Here is the actual story from the Humeston Iowa newspaper from 1896
A sad accident happened five miles south of town on last Monday morning, resulting in the death of Wm. Coffey. He was assisting at a horse power wood saw, and the belt coming off, he started to stop the power, when the tumbling rod between the power and the jack came apart and one portion struck Mr. Coffey on the back of the head with such force as to knock him several feet and kill him instantly. An inquest was held which gave a verdict in accordance with above facts. Mr. Coffey was esteemed by all who knew him, and his death causes deep regret. He leaves a wife and six children, who have the heartfelt sympathy of all. The funeral services will be held this afternoon at his home.
And here are portions of the same event, fictionalized for Into the Future:
I felt as if I was going to topple over; the effect of a dozen horses in double harness moving in a blur around me as I stood high above them at the center, was causing me to feel dizzy. I crouched down to grab the platform I was standing atop. It was like I was standing in the center of a wagon wheel; the spokes of the wheel were attached to each team of two horses.
I instantly knew what this was. This was how machinery was run at the turn of the century when real horse power was the energy behind saws and threshing machines. I had seen lots of photographs of this process. The circling horses were turning a rod which ran along the ground and was attached to a gear and belts that were, in turn, powering a wood saw. Several men were working at a table nearby, sawing lumber. The wood saw being used was literally a twelve horsepower saw.
“Jake, you need a break?” a man shouted loudly to be heard over the sound of the saw and the horse’s snorts and harnesses rattling....
And another snippet from later in the chapter...
“Whoa, whoa, whoa!” several men shouted and then in the time it took me to turn around; it happened. The belt was coming off the saw and as they tried to stop the horses, the tumbling rod just came apart in pieces and a portion of the rod struck a horse in a rear leg severing the limb at the knee and the horse collapsed screaming in agony and pulling its harness mate to the ground, as well. Both animals thrashed and whinnied in terror as several men came to their aid. Another portion of the rod had flown with such force that it had hit a man standing at the saw in the back of the head knocking him several feet away where he lay on the ground, motionless.
I knew he was dead. I knew he had been killed instantly because I knew, all at once, exactly who he was. I turned back to the wagon and grabbed a shotgun from the bench seat and dashed back to the team of horses.
“Jake, let me. Go see about your father,” the man who had relieved me from the platform duty said.
I handed him the gun and hurried toward the saw and the gathering of men who were crouched around my fallen great-great-grandfather William McFall and I jumped as the shot rang out and the screaming of the maimed horse suddenly came to an abrupt end.