IlUTIAL REPCRT BY SIR JAMES CHADWICK The implosion gadget containing 6 kg of 49 was fired this morning at 5 30 a m Mountain War Time The test appears to have been completely successful There is no doubt that the nuclear reaction took place but so far I have no experimental estimate of the efficiency of the reaction The bal 1 of fire was intensely bright equivalent to several suns by general estimate so that it seems reasonably certain that the explosion was equivalent to more than 1000 tons of T N T and possibly several thousand This I call completely successful It was a wonderful even fantastic e xperience which I shall not attempt to describe now as I am rather tired and should get things in wrong proportion I am sending you this news through General Groves who has kindly offered to convey it to you He is le ving immediately for Washington while I am staying on for a day or so I hope in an hour or t M to get ft rough estirna te of the amount of the explosion A provisional and very rough estimate now is that the explosion was equivalent to about 10 000 to 15 000 tons of T N T It is nlikely that any publicity will arise The event is being explained as the unforeseen explosion of an anmunition magazine on the air base either to persons or to property July 16th 1945 There was no damage