" April 27: The Adams arrived with six townspeople at sunrise. We set stringers and put the kingposts in place. We have made a fine bridge. Father put a brush atop the posts and we all sing and drank.* Sarah brought a cake. One man fell into the brook but he was not hurt. We knocked down the old bridge, which made me a little sad.
28: Without yet a floor in the new bridge, we could not yet proceed over it to Sunday Meeting so held services at home."
"Another ancient custom is seen in Izaak's 'putting a brush on top' of the new structure. Even nowadays you will see workmen put a small tree or brush on the top of a new roof when it has been completed. That ceremony always calls for a round of drinks for the builders,* and although we don't seem to know why we do it, we say 'just to give the house luck.' That tree tacked atop a new building goes all the way back to Druid lore when men worshipped trees!"
* Maybe rum distilled from molasses brought from the West Indies in a Bartram-Captained ship?
"If you will look at the drawing of the bridge-raising, you can see how the timbers were put in place and raised into a permanent truss, first with the help of Daniel the ox, and then with the help of the Adams family and other neighbors. You may also see how the slanted beams tend to push against each other as 'compression pieces' and lift the kingpost..."
I speculate that it was about at this stage of the construction of Henry's bridge that the accident took place. What usually happens with industrial accidents is that some component or piece of equipment fails with fatal consequences, in this case maybe a rope broke or a prop slipped or maybe he didn't have enough manpower. Remember in his diary entry for the day before the accident he said they were raising the braces and complained that the work was going slow "..for want of help..." ?
I had a similar experience back in 1955 when I was Division Superintendant for a natural gas pipeline company. Five of my guys were killed in a pipeline explosion caused by the failure of a specially-manufactured coupling. Telling wives that they are widows is very tough duty.