The Scent of Gunpowder on the Knoll
Right after the shots were fired, several witnesses reported smelling gunpowder on or near the grassy knoll. British journalist Anthony Summers:
Three witnesses in the motorcade--the Mayor's wife, Mrs. Cabell, Senator Ralph Yarborough, and Congressman Ray Roberts--all later mentioned the acrid smell in the air. It is highly improbable that any of these people--sweeping past in the motorcade--could have picked up the smell of gunpowder from a sixth-floor window high above them. It is remarkable too that they could have smelled it from the grassy knoll, but it seems it was in that general area that they did notice it. Police Officer Earle Brown, on duty at the railway bridge, and Mrs. Donald Baker, at the other end of the knoll, reported the same distinctive smell. Another policeman, Patrolman Joe Smith, was holding up traffic across the road from the Texas School Book Depository when the motorcade passed by. He heard gunfire, and when a woman cried out, "They're shooting the President from the bushes!" Smith ran to the grassy knoll, the only bushy place in the area. In 1978 he still remembered what he reported shortly after the assassination, that in the parking lot, "around the hedges, there was the smell, the lingering smell of gunpowder." (Summers 29)
http://michaelgriffith1.tripod.com/knoll.htm