314 Proceedings of Indiana Academy of Science. 
The object of the present paper is to describe an extension of the 
Mayer experiment in which the magnets or needles are rotated. In 
order to understand how the experiment illustrates the structure of an 
atom it will be well to point out some of the properties of atoms. All 
atoms have mass and all the atoms of the same element have the same 
mass. We find that the elements have different atomic weights. Hydro- 
gen has the atomic weight, one; and uranium, the heaviest, has the atomic 
weight, 238. Thus the mass of the uranium atom is 238 times that of 
the hydrogen atom. 
The atoms of certain elements have the ability to unite with certain 
other elements to form compounds. Certain elements form the bases 
and certain others the acid radicals of the compounds. Or certain are 
said to be electropositive and others are said to be electronegative. 
If we examine the elements, starting with the lightest, hydrogen, and 
taking them one by one in order of their atomic weight or mass, we find 
that this property of combining varies periodically. In this manner we 
can form the periodic table. 
All elements have a definite spectrum. That is, they give off light 
of a certain wave length. Light is a vibratory motion of the ether. 
The wave length or frequency depends upon the source. Thus the atoms 
or something in the atoms must vibrate with certain frequencies. The 
same as in music, when one hears the note middle C one knows that 
there is a string, reed, or something vibrating so as to make 261 vibra- 
tions per second. In the same manner when one sees the D line of 
sodium one knows that there must be something in the sodium atom 
which makes 5. X 10" vibrations per second. 
The X-rays are known to be due to a wave disturbance whose wave 
length is one thousandth that of sodium light. Thus when a swiftly 
moving electron or cathode ray strikes an atom of platinum there must 
be a disturbance set up in the atom whose frequency of vibration is one 
thousand times that which produces the disturbance which we call light. 
Besides the radiations or wave disturbances of the ether which are 
set up by the atom, there are the corpuscular radiations which are given 
off by the atom, such as in the photo-electric effect, ionization by hot 
objects and flames, and the cathode rays, in all of which electrons are 
shot off from the atom. 
A theory of atomic structure must account for all of these phenom- 
ena. Several theories and modifications have been suggested, all of 
which involve electrons rotating about or in a central body or region of 
force which has been called the positive nucleus. 
The Mayer experiment with the extension which I propose can be 
used as an analogy or as an illustration of what happens in an atom. 
The various phenomena of wave motion and corpuscular radiations can 
