By Gordon Rugg
This is a Tempest Prognosticator.
“Tempest Prognosticator” by Badobadop – Own work. Licensed under CC BY-SA 4.0 via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Tempest_Prognosticator.jpg#/media/File:Tempest_Prognosticator.jpg
It’s a splendid example of nineteenth century ingenuity, right down to the name. What does it do? It’s intended to let you know if a storm is approaching. The way it does this is as wonderfully nineteenth century as the name. The Prognosticator is operated by twelve leeches, each of which lives in a bottle. When storms are approaching, the leeches become agitated, and climb out of the bottle. When they climb out, they disturb a piece of whalebone, which activates a bell. The more serious the risk of storm, the more leeches climb out, and the more bells ring.