122 Transactions.— Miscellaneous. 
The sun, by attracting a body from infinite space, would give it a velocity 
of 378 miles a second, or each unit of mass would develope about forty 
million units of heat. If we suppose two bodies, each half the size of the 
sun, to come together by mutual attraction alone, then each unit of mass 
would develope about twenty million units of heat. If, on the other hand, 
two bodies twice the mass of the sun come together, each unit of mass 
would have four times the force acting upon it through equal spaces, and 
each unit of mass would consequently develope four times as much heat. 
If the impact of such bodies were imperfect, as we have seen the general 
case would be, a piece of each would be cut off, and these two pieces would 
coalesce. Suppose a quarter of each be struck off, a body of the mass of 
the sun would be produced, but it would have four times the temperature 
the sun would have, assuming the sun to have been formed by direct impact 
and complete coalescence. Each unit of mass in this case would have 
approximately eighty million units of heat; and the temperature will depend 
upon the specific heat of the material, and may be much higher than this. 
I will now show, in the case of partial collision, how small relatively the 
work of cutting off the piece is compared to the energy available. It 
appears to me that in all cases the energy needed for shearing force has its 
superior limit in the latent heat of fusion. This, in the case of ice, is about 
one-fiftieth that of combustion, and combustion is about one twenty- 
thousandth part that of percussion, in the case we have been considering. 
The work of shearing would consequently not be greater than one millionth 
that of the energy of velocity, and soit appears it may safely be disregarded. 
Thus in the case of such a partial collision it may certainly be accepted that 
those parts not in the line of motion of the other body will not coalesce with 
the other body, but will pass on in space. In the piece struck off we shall 
have partial destruction of motion in space, with development of heat; 
many pieces will fly off, and a rotary motion of the whole will ensue. 
There wil be a slight pause from inertia, then the powerful outward 
pressure due to the expansion by heat will overcome all resistance, and will 
expand the whole into gas, much of it certainly passing beyond the limits of 
effective attraction, and away into distant space. Let us pause for an 
instant to examine a little more fully what has happened. 
Two pieces of different bodies, each with a velocity of about 500 miles a 
second, have coalesced, but although the motion of translation is destroyed 
the larger part of each side of the mass is made up chiefly of one of the two 
different bodies: as these are moving in opposite directions, there is con- 
sequently a couple acting on the mass, and this couple spins the mass on 
its centre. Consequently many pieces fly off, and are followed by the mass 
of gas, being impelled outward by the energy of heat and centrifugal force ; 
