August 6 is also an important date in world history: the fateful day on which the first atomic bomb was dropped on Hiroshima in Japan. On that day, a Monday, at 8.15 in the morning, an American B-29 bomber, Enola Gay, dropped its bomb “Little Boy”, which fell to a predetermined detonation height of about 1,900 feet above the city. It exploded with a blinding flash, creating a giant fireball, which vaporised practically everything and everyone within a radius of about a mile of the point of impact. It is estimated that up to 80,000 people were directly killed by the blast, and by the end of the year, that figure had climbed considerably higher, due to injuries and the effects of radiation. Over two thirds of the city’s buildings were completely destroyed.

But in the midst of this terrible carnage, something quite remarkable happened: there was a small community of Jesuit Fathers living in a presbytery near the parish church, which was situated less than a mile away from detonation point, well within the radius of total devastation. And all eight members of this community escaped virtually unscathed from the effects of the bomb. Their presbytery remained standing, while the buildings all around, virtually as far as the eye could see, were flattened.

Fr Hubert Schiffer, a German Jesuit, was one of these survivors, aged 30 at the time of the explosion, and who lived to the age of 63 in good health. In later years he travelled to speak of his experience, and this is his testimony as recorded in 1976, when all eight of the Jesuits were still alive. On August 6 1945, after saying Mass, he had just sat down to breakfast when there was a bright flash of light.

Since Hiroshima had military facilities, he assumed there must have been some sort of explosion at the harbour, but almost immediately he recounted: “A terrific explosion filled the air with one bursting thunderstroke. An invisible force lifted me from the chair, hurled me through the air, shook me, battered me [and] whirled me round and round…” He raised himself from the ground and looked around, but could see nothing in any direction. Everything had been devastated.

He had a few quite minor injuries, but nothing serious, and indeed later examinations at the hands of American army doctors and scientists showed that neither he nor his companions had suffered ill-effects from radiation damage or the bomb. Along with his fellow Jesuits, Fr Schiffer believed “that we survived because we were living the message of Fatima. We lived and prayed the rosary daily in that home.”

via The priests who survived the atomic bomb | CatholicHerald.co.uk.

Dr. Stephen Rinehart of the U.S. Department of Defense is widely recognised as an international expert in the field of atomic blasts. Says Rinehart: “A quick calculation shows that at one kilometre the bulk temperature was in excess of 20,000 to 30,000 degrees Fahrenheit, and the blast wave would have hit at sonic velocity with pressures on buildings greater than 600 psi [pounds per square inch]. If the Jesuits, at one kilometre from the geometric epicentre, were outside the atomic bomb’s plasma their residence should still have been utterly destroyed. Unreinforced masonry or brick walls, representative of commercial construction, are destroyed at three psi, which will also cause ear damage and burst windows. At ten psi, a human will experience severe lung and heart damage together with burst eardrums and at 20 psi your limbs can be blown off. Your head will be blown off by 40 psi and no human would be alive because your skull would be crushed. All the cotton clothes would be on fire at 350 Fahrenheit, and your lungs would be inoperative within a minute of breathing even one lungful of air at these temperatures.
No way could any human have survived – nor should anything have been left standing at one kilometre. At ten times the distance, about ten to fifteen kilometres, I saw the brick walls standing from an elementary school and I think there were a few badly burned survivors; all died within fifteen years of some form of cancer.
http://www.fatima.org.au/showarticle.php?ArticleTitle=The%20amazing%20story%20of%20the%20Hiroshima%20Eight

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