A different etymology was offered by Edward Morris in 1898: "Jumbuck is aboriginal pidgin-English for sheep. Often used in the bush. The origin of this word was long unknown. It is thus explained by Mr. Meston, in the Sydney Bulletin, April 18, 1896: The word jumbuck for sheep appears originally as jimba, jombock, dombock, and dumbog. In each case it meant the white mist preceding a shower, to which a flock of sheep bore a strong resemblance. It seemed the only thing the aboriginal mind could compare it to."
In an account of "The Murray Expedition", published in the Southern Australian on 6 July 1841, the following passage occurs:
"...we found that the whole of the sheep had long before been slaughtered, as we saw their carcases and bones thrown about in vast heaps in various places where the blacks had formed large encampments, and had folded the sheep; and though we saw and chased thirteen natives, (the only number seen on our side of the river, though numerous enough, on the other), they were ever too closer to the water's edge to admit of our securing them, for they took to the river when driven through the high reeds on its banks, and which rose above our heads when on horseback, and thus, from the want of boats, escaped us, though only a few yards distant. They might, all with certainty have been shot, but when they found we would not fire, the villains laughed at and mocked us, roaring out "plenty sheepy," "plenty jumbuck," (another name of theirs for sheep)..."