58 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
to. The profound mind of Boscovich was forced to accept repul- 
sion as a primal quality, but in deference to the physical hypotheses 
of his time, he overloaded it with complication. This has been 
weighed in the balance of philosophical judgment and found want- 
ing. I have intimated that there are possible grounds for surmising 
that it may not be a simple property of the atom, but a mere mode 
of distribution of energy dependent on composition of motion of 
atomic mass after change of sign, 7. ¢., a mode of vis impressa after 
exhaustion of the space relation; for, mathematically, the hyperbolic 
lines of approach and recession of two atoms under the high proper 
motion characteristic of the atom, and on lines not directly central, 
would be similar, at sensible distances, in their asymptotes (which 
would be the practical paths), whether the deflection were due to 
attractive or repulsive stress, though acceleration and retardation 
at the passage of the infinitesimal focus would be inverted.* 
* It is well known that for any finite system of two particles controlled 
by gravity the lines of movement are closed curves of the second order, of 
more or less eccentricity, about the common center of gravity, which, for 
equal masses, would be midway. For an infinite system under the same 
conditions the orbits are parabolic, but for a system to which the particles 
enter by extraneous motion the lines of movement are hyperbolic, thus: 
WIG. bs 
Now, under repulsion, the lines of motion are seen to be similar, A B, D E, 
Fig. 2, being asymptotes of the hyperbolas representing the two paths at 
sensible distances : - 
