His prospects had been cruelly clouded by his long detention in captivity, and on the conclusion of peace he at once joined the _Cyrus_, sloop of war; but when the Government proposed to send out an expedition to explore the Zaire or Congo, and appointed Tuckey in command, Lieutenant Hawkey eagerly accepted the invitation of his friend to join him and act as second in command. At this time little was known of the Congo and the Niger. Hitherto what was known was due to Arabian writers of the Middle Ages, and to what leaked out from the Portuguese; but these latter, who carried on an extensive slave trade thence, did their utmost to keep their knowledge of these rivers to themselves. But even they were not well acquainted with the rivers far up from their mouths. Mungo Park was preparing for his second expedition to explore the Niger, and it was even supposed that the Congo or Zaire that flows into the South Atlantic was an outlet of the Niger, and not an independent river; and this opinion was warmly expounded by Park in a memoir addressed to Lord Camden previous to his departure from England, and he added that, if this should turn out to be a fact, "considered in a commercial point of view, it is second only to the discovery of the Cape of Good Hope; and, in a geographical point of view, it is certainly the greatest discovery that remains to be made in this world." On March 19th, 1816, the _Congo_, accompanied by the _Dorothy_ transport, sailed on a voyage of exploration to the Zaire. The _Congo_ was about ninety tons, schooner rigged, and drew five feet of water. She was fitted up entirely for the accommodation of officers and men, and for the reception of the objects of natural history which might be collected on her progress up the river. The gentlemen engaged on the expedition, in the scientific department, were: Professor Smith, of Christiania, botanist and geologist; Mr. Tudor, comparative anatomist; Mr. Cranch, collector of objects of natural history; and a gardener to gather plants and seeds for Kew; also Mr. Galway, a gentleman volunteer. There were two negroes, who would serve as interpreters, one of whom came from eight hundred miles up the Zaire. The officers were: Captain Tuckey, Lieutenant Hawkey, Mr. Fitzmaurice, master and surveyor, Mr. McKernow, assistant surgeon, two master's mates, and a purser. In addition to the _Congo_, the transport took out two double whale-boats, so fitted as to be able to carry eighteen to twenty men, with three months' provisions. Lieutenant Hawkey was an excellent draughtsman; he sketched in a bold and artistic manner, and to a general knowledge of natural history he united the talent of painting the minutest sea and land animals with great spirit and accuracy.