It is the Lord Kelvin’s Water Dropper aka Lord Kelvin’s Thunderstorm, invented in the 1860s by William Thomson, 1st Baron Kelvin, the same fellow for whom the Kelvin temperature scale is named.

Shan writes - Sir William Thomson (Lord Kelvin 1824 - 1907) was appointed to the position of Chair of Natural Philosophy (the subject we now call Physics) in 1846. He remained at the University of ...

Lord Kelvin’s name comes up anytime you start looking at the history of science and technology. In addition to working on transatlantic cables and thermodynamics, he also built an early ...