oat, 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 de