In a memorandum of 28 September 1860 he wrote:[1][5]"the western boundary ... appears to be the 141st meridian; but it is probable that it was not described in the Letters Patent erecting the Colony, with greater distinctness, expressly with a view to a future adjustment, when more certain information should have been collected as to the natural features of the country...

It is now submitted that the 141st meridian passes through the tract of country known as the `Plains of Promise" and that the Eastern shore [of the Gulf of Carpentaria] possesses no harbours.

It would therefore be desirable to adopt the 138th meridian as the boundary; as that line would pass through a barren tract of country, and bring 'Investigator's Road' [an anchorage] within the limits of Queensland.

"Furthermore, expeditions in 1861-1862 funded by the South Australian, Victorian and Queensland governments to rescue the missing explorers Burke and Wills, who had failed to return from a journey from Cooper Creek to the Gulf of Carpentaria, led to the exploration of an enormous area of the inland and were predicted to stimulate interest in this previously unknown tract of land beyond Queensland's western boundary.

[1][6] In response, a despatch dated 14 December 1861 from the Secretary of State for the Colonies advised that the proposed annexation to the 138th Meridian of longitude should be revoked under Act 24 and 25 Victoria, c.44.

This immediately provoked a despatch from Sir George Bowen, dated 18 January 1862, stating that Queensland had taken provisional control of this area.

[7] Thereby two more corners in Queensland's western boundary were created and the colony acquired part of the Barkly Tableland and the area which later became the Mount Isa mineral field.

This land, comprising the floodplains of the Mulligan, Georgina, Diamantina and Bulloo Rivers and Cooper Creek, which form part of a vast inland drainage system originating in Queensland's central west and north-west and eventually reaching Lake Eyre, became known as Channel Country.

In 1877 James McLeod, the new owner of Cullamurra run, applied to the South Australian Commissioner of Crown Lands to have the colony's border surveyed urgently, after finding himself in dispute with his eastern neighbour John Conrick of Nappa Merrie over their station boundaries.

A small Customs Border Patrol consisting of a police inspector, sub-inspector and four constables was appointed with powers to collect duties from 1 January 1871.

In 1878, after short periods in New Zealand and Western Australia, Poeppel joined the South Australian Lands Department and was soon appointed to the border surveys.

During the Queensland- Northern Territory border survey, from the 142-mile post, he suffered from trachoma and lost 13 kilograms (29 lb) in weight, forcing his withdrawal in July 1885.

Later Wells held administrative positions in the state and federal public services, and was appointed Order of the British Empire in 1937.

In 1936, Edmund Albert (Ted) Colson, a pastoralist of Blood Creek Station, near Abminga, in northern South Australia, became the first European to cross the Simpson Desert.

Colson crossed from west to east, travelling along the 26th parallel from Mount Etingambara, hoping to locate the Poeppel Corner post and then follow the border mileposts to Birdsville.

Other explorations across Simpson Desert, notably those by David Lindsay in 1886 and Cecil Madigan in 1939, came close by Poeppel Corner but did not actually visit it.

By that time the original corner post had deteriorated due to white ants and dry rot, prompting Sprigg to take it to Adelaide for conservation treatment.

'[1][19] The area was opened up to scientific investigation and tourism by the Sprigg expeditions, together with a well-publicised crossing made in 1966 by the Leyland Brothers which proved that the Simpson Desert was accessible to four-wheel drive vehicles.

[1][21] Poeppel Corner Survey Marker was listed on the Queensland Heritage Register on 9 November 2012 having satisfied the following criteria.

Set borders were an important part of colonial economic and administrative development, providing certainty for governments and pastoralists, and enabling the collection of customs duties.

[1] Poeppel Corner is the result of early cooperation between Australian colonies and provides lasting evidence of the feat of endurance which marking the Queensland-South Australia border involved.