Arrowsmith's maps were regularly updated with the latest discoveries.
The above map from 1850 now has Boothia correctly attached to the mainland, thanks to John Rae's 1847 survey of the western shore of Boothia Gulf, and it includes Peel Sound, discovered by James Ross in the spring of 1849. Bellot Strait had not yet been found so North Somerset is shown contiguous with Boothia. The West coast of Boothia, denoted by a dotted line, is a guess which would later prove to be remarkably accurate.
Both the main map and the lower strip now uses Dease and Simpson's longitude values for the coastline South of King William Island.
In the lower strip, King William Island is still connected to Boothia by a spindly isthmus - a guess which would later prove to be remarkably inaccurate. The imaginary Poctes Bay has now morphed into Poets Bay, which John Ross had surely intended, to balance Artists bay opposite.
In the main map the geography to the West of KWI is somewhat ambiguous with the supposed isthmus lacking a southern coastline so that the blue wash representing the sea is divided only by a single dashed line. This could be considered the first depiction of the track which would be sailed by Roald Amundsen in his epic transit of the Passage more than fifty years later.
Cornwallis and Bathurst Islands are shown joined, a detail which wouldn't be corrected until the Victory Point record revealed that Erebus and Terror had passed between them en-route to Beechey Island.
Rae's 1854 survey of the West coast of Boothia has proven that King William Island is just that and Bellot Strait also confers island status on North Somerset.
The colouring, Red for the Hudson's Bay Company's discoveries and Blue for the Royal Navy's, is slightly inaccurate as the coast South of Cape Colville (charted by Rae) is wrongly coloured blue and the unsurveyed West side of King William Island should not be coloured at all.
Ironically if this had been the best map which Amundsen had had before he set off he may well have shared the fate of Franklin.
Arrowsmith's 1855 map gives no hint as to the existence of McClintock Channel. That strait between Prince of Wales Island and Victoria Island enables masses of heavy ice to drift South into Victoria Strait where it is trapped against the barrier formed by Royal Geographical Society Islands and the Crozier Peninsula on the West side of King William Island.
Without this information, and the knowledge, which McClintock learned from the inuit, that the was open water in Rae Strait during the short Arctic summer, Amundsen may reasonably have chosen the obvious path to the West of King William Island resulting in the Gjoa becoming beset in the same place Erebus and Terror.