Dr. Joseph Clover (1825-1882), an English physician, first described his Portable Regulating Ether Inhaler on Jan. 20, 1877. Clover was an especially sought after anesthesiologist and early pioneer in the specialty. This was the best-known of many inhalers that Clover designed. The dome-shaped reservoir was turned to points on a control dial to gradually increase or decrease the percentage of the air that passed over the ether. Several inventors based new inhalers on this, while the original continued to be manufactured as late as the beginning of WWII. Clover, to spare the patient the unpleasantness of induction with his "closed" inhaler (1877), suggested the "mitigated-ether" technique. The inhaler was fitted with a bypass tap for the reception of N2O. The bag was filled with the gas and anaesthesia was inducted a combination of N2O and asphyxiation. Ether was then admitted gradually by rotation of the bowl of the inhaler. When the patient had been duly "weaned over" to ether, the mask was lifted, the N2O allowed to escape, the bag refilled with exhaled air, and normal anaesthesia "a la Clover's inhaler" was continued.Metal domed chamber with a bulb attachment for rebreather bag, including a tap mechanism. Remnants of the paper rebreather bag are attached to the bulb. At the other end is a yellow facemask made of plastic (probably celluloid). The manufacturer's logo has been moulded into the dome of the chamber.Manufacturer's logo: THE HOLBORN / SURGICAL INSTRUMENT CO. LTD. / LONDON •Blue sticker with white writing: O.2.4.joseph clover, mitigated-ether, nitrous oxide, n2o, closed method