SCIENCE. 
238 
ON SOME NEEDED CHANGES AND ADDITIONS 
TO PHYSICAL NOMENCLATURE. 
By Professor A. E. Dolbear. 
I. — Physics is now defined to be the science of 
energy. Previous to 1840 what was known concern- 
ing energy was embodied in Newton’s laws of Motion, 
and was confined to what we may call molar mechan- 
ics, to distinguish it from atomic and molecular me- 
chanics, which has since that time been developed. 
Friction was looked upon as resulting in an absolute 
loss of energy, and no attempt appears to have been 
made to find it in other forms. Both Rumford and 
Davy proved, to their own satisfaction, that friction re- 
sulted in the creation of heat — an idea entirely differ- 
ent from the conception of heat then in vogue, that it 
consisted in imponderable corpuscles. No attempt 
was made to find the quantitative relation between 
molar energy expended and the heat produced, so 
that many years elapsed before any advance was made 
beyond the qualitative work of Rumford and Davy. 
Even for a time after Faraday’s researches had estab- 
lished a quantitative relation between chemical reac- 
tions and electricity, the facts were looked upon as 
rather curious information, out of relation with physics 
proper, and so the latter was kept strictly what is in- 
volved in 
Energy E 
111 v\ 
2 
the form of the energy being modified by so-called 
“ Mechanical Powers,” the lever, the pulley, the in- 
clined plane, etc. Since 1840, however, through the 
labors of Mayer, Joule, Thomson and others, the 
quantitative relations between the various known 
forms of energy have been determined with great pre- 
cision, and has led to a complete and inclusive gener- 
alization of the laws of energy — namely, that the 
energy in the universe is a constant quantity, the form 
that it may assume at a given time and place depend- 
ing solely upon the other forms of energy which are 
present at the same place at that time. By the form 
of energy is meant the character of the motion that em- 
bodies the energy , for when there is no motion there is 
no energy, so that each different form of motion is a 
different form of energy. Rectilinear motion is a dif- 
ferent form from rotatory motion, inasmuch as in rec- 
tilinear motion there is a change of position in space 
of the centre of mass, while rotatory motion does not 
involve such change, yet both embody energy though 
each in a special form and each should have a specific 
name. 
Generically, all motion of translation in space is 
called mechanical motion or molar motion, and its 
energy, once called its vis viva , is proportional to 
m v' 1 
, and is true for masses of all dimensions. 
Nevertheless, what a given amount of energy will do 
depends solely upon its form. Rectilinear motion 
cannot continuously produce rotatory motion ; but 
vibratory motion can. For convenience in descrip- 
tive work as well as for clearness of conception — the 
latter of great importance — it is necessary to have 
specific names for the various forms of energy. As 
each form embodies a particular form of motion, one 
will only need to specify the various possible forms of 
motion in order to cover all possible cases. We have 
then the following table for such mechanical or molar 
motions : 
/ Rectilinear, like a locomotive upon a straight 
1 track 
\ Rotatory, like that of a balance wheel. 
, 1 Vibratory, like that of a tuning fork. 
E = m v - < Curvilinear, like that of a projected cannon 
2 ] ball. 
/ Spiral (unusual), like some forms of projected 
[ rockets. 
\ Vortical, like smoke rings. 
As the energy of each of these forms is expressed 
by the same formula there is no way of identifying 
either of them, except by some roundabout expression 
as “ The energy of vibration,” “ The energy of curv- 
ilinear motion.” It is true that for one of these 
forms we have a particular name, sound, for vibratory 
motion, provided its frequency is within the limits of 
hearing, but as the same name is applied to the sen- 
sation itself we are without a distinctive name. 
II. If instead of large masses we consider atoms and 
molecules, it will be clear at once that the same forms 
of motions are possible as with the large masses, and 
the same general descriptive terms are applica- 
ble. Thus for an atom there is a rectilinear motion 
which we call its free path, but for its vibratory motion 
we use a distinct and and specific name, heat. Also 
for the rotation of the atom in its own plane, we have 
the specific name, electricity ; for possible curvilinear 
spiral or vortical motions there are no names. 
The energy embodied in atomic and molecular 
motions exclusive of rectilinear, that is, that do not 
involve a change of position of the centre of mass or 
of inertia of such atom is generally called internal 
energy , and if we let e represent its value then the 
complete expression for the energy of the atom will be 
111 V 2 . 
E = E 
2 
Now such changes and conditions as are involved 
in what we call latent heat , specific heata.n& specific in- 
ductive capacity are all involved in that factor «, but 
the terms specific heat and latent heat are certainly 
misapplied, for whatever the forms of energy may be, 
they are certainly not heat, consequently not vibratory. 
Specific names then are needed for these. 
III. The observed transference of energy from one 
atom to another without contact has necessitated the 
