occasionally broken windows at a distance of 7 miles southeast of X).

As intended, the bomb was exploded at an almost ideal location over
Nagasaki to do the maximum damage to industry, including the Mitsubishi
Steel and Arms Works, the Mitsubishi-Urakami Ordnance Works (Torpedo
Works), and numerous factories, factory training schools, and other
industrial establishments, with a minimum destruction of dwellings and
consequently, a minimum amount of casualties. Had the bomb been dropped
farther south, the Mitsubishi-Urakami Ordnance Works would not have been so
severely damaged, but the main business and residential districts of
Nagasaki would have sustained much greater damage casualties.

Calculations show that the structural steel and reinforced concrete frames
which survived the blast fairly close to X could not have withstood the
estimated peak pressures developed against the total areas presented by the
sides and roof of the buildings. The survival of these frames is explained
by the fact that they were not actually required to withstand the peak
pressure because the windows were quickly knocked out and roof and siding
stripped off thereby reducing total area and relieving the pressure. While
this saved the building frame, it permitted severe damage to building
interior and contents, and injuries to the building occupants. Buildings
without large panel openings through which the pressure could dissipate
were completely crushed, even when their frames were as strong as those
which survived.

The damage sustained by reinforced concrete buildings depended both on the
proximity to X and the type and strength of the reinforced concrete
construction. Some of the buildings with reinforced concrete frames also
had reinforced concrete walls, ceilings, and partitions, while others had
brick or concrete tile walls covered either with plaster or ornamental