William Brooke O'Shaughnessy (1809-1889), Irish physician. O'Shaughnessy is best known for introducing the therapeutic use of cannabis to Western medicine. He was introduced to medicinal uses for cannabis while working in Calcutta, India, for the British East India Company. He undertook safety trials in animals and the first clinical trials of cannabis for a wide number of conditions. Publication of his results led to great interest in the medicinal use of cannabis. While in India O'Shaughnessy installed the country's first telegraph system of his own design.