Wow...I missed this news. As an avid baseball fan growing up, Feller's name became synonomous with "fast ball"....he was the Nolan Ryan...before Nolan Ryan was Nolan Ryan! I don't think they had the technology to measure the exact speed of his fastball at that time, which is unfortunate.
A big loss not only for his family, but also for avid baseball fans.....
Re. measuring the speed of his fastball, I saw a video on how they did it when he first started out. They set up two targets, looked like paper, side by side. One the left was one with a hole in the center he was to aim at, the other a motorcycle rider rode through it. When the bike passed him at full speed, he threw a pitch. The ball actually passed the rider and his aim was perfect as well....went through the hole in the center of his target. His ball speed....it passed the bike that was doing 104. The film taken from the backside shows the ball coming through before the bike hit the paper target. May not have been an exact measurement, but close enough for old admirer.