94 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 13, No. 5 
SCIENTIFIC NOTES AND NEWS 
The third paper of the series discussing the Quantum Theory was presented 
before the Physics Club, Bureau of Standards, by F. L. Monter, January 
22, 1923. The subject was The atomic structure of chemical elements. An 
abstract by the author follows: 
We assume that a chemical element of atomic number Z contains Z elec- 
trons each in an orbit determined by quantum conditions similar to those 
demonstrated experimentally for hydrogen and helium. A rigid mathemat- 
tical solution is impossible but ina heavy atom the inner X-ray orbits approx- 
imate hydrogen orbits around a charge Z. An analysis of X-ray spectra 
shows that all positions of equilibrium within the atom are occupied by 
electrons. There are one K, three L, five M, seven N, and five O levels 
known. The total quantum numbers are Kj, Le, M3, ete. The number 
of electrons within each orbit can be estimated and the ellipticity of orbits 
is known. There are as many shapes as allowed by the total quantum 
number. It is concluded that both in the formation of an atom and in 
the course of the periodic table groups K, L, M, ete., appear in the order 
of their quantum number and within each group it is the most elliptical 
orbit which appears first. 
The space configuration must be symmetrical in a complete group and by 
non-mathematical reasoning we see that the rare gases mark stages in com- 
pletion of groups and that chemical and physical properties of successive 
elements can be predicted in some detail from the scheme of atom building 
indicated by X-ray spectrum theory. 
Dr. L. B. TucKEeRMAN delivered the fourth lecture of the above series on 
January 29, 1923. His subject was Continuity vs. discontinuity. 
Since the beginning of human thinking there have been two different 
ways of looking at the physical universe. From the one viewpoint the 
apparent discontinuities of physical phenomena are only singularities in an 
underlying continuous substratum. From the other viewpoint the apparent 
continuities of physical phenomena are only statistical averages over under- 
lying discontinuities. Nearly twenty-five hundred years ago Zeno of Elea in 
his paradoxes pointed out the difficulties involved in both these conceptions. 
After the introduction of the calculus as the basic mathematical tool of 
theoretical physics, the viewpoint of continuity grew to be the customary 
viewpoint of the physicist. The critical investigation into the mathematical 
idea of continuity by Bolzano, Weierstrass, Cantor, and others, together 
with the growth of the modern atomic theory in the hands of Dalton and his 
-followers, the introduction of the electron by J. J. Thomson and finally the 
quantum by Planck, have rendered this viewpoint less satisfactory. 
The development of a theory which shall weld these discontinuities into 
a coherent whole with the continuities of the older physics is a leading prob- 
lem of physics today. It is too early to be certain in which direction this 
development will take place. It may be that the electron, the atom and the 
quantum will finally be interpreted in terms of an underlying continuity. 
On the other hand it may be (and the development of the Bohr atomic 
model seems to make this more probable) that our future picture of the 
physical world will be essentially discontinuous in all its elements. 
