depth to which this temperature
occurred and helped to determine the average ground temperatures in the
instant following the explosion. This effect was noted for distances
about 1 1/2 times as great in Nagasaki as in Hiroshima.

The second remarkable effect was the bubbling of roof tile. The size
of the bubbles and their extent was proportional to their nearness to
the center of explosion and also depended on how squarely the tile
itself was faced toward the explosion. The distance ratio of this
effect between Nagasaki and Hiroshima was about the same as for the
flaking of polished granite.

Various other effects of the radiated heat were noted, including the
lightening of asphalt road surfaces in spots which had not been
protected from the radiated heat by any object such as that of a person
walking along the road. Various other surfaces were discolored in
different ways by the radiated heat.

As has already been mentioned the fact that radiant heat traveled only
in straight lines from the center of explosion enabled observers to
determine the direction toward the center of explosion from a number of
different points, by observing the "shadows" which were cast by
intervening objects where they shielded the otherwise exposed surface
of some object. Thus the center of explosion was located with
considerable accuracy. In a number of cases these "shadows" also gave
an indication of the height of burst of the bomb and occasionally a
distinct penumbra was found which enabled observers to calculate the
diameter of the ball of fire at the instant it was exerting the maximum
charring or burning effect.

One more interesting feature connected with heat radiation was the
charring of fabric to different degrees depending upon the color of the
fabric. A number of instances were recorded in which persons wearing
clothing of various colors received burns greatly varying in degree,
the degree of burn depending upon the color of the fabric over the skin
in question. For example a shirt of alternate light and dark gray
stripes, each about 1/8 of an inch wide, had the dark stripes
completely burned out but the light stripes were undamaged; and a piece
of Japanese paper exposed nearly 1 1/2 miles from X had the characters
which were written in black ink neatly burned out.

CHARACTERISTICS OF THE INJURIES TO PERSONS

Injuries to persons resulting from the atomic explosions were of the
following types:

A. Burns, f