_Tommy._--I see them to be so, sir. The stars are so small, that they are hardly to be seen at all; and the sun itself, which is much bigger, does not seem bigger than a small round table.
The day after this conversation, as the weather was bright and clear, Mr Barlow went out to walk with Harry and Tommy. As by this time Tommy was inured to fatigue, and able to walk many miles, they continued their excursion over the hills, till at last they came in sight of the sea. As they were diverting themselves with the immense prospect of water that was before them, Mr Barlow perceived something floating at a distance, so small as to be scarcely discernible by the eye. He pointed it out to Tommy, who with some difficulty was able to distinguish it, and asked him what he thought it was.
Tommy answered that he imagined it to be some little fishing-boat, but could not well tell, on account of the distance.
_Mr Barlow._--If you do not then see a ship, what is it you do see? or what does that object appear to your eyes?
_Tommy._--All that I can see is no more than a little dusky speck, which seems to grow bigger and bigger.
_Mr Barlow._--And what is the reason it grows bigger and bigger?
_Tommy._--Because it comes nearer and nearer to me.
_Mr Barlow._--What, then, does the same thing sometimes appear small and sometimes great?
_Tommy._--Yes, sir; it seems small when it is at a great distance; for I have observed even houses and churches when you are at some miles"
distance, seem to the eye very small indeed; and now I observe that the vessel is sailing towards us, and it is not, as I imagined, a little fishing-boat, but a ship with a mast, for I begin to distinguish the sails.
Mr Barlow walked on a little while by the side of the sea, and presently Tommy called out again: "I protest I was mistaken again; for it is not a vessel with one mast, as I thought a little while ago, but a fine large ship with three great masts, and all her sails before the wind. I believe she must either be a large merchantman or else a frigate."
_Mr Barlow._--Will you then take notice of what you have now been saying? What was first only a little dusky speck became a vessel with one mast, and now this vessel with one mast plainly appears a ship of a very large size, with all her masts and sails, and rigging complete. Yet all these three appearances are only the same object at different distances from your eye.
_Tommy._--Yes, sir; that is all very true indeed.
_Mr Barlow._--Why, then, if the ship, which is now, full in sight, were to tack about again, and sail away from us as fast as she approached just now what do you think would happen?
_Tommy._--It would grow less and less every minute, till it appeared a speck again.
_Mr Barlow._--You said, I think, that the sun was a very small body, not bigger than a round table?
_Tommy._--Yes, sir.
_Mr Barlow._--Supposing, then, the sun were to be removed to a much greater distance than it is now, what would happen? Would it appear the same to your eyes?
Tommy considered some time, and then said, "If the ship grows less and less, till at last it appears a mere speck, by going farther and farther, I should think the sun would do the same."
_Mr Barlow._--There you are perfectly right; therefore, if the sun were to depart farther and farther from us, at last it would appear no bigger than one of those twinkling stars that you see at so great a distance above your head.
_Tommy._--That I perfectly comprehend.
_Mr Barlow._--But if, on the contrary, one of those twinkling stars were to approach nearer and nearer to where you stand, what do think would happen? Would it still appear of the same size?
_Tommy._--No, sir. The ship, as it came nearer to us, appeared every moment larger, and therefore I think the star must do the same.
_Mr Barlow._--Might it not then appear as big as the sun now does, just as the sun would dwindle away to the size of a star, were it to be removed to a still greater distance?
_Tommy._--Indeed I think it might.
_Mr Barlow._--What, then, do you imagine must happen, could the sun approach a great deal nearer to us? Would its size remain the same?
_Tommy._--No; I plainly see that it must appear bigger and bigger the nearer it comes.
_Mr Barlow._--If that is the case, it is not so very certain that the earth we inhabit is bigger than the sun and stars. They are at a very great distance from us; therefore, if anybody could go from the earth towards the sun, how do you think the earth would appear to him as he journeyed on?
_Tommy._--Really I can hardly tell.
_Mr Barlow._--No! Why, is it not the same thing, whether an object goes from you, or you from the object? Is there any difference between the ship sailing away from us, and our walking away from the ship?
_Tommy._--No, sir.
_Mr Barlow._--Did you not say that if the sun could be removed farther from our eyes, it would appear less?
_Tommy._--To be sure it would.
_Mr Barlow._--Why, then, if the earth were to sink down from under our feet, lower and lower, what would happen? Would it have the same appearance?
_Tommy._--No, sir; I think it must appear less and less, like the ship that is sailing away.
_Mr Barlow._--Very right, indeed; but now attend to what I asked you just now. If a person could rise slowly into the air, and mount still higher and higher towards the sun, what would happen?
_Tommy._--Why the same as if the earth were to sink from under us; it would appear less and less.
_Mr Barlow._--Might not the earth then at least appear as small as the sun or moon does?
_Tommy._--I can hardly conceive that, and yet I see it would appear less and less the farther we went.
_Mr Barlow._--Do you remember what happened to you when you left the island of Jamaica?
_Tommy._--Yes, I do. One of the blacks held me upon the deck, and then I looked towards the island, and I thought that it began to move away from the ship, though in reality it was the ship moving away from the land; and then, as the ship continued sailing along the water, the island appeared less and less. First, I lost sight of the trees and houses that stood on the sh.o.r.e; and then I could only see the highest mountains; and then I could scarcely see the mountains themselves; and at last the whole island appeared only like a dark mist above the water; and then the mist itself disappeared, and I could see nothing but a vast extent of water all round, and the sky above.
_Mr Barlow._--And must not this be exactly the case if you could rise up into the air, higher and higher, and look down upon the earth?
_Tommy._--Indeed it must.
_Mr Barlow._--Now, then, you will be able to answer the question I asked you a little while ago: Could a person travel straight forward from the earth to the sun, how would they both appear to him as he went forward?
_Tommy._--The earth would appear less and less as he went from it, and the sun bigger and bigger.
_Mr Barlow._--Why, then, perhaps it would happen at last that the sun appeared bigger than the earth.
_Tommy._--Indeed it might.
_Mr Barlow._--Then you see that you must no longer talk of the earth"s being large and the sun small, since that may only happen because you are nearer the one and at a great distance from the other; at least, you may now be convinced that both the sun and stars must be immensely bigger than you would at first sight guess them to be.
As they were returning home they happened to pa.s.s through a small town on their way, and saw a crowd of people going into a house, which gave Mr Barlow the curiosity to inquire the reason. They were told that there was a wonderful person there who performed a variety of strange and diverting experiments. On Tommy"s expressing a great desire to see these curious exhibitions, Mr Barlow took them both in, and they all seated themselves among the audience.
Presently the performer began his exhibitions, which very much diverted Tommy, and surprised the spectators. At length after a variety of curious tricks upon the cards, the conjuror desired them to observe a large basin of water, with the figure of a little swan floating upon the surface. "Gentlemen," said the man, "I have reserved this curious experiment for the last, because it is the most wonderful of all that I have to show, or that, perhaps, was ever exhibited to the present hour.
You see that swan, it is no more than a little image, without either sense or life. If you have any doubt upon the subject, take it up in your hands and examine it." Accordingly, several of the spectators took it up in their hands, and, after having examined it, set it down upon the water. "Now," continued he, "this swan, which to you appears totally without sense or motion, is of so extraordinary a nature that he knows me, his master, and will follow in any direction that I command." Saying this, he took out a little piece of bread, and whistling to his bird, ordered him to come to the side of the basin to be fed. Immediately, to the great surprise of all the company, the swan turned about and swam to the side of the basin. The man whistled again, and presently the swan turned himself round and pursued the hand of his master to the other side of the basin.