His plan of starting from the Moreton Bay district, and proceeding to Port Essington, differed considerably from that proposed by Sir Thomas Mitchell. The course adopted by Leichhardt, although longer and more roundabout than that suggested from Fort Bourke, would be safer for his little band, keeping as it would, more to the well-watered coastal districts, and avoiding the constant separations entailed upon parties traversing the interior. Leaving the head waters of the Condamine, the river which receives so many of the tributary streams of the Darling Downs, Leichhardt struck a river, which he named the Dawson, thence he passed westward, on to the fine country of the Peak Downs, whereon he named the minor waters of the Comet, Planet, and Zamia Creeks. On the 10th of January, 1845, the Mackenzie River was discovered, and here the Doctor and the black boy, Charlie, managed to get lost for two or three days, a faculty which apparently most of the party happily possessed. Following up the Isaacs River, a tributary of the Fitzroy, they crossed the head of it on to the Suttor; the only variation in the monotonous record of the daily travel being the occasional capture of game, and the mutinous conduct of the two black boys, who at various times essayed to leave the party and shift for themselves, but were on each occasion glad to return. Following down the Suttor, they arrived at the Burdekin, the largest river on the east coast, discovered by Leichhardt, up the valley of which they travelled, until they crossed the dividing watershed between the waters of the east coast and the Gulf of Carpentaria, on to the head of the Lynd, which river they followed to its junction with the Mitchell. Finding the course of this river leading them too high north, on the eastern shore of the Gulf, they left it, and struck to the sea coast, intending to follow round the southern coast at a reasonable distance inland. Up to this time they had been so little troubled by the natives, that they had ceased almost to think of meeting with any hostility from them. On the night of the 28th June, 1845, they were encamped at a chain of shallow lagoons, when soon after seven o'clock, a shower of spears was thrown into the camp, wounding Messrs. Roper and Calvert, and killing Mr. Gilbert instantly. So unprepared were the party, that the guns were uncapped, and it was some time before three or four discharges made the blacks take to their heels. The body of the naturalist was buried at the camp, but his grave was unmarked, as in order to prevent the blacks from disinterring it, a large fire was lit over the grave to hide its site.