As often happens in science, radioactivity came close to being discovered nearly four decades earlier in 1857, when Abel Niepce de Saint-Victor, who was investigating photography under Michel Eugène Chevreul, observed that uranium salts emitted radiation that could darken photographic emulsions.
Henri Matisse | Henri de la Tour d'Auvergne, Vicomte de Turenne | Bernard-Henri Lévy | Henri Dutilleux | Paul-Henri Mathieu | Henri Poincaré | Robert Henri | Henri Mignet | Henri Cartier-Bresson | Henri Fayol | Henri Bendel | Henri Barbusse | Jean-Henri Fabre | Henri-Pierre Roché | Henri Langlois | Henri, Grand Duke of Luxembourg | Henri Fantin-Latour | Paul-Henri Spaak | Jacques-Henri Bernardin de Saint-Pierre | Henri Wallon | Henri Vieuxtemps | Henri Vernes | Henri Salvador | Henri Pousseur | Henri Michaux | Henri Guillaumet | Henri Estienne | Lycée Henri-IV | Henri Tajfel | Henri Sauguet |
Brachytherapy dates back to 1901 (shortly after the discovery of radioactivity by Henri Becquerel in 1896) when Pierre Curie suggested to Henri-Alexandre Danlos that a radioactive source could be inserted into a tumour.