He would also,of course,need a sun to warm him,if he wished to go beyond this system,but that would not have to be a large affair--in fact,it might be smaller than the planet,and could revolve about it like a moon.""Though a sun of that size,"replied Cortlandt,"might retain its heat for the time you wished to use it,the planet part would be nothing like as comfortable as what we have here,for it would be very difficult to get enough air-pressure to breathe on so small a body,since,with its slight gravitation-pull,to secure fifteen pounds to the square inch,or anything like it,the atmosphere would have to extend thousands of miles into space,so that on a cloudy day you would be in darkness.It would be better,therefore,to have such a sun as you describe and accompany it in a yacht or private car like this,well stocked with oxygen and provisions.When passing through meteoric swarms or masses of solid matter,collision with which is the most serious risk we run,the car could follow behind its sun instead of revolving around it,and be kept from falling into it by partially reversing the attraction.As the gravitation of so small a sun would be slight,counteracting it for even a considerable time would take but little from the batteries.""There are known to be several unclaimed masses,"added Ayrault,"with diameters of a few hundred yards,revolving about the earth inside the orbit of the moon.If in some way two of these could be brought into sufficiently violent collision,they would become luminous and answer very well;the increase in bulk as a result of the consolidation,and the subsequent heat,about serving to bring them to the required size.Whenever this sun showed spots and indications of cooling,it could be made to collide with the solid head of some comet,or small asteroid,till its temperature was again right;while if,as a result of these accretions,it became unwieldy,it could be caused to rotate with sufficient rapidity on its axis to split,and we should have two suns instead of one.""Bravo!"said Bearwarden."There is no limit to what can be done.The idea of our present trip would have seemed more chimerical to people a hundred years ago than this new scheme appears now."Thus they sat and talked,or studied maps and star-charts,or the stars themselves,while the hours quickly passed and they shot through space.They had now a straight stretch of over three hundred million miles,and had to cross the orbits of innumerable asteroids on the way.The apparent size of the sun had by this time considerably decreased,and the interior of the Callisto was no longer uncomfortably warm.They divided the day into twenty-four hours from force of habit,and drew the shades tightly during what they considered night,while Bearwarden distinguished himself as a cook.
CHAPTER III.
HEAVENLY BODIES.
The following day,while in their observatory,they saw something not many miles ahead.They watched it for hours,and in fact all day,but notwithstanding their tremendous speed they came but little nearer.
"They say a stern chase is a long one,"said Bearwarden;but that beats anything I have ever seen."After a while,however,they found they WERE nearer,the time taken having been in part due to the deceptive distance,which was greater than they supposed.
"A comet!"exclaimed Cortlandt excitedly."We shall really be able to examine it near.""It's going in our direction,"said Ayrault,"and at almost exactly our speed."While the sun shone full upon it they brought their camera into play,and again succeeded in photographing a heavenly body at close range.The nucleus or head was of course turned towards the sun;while the tail,which they could see faintly,preceded it,as the comet was receding towards the cold and dark depths of space.The head was only a few miles in diameter,for it was a small comet,and was composed of grains and masses of stone and meteoric iron.Many of the grains were no larger than peas or mustard-seeds;no mass was more than four feet in diameter,and all of them had very irregular shapes.The space between the particles was never less than one hundred times their masses.
"We can move about within it,"said Ayrault,as the Callisto entered the aggregation of particles,and moved slowly forward among them.
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 slightly also,the resulting motion in either being in inverse ratio to its weight.There was constant and incessant movement among the individual fragments,but it was not rotary.Nothing seemed to be revolving about anything else;all were moving,apparently swinging back and forth,but no collisions took place.
When the separate particles got more than a certain distance apart they reapproached one another,but when seemingly within about one hundred diameters of each other they swung off in some other direction.The motion was like that of innumerable harp-strings,which may approach but never strike one another.
After a time the Callisto seemed to become endowed with the same property that the fragments possessed;for it and they repelled one another,on a near approach,after which nothing came very near.
