In 2018 another coin, also thought to be from Kilwa, was found on a beach on Elcho Island, another of the Wessel Islands, by archaeologist and member of the Past Masters group, Mike Hermes. Hermes speculated that this may indicate trade between indigenous Australians and Kilwa, or that they coins had arrived as a result of Makassan contact with Australia. Mike Owen, another member of the group, speculated that this may indicate the Portuguese visited the Wessel Islands sometime after they had installed Muhammad Arcone on the Kilwa throne as a Portuguese vassal, from 1505 to 1506. Possibly because of the degree of conjecture involved in the theory of Portuguese discovery of Australia, there have been a number of critics. Matthew Flinders cast a sceptical eye over the "Great Java" of the Dieppe maps in "A Voyage to Terra Australis," published in 1814, and concluded: "it should appear to have been partly formed from vague information, collected, probably, by the early Portuguese navigators, from the eastern nations; and that conjecture has done the rest. It may, at the same time, be admitted, that a part of the west and north-west coasts, where the coincidence of form is most striking, might have been seen by the Portuguese themselves, before the year 1540, in their voyages to, and from, India". In the last chapter of "The Secret Discovery of Australia," Kenneth McIntyre threw down a challenge, stating: "Every critic who seeks to deny the Portuguese discovery of Australia is faced with the problem of providing an alternative theory to explain away the existence of the Dieppe maps. If the Dauphin is not the record of real exploration, then what is it?" By far the most prolific writer on this theory, and also its most consistent critic, has been Flinders University Associate Professor W.A.R (Bill) Richardson, who has written 20 articles relating to the topic since 1983. As Richardson, an academic fluent in Portuguese and Spanish, first approached the Dieppe maps in an effort to prove they did relate to Portuguese discovery of Australia, his criticisms are all the more interesting. He suggests he quickly realised there was no connection between the Dieppe maps and modern Australia's coastline: The case for an early Portuguese discovery of Australia rests entirely on imagined resemblances between the "continent" of Jave La Grande on the Dieppe maps and Australia. There are no surviving Portuguese 16th-century charts showing any trace of land in that area, and there are no records whatsoever of any voyage along any part of the Australian coastline before 1606.