Drawing by William Thomson (Lord Kelvin) of his water-powered electrostatic generator, now called the Kelvin water dropper. This drawing appears in his original 1867 paper. This original version used funnels at the bottom of the water drops' path to collect the charge on the drops while letting the water fall through, and Leyden jars "(large cylinders)" to store the charge, instead of the pails which are often used in modern versions.