Giovanni Battista Guglielmini

If he was a relative of the famous engineer and physician, Domenico Guglielmini, who had been general superintendent of the Bologna waterworks a hundred years before, he was certainly not his direct descendant.

In 1789 Guglielmini published his first treatise, Riflessioni sopra un nuovo esperimento in prova del diurno moto della terra (Reflections on a new experiment to prove the daily motion of the Earth).

Sixteen balls were dropped from a height of 241 feet, between June and September, 1791, and the plumb-line fixed in February, 1792, all during the night, to minimize the effects of road traffic.

[2] In spite of their agreement both observation and calculation were defective, the plumb-line having been determined half a year later, and the theory of motion relative to the moving earth being as yet undeveloped.

Guglielmini's experimental skill and laborious precautions, however, served his followers, Johann Friedrich Benzenberg (1802 and 1804) and Ferdinand Reich (1831), as models, and the inner agreement of his results was never surpassed.