Sir J. 3. Thomson bad already before expounded a theory of the atom forming a positively charged sphere on the surface of which the electrons were swimming.—This, however, had to be abandoned owing.
the discrepancies from the observed facts. to which it lead.
Rutherford let Alpha rays penetrate thin metal foil and observed the fcintllations ona luminiscent screen. Instead of going straight through, some of the particles were deviated suggesting a collision or strong deviation by the electric field of the positive nucleus of an atom near which it had passed and he was able to calculate the number of particles which should be deviated in this manner. Geiger and Marsden actually counted them and found them well in agreement with the theoretic figure. Since then we have to picture the atom 3 consisting of a positive nucleus of very small dimensions relative to the size of the atom and even to the electron, but containing a highly concentrated mass; in fact nearly the mass of the whole atom. The electrons are in motion circling orbits around the positive nucleus thus being prevented from falling nucleus. The 5 therefore most of empty space.
Text read from the printed page and cleaned; old type leaves the occasional error.