182 Atomic Matter and Luminiferous Ether. (April, 
of the mass of matter in the universe are, by inference, 
without proof, held to differ in essence from the observed 
qualities of an indefinitely small fraction of the mass, and 
that fraction a totally different kind of matter. 
It is a disruption of the idea of continuity, and of the 
unity of creation, to assume that the larger and unknown 
quantity of matter differs totally from that which is known. 
The proposition that we judge of the unknown by the 
known implies that the unknown resembles the known, or it 
cannot be appreciated; and in this sense scientific method 
requires that the unknown properties of ether should be 
proved, for they do not resemble any of the known properties 
of matter. 
The admitted want isa medium for conveying force, or, in 
other words, motion of all kinds; and if we ascertain in 
what way force or motion is most probably conveyed in 
known instances, we shall then know more of the probably 
necessary qualities of the required medium. 
Grove’s experiment of a silver gridiron on a daguerreotype 
plate, placed in the sunlight and connected with a galvano- 
meter, proves that the sun’s rays are converted into chemical 
action on the plate, electricity through the wires, magnetism 
in the coil, sensible heat in the helix, and motion in the 
needle, exhausting all the forces in the sun’s visible rays, so 
far as known. These forces must all have some property in 
common, as they are mutually convertible, and that property 
is motion. 
All natural motion is, or becomes, rhythmical. No in- 
stance occurs to me either of natural uniform motion, or of 
motion in a straight line or ina circle. The path of the 
planets, as regards the sun, are elliptical, and their motions 
accelerate and retard; and as regards space, their paths are 
still more complicated. Hence the medium we require to 
transmit force must transmit vibratory motion. 
Vibratory motion is of two kinds, or may be resolved 
into two kinds, viz., vibration across the line of progression, 
like all the vibrations or forces accompanying light and the 
waves of the sea; and vibratory in the line of progression, 
to and fro, like the waves of sound. 
The action or force called gravitation is a special property 
of atomic matter; on it all the properties of mechanical 
“mass” depend. 
Many of the concrete arguments as to the conservation 
of force turn on the “‘mass” of matter remaining un- 
changed under all circumstances: relative unalterability of 
‘‘mass” is the chemist’s absolute creed. 
Aes. 
