The electron, its isolation and measurement and the determination of some of its properties

by Robert Andrews Millikan

, and

are all known. It is thus that the number of free positive electrons in the nucleus is found to be roughly half the atomic weight of the atom, and that the size of the nucleus is found to be very minute in comparison with the size of the atom.

APPENDIX G
BOHR’S THEORETICAL DERIVATION OF THE VALUE OF THE RYDBERG CONSTANT

The Newtonian equation of a circular orbit of an electron

rotating about a central attracting charge

, at a distance