wastage of efficiency, is such as to demand for the full realization of that power targets in which the enemy's basic strength is comparably concentrated. Thus, the city is a made-to-—-order target, and the cegree of urbanization of a country furnishes a rough index of its relative vulnerability to the atomic bomb. And since a Single properly-aimed bomb can destroy a city of 100,000 about as effectively as it can one of 25,000, it is obviously an advantage to the attacker if the units of 25,000 are combined into units of 100,000. Moreover, a city is after all a fairly integrated commmity in terms of vital services and transportation. If half to two-thirds of its area is obliterated, one may count on it that the rest of the city will, under prevailing conditions, be effectively prostrated, . . fe _ Thus, the more the population and intustry:of a state are concentrated into urban areas and the larger individuelty YapgeoAncentration become, the fewer are the atomic bombs necessary to effect their destruction, In 1940 there were in the United States five cities with 1,000, 00¢ or more inhabitants (one of which, Los Angeles, is spread out over more than 400 square miles}, nine cities between 500,000 and 1,000,000, iventy-—three cities between 250,000 and 500,000, fifty-five between 100,000 and 250,000 and one hundred and seven between 50,000 and 100,000 ponulation. Thus, there were ninety-two cities with a population of 100,000 and over, and these contained approximately 29 per cent of our total population. Ole Reaching down to the level of 50,000 or more, the In this respect the atomic bomb differs markedly from the TNT bomb, due to the much smaller radius of destruction of. the latter. The amount of destruction the THT bomb accomplishes depends not on what is in the general locality but on what is in the immediate proximity of the burst. A factory of given size requires a given number of bombs to destroy it regardless of the size of the city in which it is situated. To be sure, the "misses" count for more in a large city, but from the point of view of the defender there are certain compensating advantages in having the objects to be defended gathered in large concentrations, It makes a good aeal easier the effective deployment of fighter patrols and antiaircraft guns. But the latter advantage does not count for much in the case of atomic bombs, since, as argued in the previous chapter, it is practically hopeless to expect fighter planes ans antiaircraft guns to stop atomic bomb attack so com pletely as to save the city. .