January 22 – At 9:30 in the evening, the Vigarano Meteorite splits as it falls to Earth in Italy at the locality of the same name, near Emilia. Weighing 11.5 kg (or 25 lb.), the stone that is recovered is the first of the CV chondrites named for the location. CV chondrites are described as the oldest rocks in the solar system.[2] The other piece of the meteorite, weighing 4.5 kilograms (9.9 lb), is found a month later.
April 10 – Halley's Comet becomes visible with the naked eye (perihelion: April 20);[3] Earth passes through its tail about May 19[4] (its next visit will be in 1986).
Hoechst AG market Arsphenamine under the trade nameSalvarsan, the first organic antisyphilitic, its properties having been discovered the previous fall by bacteriologist Sahachiro Hata during systematic testing in the laboratory of Paul Ehrlich; it rapidly becomes the world's most widely prescribed drug.[7]
Frederick Soddy shows that the radioelements mesothorium (later shown to be 228Ra), radium (226Ra, the longest-lived isotope), and thorium X (224Ra) are impossible to separate, leading to the identification of isotopes.[9]
February 3 – The first pyloromyotomy, a surgery to correct the congenital narrowing (in infants) of the path between the stomach and the intestines (pyloric stenosis) is performed in Edinburgh by Sir Harold Stiles; however, the procedure is named for Dr. Wilhelm Ramstedt, who performs the surgery in 1911.[11]
March 20 – The first clinic for treatment of occupational diseases is opened in Milan (Italy). (The first in the United States will be established in 1915.)[12]
May 18 – At the annual meeting of the American Association for the Study of the Feeble-Minded, Henry H. Goddard introduces a system for classifying individuals with mental retardation based on intelligence quotient (IQ): moron for those with an IQ of 51–70, imbecile for those with an IQ of 26–50, and idiot for those with an IQ of 0-25.
October (approx.) – Approximate date of origin of Manchurian plague, a form of pneumonic plague which by December is spreading through northeastern China, killing more than 40,000.[14][15][16]
January 12–13 – Lee De Forest conducts an experimental broadcast of part of a live performance of Tosca and, the next day, a performance with the participation of the Italian tenor Enrico Caruso from the stage of Metropolitan Opera House in New York City.[23][24]
February 25 – Thomas Edison's "trolleyless street car", powered by storage batteries rather than by overhead electric wires, is publicly demonstrated on New York City's 29th Street horse car tracks.[26]
^Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 2007-03-15.
^Ridpath, Ian (1985). "Through the comet's tail". Revised extracts from "A Comet Called Halley", published by Cambridge University Press in 1985. Retrieved 2011-06-19.
^Fahn, S. (2008). "The history of dopamine and levodopa in the treatment of Parkinson's disease". Movement Disorders. 23 Suppl 3: S497–508. doi:10.1002/mds.22028. PMID18781671. S2CID45572523.
^Bax, N. M. A.; et al. (2008). Endoscopic Surgery in Infants and Children. Springer. p. 281.
^Fielding, H. Garrison (1917). An Introduction to the History of Medicine: With Medical Chronology, Suggestions for Study and Bibliographic Data. W.B. Saunders Co. p. 775.
^Berchtold, N. C.; Cotman, C. W. (1998). "Evolution in the conceptualization of dementia and Alzheimer's disease: Greco-Roman period to the 1960s". Neurobiology of Aging. 19 (3): 173–89. doi:10.1016/S0197-4580(98)00052-9. PMID9661992. S2CID24808582.
^Jacobaeus, Hans Christian (1911). "The Possibilities for Performing Cystoscopy in Examinations of Serous Cavities". Münchner Medizinischen Wochenschrift.
^Hatzinger, Martin; et al. (4 December 2006). "Hans Christian Jacobaeus: Inventor of Human Laparoscopy and Thoracoscopy". Journal of Endourology. 20 (11): 848–850. doi:10.1089/end.2006.20.848. PMID17144849.
