rise.  During this motion the gadget went off while I was looking at it or possibly a small fraction of a second before.  What I saw first was a brilliant violet glow entering my eyes by reflection from the ground and from the surroundings generally.  I had not raised my head quite enough to provide a clear vision of Zero.  Immediately after this brilliant violet flash, which was somewhat blinding, I observed through the welding glass, centered at the direction of the tower an enormous and brilliant disk of white light.  The sensation lasted for such a short time and the light was so great that I cannot be sure of the shape observed.  I remember it only as a well-marked vaguely round pattern.  This disk was a true white in color, even through the welding glass which makes the sun's disk distinctly deep green.  On subsequently looking at the noon sun through these glasses I have been led to estimate this initial stage of the gadget as corresponding to a color much whiter or bluer and a brightness