adduced in this and the previous paper, to expect that
the available area for even the common daily toilers of the great city
of the year 2000, or earlier, will have a radius very much larger even
than that? Now, a circle with a radius of thirty miles gives an area of
over 2800 square miles, which is almost a quarter that of Belgium. But
thirty miles is only a very moderate estimate of speed, and the reader
of the former paper will agree, I think, that the available area for the
social equivalent of the favoured season-ticket holders of to-day will
have a radius of over one hundred miles, and be almost equal to the area
of Ireland.[17] The radius that will sweep the area available for such
as now live in the outer suburbs will include a still vaster area.
Indeed, it is not too much to say that the London citizen of the year
2000 A.D. may have a choice of nearly all England and Wales south of
Nottingham and east of Exeter as his suburb, and that the vast stretch
of country from Washington to Albany will be all of it "available" to
the active citizen of New York and Philadelphia before that date.

This does not for a moment imply that cities of the density of our
existing great cities will spread to these limits. Even if we were to
suppose the increase of the populations of the great cities to go on at
its present rate, this enormous extension of available area would still
mean a great possibility of diffusion. But though most great cities are
probably still very far from their maxima, though the network of feeding
railways has still to spread over Africa and China, and though huge
areas are still imperfectly productive for want of a cultivating
population, yet it is well to remember that for each great city, quite
irrespective of its available spaces, a maximum of population is fixed.
Each great city is sustained finally by the trade and production of a
certain proportion of the world's surface--by the area it commands
commercially. The great city cannot grow, except as a result of some
quite morbid and transitory process--to be cured at last by famine and
disorder--beyond the limit the commercial capacity of that commanded
area prescribes. Long before the population of this city, with its inner
circle a third of the area of Belgium, rose towards the old-fashioned
city density, this restriction would come in. Even if we allowed for
considerable increase in the production of food stuffs in the future, it
still remains inev