Back bar for Boyle's type anaesthetic machine with vaporisers for ether and trilene, flowmeters for oxygen, cyclopropane and nitrous oxide and rebreathing bag, by the British Oxygen Company, Ltd., London, 1941-1963

This is the back bar for a Boyle's-type anaesthetic machine. It has vaporisers for the anaesthetics ether and trilene, and flow meters for oxygen, cyclopropane and nitrous oxide – the last two are also anaesthetics – and a re-breathing bag.

The basis of the modern anaesthetic machine was pioneered by Henry Gaskin Boyle (1875-1941), an anaesthetist. The original machine from 1917 was carried around in a wooden box and used ether and nitrous oxide.