Original documents that relate to Cook's career are of extreme rarity, and this example, from a period of active duty off the American coast and a major stage in his early development, is particularly desirable.

Original documents that relate to Cook's career are of extreme rarity, and this example, from a period of active duty off the American coast and a major stage in his early development, is particularly desirable.

Cook's time on the Pembroke was pivotal in his career. He served under the intellectual Captain John Simcoe on the voyage that took them to the Gulf of St. Lawrence for surveying work between 1757 and 1759. Simcoe guided the young Cook in the study of mathematics and astronomy and started him in the field of hydrographic survey. He lent Cook reference books, and from various sources we know that during the very severe winter of 1758-59 at Halifax, Cook used every moment for detailed study.

The military surveyor Major Samuel Holland later recollected that when he met Cook in London in 1776, before he set out on his third voyage and by then the most famous sailor in the world, Cook "candidly confessed that the several improvements and instructions he had received on board the Pembroke had been the sole foundation of the services he had been enabled to perform" (Holland's letter to Simcoe's son 11 January 1792). He also remembered that "I was on board the Pembroke where the great cabin [was] dedicated to scientific purposes and mostly taken up with a drawing table… Under Capt. Simcoe's eye Mr. Cook and myself compiled materials for a chart of the Gulf and River St. Lawrence".

Cook's time on the Pembroke was certainly the turning point in his career. The hydrographic skills that he acquired from working with Simcoe and Holland, exemplified in the charting and survey of the St. Lawrence River, led directly to his recognition by the Admiralty and his subsequent appointment to the Endeavour. This certificate, to the Treasurer of the Navy, is for payment of wages to First Lieutenant John Quick. It has four signatories, James Cook as master along with James Norman, Richard Wise as purser and William Thompson as boatswain.