Levels 4 and 3 are designed on the same principle as Level 5. They have similar equipment and they are to house important people—though not so important as the élite of Level 5. The higher the level, once you get above the military units, the lower the social status of its prospective inhabitants.
Level 4 is sub-divided into ten independent and self-sufficient units, each holding 10,000 people. They are dispersed throughout the country, about 1,000 feet deep, and their food and energy supplies are planned to last about a century.
Level 3 is higher, about 500 feet deep, and has twenty-five units which will contain 20,000 persons each. So it will shelter in all half a million people. It has enough food and energy for about twenty-five years only.
The construction of Level 3 was in a way a harder task than that of Levels 4 and 5, simply because of the size of the units. Each must contain everything necessary for the life of 20,000 people, and though they will be more crowded and less convenient to live in than the units of Levels 4 and 5, not to mention Levels 6 and 7, the sheer magnitude of the building operation gave the designers some severe headaches.
Incidentally, the analogy of a ship was used by today’s speaker, though rather differently from the way I used it. Levels 5, 4 and 3 correspond, according to him, to the first, second and third classes on a boat. Each is bigger than the preceding one and accommodates more passengers; and it is not quite as comfortable or well equipped.
I am sure the speaker was understating the facts. If he had to use a naval analogy, it would have been nearer the mark to compare Level 5 to the cheapest third-class berths, Level 4 to the deck of an immigrant ship, and Level 3 to the hold of a cattle boat or one of those hulks sailed by the old slave-traders. To start with first class was ridiculous. Even we. Level 7 personnel are no more comfortable, by and large, than tourist-class passengers on a not very luxurious ship.
Besides, the analogy breaks down, as most analogies seem to below ground, unless you turn one half of it on its head. Whoever heard of a ship with the very best cabins at the bottom of the hold?