THE ORIGIN OF NEW STARS. 15 
seen a photograph of such a remarkable coincidence having 
occurred. So it seems to have happened in this instance, 
that two of the dark bodies in space have come together. 
They need not have been very large bodies. The probability 
is that they were not very large bodies. Also it is not 
necessary to suppose that they came actually square together. 
It may have been hardly a collision at all—a mere grazing 
collision. If they came excessively close it is conceivable 
that the blow would produce a tremendous amount of friction, 
and it would develop a considerable quantity of heat. It 
may be said, “ Yes, but if they come together at a tempera- 
ture so cold as that at which we know even air itself is a 
solid lump, is it conceivable that the mere knocking together 
of those two bodies can create a temperature so great as 
to render incandescent those vast bodies of hydrogen, whose 
light is radiated millions and millions of miles throughout 
the universe?” <A few figures will show that it is conceiv- 
able this might take place. 
I am not going to trouble you with more figures than are 
absolutely necessary. Youremember that a rifle bullet when 
fired from a rifle and hitting a target, is warm when it is 
picked up. That warmth is due to its motion being stopped 
by the blow against the target. Ifa body moving at a 
velocity far faster than that of a rifle bullet strikes against 
another, the heat developed in that body would be greater 
still. Take a piece of coal and suppose it to be sent through 
space at a velocity of five miles a second—ten times the 
velocity of any bullet fired from a rifle, then that piece 
of coal, if it struck against a wall, or came into collision 
with another piece of coal travelling in the opposite 
direction, would develop from the blow as much heat as 
could be produced by the combustion of the coal itself. But 
these objects move at a pace far greater than five miles a 
second. This earth moves at a velocity of about four times 
that. A number of the stars move at a far greater velocity. 
It is certain that those bodies in the new star had speeds 
which may have amounted to hundreds of miles a second. 
Let us suppose it to be two hundred miles a second, which is 
not unreasonable. A body going at five miles a second has 
as much energy in virtue of its motion as an equal weight of 
coal would yield in perfect combustion, so that if it is going 
at two hundred miles a second, that means it has as much 
energy as sixteen hundred globes of coal of the same size. 
Imagine two such bodies meeting in space; the energy 
