Around 1850, Hermann von Helmholtz measured how fast impulses travel along which body parts?

Around 1840, chemist John William Draper took the first photograph of which heavenly body? Around 1846, Sarah Bagley became the first female operator of which communications device? Around 1850, George Boole devised a new kind of which branch of mathematics, now used in computer logic? Around 1850, which scientist came up with the idea for an absolute temperature scale? In the mid-1800s, which U.S. industry sent out hundreds of ships, many from New Bedford, Massachusetts? Around 1850, Eugène Delacroix painted the central ceiling of the Galerie d'Apollon in which French museum? Around 1862, which American locksmith introduced a dial-operated combination lock for bank vaults? In 1862, which doctor invented a hand-cranked, multi-barrel machine gun?