously held, the problem of the physicist remains to form a picture of optical processes that will explain the phenomena of polarization and of diffraction by means of G. 1;. S. the properties of an elastic medium.” The Continuous Spectrum of Hydrogen. 0. OLDENBERG. was a time when it was said that (Z&t. f. Phys., 41, No. r.)-There continuous spectra could be obtained only from solids and liquids. Now we know better, for hydrogen possesses two such spectra. One, discovered in the light of stars by Hartmann and interpreted on 737
738
CURRENT
TOPICS.
[J. F. I.
Bohr’s theory by Debye, connects with the end of the Balmer series. The other found by E. P. Lewis and the subject of several explanations, extends from the Schumann region of the spectrum up well into the visible part. It is the second continuous spectrum with its units that is the subject of range from 1450 to 5500 Angstrijm this paper. That it really is due to hydrogen was first established. It had been claimed that this spectrum cannot be got from hydrogen at low pressure and carefully dried and that water vapor, not hydrogen, is the origin. Experiments were conducted with very carefully dried hydrogen. At low pressure the continuous spectrum was relatively less intense but it was certainly present.O At high pressures it was very bright and extended up to 5500 A. U. When a tube was giving the continuous spectrum the. admission of argon extinguished it. It was of interest to examine whether all parts of the continuous spectrum of hydrogen reacted in the same way to modifying influences. A difference in effect might well exist, especially iq consideration of the occurrence of a maximum of intensity at 4000 A. U. in the long spectrum. By means of a quartz prism spectroscope Rhotographs were taken that covered a range from 2200 to 5500 A. U. at one exposure. Increasing the pressure of the hydrogen, adding to or subtracting from the quantity of argon present, changof a ing the density of current in the ratio I :80, the application magnetic field of 20,000 gauss, all of these failed to divide the spectrum into portions differently affected. “ To every change in the discharge tube the continuous spectrum reacts as a uniform whole. It therefore probably is due to a single elementary process.” G. F. S. Another Centenary.-Many of the inventions which we are using to-day have become so much a part of our life that we can scarcely imagine a condition of society without them. Presumably the telephone and automobile will occur to most persons as being the promptings of this remark, but it has a humbler source. The ordinary match, the source of much convenience, but unfortunately also of much damage, has now a history of a little over one hundred From an article in Nature (1927, 119, 495) we learn that it years. was on April 7, 1827, that John Walker, a pharmacist of Stocktonon-Tees, recorded in his sales book the first sale of his newly invented “ Friction Lights.” Scarcely anybody is now living who recollects the old flint and tinder days, but some of us have heard in earlier years the stories of our ancestors as to the extreme annoyance and delay in getting a light in that manner. A distinguished professor of one of our medical schools said in his latter years that he had seen many of the inventions of the nineteenth century come into vogue, but the friction match was to him the most acceptable. Further back, of course, we have the matchlock used by the soldiers, long ropes of
TOPICS.
An Experiment Planned to Test the Ether Theory of Light. A. H. BUCHERER. (Z&t. f. Phys., 41, No. I.)-Much interest is being manifested at the present time in the Michelson-Morley experiment. To the negative results obtained1 from it arose the supposition that the dimension of moving matter is shortened in the direction of motion and, further, they had much to do with the establishment of the Theory of Relativity. On the other hand, Dayton C. Miller within the last years has obtained positive results that are interpreMore recently both in America tated as militating against the theory. and in Europe other investigations have challenged the accuracy of Miller’s results so that at the present time the whole matter is under consideration and much hangs on the issue of the scientific process under way. ‘1here are points in the interpretation of any results furnished by the experiment that are not clear. For example, there is uncertainty as to just what takes place when light is reflected from a mirror in rapid motion. Thus Professor Bucherer is led to seek a crucial experiment free of theoretical complications. He suggests the use of a tube whose length is 10,000 times its diameter, because the velocity of light is about 10,000 the velocity of the earth in its orbit about the sun. Let the tube be placed in the direction of the earth’s motion It will reach the and let a beam of parallel light enter at one end. other end. On the other hand, turn the tube so that its length is at right angles to the direction of the earth’s motion and again send in at the end a beam travelling parallel to the tube. As the light advances along the tube the latter is carried sidewise by the earth so that finally the light will strike the side of the tube instead of emerging at the end). This result is predicted on the basis that light from a moving source spreads out in the ether just as it would from a source at rest. Actual experiments according to the method mentioned are in preparation. Instead of the eye a thermo-element or eventually a photographic plate will be used to register the arrival of light at the “ However this experiment may turn out, whether end of the tube. for or against the theory of ether previously held, the problem of the physicist remains to form a picture of optical processes that will explain the phenomena of polarization and of diffraction by means of G. 1;. S. the properties of an elastic medium.” The Continuous Spectrum of Hydrogen. 0. OLDENBERG. was a time when it was said that (Z&t. f. Phys., 41, No. r.)-There continuous spectra could be obtained only from solids and liquids. Now we know better, for hydrogen possesses two such spectra. One, discovered in the light of stars by Hartmann and interpreted on 737
738
CURRENT
TOPICS.
[J. F. I.
Bohr’s theory by Debye, connects with the end of the Balmer series. The other found by E. P. Lewis and the subject of several explanations, extends from the Schumann region of the spectrum up well into the visible part. It is the second continuous spectrum with its units that is the subject of range from 1450 to 5500 Angstrijm this paper. That it really is due to hydrogen was first established. It had been claimed that this spectrum cannot be got from hydrogen at low pressure and carefully dried and that water vapor, not hydrogen, is the origin. Experiments were conducted with very carefully dried hydrogen. At low pressure the continuous spectrum was relatively less intense but it was certainly present.O At high pressures it was very bright and extended up to 5500 A. U. When a tube was giving the continuous spectrum the. admission of argon extinguished it. It was of interest to examine whether all parts of the continuous spectrum of hydrogen reacted in the same way to modifying influences. A difference in effect might well exist, especially iq consideration of the occurrence of a maximum of intensity at 4000 A. U. in the long spectrum. By means of a quartz prism spectroscope Rhotographs were taken that covered a range from 2200 to 5500 A. U. at one exposure. Increasing the pressure of the hydrogen, adding to or subtracting from the quantity of argon present, changof a ing the density of current in the ratio I :80, the application magnetic field of 20,000 gauss, all of these failed to divide the spectrum into portions differently affected. “ To every change in the discharge tube the continuous spectrum reacts as a uniform whole. It therefore probably is due to a single elementary process.” G. F. S. Another Centenary.-Many of the inventions which we are using to-day have become so much a part of our life that we can scarcely imagine a condition of society without them. Presumably the telephone and automobile will occur to most persons as being the promptings of this remark, but it has a humbler source. The ordinary match, the source of much convenience, but unfortunately also of much damage, has now a history of a little over one hundred From an article in Nature (1927, 119, 495) we learn that it years. was on April 7, 1827, that John Walker, a pharmacist of Stocktonon-Tees, recorded in his sales book the first sale of his newly invented “ Friction Lights.” Scarcely anybody is now living who recollects the old flint and tinder days, but some of us have heard in earlier years the stories of our ancestors as to the extreme annoyance and delay in getting a light in that manner. A distinguished professor of one of our medical schools said in his latter years that he had seen many of the inventions of the nineteenth century come into vogue, but the friction match was to him the most acceptable. Further back, of course, we have the matchlock used by the soldiers, long ropes of