Sir William Brooke O'Shaughnessy (from 1861 as William O'Shaughnessy Brooke) MD FRS (October 1809, in Limerick, Ireland – 8 January 1889, in Southsea, England) was an Irish physician famous for his wide-ranging scientific work in pharmacology, chemistry, and inventions related to telegraphy and its use in India. His medical research led to the development of intravenous therapy and introduced the therapeutic use of Cannabis sativa to Western medicine. Early life O'Shaughnessy was born at Limerick in 1809 to Daniel O'Shaughnessy and Sarah Boswell. His mother was a Protestant and many in the family were clergymen. An uncle of his was the Dean of Ennis and a great uncle the Roman Catholic Bishop of Killaloe. William studied briefly at Trinity College, Dublin matriculating in 1825 but moved to Scotland before graduating. O'Shaughnessy studied forensic toxicology and chemistry in Scotland, and graduated in 1829 with an MD from the University of Edinburgh Medical School. In 1829 he was a clinical assistant of William Alison. In 1831, at the age of 22, as a result of his analysis of the blood of cholera victims, O'Shaughnessy laid the foundation, along with Thomas Aitchison Latta, for what was to become intravenous fluid and electrolyte-replacement therapy in the treatment of cholera. O'Shaughnessy analyzed the urine and blood of cholera patients and came to the conclusion that oxygen in the blood could reverse the actions. He found the blood deficient in water, salt, and "free alkali" and suggested that injecting salts would help. The method used by O'Shaughnessy on a dog and was developed further by Latta. O'Shaughnessy failed to obtain a position Professor of Medical Jurisprudence in the University of London and his first marriage forced him to join the service of the British East India Company on 8 August 1833 and he moved to Calcutta, remaining in India and serving initially at Gyah and Cuttack before joining the 72nd Bengal Native Infantry. He joined the 10th Regiment Bengal Light Cavalry in 1835 and was an assistant to the Opium Agent in Bihar till 5 August 1835 when he became Professor of the medical college in Calcutta. He served on the committee of the Materia Medica until 1840 and later was Chemical Examiner to the government. As chemical examiner he developed methods for forensic studies for detecting arsenic poisoning as well as botanical toxins (such as from Plumbago used as an abortifacient). He went on furlough