Clear CAB Tubing At Monticello

Published: January 3, 2018
by Charles Busada
The cannonball clock weight system in the Monticello basement before the transparent tubing was installed

One of Monticello’s most memorable features is the Great Clock, designed by Thomas Jefferson and built by Peter Spruck in 1792. It is fully functional today. The clock, with both an interior and exterior face, (and loud chime) dictated the schedule of the entire plantation, inside the building and out.


Thomas Jefferson’s commissioned a great clock for his Virginia plantation. Completed in 1793 in Philadelphia. Jefferson was not very happy about the workmanship: “My great clock could not be made to go by Spruck. I ascribe it to the bungling manner in which he had made it. I was obliged to let him make the striking movement anew on the common plan, after which it went pretty well…”

It was not until 1804, with the clock now in Monticello where Jefferson came upon a problem. His clock was powered by 12, 18lb cannon-ball weights, but his Monticello hall was not tall enough for the weights to fully descend before hitting the floor. Jefferson originally planned on having the weights descend into a box, So, Jefferson simply cut a hole in the floor whereby Friday evenings the balls would descend into the basement where they would spend their Saturdays. Sunday was wind-up day.

See the weights after the butyrate tubing to the right.

So, when Monticello ordered Busada Butyrate tubing last year for the basement clock weights they solved three problems. The tube fits hard against the hole in the Main Hall floor keeping out the cold. And due to its clarity, we folks can not only see the balls as they would descent into Saturday’s position but even see the “Saturday” sign through the tube. Finally, it kept people from touching the balls of this valuable museum piece. Now we know what day of the week it is.

The display tube protecting the cannonball clock weights installed in Monticello.

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