PRESIDENTIAL ADDRESSES. : 25 
to a greater or less extent from ether impacts on their sides facing each other, 
and would thereby be driven together. Thus would arise the molecules, their 
sizes also being determined on the same principle as that which determined the 
sizes of the atoms. Atomic aggregates of like size and vibration associated to- 
gether would constitute molecules of elements. But when atomic aggregates of 
unlike size and vibration are brought into proximity they may be driven together 
in greater numbers, and because of their very difference they may be held to- 
gether with greater force. Thus very complex molecules may arise, as in organic 
compounds. Here, then, in the vibration of the protatoms of the ether we find 
an explanation of chemism. 
But we shall find more. The molecules are under the same influence of prot- 
atomic vibration, and are driven together by their interior faces being shielded 
to some degree from impact, thus making a preponderance of impulse on the ex- 
terior; and we have aggregates of molecules resulting, ranging in size from 
those more than microscopically small to those we can handle, and others too 
large to handle. Thus we find cohesion and adhesion explained. But we have 
yet more. The masses in turn shield each other from the impacts of ether 
waves, and the blows are more numerous on their exterior faces than they are on 
their sides turned toward each other, and in consequence they are driven to- 
gether, or at least toward each other. Herein we find an explanation of gravity. 
Remember, the impacts are not of protatoms moving immensely long distances; 
this is no ‘‘corpuscular’’ theory. The motion is a wave motion, and the masses 
are not struck as such; but the individual protatoms at the surface and to some 
depth have received the impacts, taken up the motion and imparted it to the 
next series of protatoms toward the interior, then rebound. Thus the whole 
body is influenced to move by reason of the motion imparted to its constituent 
protatoms. 
Therefore every material body, however small or great, tends to move towards 
every other body, being driven to do so with a tendency directly proportional to 
their masses, and inversely as the square of their distances apart. To say that 
they attract each other is meaningless, but to say that they are driven together 
under the force of ether vibrations may be an explanation. 
But how is it possible that the external pressures due to ethereal impacts on 
the two masses are greater than the pressures due to the impacts against the in- 
terior faces ? 
To explain how this may be we will recall a very interesting experiment in the 
physics of sound, as follows: If two tuning-forks are suspended near to each 
other and are made to vibrate they will approach each other. Various expla- 
nations for this and similar phenomena have been given, the usual one being that 
they are due to air currents established. The explanation I would offer is: The 
sound waves of condensed and rarefied air between the two forks meet and 
neutralize each other to a greater or less extent by crests of condensation meeting 
troughs of rarefaction, while the pressure of the air on the more remote sides of 
the forks remains practically the same. Thus the forks are driven together by 
the excess of prassure from the outer sides. 
Now, let us apply this to the ether. According to our theory, the protatoms 
are in eternal motion, meeting and rebounding continually. For the most part, 
this motion in the outer ether is chaotic; that is, it lacks rhythm. But even in 
such a chaotic ether there must exist regions where the protatoms are more 
numerous and closer together than in other regions. The irregular vibrations 
striking into such aggregates will be more or less absorbed; that is, the motion 
will become, to a great extent, a resultant motion, belonging to the aggregate as 
