THE LENGTH OF OUR VOYAGE
if he had lived he might, perhaps, have been an even greater man than Newton.
We see that our Voyage in Space will take us over big distances; 240,000 miles to the Moon, and 93 million miles to the Sun. It hardly seems worth while in starting to bother about the first few miles. But perhaps you have noticed, when you have taken
a railway journey, what a long time it takes to get out of the station; or if you take a voyage on a ship, what a business it is getting out of dock. Afterwards when the ship has started the voyage becomes rather uneventful; but at any rate the first bit is not uneventful. So I think for a few moments we might think about the air through which we must first ascend, and which corresponds to the dock from which we start for a sea voyage.
There is one property of the air that seems very