entered the aggregation of particles, and moved slowly forward

The windows in the dome, being made of toughened glass, set

somewhat slantingly so as to deflect anything touching them, and

having, moreover, the pressure of the inside air to sustain them,

were fairly safe, while the windows in the sides and base were

but little exposed. Whenever a large mass seemed dangerously

near the glass, they applied an apergetic shock to it and sent it

kiting among its fellows. At these times the Callisto recoiled