A prelude to Ether Day 1846: Charles F Heywood's letter to William TG Morton.

On 14 October 1846, Charles F Heywood, house-surgeon at the Massachusetts General Hospital, Boston, MA, USA, penned an invitation to the dentist William TG Morton to demonstrate his preparation to prevent pain during a surgical operation at the Hospital on 16 October 1846. The operation would become the first public operation performed with the aid of insensibility produced by the inhalation of sulphuric ether. From Boston, news of the discovery spread around the world-the date of this momentous operation is now celebrated as Ether Day. Although Heywood's letter is well-known from 19th century transcripts, it is apparent from examining a letter believed to be the original, now preserved in the WTG Morton papers held by the Massachusetts Historical Society, Boston, MA, USA, that these transcripts were edited before publication. A faithful transcript of Heywood's letter is published along with two images of the historic letter.