1804 births

Antoine Hercule Romuald Florence (February 29, 1804 – March 27, 1879) was a Monegasque-Brazilian painter and inventor, known as the isolate inventor of photography in Brazil, three years before Daguerre (but six years after Nicéphore Niépce), using the matrix negative/positive, still in use. According to Kossoy, who examined Florence's notes, he referred to his process, in French, as photographie in 1834, at least four years before John Herschel coined the English word photography.

Pierre François Verhulst (28 October 1804, in Brussels – 15 February 1849, in Brussels) was a Belgian mathematician and a doctor in number theory from the University of Ghent in 1825. He is best known for the logistic growth model.

Charles-Emmanuel Sédillot (18 September 1804 – 29 January 1883) was a French military physician and surgeon. He was the son of orientalist Jean Jacques Emmanuel Sédillot (1777–1832), and an older brother to historian Louis-Pierre-Eugène Sédillot.
Born in Paris, he studied surgery under Alexis Boyer and Philibert Joseph Roux. In 1836 he became professor of operative surgery at Val-de-Grâce, followed by a professorship at Strasbourg five years later.Sedillot was a pioneer of urethrotomic and gastrointestinal operations, and known for his work with dislocations and his treatment of pyaemia. He is credited with coining the term "microbe" (from micros "small" and bios "life").

Jean-Henri Magne (15 July 1804, Sauveterre-de-Rouergue – 27 August 1885) was a French veterinarian.

During his career, he worked as a professor at the École royale vétérinaire de Lyon and at the École nationale vétérinaire d'Alfort, where from 1846, he served as director.In 1836 he became a member of the Société linnéenne de Lyon, serving as its president in 1841/42. He was also a member of the Académie d'agriculture de France and the Académie vétérinaire de France, being chosen as its president in 1855.

Louis Francisque Lélut (1804–1877) was a French medical doctor and philosopher known for his works Démon de Socrate and L'Amulette de Pascal, where he stated that Socrates and Blaise Pascal were insane.
Born at Gy, a small village in the Haute-Saône department, he was member of the Academy of Moral and Political Sciences and researched mental illnesses and phrenology. His main work was Physiologie de la pensée, published in 1861.
During the Second French Empire he was member of the Legislative Body.

Pierre Charles Huguier (4 September 1804 – 12 January 1873) was a French surgeon and gynecologist born in Sézanne.In 1834 he received his medical doctorate at Paris, and was later a surgeon at the Hôpital Beaujon. In 1835 he became an associate professor of the faculty of medicine at Paris.Huguier is remembered for his pioneer work with genitourinary diseases such as lymphogranuloma venereum and uterine fibroma, with the latter disorder being formerly referred to as "Huguier's disease". He provided an early description of the anastomosis around the isthmus of the uterus, which is sometimes referred to as "Huguier's circle". His name is also lent to two anatomical structures associated with the ear:

"Huguier's canal", or the "anterior canaliculus of chorda tympani": A canal at the medial end of the petrotympanic fissure, through which the chorda tympani nerve exits the tympanic cavity. Also known as the "canal of Huguier", or "iter chordae anterius".
"Huguier's sinus": or the "fossula fenestrae vestibuli": A depression on the medial wall of the middle ear which has the vestibular window in its lower portion. Also called the little fossa of the vestibular window.He is also credited with development of a specialized hysterometer (uterine sound).

Louis François Clément Breguet (22 December 1804 – 27 October 1883), was a French physicist and watchmaker, noted for his work in the early days of telegraphy.
Educated in Switzerland, Breguet was the grandson of Abraham-Louis Breguet, founder of the watch manufacturing company Breguet. He became manager of Breguet et Fils watchmakers in 1833 after his father Louis Antoine Breguet retired.
Between 1835 and 1840 he standardized the company product line of watches, then making 350 watches per year, and diversified into scientific instruments, electrical devices, recording instruments, an electric thermometer, telegraph instruments and electrically synchronized clocks. With Alphonse Foy, in 1842 he developed the Foy-Breguet telegraph, an electrical needle telegraph to replace the optical telegraph system then in use. and a later step-by-step telegraph system (1847) was applied to French railways and exported to Japan. He observed in 1847 that small wires could be used to protect telegraph installations from lightning, the ancestor of the fuse.
In 1850 he manufactured a rotating mirror used by Hippolyte Fizeau to measure the relative speed of light in air and water.: 129  In 1856 he designed a public network of synchronized electric clocks for the center of Lyon. In 1866 he patented an electric clock controlled by a 100 Hz tuning fork.In 1870 he transferred the leadership of the company to Edward Brown. Breguet then focused entirely on the telegraph and the nascent field of telecommunications. He collaborated in the development of an induction coil, later improved by Heinrich Ruhmkorff.
In terms of honors, in 1843 he was appointed to the Bureau of Longitudes. In 1845 Breguet was awarded the Legion d'Honneur. He was made a member of the French Academy of Sciences in 1874, and was elevated to Officer of the Legion d'Honneur in 1877. He is one of the 72 French scientists whose names are written around the base of the Eiffel Tower.Breguet was married and had one son Antoine (1851–1882) who also joined the family electrical business. With his son, he met Alexander Graham Bell and obtained a license to manufacture Bell telephones for the French market. He was the grandfather of Louis Charles Breguet and the uncle of Sophie Berthelot.

Adrien Dauzats (16 July 1804 – 18 February 1868) was a French landscape, genre painter and painter of Oriental subject matter. He travelled extensively throughout the Middle East and illustrated a number of books for the travel writer, Baron Taylor.

Élie Frédéric Forey (10 January 1804 – 20 June 1872) was a Marshal of France.

Pierre-Marie-Charles de Bernard du Grail de la Villette (24 February 1804 – 6 March 1850), better known simply as Charles de Bernard, was a French writer.