is twenty billions of miles.  So I am now going to ask your attention to the simple question as to the fare which it would be reasonable to charge for the journey.  We shall choose a very cheap scale on which to compute the price of a ticket.  The parliamentary rate here is, I believe, a penny for every mile.  We will make our interstellar railway fares much less even than this; we shall arrange to travel at the rate of one hundred miles for every penny.  That, surely, is moderate enough.  If the charges were so low that the journey from London to Edinburgh only cost fourpence, then even the most unreasonable passenger would be surely contented.  On these terms how much do you think the fare from London to this star ought to be?  I know of one way in which to make our answer intelligible.  There is a National Debt with which your fathers are, unhappily, only too well acquainted; you will know quite enough about it yourselves in those days when you have to pay income tax.  This debt is so vast that the interest upon it is about sixty thousand pounds a day, the whole amount of the National Debt being six hundred and thirty-eight millions of pounds.

If you went to the booking-office with the whole of this mighty sum in your pocket—­but stop a moment; could you carry it in your pocket?  Certainly not, if it were in sovereigns.  You would find that after you had as many sovereigns as you could conveniently carry there would still be some left—­so many, indeed, that it would be necessary to get a cart to help you on with the rest.  When the cart had as great a load of sovereigns as the horse could draw there would be still some more, and you would have to get another cart; but ten carts, twenty carts, fifty carts, would not be enough.  You would want five thousand of these before you would be able to move off towards the station with your money.  When you did get there and asked for a ticket at the rate of one hundred miles for a penny, do you think you would get any change?  No doubt some little time would be required to count the money, but when it was counted the clerk would tell you that there was not enough—­that he must have nearly two hundred millions of pounds more.

That will give some notion of the distance of the nearest star, and we may multiply it by ten, by one hundred, and even by one thousand, and still not attain to the distance of some of the more remote stars that the telescope shows us.

On account of the immense distances of the stars we can only perceive them to be mere points of light.  We can never see a star to be a globe with marks on it like the moon, or like one of the planets—­in fact, the better the telescope the smaller does the star seem, though, of course, its brightness is increased with every addition to the light-grasping power of the instrument.

The Brightness and Color of Stars.