 Cook's second voyage marked a successful employment of Larcum Kendall's K1 copy of John Harrison's H4 marine chronometer, which enabled Cook to calculate his longitudinal position with much greater accuracy.Cook's log was full of praise for this time-piece which he used to make charts of the southern Pacific Ocean that were so remarkably accurate that copies of them were still in use in the mid-20th century.Upon his return, Cook was promoted to the rank of post-captain and given an honorary retirement from the Royal Navy, with a posting as an officer of the Greenwich Hospital.