T
On the light thrown by recent
investigations on Electricity on the relation between Matter and Ether.
THE ADAMSON LECTURE DELIVERED AT THE UNIVERSITY
ON NOVEMBER 4, 1907
BY
J. J. THOMSON, D.Sc, F.R.S.
Cavendish Professor of Experimental Physics in the University of Cambridge

MANCHESTER AT THE UNIVERSITY PRESS
1908

a*> 3 3S

The Adamson Lecture, delivered biennially by some person of distinction in Philosophy, Literature,
or Science, was founded in 1903 by friends and
former colleagues in memory of Robert Adamson, LL.D., Professor of Logic in Owens College from
1876 to 1893.

On the light thrown by recent investigations
on Electricity on the relation between
Matter and Ether.
By J. J. Thomson.
When I received the invitation to give the Adamson
Memorial Lecture I felt considerable hesitation about accepting it. I felt there was some incongruity in a
lecture founded in memory of a great master of Metaphysics being given by one who had no qualifications to speak on that subject. I was reassured however when I remembered how wide were Professor Adamson 's sympathies with all forms of intellectual activity and how
far reaching is the subject of Metaphysics. There is indeed one part of Physical Science where the problems are very analogous to those dealt with by the metaphysician, for just as it is the object of the latter to find the fewest and simplest conceptions which will cover mental phenomena, so there is one branch of physics which is concerned not
so much with the discovery of new phenomena or the
commercial application of old ones, as with the discussion of conceptions able to link together phenomena apparently as diverse as those of light and electricity,
sound, and mechanics, heat and chemical action. To some men this side of Physics is peculiarly attractive,
they find in the physical universe with its myriad phenomena and apparent complexity a problem of inexhaustible and irresistible fascination. Their minds chafe under the diversity and complexity they see around them, and they are driven to seek a point of view from which phenomena as diverse as those of light, heat, electricity, and chemical action appear as different mani-

6

THE ADAMSON LECTURE

festations of a few general principles. Regarding the universe as a machine such men are interested not so

much in what it can do as in how it works and how it is

made; and when they have succeeded, to their own

satisfaction at any rate, in solving even a minute portion

of this problem they experience a delight which makes

the

question

" what

is

the

value

of

" hypothesis?

appear to them as irrelevant as the questions " what is

the value of poetry? " " what is the value of music? "

11 what is the value of philosophy? M

Recent investigations on Electricity have done a

good deal to unite various branches of Physics,

and I wish this evening to call your attention to

some of the consequences of applying the principle
— of the equality of action and reaction Newton's — Third Law of Motion to some of these researches.

According to this law the total amount of momentum in

any self contained system, that is any system uninflu-

enced by other systems, is constant, so that if any part

of such a system gains momentum another part of the

system must simultaneously lose an equal amount of

momentum. This law, besides being the foundation of

our ordinary system of dynamics, is closely connected

with our interpretation of the great principle of the

Conservation of Energy, and its failure would deprive

that principle of much of its meaning. According to

that principle the sum of the kinetic and potential

energies

of

a

system

is

constant ;

let us consider a

moment how we are to estimate the kinetic energy. To

us the objects in this room appear at rest, and we should

say that their kinetic energy was zero, but to an observer

say on Mars, these objects would not appear to be at rest

but moving with a considerable velocity, for they would

have the velocity due to the rotation of the earth round

its axis and also that due to the revolution of the earth

round the sun ;

thus the estimate of the kinetic energy

made by a Martian observer would be very different

from our estimate. Now the question arises does the

MATTER AND ETHER

7

principle of the Conservation of Energy hold with both these estimates of the kinetic energy, or does it depend upon the particular system of axes we use to measure the velocity of the bodies ? Well we can easily show that if the principle of the equality of action and reaction is true the Conservation of Energy holds whatever axes we use to measure our velocities, but that if action and
reaction are not equal and opposite this principle will only hold when the velocities are measured with reference to a

particular set of axes.
The principle of action and reaction is thus one of
the foundations of Mechanics and a system in which this principle did not hold would be one whose behaviour could not be imitated by any mechanical model. The study of electricity however makes us acquainted with cases where the action is apparently not equal to the reaction. Take for example the case of two electrified
A bodies and B in rapid motion, we can, from the laws
of electricity, calculate the forces which they exert on each other, and we find that, except in the case when they are moving with the same speed and in the same direction,
A the force which exerts on B is not equal and opposite
to that which B exerts on A, so that the momentum of
the system formed by B and A does not remain constant.
Are we to conclude from this result that bodies when

electrified are not subject to the Third Law, and that

therefore any mechanical explanation of the forces due

to such bodies is impossible, this would mean giving

up the hope of regarding electrical phenomena as arising

from the properties of Matter in Motion. Fortunately,

We however, it is not necessary.

can follow a famous

precedent and call into existence a new world to supply

We the deficiencies of the old.

may suppose that

A connected with and B there is another system, which

though invisible possesses mass and is therefore able
to store up momentum, so that when the momentum of
the system A, B alters, the momentum which has been
A lost by and has not gone to B has been stored up in

8

THE ADAMSON LECTURE

the invisible system with which they are in connection,

A and that

and B plus the invisible system, together

form a system which obeys the ordinary laws of mechanics

We and whose momentum is constant.

meet in our

ordinary experience cases which are in all respects
analogous to the one just considered. Take for example
the case of two spheres A and B moving about in a tank A of water, as moves it will displace the water around it
and produce currents which will wash against B and

alter its motion, thus the moving spheres will appear to exert forces on each other, these forces have been

calculated by Kirchhoff and resemble in many respects
the forces between moving electric charges, in particular unless the two spheres are moving with the same speed and in the same direction the forces between them are

not equal and opposite so that the momentum of the two
spheres is not constant, if, however, instead of confining
our attention to the spheres we include the water in which
they are moving we find that the spheres plus the water form a system which obeys the ordinary laws of dynamics and whose momentum is constant, the momentum lost or gained by the spheres is gained or lost by the water. The case is quite parallel to that of the moving electric charges and we may infer from it that when we have a system whose momentum does not remain constant the conclusion we should draw is not

that Newton's Third Law fails, but that our system,
instead of being isolated as we had supposed, is connected with another system which can store up the momentum
lost by the primary, and that the motion of the complete system is in accordance with the ordinary laws of

dynamics.
Returning to the case of the electrified bodies we see then that these must be connected with some invisible

universe, which we may call the ether, and that this

ether must possess mass and be set in motion when the

We electrified bodies are moved.

are thus surrounded

by an invisible universe with which we can get into

MATTER AND ETHER

9

touch by means of electrified bodies, whether this universe can be set in motion by bodies which are not electrified, is a question on which we have as yet no
decisive evidence.
Let us for the moment confine ourselves to the case of
electrified bodies, the fact that when these move they have to set some of the ether in motion must affect
their apparent mass : for exactly the same reason that the apparent mass of a body is greater when it is immersed in water than when it is in a vacuum
;
when we move the body through the water we have to set in motion not merely the body itself but also some of the water around it, in some cases the increase in the apparent mass of the body due to this cause may be much greater than the mass of the body itself, this is the case, for example with air bubbles in water which behave as if their mass were many hundred times the mass of the air enclosed in them. In the case of the electrified bodies we
may picture to ourselves that the connection between
them and the ether around them is established in the
following way, we may suppose that the lines of electric
force which proceed from these charged bodies and pass through the ether, grip as it were some of the ether and carry it along with them as they move; by means of the laws of electricity we can calculate the mass of ether
gripped by these lines in any portion of space through which they pass. The results of this calculation can be expressed in a very simple way. Faraday and Maxwell have taught us to look for the seat of the potential energy of an electrified system in the space around the system and not in the system itself, each portion of space possessing an amount of this energy for which Maxwell has given a
very simple expression. Now it is remarkable that if we
calculate the mass of the ether gripped by the lines of electric force in any part of the space surrounding the charged bodies we find that it is exactly proportional to the amount of potential energy in that space, and is given by the rule that if this mass were to move with the

10

THE ADAMSON LECTURE

velocity of light the kinetic energy it would possess would be equal to the electrostatic energy in the portion of space for which we are calculating the mass. Thus the total mass of the ether gripped by an electrical
system is proportional to the electrostatic potential energy of that system. Since the ether is only set in motion by the sideways motion of the lines of force and not by their longitudinal motion, the actual mass of the ether set in motion by the electrified bodies will be somewhat less than that given by the preceding rule, except
in the special case when all the lines of force are
moving at right angles to their length. The
slight correction for this slipping of the lines of
force through the ether does not affect the general character of the effect, and in what follows I shall
for the sake of brevity take the mass of the ether set in motion by an electrified system to be proportional to the potential energy of that system. The electrified body has thus associated with it an etherial or astral body which it has to carry along with it as it moves and which
increases its apparent mass. Now this piece of the unseen
universe which the charged body carries along with it
may be expected to have very different properties from
ordinary matter : it would of course defy chemical analysis and probably would not be subject to gravita-
tional attraction, it is thus a very interesting problem to see if we can discover any case in which the etherial mass is an appreciable fraction of the total mass, and to
compare the properties of such a body with those of one
whose etherial mass is insignificant. Now in any
ordinary electrified system, such as electrified balls or
charged Leyden jars the roughest calculation is sufficient to show that the etherial mass which they possess in
virtue of this electrification is absolutely insignificant in comparison with their total mass. Instead, however,
of considering bodies of appreciable size let us go to the atoms of which these bodies are composed, and suppose as seems probable that these are electrical

MATTER AND ETHER

n

systems and that the forces they exert are electrical in

their origin.

Then the heat given out when the atoms

of different elements combine will be equal to the diminu-

tion of the mutual electrostatic potential energy of the

atoms combining, and therefore by what we have said

will be a measure of the diminution of the etherial mass

attached to the atoms; on this view the diminution in the
etherial mass will be a mass which moving with the velocity of light possesses an amount of kinetic energy
equal to the mechanical equivalent of the heat developed
by their chemical combination. As an example, let us
take the case of the chemical combination which of all

those between ordinary substances is attended by the greatest evolution of heat, that of hydrogen and oxygen. The combination of hydrogen and oxygen to form one gramme of water evolves 4000 calories, or 16*8 x io10 ergs, the mass which moving with the velocity of light, i.e., 3 x io10 centimetres per second possesses this amount of kinetic energy is 3*7 x io-10 grammes, and this therefore is the diminution in the etherial mass which takes place
when oxygen and hydrogen combine to form 1 gramme
of water; as this diminution is only about one part in 3000 million of the total mass it is almost beyond the
reach of experiment, and we conclude that it is not very

promising to try to detect this change in any ordinary case of chemical combination. The case of radio-active

substances seems more hopeful, for the amount of heat
given out by radium in its transformations is enormously
greater weight for weight than that given out by the ordinary chemical elements when they combine. Thus Professor Rutherford estimates that a gramme of radium gives out during its life an amount of energy equal to 617 x io 16 ergs, if this is derived from the electric
potential energy of the radium atoms, the atoms in a
gramme of radium must possess at least this amount of
potential energy, they must therefore have associated with them an etherial mass of between one-eighth and one-seventh of a milligramme, for this mass

12

THE ADAMSON LECTURE

if moving with the velocity of light would have kinetic energy equal to 67 x io16 ergs. Hence we
conclude that in each gramme of radium at least J of a
milligramme, i.e., about 1 part in 8,000, must be in the
ether. Considerations of this nature induced me some

time ago to make experiments on radium to see if I could get any evidence of part of its mass being of an abnormal kind. The best test I could think of was to see

if the proportion betwen mass and weight was the same for radium as for ordinary substances. If the part of the mass of radium which is in the ether were

without weight then a gramme of radium would weigh

less than a gramme of a substance which had not so large a proportion of its mass in the ether. Now the

proportion between mass and weight can be got very

accurately by measuring the time of swing of a pendulum ;

so I constructed a pendulum whose bob was made of

radium, set it swinging in a vacuum and determined its

time of vibration, to see if this were the same as that of

a pendulum of the same length whose bob is made of

brass or iron. Unfortunately radium cannot be obtained

in large quantities, so that the radium pendulum was

very light, and did not therefore go on swinging as long

as

a

heavier

pendulum

would

have

done ;

this

made

very

accurate determinations of the time of swing impossible, but I was able to show that to about 1 part in 3,000 the
time of swing of a radium pendulum was the same as that of a pendulum of the same size and shape made of brass or iron. The minimum difference we should expect

from theory is 1 part in 8,000, so that this experiment shows that if there is any abnormality in the ratio of the
mass to weight for radium it does not much exceed that calculated from the amount of heat given out by the radiumduring its transformation. With larger pendulums the value of the ratio of mass to weight can be determined

with far greater accuracy than 1 part in 8,000; for
example, Bessel three-quarters of a century ago showed that this ratio was the same for ivory as for brass to an

MATTER AND ETHER

13

accuracy of at least 1 part in 100,000; and with apparatus

specially designed to test this point an even greater
accuracy could be obtained. When I made my experi-
ments with the radium pendulum the close connection

between the amounts of uranium and radium in radio-

active minerals had not been discovered; this connection

makes it exceedingly probable that radium is derived
from uranium and that this metal may have weight for
weight more electric potential energy, and therefore a larger proportion of its mass in the ether, than radium

itself. This points to the conclusion that the proper

substance to use for the pendulum experiment is uranium

rather than radium, especially since uranium can easily be obtained in sufficiently large quantities to enable us to construct the pendulum of the shape and size which would give the most accurate results, it would not, I

think, be impossible to determine the ratio of mass to

weight for uranium to an accuracy of 1 part in 250,000.
Though we have not been able to get direct experimental evidence of the existence of the part of the mass in the ether in this way, we are in a more fortunate

position in respect to a closely-allied phenomenon, viz.,

the effect of the speed of a body on its apparent mass.
We have seen that the mass of the ether bound by any

electrical system is proportional to the electric potential
— energy of that system. Now let us take the simplest
electrical system we can find a charge of electricity
concentrated on a small sphere. When the sphere is at

rest the lines of electric force are uniformly distributed in
all directions round the sphere. When the lines are

arranged in this way the electric potential energy is

smaller than for any other possible distribution of the

Now lines.

let us suppose that the sphere is set in rapid

motion, the lines of electric force have a tendency to set

themselves at right angles to the direction in which they are moving; they thus tend to leave the front and rear
of the sphere and crowd into the middle. The electrical

potential energy is increased by this process, and since

14

THE ADAMSON LECTURE

the mass of the ether bound by the lines of electric force

is proportional to this energy, this mass will be greater than when the sphere was at rest. The difference is very

small unless the velocity of the spheres approaches the
velocity of light, but when it does so the augmentation of mass is very large. Kaufman has succeeded in

demonstrating the existence of this effect for the "0"

particles

emitted

by

radium ;

these are negatively

electrified particles projected at high speeds from the radium ; the velocity of the fastest is only a few per cent,

less than the velocity of light ; along with these there are
others moving much less rapidly. Kaufman determined

the masses of the different particles, and found that the

greater the speed the greater the mass, the mass of the
more rapidly moving particles being as much as three

times that of the slower ones. These experiments also

led to the very interesting result that the whole of the
mass of these particles is due to the charge of electricity
they carry. On the view we have been discussing this
means that the whole of the mass of these particles is due

to the ether gripped by their lines of force.

If lines of electric force grip the ether, then, since
waves of light, according to the Electromagnetic

Theory of Light, are waves of electric force travelling

at the rate of 180,000 miles per second, and as the lines

of electric force carry with them some of the ether, a wave of light will be accompanied by the motion of a

portion of the ether in the direction in which the light is
travelling. The amount of this mass can be easily

calculated by the rule that it would possess, if travelling with the velocity of light, an amount of kinetic energy

equal to the electrostatic potential energy in the light;

as the electrostatic energy is one-half the energy in the

light wave, it follows that the mass of the moving ether

per unit volume is equal to the energy of the light in that volume divided by the square of the velocity of light. Thus when a body is radiating a portion of the mass of

the ether gripped by the body is carried out by the

MATTER AND ETHER

15

radiation ;

this

mass

is

in

general

exceedingly

small ;

for

example, we find by the application of the rule we have

just given that the mass emitted by each square

centimetre of surface of a body at the temperature of the

We sun is only about 1 milligram per year.

should

expect that when some of the ether, bound to a body by

its lines of force is carried off by the radiation, other

portions of ether which will not be connected with the

body will flow in to take its place. Thus, in consequence of the radiation which proceeds from all bodies the ether around them will be set in motion in much the same way as if a series of sources and sinks were distributed

throughout the bodies.
Though the actual mass of the ether travelling with a wave of light is exceedingly small, yet its velocity is so great, being that of light, that even a very small mass
possesses an appreciable amount of momentum. When
the light is absorbed in its passage through a medium which is not perfectly transparent this momentum will also be absorbed and will be communicated to the

medium, and will tend to make it move in the direction in

which the light is travelling ; the light will thus appear to

exert

a

pressure

on

the

medium ;

the

pressure,

which

is

called the pressure of radiation, has been detected and

measured by Lebedew, Nicols and Hull and Poynting.

All the phenomena associated with this pressure may

be explained very simply by the view that light possesses
momentum in the direction in which it is travelling.

The possession of momentum by light, supposing light

to be an electric phenomenon, has been deduced by

somewhat abstruse consideration. On the old Newtonian

emission theory it is obvious at once that this momentum must exist, for it is just the momentum of the particles which constitute the light. It is remarkable how recent investigations have shown that many of the properties of
light which might be supposed to be peculiar to a process similar to that contemplated on the emission theory, would also be possessed by the light if it were an electric

16

THE ADAMSON LECTURE

phenomenon. There is one consequence of the emission theory to which I should like briefly to allude, because I think it is more in accordance with the actual properties of light than the view to which we should be led if we
took the electromagnetic theory in the form in which it
is usually presented. The active agents on the emission
theory are discrete particles, a ray of light consisting of a
swarm of such particles, the volume occupied by these particles being only a very small fraction of the volume through which they are distributed. The front of a wave of light would on this view consist of a multitude of
small bright specks spread over a dark ground; the wave
front in fact is porous, and has a structure. Now on the
electric theory of light as usually given, it is tacitly
assumed that the electric force is everywhere uniform over the wave front, that there are no vacant spaces, and that the front has no structure. This is no necessary part of the electric theory, and I think there is evidence that the wave front does in reality much more closely resemble a number of bright specks on a dark ground
than a uniformly illuminated area. Let me mention one
such piece of evidence. If a flash of light, especially ultra-violet light, fall on a metal surface, negatively electrified corpuscles are emitted from the surface; but
when we measure, as we can do, the number of these, we find that only a most insignificant fraction of the number of molecules passed over by the wave front have emitted these corpuscles. If the wave front were
continuous then all the molecules of the metal exposed to the light would be under the same condition, and
although, like the molecules of a gas, the molecules might possess very different amounts of kinetc energy, this difference would be nothing like sufficient to account
for the enormous discrepancy between the number of molecules struck by the light and those which emit corpuscles. This discrepancy would, however, easily be understood if we suppose that the wave front is not continuous but full of holes, so that only a small number

MATTER AND ETHER

17

of molecules come under the influence of the electric force

We in the light.

may suppose that light consists of small

transverse pulses and waves travelling along discrete

lines of electric force, disseminated throughout the ether,

and that the diminution in the intensity of the light as it

travels outwards from a source is due not so much the

enfeeblement of the individual pulses as to their wider separation from each other, just as on the emission theory the energy of the individual particles does not decrease as the light spreads out; the diminution of the
intensity of the light is produced by the spreading out of

the particles.
The idea that bodies are connected by lines of electric
force with invisible masses of ether has an important bearing on our views as to the origin of force and the nature of potential energy. In the ordinary methods of

dynamics a system is regarded as possessing kinetic energy which depends solely upon the velocities of the various parts of which it is composed, and potential energy depending on the relative position of its parts.
The potential energy may be of various kinds; thus we may have potential energy due to gravity and potential
energy due to stretched springs, or electrified systems,
and we have rules by which we can calculate the value of

these potential energies corresponding to any position

of the system. When we know the value of the potential

energy

the

method

known

as

that

of

" Lagrange's

equations " enables us to determine the behaviour of the

system. As a means of calculation and investigation this

use of the potential energy works admirably, and is very

unlikely to be superseded ; but, regarded from a philo-

sophical point of view, the conception of potential energy

is much less satisfactory, and stands on quite a different

footing from that of kinetic energy. When we recognise

energy as kinetic we feel that we know a great deal about

it ;

when

we

describe

energy

as

potential

we

feel

that

we

know very little about it, and though it may be objected

that from a practical point of view that little is all that

18

THE ADAMSON LECTURE

is worth knowing, the answer does not satisfy an
inquisitive thing like the human mind.
Let us consider a commercial analogy and compare kinetic energy to money in actual cash and potential energy to money at our credit in a bank, and suppose
such a state of things to exist that when a man lost a sovereign from his pocket it was invariably collected, he did not know how, and placed to his credit in a bank situated he knew not where, from which it could always be recovered without loss or gain. Though the knowledge that this was so might be sufficient for all
commercial purposes, yet one could hardly suppose that
even the most utilitarian and matter-of-fact of men could

refrain from speculating as to where his money was when it was not in his pocket, and endeavouring to penetrate

the mystery which envelopes the transfer of the sovereign backwards and forwards. Well, so it is with the

physicist and the conception of different forms of potential energy ; he feels that these conceptions are not simple, and he asks himself the question whether it is
— necessary to suppose that these forms of energy are all
different; may not all energy be of one kind kinetic? and may not the transformation of kinetic energy into

the different kinds of potential energy merely be the transfer of kinetic energy from a part of the system which affects our senses to another which does no(, so

that what we call potential energy is really the kinetic

energy of parts of the ether which are in kinematical

connection with the material system. Let me illustrate
this by a simple example. Suppose I take a body A

and project it in a region where it is not acted on by

A any force.

will move uniformly in a straight line.

Suppose now I fasten another body B to it by a rigid
connection, and again project it. A will not now move

in a straight line nor will its velocity be uniform ; it may,

on the contrary, describe a great variety of curves, circles,

trochoids, and so on, the curves depending on the mass
and velocity of B when A was projected. Now if B and

MATTER AND ETHER

19

A its connection with were invisible so that all we could

observe was the motion of A, we should ascribe the

deviation of A's path from a straight line to the action

of a force, and the changes in its kinetic energy to
A changes in the potential energy of as it moved from

place to place. This method is, however, the result of

our regarding A as the sole member of the system under

A observation, whereas

is in reality only a part of a

larger system ; when we consider the system as a whole

we see that it behaves as if it were free from the action

of external forces and that its kinetic energy remains

constant ;

what

on

our

restricted

view

we

regarded

as

the

A potential energy of is seen on the more general view-

to be the kinetic energy of the system B. It is now

many years ago since I showed that the effects of force

and the existence of potential energy may be regarded as

due to the connection of the primary system with

secondary systems, the kinetic energy of these systems

being the potential energy of the primary, the complete system having no energy other than the kinetic energy of its constituents; a similar view is the foundation of

Hertz's system of Mechanics.

Let us consider one or two* simple mechanical systems in

which the motion of matter attached to the system produces

A the same effect as a force. Suppose

and B (Fig. 1)

are two bodies attached to tubes which can slide vertically
up and down the rod E F, and that two balls C and D
are attached to A and B by rods hinged at A and B, then

if the balls rotate about the rod they will tend to fly

apart, and as the balls move further from the rod their

A points of attachment

and

B

must

approach

each

other ;

A thus and B will tend to move towards each other,

i.e., they will behave as if there were an attractive force

A acting

between ;

the

velocities

of

and B, and therefore

their

kinetic

energy

will

change

from

time

to

time ;

the

A kinetic energy lost by and B will really have gone to

increase the kinetic energy of the balls. If the rotating
system C and D had been invisible we should have

20

THE ADAMSON LECTURE

explained the behaviour of the system by assuming an attractive force with corresponding potential energy
between A and B. This is due to our considering A and
B as a complete system, whereas it is in reality part of a larger system, and when we consider the complete system we see that it behaves as if it were acted on by no forces
and possessed no energy other than kinetic.
It may perhaps be of interest to note that we can in a similar way make two bodies appear to attract each other
with a force varying inversely as the square of the
Fig. 2,

MATTER AND ETHER

21

distance between them. Let A and B be the bodies, and
suppose that parabolic wires without mass are fixed to
them, if these are threaded through a ring P with a small
but finite mass and the system caused to rotate round
A and B, the effort of the ring to get away from the axis A of rotation will cause and B to approach each other, and the law of approach may easily be shown to be the
same as if there was a force between them varying
inversely as the square of the distance.
The result mentioned on page 10 that the potential
energy of a system charged with electricity is equal to the kinetic energy of the mass of ether bound to the
system when moving with the velocity of light is another example of potential energy, being in
reality the kinetic energy of an associated system, and indeed, as I have endeavoured to bring before
you this evening, the study of the problems brought before us by recent investigations leads us to the conclusion that ordinary material systems must be connected with invisible systems which possess mass whenever the material systems contain electrical charges. If we regard all matter as satisfying this condition we
— are led to the conclusion that the invisible universe the — ether is to a large extent the workshop of the material
universe, and that the phenomena of nature as we see them are fabrics woven in the looms of this unseen
universe.