12. Thermal Rays Leave Human Shadow On Stone Steps / Shadow Of Handrail
The left photograph shows the stone steps of the main entrandce of Sumitomo Bank which is only 250 meters from the hypocenter. It is believed that a person sat down on the steps facing the direction of the hypocenter, possibly waiting for the bank to open. By a flash of the heat rays with temperatures well over a 1,000 degrees or possibly 2,000 degrees centigrade, that person was incineratied on the stone steps.
Up to about 10 years after the explosion, the shadow remained clearly on the stones, but exposure to rain and wind has been gradually blurring it. So, when the bank was newly built, the stone steps were removed and are now preserved at the Hiroshima Peace Memorial Museum.
The right photograph shows the shadow made by the heat rays. This place is about 800 meters from the hypocenter, and the unshielded asphalt surface was scorched, whereas the surface shielded by the handrail appears to be a whitish shadow.
The peculiarity characterizing the heat rays from the A-bomb is that an enormous amount of heat is emitted in a short time -- for 3 seconds after the explosion. The thermal loss by heat conductivity is very little because of the short time, and consequently the surface temperature of a material becomes very high. Within a 1 kilometer radius of the hypocenter, there were many instances where the roof tiles melted and left bubbles.