5io The Velocity of Light . [September, 
When we hold an opaque objeCt before a flame it dis- 
appears, but we see the air, matter, illuminated to the sides 
of the shadow. When our side of the earth is away from 
the sun, and the refraction of light by our limited atmosphere 
no longer carries it to us, when the attraction of the earth 
no longer finds matter productive of light, the light of the 
sun disappears until it meets matter, which reflects on us 
the motion direCtly received from the sun. 
If all space were filled with matter, indifferently how we 
call it, we ought to see all space illuminated outside the 
shadow of our earth. When the tail of a comet is matter 
so attenuated that we see beyond it stars with undiminished 
splendour, it is visible because the motion communicated to 
single particles by the sun is transferred by their motion to 
the earth. 
With the ether hypothesis, bridging a chasm by a word, 
the imaginary only in the undulatory theory falls. 
There was a time when heat was a fluid accumulating 
round molecules ; now few physicists will deny that it is a 
motion of the molecules. Why, then, appeal to phantoms 
when it comes to light ? The apparently uniform velocity 
of light in space, which great, is not instantaneous, as 
aCtion at a distance might be supposed to be, and prime 
gravity is, disturbs the mind. But is not radiant heat the 
rapid companion of light ? Is not sound made the com- 
panion of both ? Do the ethereans furnish any reasons for 
this great and uniform velocity of light travelling through 
the heavens ? And if they cannot, what is the value of the 
idol which does not lead them out of their perplexities ? 
Light and radiant heat shall be propagated in straight 
lines, whereas other forms of energy follow the sinuosities 
of conducting substances. But even this distinction is illu- 
sory ; the beam of light is not merely refraCted and reflected, 
but also diffracted, bent, and divided. 
The smallest, like the largest, portion of matter is an in- 
dividuality ; it has in itself a distribution of force, according 
to its past and present relations to other individualities 
which lead to various inward and outward motions. 
Examining the nature of these motions, the condition for 
the existence of matter is attraction ; without it, no matter. 
The consequence of attraction is repulsion, which may be 
rectilinear and re-destruCtive, or curvilinear, rotary, and 
orbital. Matter has temperature depending on its relations 
to other matter; vacuum has no temperature, but volume, 
depending — in its definite or indefinite limitations — on the 
mass, volume, and motions of matter. 
