. The Bell System technical journal . ough the manner in which theyare bound into the atomic structure differs from one to to our knowledge of the astronomy of the atom, the nucleusis the only part where they can be. Moreover, though the masses ofnuclei generally are not exactly integer multiples of the mass of the CONTEMPORARY ADVANCES IN PHYSICS 639 proton, this is so nearly the rule as to suggest very forcibly that themajor part of every nucleus consists of protons. All this strengthensthe belief that in witnessing these flashes of long-range particles oneis witnessing the
. The Bell System technical journal . ough the manner in which theyare bound into the atomic structure differs from one to to our knowledge of the astronomy of the atom, the nucleusis the only part where they can be. Moreover, though the masses ofnuclei generally are not exactly integer multiples of the mass of the CONTEMPORARY ADVANCES IN PHYSICS 639 proton, this is so nearly the rule as to suggest very forcibly that themajor part of every nucleus consists of protons. All this strengthensthe belief that in witnessing these flashes of long-range particles oneis witnessing the signs of transmutation. The next step, then, consists in finding which of the elements maybe transmutable. I repeat that for the present, a strict assessment ofthe evidence permits us to proclaim a transmutation only when thereare corpuscles of greater range than either the primary alpha-particles,or hydrogen nuclei which suffer elastic impacts. The condition, how-ever, is not quite so harsh as I have intimated. If hydrogen atoms be. Fig. 4—Curve showing evidence that the particles emitted from aluminium bom-barded by a-rays comprise protons and deflected alpha-particles (G. Stetter). Struck by alpha-particles, those and only those which are projectedstraight ahead have the full computed range; those which bounce offat an angle go less far; those which start off at 90° have no range at allwhich is to say, no elastic impact can send a nucleus off in the planethrough the bombarded substance at right angles to the alpha-raystream. Thus, if one stations the fluorescent screen somewhere in thisplane, one may confidently count all of the scintillations as signs oftransmutation, excepting such as may be due to primary alpha-parti-cles deflected through 90° by kernels which they approach withoutdisrupting them, or to hydrogen nuclei which after sufiering elasticimpacts got deflected. (The reader will have noticed in Fig. 3 thatthe angle between the paths of the a-particles to the
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