Gwathmey developed this apparatus while with the American Red Cross. It has yokes for two cylinders of nitrous oxide and one of oxygen. It is controlled by a needle valve and tubes take gases to the bottle cap.
Geoffrey Marshall developed an anaesthetic apparatus based on a machine designed by Gwathmey. It gave gas, oxygen and ether and had flowmeters. It became the standard model in Royal Army Medical Corps practice.
This is Boyle’s original nitrous oxide/oxygen/ether apparatus which closely resembled those of Gwathmey and Marshall. British gas cylinders would not easily fit Gwathmey’s apparatus and so Boyle modified it to produce this machine.