Ether was one of the earliest anaesthetics. but it had some drawback for example,
it could cause vomiting.
It quickly replaced by chloroform.
which more potent and easier to use than ether.
However, it was not safe to use as ether, and could cause sudden death.
By the 1920s. intravenous induction agents were introduced. They enabled patients to fall asleep quickly pleasantly. In the 1940s muscle relaxants became available.