The Eagle returned with her consort and her prize to Plymouth, and soon afterwards Cook's connection with her came to an end. According to Dr. Kippis, Mr. Walker had interested the Member for Scarborough, Mr. Osbaldiston, on the subject of Cook's promotion, but the rule was that candidates for Lieutenancy must have been employed on board a king's ship for a period of not less than six years, and an order had recently been issued that this regulation was to be strictly adhered to. Captain Pallisser therefore wrote to Mr. Osbaldiston that Cook: "had been too short a time in the service for a commission, but that a Master's warrant might be given him, by which he would be raised to a station that he was well qualified to discharge with ability and credit." The result of this correspondence is shown in the Eagle's muster roll, for on 27th June James Cook attended his last muster, and on the 30th he was discharged. The succeeding rolls registering "D. 30th June 1757. Solebay prefmnt." THE MERCURY COOK. At this point all the writers on Captain Cook have been led into error by following the lead of Dr. Kippis. Everyone (with the single exception of Lord Brougham, who by an evident slip of the pen puts him on board the Mersey) writes that he was appointed Master of H.M.S. Mercury, and that he joined the fleet of Admiral Saunders in the Gulf of St. Lawrence at the time of the capture of Quebec in that ship. From the Public Records it has been ascertained that the Mercury was not in the Gulf of St. Lawrence with Saunders, but in the latter half of 1759 was sent to New York, thence to Boston, and was at Spithead in April the following year. The same source also shows that not only was the Circumnavigator never on board the Mercury in any capacity, but in all probability he never even saw her. He is also said to have been Master's mate on the Pembroke, and Dr. Kippis has him appointed to three different ships on three consecutive days: the Grampus, but she sailed before Cook could join her; the Garland, but she was found to have a Master when Cook joined; and, lastly, the Mercury.